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HomeMy WebLinkAboutTB Phase II & III Draft SEIR 07-1998Draft Supplemental ~'nvironmental impact Report TERRABAY PHASE 11 AND 111 • Precise Plan Approval -Phase 11 • Specfic Plan Amendment -Phase I! and 111 • Vesting Teniatve Subdivision Map Approval • Terrabay Specific Plan District Amendment • Development Agreement Amendment • CC&R Approve! • Grading Permit Issuance CITY OF SOUTH SAN FRANCISCO JuLr 1998 Draft Supplemental Environmental Impact Report TERRABAY PHASE ll AND ll/ • Precise Plan Approval -Phase !1 • Specific Plan Amendment -Phase ll and 111 • Vesting Tentative Subdivision Map Approval • Terrabay Specific Plan District Amendment • Development Agreement Amendment • CC&R Approval • Grading Permit Issuance CITY OF SOUTH SAN FRANCISCO JULY 7998 TABLE OF CONTENTS 1.0 INTRODUCTION 1 1.1 EIR Requirement 2 1.2 EIR Detail and Objectivity 4 1.3 Information Used to Prepare the EIR 6 1.4 Public Review and Comment 9 1.5 Report Organization 9 1.6 Frequently Used Acronyms 10 2.0 DESCRIPTION OF THE PROPOSED PROJECT 12 2.1 Location, Land Use, Zoning 12 2.2 Project Background 21 2.3 Project Description 25 2.4 Cumulative Development 64 2.5 Administrative Actions 68 3.0 SUMMARY OF F/ND/NGS 71 3.1 Significant Unavoidable Impacts 72 . 3.2 Significant Impacts 72 3.3 • Less-than- Significant Impacts 73 3.4 Alternatives Evaluated 74 3.5 Areas of Controversy 75 4.0 ENVIRONMENTAL ASSESSMENT -SETTING, IMPACTS, AND MITIGATION 102 MEASURES 4.1 Geology, Soils, and Seismicity 104 4.2 Hydrology and Drainage 129 4.3 Biology 147 4.4 Traffic and Circulation 162 4.5 Air Quality 210 4.6 Noise 223 4.7 Public Services 237 • Police Services 237 • Public Schools 247 4.8 Hazards 257 • Aerial Lead 264 • Magnetic Fields 260 4.9 Archaeology 276 5.0 ALTERNATIVES TO THE PROJECT 298 5.1 No Development Alternative 306 5.2 Existing Specific Plan Alternative 309 5.3 Phase II Reduced Residential Development Alternative 314 5.4 Phase III Reduced Commercial Development Site Plan Alternative 318 5.5 Permanent Open Space Alternative 324 5.6 Environmentally Superior Alternative 326 Environmentally Preferred Development Alternative 328 6 0 IMPACT OVERVIEW 334 6.1 Cumulative Impacts 334 6.2 Growth Inducing Impacts 335 6.3 Significant Unavoidable Impacts 336 6.4 Effects of No Significance 337 6.5 Areas of Controversy and Issues to be Resolved 340 7.0 APPENDICES 7.1 Report Preparers 7.2 People and Organizations Contacted 7.3 Bibliography 7.4 Biology 7.5 Traffic 7.6 Air Quality L/ST OF EXHIBITS 2.1-1 Regional Location Map 13 2.1-2 Site Location Map 14 2.1-3 Project Site Subareas 16 2.1-4 Terrabay Site Summary 15 2.3-1 Land Use Summary 28 23-2a Phase II Residential Site Land Use -- Terrabay Point and Commons 29 2.3-2b Phase II Residential Site Land Use -- Terrabay Woods 30 2.3-2c Phase II Residential Site Precise Plan -- Terrabay Point and Commons 31 2.3-Zd Phase II Residential Site Precise Plan -- Terrabay Woods 32 2.3-3 Precise Plan Housing Summary ~ 33 2.3-4 Residential Lot and Building Sumrnary 35 2.3-5 Housing Breakdown by Subarea 37 2.3-6 Comparison of Unit Types and Sizes 38 2.3-7 Comparison of Residential Densities 38 23-8a Phase III Commercial Site Land Use 39 2.3-8b Phase III Commercial Site Precise Plan 40 2.3-9 Commercial Development Summary 41 2.3-10 Bayshore Boulevard Segments 46 2.3-11 Parking Supply Summary 47 2.3-12 Residential Parking Dimension Summary 48 2.3-13 Landscaping Plan Plant List 51 1 Exhibits shown in bold type are maps, and those shown in plain type are tables. 23-14a Phase II Residential Site Grading Plan -- Terrabay Point and Commons 57 23-14b Phase II Residential Site Grading Plan -- Terrabay Woods 58 2.3-14c Phase III Commercial Site Grading Plan 59 2.3-15 Grading Volumes 60 2.3-16 Retaining Walls 60 2.4-1a Year 2000 Cumulative Development 66 2.4-1b Year 2001-2010 Cumulative Development 67 3.0-1 Summary of Impacts and Mitigation Measures 76 4.1-1a Phase II Site Existing and Proposed Grading -- Terrabay Point and 106 Commons 4.1-1b Phase II Site Existing and Proposed Grading -- Terrabay Woods 107 4.1-1c Phase III Site E~sting and Proposed Grading 108 4.1-2 Site Geology 109 4.2-1 Regional Location and Watershed Map 130 4.2-2 Existing Hydrologic Features Map 131 4.2-3 Debris Basin Locations 136 4.3-1 Sensitive Biological Features 155 4.4-1 Area Map 164 4.4-2 Locations of Intersection, Freeway Ramp, and Mainline Freeway Analysis 167 4.43 Existing Traffic Volumes, AM Peak Hour (7:30-8:30) ~ 169 4.4-4 Existing Traffic Volumes, PM Peak Hour (5:00-6:00) 170 4.4-5 Existing Intersection Lane Geometrics 171 4.4-6 Intersection Levels of Service 172 4.4-7 U.S. 101 Freeway Levels of Service 174 4.4-8 Existing and Base Case Freeway Ramp Operation, AM and PM Hour, Without 176 and With Project 4.4-9 Local SamTrans Bus Route Descriptions 175 4.4-10 Mitigated Intersection Level of Service Year 2010 182 4.4-11 Terrabay Project Trip Generation Phases II and III 185 4.4-12 Terrabay Phase III Lane Striping 187 4.413 Year 2000 Volumes with Terrabay Phases II and III -- AM & PM Peak Hour 188 4.4-14 Year 2010 Volumes with Terrabay Phases II and III •- AM & PM Peak Hour 189 4.4-15 Year 2010 Terrabay Project Phase III and Phases II + III Intersection 192 Mitigations 4.416 Terrabay Phase II Residential Roadway Standards 196 4.4-17 Proposed Parking Supply 199 4.4-18 Proposed Parking Space Dimensions 200 4.4-19 Year 2020 Cumulative Volumes with and without Terrabay Phases II and III 205 4.4-20 Intersection Levels of Service, Year 2020 Hook Ramp Analysis 206 4.5-1 Ambient Air Quality Standards1996, Arkansas Street 211 4.5-2 San Francisco Air Pollutant Summary, 1992 213 4.5-3 Predicted Carbon Monoxide Concentrations Near the Terrabay Site 219 4.5-4 Terrabay Emissions of Regional Air Pollutants 221 4.5-5 Difference in Regional Air Pollutant Emissions between 1996 and 1998 Plans 221 4.6-1 Definitions of Acoustical Terms 224 4.6-2 Typical Sound Levels Measured in the Environment and Industry 225 4.6-3 Noise Measurement Results 227 4.6-4 Aircraft Noise /Land Use Compatibility Guidelines 229 4.6-5 Construction Equipment Noise Level Range 231 4.6-6 Typical Ranges of Energy Equivalent Noise Levels at Construction Sites 231 4.6-7 Barriers to Mitigate Traffic Noise in Residential Backyards 236 4.7-1 Call for Service Ratios for Commercial Land Use 238 4.7-2 Comparison of Household Density Rates 239 4.7-3 Estimated Phase III Police Service Needs _ 241 4.7-4 Cumulative Development Requiring Police Protection 245 4.7-5 Summary of Cumulative Police Impacts 245 4.7-6 Comparison of Unit Sizes 252 4.7-7 SSFUSD Student Generation 254 4.7-8 Cumulative Development in South San Francisco Unified School District 256 4.8-1 Federal and State Regulatory Levels for Lead 258 4.8-2 DTSC Aerially Deposited Lead Variance 259 4.8-3 Magnetic Fields Due to Typical Household Appliances 266 4.8-4 Location of Commons Neighborhood 267 4.8-5 Sketch of PG&E Transmission Lines at Site ~ 268 4.8-6 Photographs of PG&E Transmission Lines 269 4.8-7 Transmission Line Loading Values at Time of PG&E Measurements 270 4.8-8 Building Pad Measurement Locations 271 4.8-9 Approximate Height of PG&E Transmission Line Conductors 272 4.8-10 Magnetic Field Levels Measured at Building Pads 272 4.8-11 Summary of IRPA / INIRC Exposure Guidelines 273 4.8-12 Summary of ACGIH Exposure Guidelines 273 4.8-13 State Regulations Limiting Field Strengths on Transmission Line ROWS 274 4.9-1 Archaeological Mitigation 294 5.0-1 Comparison of Alternatives' Assumptions 300 5.2-1 Existing Specific Plan Altemative Trip Generation 311 5.2-2 Gross Trip Generation Comparison of Project and Alternatives 311 5.3-1 Phase II Reduced Residential Alternative Trip Generation 315 5.4-1 Phase III Reduced Commercial Development Alternative 320 5.4-2 Phase III Reduced Commercial Development Alternative Development Summary 319 5.4-3 Phase III Reduced Commercial Development Alternative Trip Generation 322 5.6-1 Comparison of Project and Altematives 331 5.6-2 Environmentally Preferred Development Alternative (Phase III Site) 333 7.5-1 Terrabay Phase I Remaining Development Trip Generation 7.5-2 Year 1998 to 2000 Expected Cumulative Development Trip Generation (Not Including Terrabay) 7.5-3 Yeaz 2001 to 2010 Expected Cumulative Development Trip Generation (Not Including Terrabay) 7.5-4 Yeaz 2000 Base Case Volumes - AM Peak Hour 7.5-5 Year 2000 Base Case Volumes - PM Peak Hour 7.5-6 Year 2010 Base Case Volumes - AM Peak Hour 7.5-7 Year 2010 Base Case Volumes - PM Peak Hour 7.5-8 Year 2010 Base Case and Terrabay Project -Phase -II Mitigations 7.5-9 Terrabay Phase II Project Increment - AM & PM Peak Hour 7.5-10 Terrabay Phase III Project Increment - AM & PM Peak Hour 7.5-11 Terrabay Phase II Residential Roadway Cross-Sections 7.5-12 Maximum Queue Lengths at Intersections 1.0 INTRODUCTION 1.0 INTRODUCTION This Draft Supplemental Environmental Impact Report (1998 SEIR) considers the environmental impacts which could result from (1) amending the Terrabay Specific Plan (last amended in 1996) related to the Phase II and III Terrabay sites, (2) approving (and ultimately implementing) a Precise Plan for the Phase II site, (3) approving a vesting tentative subdivision map for the Phase II and III sites, (4) amending the Terrabay Specific Plan District in the Municipal Code (Zoning Ordinance), (5) amending the Development Agreement (last amended in 1996), (6) approving Covenants, Conditions, and Restrictions, (7) granting of (and implementing) grading permits for the Phase II and III sites, all requested by SunChase G.A. California I, Inc., the sponsor of the Terrabay development project. This 1998 SEIR also covers (8a) reconstruction of the existing southbound U.S. 101 /Bayshore Boulevard off-ramp, (8b) construction of a new southbound U.S. 101 on-ramp, and (9) realignment of a segment of Bayshore Boulevazd. The City of South San Francisco is sponsor of the hook ramps project, and the Cities of South San Francisco and Brisbane are discussing which will be the sponsor of the Bayshore Boulevard realignment project. The City of South San Francisco is the lead agency for the SEIR. 1 Other government entities will be responsible agencies for various aspects of the project, as outlined in 2.5 Administrative Actions. Summary Projecf Location The entire private development and public road facility site is composed of three parts generally bounded by unincorporated San Bruno Mountain County Park (north), Sister Cities Boulevard-Hillside Boulevard (south), U.S. 101 (east), and the developing Terrabay Phase I site (west). One part of the site consists of the approximately 65-acre Terrabay Phase II residential site development area, the second part covers the ± 37-acre Tertabay Phase III commercial site development area, and the third part encompasses the ± 15-acre hook ramps and Bayshore Boulevard realignment site (for a total site azea of about 117 acres). The proposed development areas of the Terrabay Phase II and III aze located entirely within the City of South San Francisco (although additional Temabay project site land designated as permanent Habitat Conservation Plan area is unincorporated and remains in San Mateo County jurisdiction). The hook ramps site is located within both the corporate boundaries of the Cities of South San Francisco and Brisbane and within the U.S. 101 right-of--way owned by the California Department of Transportation (Caltrans). The existing alignment of Bayshore Boulevazd is located within the corporate boundaries of the City of Brisbane, and the proposed realignment would be located primarily in Brisbane (about nine acres) and secondarily in South San Francisco (about two acres formerly part of the Terrabay Phase III site). Summary Project Description If the City approves the pending Terrabay project entitlements (items 1 through 7 listed above), SunChase would create 348 residential lots (26 acres), 17 common open space lots (23 acres) and seven Habitat Conservation Plan lots (three acres), build internal roadways (13 acres), and install utilities on the Phase II site. On the Phase III site, Sunchase would create 1 The State CEQA Guidelines (Guidelines) define the "lead agency" as the public agency responsible for preparing environmental documents under the California Environmental Quality Act (CEQA) where more than one agency would be responsible for approving or carrying out a project. Both the "lead agency" and "responsible agencies" use the resulting documents (EIRs or Negative Declarations) in making decisions for which they have authority. 1.0 /NTRODUCTIOIr Terra6ay Phase //and /ll SE/R parcels defming seven commercial lots (31 acres), a park and adjacent parking (two acres) and additional common open space (three acres), and internal roadways (one acre) and install utilities. Apart from grading and constructing infrastructure, SunChase would not develop either the Phase II or III sites. Two housing developers, Sunstream and Centex Homes, would develop the Phase II site, but no commercial developers have been identified to date to build out the Phase III site. Sunstream would build single-family attached duplex (72) and triplex (141) units in the Terrabay Point and Commons neighborhoods, and Centex Homes would build single-family detached (135) units in the Terrabay Woods neighborhood of the Phase II site. The City of South San Francisco would build the hook ramps and Bayshore Boulevard realignment projects with funding by the Terrabay developer and local public funds. The southbound U.S. 101 off- ramp reconstruction (Ramp "A") would replace the existing southbound Bayshore Boulevard exit from U.S. 101, known as the "scissors ramp", and would terminate at a new "'I"' intersection on Bayshore Boulevard. The southbound U.S. 101 on-ramp (Ramp "B") would create a new entrance onto the freeway from the new Bayshore Boulevard "T" intersection. The new intersection would be signalized. The hook ramps and intersection would be located within the existing alignment of Bayshore Boulevard. In order to build those facilities and accommodate through traffic on Bayshore Boulevard, the roadway realignment project would relocate a segment of Bayshore Boulevard west onto the present Terrabay Phase III site. All aspects of the proposed project are described in 2.3 Project Description. 1.1 EIR REQUIREMENT The California Environmental Quality Act (CEQA), the State CEQA Guidelines (Guidelines), and subsequent judicial decisions require public agencies to review and make determinations about the environmental consequences of proposed public and private actions within their jurisdictions. In August 1997, City Planning Division staff prepared an Initial Study /Environmental Checklist on application materials submitted to date for residential development of the Tetrabay Phase II site and a commercial development program for the Terrabay Phase III site. 2 The Initial Study /Environmental Checklist focused on identifying the differences between the 1996 and 1997 projects and on identifying potential effects not covered (or not covered adequately) by prior environmental review (see I.2 EIR Level of Detail further below). 3 Based on the Initial Study, the City required the preparation of a focused Supplemental EIR to evaluate potentially significant impacts related to: Geology Hydrology (drainage and runoff) Biology (wetlands) Transportation, circulation, and parking Air quality Noise 2 Environmental Checklist, Jim Harnish, Chief Planner, City of South San Francisco, August 20, 1997. 3 The project sponsor subsequently revised application materials originally submitted in 1997 and resubmitted them in January 1998. Thus, this document refers to the entitlement requests of 1998, although they were initiated in 1997. 1.0 INTRODUCTrON Terrabay Phase 11 and 111 SEIR Police protection Cultural resources 4 Electromagnetic field (EMF) health hazards Alternatives The City also prepared a Notice of Prepazation (NOP) in August 1997 and sent it to government agencies, special districts, and organizations with jurisdiction over or an interest in the project in order to consult with and obtain eazly input on the scope of the EIR. Comments on the NOP were received from the respondents listed below. • California Depaztment of Transportation (Caltrans) District 4, IGR / CEQA Branch • City of South San Francisco Historic Preservation Committee • City /County Association of Governments of San Mateo County, Airport Land Use Committee • Jefferson Union High School District • San Bruno Mountain Watch ' • San Francisco International Airport, Planning and Environmental Affairs The NOP and responses aze part of the public record for the project. They aze on file and available for public review during normal business hours at the City of South San Francisco Planning Division, City Hall, 400 Grand Avenue, South San Francisco, California, as aze other environmental and planning documents compiled for the project. In October 1997, the Planning Commission held a public scoping session to give individuals an opportunity to identify issues and concerns about the project for evaluation in the EIR. In January 1998, the City held a joint Planning Commission-Historic Preservation Commission working session to review revised project plans and present the project sponsor's and City EIR consultant's archaeologists. . Comments and concerns raised by the Initial Study /Environmental Checklist, responses to the NOP, scoping meeting, and working session were taken into account in the analyses conducted for this SEIR. However, comments and requests for analyses were not addressed in this SEIR if prior environmental documents adequately analyzed those topics, if the concerns involved environmental consequences of the project deemed insignificant under CEQA, or if the issues related to merits of the project or subjects beyond the scope of an EIR. 5 In addition to these efforts to determine the scope of this 1998 SEIR, other topics for analysis were identified during City staff review of the project sponsor's application materials. Further issues also 4 Ibid. The Checklist text identifies and discusses the potential impact on cultural resources (as did the scope of services required for preparation of the SEIR) although omitted from the determination that an EIR was required. Under CEQA, environmental documents focus on "significant" or "potentially significant" effects. This is in order to identify measures to mitigate project effects and to determine their effectiveness, identify any secondary effects of the mitigation measures, and disclose any unmitigable aspects of a proposed action. In order to focus on "significant" or "potentially significant" impacts, EIRs "focus out" and do not analyze effects of little or no significance ("less-than- significant"impacts). CEQA defines "significant effect on the environment" as a "substantial, or potentially substantial, adverse change in any of the physical conditions within the area affected by the project including land, air, water, minerals, flora, fauna, ambient noise, and objects of historic or aesthetic significance". According to CEQA, "an economic or social change by itself shall not be considered a significant effect on the environment", but "social or economic change related to a physical change may be considered in determining whether the physical change is significant". The introduction to this 1998 SEIR's environmental assessment, 4.0 Environmental Setting, Impacts, and Mitigation, discusses the determination of "significance", and each environmental topic analyzed in this document identifies, in the respective report sections, the "significance criteria" used to determine the magnitude of impact. 1.O INTRODUCTION Terrabay Phase 11 and 111 SEIR were revealed by the EIR consultants' independent peer reviews, subsequent analyses, and regulatory changes requiring consideration in finalizing the 1998 SEIR's scope (such as Federal listing as endangered of the Callippe Silverspot butterfly in December 1997). This Draft 1998 SEIR has been prepared in accordance with CEQA, the State Guidelines, and the City's environmental review procedures to implement CEQA. 2.5 Administrative Actions lists the reviews or approvals for which this 1998 SEIR will be used by the City and other permit granting agencies. This 1998 SEIR is intended to cover all actions involved in implementing the proposed Precise Plan for the Phase II site and similarly is designed to address amendment of the Terrabay Specific Plan for both the Phase II and III sites. Delays in implementing either the Phase II Precise Plan or Phase III Specific Plan development concept, if approved, potentially could result in the intervening time in significant changes in environmental conditions or substantial changes in the project from those studied in this document. The City will review future project applications when submitted to determine the need, if any, for additional focused environmental analysis at that time. 1.2 EIR DETAIL AND OBJECTIVITY The entire three-phased Terrabay project site, encompassing both the developing Phase I site and the Phase II and III sites examined in this SEIR, has been the subject of prior environmental documents. These include an EIR in 1982 on the Terrabay Specific Plan (the 1982 EIR) 6 and a Supplemental EIR in 1996 on the Terrabay Specific Plan and Development Agreement Extension (the 1996 SEIR). ~ The 1982 EIR was a "project EIR" which evaluated development of the entire three-phased site, as then proposed at the same level of detail. This 1982 EIR provided the basis on which grading permits were approved and grading was initiated on the site. The 1996 SEIR analyzed changes to conditions under which the project would be undertaken, since the original project approved in 1982 for the extension of the terns of the Specific Plan and Development Agreement for ten years. It considered proposed Phase I development at a "project" level of detail as a "project EIR" and assessed Phase II and III development at a planning or "program" level of detail as a "program EIIt". It provided the basis for residential construction now underway and partly complete on the Phase I site. The hook ramps were analyzed as part of the Terrabay project in the 1982 EIR, but the current design was not analyzed at that time. The 1996 SEIR acknowledged that more detailed environmental review for Phase IIand / or Phase III development would be undertaken upon submittal of subsequent applications with more project- specific detail about development. As described by the 1996 SEIR, that prior report was prepared to: Provide the basis for determining, in Initial Studies for future phases, whether those specific activities may have any significant effects. 6 Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, August 1982. ~ Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996, and Final Supplemental Environmental Impact Report for the Terrabay Specz; fic Plan and Development Agreement Extension (Revised Transportation Impact and Mitigation Findings, Responses to Comments on Revised Findings, and Responses to Comments on the Draft SEIR), Wagstaff and Associates, October 1996. 1.0 INTnGDUCTION Terrabay Phase /I and l!l SEIR • Provide environmental information which can be incorporated by reference in subsequent project- level environmental documentation to address broader program-level impacts. Provide a basis for focusing any future project-level environmental documentation needs on more duect impacts and on new effects which have not been considered previously. A Supplemental EIR is prepared when substantial changes made in a subsequent project would depart significantly from the project studied or deviate significantly from the assumptions contained in the prior EIR. 8 When applications for future projects generally conform to the development studied in a certified EIR, the EIR can be amended, if necessary, to reflect minor refinements or revisions, and no additional environmental is required. In this context, the 1998 SEIR required by the City's scoping process (summarized above) is intended to be an informational document which: • Identifies all potentially significant effects on the physical environment resulting from proposed changes to the 1996 Terrabay project, changes in environmental conditions from those analyzed in the 1996 SEIR, and from construction of the roadway projects. • Determines the significance of impact. • Assesses the extent to which the significant effects could be reduced to less-than-significant levels or avoided altogether. • Identifies and evaluates feasible alternatives to the project. When an EIR determines that a project would result in significant impacts, agencies with permit granting authority for the project must take one or more of the following actions: Require changes to the project which would avoid or substantially reduce significant impacts. Approve one of the project alternatives rather than the project. Adopt a written statement of overriding considerations which fords that specific economic, social, or other considerations make the EIR's mitigation measures or project alternative(s) infeasible. The level of detail of this SEIR's analyses is commensurate to the detail afforded the project. Phase II residential development, hook ramps construction, and Bayshore Boulevard realignment have been defined in site-specific detail, including the Phase II project in a Precise Plan, and are proposed to be implemented immediately upon approval. Grading and utility plans, site plans with building pads, and the types and maximum square footage of proposed uses for the Phase III commercial development were provided. The 1998 SEIR analyzes these defined elements of the Phase III plan. The actual design of the buildings and the specific uses for each identified building pad are not provided at this time. A potential remains that further environmental review could be required on aproject-by-project basis when Precise Plans for specific development projects are submitted to the City for the Phase III site. The extent to which mitigation measures can be defined also depends on the detail afforded the project. This 1998 SEIR contains site-specific measures for the Phase II site and some aspects of the Phase III site. For aspects of the project where too little is known about the project or site conditions 8 Supplemental EIRs also are prepared when environmental conditions have changed significantly from those previously studied or when new information indicates the availability of mitigation measures or alternatives formerly considered infeasible. 1.0 INTRODUCTION Terrabay Phase !l and 111 SEIR to be explicit in mitigation measures, whether related to Phase II or III site development, this 1998 SEIR provides performance-based measures to mitigate impacts. These measures provide specific standards which future mitigation measures must meet to ensure that the severity of impact would be reduced to less-than-significant levels. This type of mitigation discloses to decision-makers and other readers that measures, if implemented in accordance with the performance criteria or standards listed, would be capable of adequately reducing significant environmental effects. This type of mitigation also contains sufficient detail to provide project sponsors and their consultants with adequate direction about acceptable methods and choices among methods of reducing project impacts. This enables sponsors and their specialists to determine the measures or combinations of measures they incorporate in their projects rather than dictating elements of project design to them in an EIR. Performance-based mitigation also avoids delaying identification of mitigation measures (and their potential secondary effects) by waiting for future studies to provide information about site-specific conditions, an approach the courts have ruled inadequate under CEQA. This 1998 SEIR is a factual, objective public disclosure document which takes no position on the merits of the project but provides information on which decisions about the project can be based. The SEIR has been prepared according to the professional standards and practices of the EIR consultants' individual disciplines and in conformance with the legal requirements and informational expectations of CEQA and the State and local guidelines to implement it. The EIR consultants are independent professionals under contract to the City and are not associated with the project or project sponsor. Report preparers are listed in 7.0 Appendices. 1,3 INFORMATION USED TO PREPARE THE ElR The Guidelines permit any person, including the project sponsor, to submit information to assist in the preparation of an EIR. At the same time, the Guidelines require independent review of sponsor- submitted information to ensure that it accurately reflects the lead agency's judgment about the environmental impacts of the project. The EIR consultants conducted independent peer reviews of the background reports and documents submitted to the City as part of the project application. Project sponsor-prepared information only was used in the EIR after the validity of the data was verified independently and, where required, updated by the EIR consultants. The 1998 SEIR indicates where the EIR consultants and project sponsor's consultants differ. Documents prepared by the project sponsor's consultants and examined in the 1998 SEIR's environmental analyses are listed below, identified in the relevant report sections, and referenced in 7.0 Appendices. • Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Holman & Associates, December 1989 (revised February 1998). • Geologic Map and Geologic Summary Report, Terrabay Development Phase II & III, South Slope San Bruno Mountain, San Mateo County, California, Parikh Consultants, Inc., September 1997. • Supplemental Subsurface Exploration (Test Pits), Terrabay Project, South San Francisco, Parikh Consultants, Inc., January 1998. • Geologic and Geotechnical Impact and Mitigation Summary Report, Terrabay Development Phase II & III, South Slope San Bruno Mountain, San Mateo County, California, Parikh Consultants, Inc., February 1998. • Revision to Phase 11 /III Specs, HCP Restoration Plan, Pacific OpenSpace, Inc. /North Coast Native Nursery, Apri121, 1998. 1.0 INTRODUC i ION Terrabay Phase /l and 111 SE/R • Storm Drainage Report-Collection System and Debris Basins, Brian Kangas Foulk, December 1997. • Terrabay Modified Specific Plan, SunChase G.A. California I, Inc., October 1997 (revised January 1998). • Terrabay Modified Specific Plan Supplement, SunChase G.A. California I, Inc., October 1997 (revised January 1998). • Viola Pedunculata Survey, Pacific Open Space, Inc., February 1998. • Preliminary Jurisdictional Determination Pursuant to Section 404 of the Clean Water Act, Terrabay Development Site, South San Francisco, California, Vicki Reynolds, April 1998. These documents are available for public review at City Hall, except for certain materials related to archaeology. Unrestricted access to site-specific information about cultural resources is limited in order to protect the integrity of the resources. The Guidelines encourage incorporation of existing pertinent documents by reference where appropriate to avoid repetition of available information. The prior EIRs document and provide background for use by the EIR consultants and the City. These materials are incorporated by reference and include: Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, August 1982. This EIR was prepazed pursuant to CEQA to analyze the environmental impacts of the Terrabay project as proposed in the 1982 Specific Plan. The 1982 EIR studied the site-specific and cumulative impacts of the project related to visual quality, geology and hydrology, air quality, land use, vegetation and wildlife, community services, noise, energy, archaeology, wind and climate, economics, and traffic and transportation. The 1982 EIR also analyzed four alternatives to the project as proposed by the 1982 Specific Plan. The 1982 EIR stated that it was to be used for the following project approvals: specific plan, pre-zoning and access application, subdivision permit, grading permit, development agreement, annexation agreement, architectural permit, building permits, service district (water) boundary change, and Bayshore Boulevard roadway transfer. The 1998 SEIR used this document primarily to describe the project's historical context but also was reviewed to obtain information about the environmental setting, such as geologic features and natural hydrologic conditions before subsequent alterations. Final Environmental Impact Report and Environmental Assessment (including Supplement) for the Adoption and Implementation of the San Bruno Mountain Habitat Conservation Plan and Endangered Species Act Section 10(a) Permit, Thomas Reid Associates, November 1982. This Environmental Assessment /Environmental Impact Report (EA /EIR) was prepared for San Mateo County and U.S. Fish and Wildlife Service in order to assess the impacts of issuing a Section 10(a) permit under the Federal Endangered Species Act and of implementing the San Bruno Mountain Habitat Conservation Plan (HCP) for development on San Bruno Mountain under the various specific plans considered by the County and Cities of Brisbane, Daly City, and South San Francisco (including the Terrabay Specific Plan). The EA /EIR analyzed the direct impacts of development on San Bruno Mountain related to biology, economic, geology, soils, and hydrology, climate and air quality, energy and water use, aesthetics, cultural resources, and education and scientific uses. The EA/ EIR also analyzed the cumulative impacts of development of all the projects described in the HCP (including influx of residents to the mountain area, 1.0 INTRODUCTION Terrabay Phase ll and 111 SEIR increased demand for development-related services, degradation of air quality, increased traffic congestion, increased energy consumption, and the change in visual settings on San Bruno Mountain) and alternatives to the proposed action. Final Environmental Impact Report and Environmental Assessment for the South Slope Geotechnical Amendment to the San Bruno Mountain Habitat Conservation Plan and Amendment to PRT2-9818 Endangered Species Act Section 10(a) Permit, Thomas Reid Associates, January 1985. This document was a supplement to the EA /EIR on the adoption and implementation of the San Bruno Mountain HCP and Endangered Species Act Section 10(a) permit. The Supplemental EA /EIR described the environmental impact of proposed landslide repair on the south slope portion of San Bruno Mountain ('Terrabay site) which required a change in the HCP designation of the preserved habitat area. The Supplemental EA /EIR studied environmental impacts of the amendment and alternatives to the proposed action. Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996. This supplement to the 1982 EIR studied the environmental impacts of the development of the Terrabay project with a proposed ten-year extension of the expiration date for the 1982 Specific Plan and Development Agreement to February 14, 2007. The Supplemental EIR (1996 SEIR) studied changes in circumstances under which the project would be undertaken due to the passage of time since the original approval in 1982. The 1996 SEIR studied environmental impacts of the project on land use and open space, population and housing, transportation, geology and soils, drainage and water quality, vegetation and wildlife, public services, noise, and air quality. The 1996 SEIR was a project-level EIR for Phase Iand aprogram-level EIR for Phases II and III of the project. The 1998 SEIR used the 1996 SEIR to describe the historical context of the pending project and relevant aspects of the environmental setting. The 1998 SEIR analyses also address specific issues raised by the 1996 SEIR (such as impacts for residents exposed to electromagnetic fields). Final Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension (Revised Transportation Impact and Mitigation Findings, Responses to Comments on Revised Findings, and Responses to Comments on the Draft SEIR), Wagstaff and Associates, October 1996. This document primarily provided a starting point for defining parameters for the traffic analysis and identifying previously expressed concerns requiring evaluation in the 1998 SEIR's traffic and circulation assessment. Route 101 / Bayshore Boulevard Hook Ramps PSR / PR Traffic Operations Analysis, CCS Planning and Engineering, Inc., March 1998. This document provided traffic volume projections for use in conducting year 2020 analyses of the U.S. 101 southbound hook ramps in compliance with Caltrans regulations for environmental review. These volumes accounted for planned and approved traffic generating land uses east and west of U.S. 101 in South San Francisco and in Brisbane. The Guidelines also provide for the use of other existing sources of information about a site, its environs, and potential environmental impacts. These secondary sources are credited in the text and appendix. Existing information was supplemented by on- and off-site field observations, as needed. However, the Guidelines permit EIRs to rely on secondary sources and do not require EIR preparers to undertake original research when sufficient existing data are available. 1.0 /NTRODUC i iON Terrabay Phase ll and l!l SEIR 1.4 PUBLIC REVIEW AND COMMENT The City of South San Francisco will circulate this Draft 1998 SEIR widely for review and comment by public agencies, interested individuals, and organizations and will accept comments in writing or orally at a public hearing of the South San Francisco Planning Commission. Comments should address the adequacy and completeness of the 1998 SEIR or contain questions about the environmental consequences of approving and implementing the project. (T'he City will invite comments on the merits of the project itself as part of its normal public review process, separate from consideration of the 1998 SEIR) "Adequacy" refers to the SEIR's completeness in disclosing significant environmental effects, identifying measures to mitigate those significant impacts, and providing sufficient information for officials to make decisions about the merits of the project. The Guidelines direct Ellis to focus on a project's significant impacts and not to dwell on all conceivable less-than-significant effects, so that reports can be succinct disclosure documents and effective decision-making tools. Written comments on the Draft 1998 SEIR should be made before the close of the 45-day public review period and mailed to Jim Hamish Planning Division City of South San Francisco P. O. Box 711 South San Francisco, California 94083 or delivered to Jim Hamish at the Planning Division at 315 Maple Avenue, South San Francisco during normal business hours. The Planning Commission will hold a public hearing on the Draft 1998 SEIR at a formally noticed hearing. A Final 1998 SEIR will be prepared after the close of the public review period. The Fina11998 SEIR will include all the comments received by the City during public review on the adequacy of the Draft 1998 SEIR and on the project's significant environmental effects. The Final 1998 SEIR also will include responses to those comments. The Final 1998 SEIR will be considered by the Planning Commission and City Council before the City considers certifying the document as complete. The Planning Commission will hold a public hearing on the 1998 SEIR before certification by the City Council. No action can be taken to approve, conditionally approve, or deny any part of the project until the 1998 SEIR is certified. City acceptance of the 1998 SEIR upon certification does not require approval of the project studied in the EIR. 1.5 REPORT ORGANIZATION After this Introduction, the 1998 SEIR is organized as follows: 2.0 Description of the Proposed Project describes the location of the project site, existing land uses on and in the vicinity of the site, all aspects of the project as proposed, cumulative assumptions used throughout the analyses, and the approvals and permits required before the project could be implemented. 3.0 Summary of Findings highlights the important effects of implementing the project and identifies measures available to mitigate sign~cant adverse impacts. 1.0 INTRODUCTION Terrabay Phase 1! and 111 SEIR • 4.0 Environmental Setting, Impacts, and Mitigation Measures describes existing environmental conditions on the site and within the study area, identifies probable impacts from implementing the project, and describes mitigation measures required to substantially reduce or eliminate significant adverse impacts. • S.0 Alternatives to the Project describes and assesses the difference in outcome between the project and five alternatives, including the mandatory "no project" alternative, a public purchase open space alternative for the Phase III site, and reduced development programs for the Phase II and III sites. • 6.0 Impact Overview presents CEQA-mandated assessments of the project, including summaries of the project's cumulative impacts, significant adverse impacts, and effects of no significance. It also identifies areas of controversy and issues still to be resolved. • 7.0 Appendices lists the report preparers and the people and organizations contacted, presents the bibliography, and includes technical background material supporting the EIR text. The Final 1998 SEIR will insert a new chapter 7.0 Comments and Responses and will add a Mitigation Monitoring Plan to chapter 8.0 Appendices. The Mitigation Monitoring Plan will include all the measures presented in the Draft 1998 SEIR and integrate the mitigation measures identified in the 1982 EIR and 1996 SEIR. Chapter 4.0 of the Draft 1998 SEIR indicates the effectiveness of mitigation measures in reducing the magnitude of impact, identifies indirect secondary effects of implementing the measures, and lists who would be responsible for implementing and monitoring the measures. Thus, the measures presented in this Draft.1998 SEIR will constitute the mitigation monitoring and reporting program required by State law. While the Fina11998 SEIR may modify measures in response to comments on the Draft 1998 SEIR, it is anticipated that only minor revisions would be made. 1,6 FREQUENTLY USED ACRONYMS Acronyms used in this document are listed below: Frequently Used Acronyms ABAG Association of Ba Area Governments ADT avera a dail traffic APN Assessor's arcel number ARB California Air Resources Board BAA MD Ba Area Air Quali Mana ement District BCDC San Francisco Ba Conservation and Develo went Commission B.P. before the resent ( ears) BSD Brisbane School District CaIEPA California Environmental Protection A enc Caltrans California De artment of Trans ortation CC&Rs Covenants, Conditions, and Restrictions CDFG California De artment of Fish and Game CEQA California Environmental Quali Act CESA California Endan ered S ecies Act CFS calls for service cfs cubic feet er second to ].U IIV I I'rUUU(. 1 IVN Terrabay Phase p and Il! SE1R Frequently Used Acronyms CNDDB California Natural Diversity Data Base CNEL communi noise a uivalent level CNPS California Native Plant Socie COE, Co s U.S. Arm Co s of En 'neers dB decibels dBA A-wei hted sound DTSC De artment of Toxic Substances Control EIR environmental im act re ort EPA U.S. Environmental Protection A enc FESA Federal Endan ered S ecies Act HCM Hi hwa Ca aci Manual HCP Habitat Conservation Plan JUHSD Jefferson Union Hi h School District Lam, day /night noise level L energy equivalent noise level LOS level-of-service LTS less-than-significant im act m / k~ milli ams er kilo am m / L milli ams er liter MPH miles er hour NOP Notice of Pre aration NPDES National Pollutant Dischar a Elimination S stem NWIC Northwest [Archaeolo 'cal) Information Center PG&E Pacific Gas and Electric Com an PM to articulate matter, ten microns h ersons er household m arts er million PS otentially si 'ficant im act RCRA Resource Conservation and Recovery Act ROW ri ht-of--way RWQCB Re 'oval Water Quali Control Board S si nificant im act SCS U.S. Soil Conservation Service (Resource Conservation Service) SEIR Su lemental Environmental Im act Re ort SSFPD South San Francisco Police De artment SSFUSD South San Francisco Unified School District STLC total soluble lead concentration SU si 'ficant unavoidable im act (unmiti able) SWPPP Stormwater Pollution Prevention Plan TLCP toxici concentration leachin otential TTLC total threshold limit concentration UBC Uniform Buildin Code USFWS U.S. Fish and Wildlife Service USGS U.S. Geolo 'cal Surve USEPA U.S. Environmental Protection A enc V / C volume-to-ca aci ratio VPH two-wa vehicles er hour WET waste extraction test 2.0 DESCRIPTION OF THE PROPOSED PROJECT 2.0 DESCRIPTION OF THE PROPOSED PROJECT 2.1 LOCATION, LAND USE, ZONING' PROJECT LOCATION Terrabay Phase 1, ll, and III Site The entire three-phased Terrabay project site is located on the lower southeastern and eastern slopes of San Bruno Mountain which forms the northern edge of the City of South San Francisco in northern San Mateo County, California. The Terrabay site consists of all parcels mapped in Assessor's Book and Blocks 070-590, 070-600, 070-611, 070-612, 070-620, 070-630, 070-641, 070-642, and 070-650. It generally is surrounded by the Cities of Brisbane (north) and San Francisco (farther north), San Francisco International Airport and the City of San Bruno (south), U.S. Highway 101 (U.S. 101 -the Bayshore Freeway), Oyster Point in South San Francisco, and San Francisco Bay (east), and the Cities of Cohna and Daly City (west). U.S. 101 provides regional access to the site via the Bayshore Boulevard southbound off-ramp and Oyster Point interchange (Exhibits 2.I-I and 2.I-2). Sister Cities Boulevard and Hillside Boulevard cunrently provide local access to the developing Terrabay Phase I site via South San Francisco Drive, an internal street on the Terrabay site. Terrabay Phase ll and Ill Project Site The Terrabay Phase II and III sites -the subjects of this Supplemental EIR (1998 SEIR) -are bounded by San Bruno Mountain State and County Park (north), Sister Cities Boulevard-Hillside Boulevard and South San Francisco Drive (south), Bayshore Boulevazd (east), and the Terrabay Phase I site and San Bruno Mountain State and County Park (west) (Exhibits 2.I-2 and 2.I-3). Sister Cities Boulevard and Hillside Boulevard provide access to the Phase II site at two locations on South San Francisco Drive. The east end of South San Francisco Drive forms a "T" intersection at Sister Cities Boulevard in the Phase II site (and currently is closed to traffic), and the west end intersects Hillside Boulevard opposite Jefferson Street in the Phase I site (and is fully operational). The latter Hillside Boulevard-Jefferson Street-South San Francisco Drive. intersection serves development in the existing Phase I site. Between these intersections, South San Francisco Drive is located north of and parallel to Sister Cities Boulevard-Hillside Boulevard and connects the Phase I and II sites. It was built during implementation of Phase I and currently is used by construction vehicles only. The Phase III site is accessible directly off of Bayshore Boulevard and is not connected to either the Phase I or II sites except by off-site roadways (Bayshore Boulevazd, Sister Cities Boulevazd, and Hillside Boulevard). 9 Based on Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996 (1996 SEIR) and Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, August 1982 (198? EIR). Exhibit 2.1 1 Regional Locafion K Golden ~'~: ~s R. 17Hhp5fp, . ~ ~W ,~` S r¢,~~ sW' 1 ~~ ~ " ~ ~= ~~ h10U5c' San ® : ~,~ 3. Francisco;=`~= ~,~ o e:w 44 _'San BVv /\ ~ M c.c~:tu~ , ;. ~~ wT P~,.~ . ~~ ...~.~ ~,~ ..~a ~~f ~~ ~~_ //~~ ~G ` r_ ,~QQ _ '~,*, ~ ~.~ .~~ ` ftt°'s ~GUYCa s'CC ~' r I ~ r"i+wvrFRS vonv -.. Rave s~+rvrnRO ~~\ ~ f a+~crrvti GaniDLF57;.X\..- V s'. RFC .tea ~" ~, u.s. Cori; GwM •~ i $fA0.AIF~ MV'iB0lt ~ noaiH TER4WA: ~ .~ l\ M~~~1GWN. , SONM ~ ~N .~~ .RNPIA( ' 1 ~~R~T~F~. _ -}lam aaaoFtr . corore aonvr ,cc ~ ., `a~u Source: Map copyrighted 1995 by the Cal'rfomia State Automobile Association. Reproduced by permission. Exhibit 2.1-2 Sife Location \ ~ i ° 5 ~At~\ ~ ~ .~'_ . ~ ~ V~UL '` _ - h~V~/LOt 1O ' *~', J~'~s z Wo G y.N ~c ~..._~r---~~~ ~~ ~~ ~ RINGS Np c, `' ., .~po °~,~~,UNO San Bruno Mountain County Paris -~T ~ ~ ~~~~FIRTM YEY...~ q` ~` ' ~'SB~.NE cry omit _B ;~ ~ - ,~ - San Mateo County ~\`_ ~ _ \\ ~ 8• ~T ~ Legend: Project Site S SAM FpAMpSp) ~ A1R ' s SAM gpuNOr RD S MNG_ TilEA7MeK.' °iAN.• _ _ ~i sP,s_a:- SOvTr_ S%.h Or PC Source: Map copyrighted 1996 by the California State Automobile Association. Reproduced by permission. 2.0 PROJECT DESCRIPTION Terrabay Phase !1 and 11l SE/R Of the entire 332-acre site examined in prior EIRs, approximately 200 acres are incorporated land located inside the City of South San Francisco, and the remaining 132 acres consist of unincorporated land in San Mateo County. 10 City land, annexed in 1983, constitutes the proposed development area of the Terrabay project, and County land, while part of the original Terrabay site, remains undeveloped open space. The corporate boundary of the City of Brisbane extends south along both sides of and includes Bayshore Boulevard adjacent to the Terrabay Phase III site. As described by previous environmental and planning documents, approximately 104 acres of the 200- acre development area comprised the Phase II and III sites (61 and 43 acres, respectively), and the Phase I site encompassed the remaining 96-acre Terrabay project development azea. This 1998 SEIR reflects two adjustments to those sizes. The first adjustment accounts for two acres• on the Phase III site which constitute part of the Hook Ramp and Bayshore Boulevazd Realignment site (described below). This first adjustment decreases the three-phased Terrabay development area from 200 to 198 acres and the Phase II and III site subtotal to 102 acres. The second reflects a readjustment of the Phase II and III azeas by the project sponsor to increase the Phase II site (from 61 to 65 acres) and decrease the Phase III site (from 43 to 37 acres). These areas aze summarized in Exhibit 2.I-4. Exhibit 2.1-4 Terrabay Sife Summary Site Area a Before Adjustment After Adjustment ` Develo ment Area Phase I 96 96 Phase II 61 65 Phase III 43 37 Development Area Subtotal 200 198 Undevelo ed Area Undevelo ed Area Subtotal (Phases I-III) 132 132 Total Site Area 332 330 Source: Brian Kangas Foulk (project sponsor's engineer), February 20, 1998. a In aces, rounded. b Subtracts two acres from Phase III site for Hook Ramps and Bayshore Boulevard Realignment site (below). The entire Terrabay site is located within the planning azea of the San Bruno Mountain Habitat Conservation Plan (HCP)(see 2.2 Project Background, below). Hook Ramps and Bayshore Boulevard Realignment Site The hook ramps and Bayshore Boulevard realignment site extends east from the Terrabay Phase III project site to U.S. 101 (Exhibit 2.I-3). The four-acre hook ramps site is located within the U.S. 101 right-of--way along the west side of the freeway where it extends for 3,000 feet between the freeway and Bayshore Boulevazd. The 11-acre Bayshore Boulevazd realignment site includes the entire 3,000- foot long roadway and right-of--way segment contiguous to the Terrabay site in the City of Brisbane. The proposed Bayshore Boulevard right-of--way varies from approximately 80 to 142 feet wide. 10 The City annexed 203 acres, and 129 acres remain unincorporated. Previous reports use the approximate 200-acre and 132-acre sizes which are cited by this document for consistency. 15 1 I ,( II I ', , I ~ I ~ ~ R9 1' ~ ...' ~ 1 A I I I ~1 t~s,`~~ 7 ~ ~~ t\ •. 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A ~ '~~lrni ~~~~~~ a `~ , t ~ ~n ~ ~~~'!^+ly o i ~ y I- 1 ~ '% ~ • L. v '~ ° ~~;. k ~` ~' ~' .~.~,' (~f) W 2.0 PROJECT DESCRIPTION Terrabay Phase ll and Ill SE/R EX/ST1NG S1TE USES Terrabay Phase ll and 111 Site General Character The Phase II and III sites are largely undeveloped but not in pristine condition. Extensive grading undertaken between 1989 and 1995 altered natural landforms throughout the site development area and created benches, pads, roads, a network of drainage facilities, and other remnants of the earthmoving operations. Disturbed areas consist of temporary slopes planned to be further graded. Grasses subsequently have become reestablished and some isolated plants characteristic of wetlands remain, such as clumps of willows, sedges, and rushes. On the Phase II site, grading occurred on the prominent ridge which descends southeast to the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevard intersection and was undertaken in the bowls formed by spur ridges of San Bruno Mountain. Part of the Phase II site currently is being used for disposal of excess material graded for construction of the Phase I site. Parts of the Phase III site also have been graded, including for a fire road and drainage facilities. Otherwise it remains undeveloped except for the presence of billboazds and utilities. Utility Easements Several developed utility corridors cross the site. 11 A 150-foot wide Pacific Gas and Electric (PG&E) power line right-of--way crosses the Phase II site in an approximately northwest-southeast direction. It is developed with six above-ground 115 kilovolt (k~ electric power transmission lines -the San Mateo-Martin Circuits -which supply San Francisco with energy from the Hetch Hetchy system. i2 The lines cross Sister Cities Boulevard at approximately North Spruce Avenue and continue north of the site over San Bruno Mountain. The power line corridor also contains a 30-foot wide right-of--way developed with a now abandoned underground natural gas transmission line (Line 101). In addition, a San Mateo County Drainage Easement is located on the Phase II site near the Bayshore Boulevard / Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevard intersection. Two San Francisco Water Department easements aze located on the Phase III site, one near the northern end of the site and one parallel to Bayshore Boulevard. They aze developed with Crystal Springs Pipelines 1 and 2, both underground water main facilities. 13 A California Water Service Company pump station serving these facilities is located on a 0.17-acre in-holding near the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevazd intersection. The in- holding is surrounded by the Phase III site and would not be affected by the proposed project. Also on 11 Terrabay Resubdivision of Parcels 1 & 2 Recorded in Volume 53 of Parcel Maps at Pages 82-83, Records of San Mcueo County, Sheets 5 and 6, prepared by Carroll /Resources Engineering & Management, May 1990, and Nichols • Berman conversations with Jan O'Flaherry, Brian Kangas Foulk (project sponsor's engineer). 12 These double circuit lines are designed to carry 115 kV, but PG&E operates one circuit at 60 kV. 13 The City of San Francisco plans to replace parts of Crystal Springs Pipeline 1, including the entire segment on the project site along Bayshore Boulevard. Crystal Springs Pipeline No. I Replacement at Locations Described, in Brisbane and Daly City, Office of Environmental Review, San Francisco Department of City Planning, June 1997. 17 2.0 PROJECT DESCRIPTION Terrabay Phase ll and 111 SE1R the Phase III site are a California Water Service Company water main and access easement. Unpaved fire roads on the adjacent San Bruno Mountain State and County Park also extend into the site. Some infrastructure facilities to be shared by the Terrabay Phase I, II, or III project have been developed on the Phase II site (in addition to those built on the Phase I site). These include a drainage trunk line to carry surface water intercepted on the Phase I and II sites (and by four Phase I debris basins), drainage collection lines, a water main transmission line, sewage line, and, as noted above, South San Francisco Drive (as a construction roadway adjacent to the Phase II site). Hook Ramps and Bayshore Boulevard Realignment Site This site currently is developed with roadways. The hook ramps site is developed with the existing southbound U.S. 101 Bayshore Boulevazd off-ramp, known as the "scissors ramp" due to the configuration of its intersection with northbound Bayshore Boulevazd traffic. Bayshore Boulevazd is a two- to four-lane arterial roadway which connects the Cities of Brisbane (north) and South San Francisco (south). (South of the Sister Cities Boulevazd /Oyster Point Boulevard intersection, at the southeast comer of the Terrabay project site, Bayshore Boulevard becomes Airport Boulevard.) North of the "scissors ramp", Bayshore Boulevard consists of one travel lane in each direction within the realignment project site. Farther north of the project site, the northbound U.S. 101 Bayshore Boulevazd off-ramp joins Bayshore Boulevazd to provide a second northbound travel lane. South of the "scissors ramp", Bayshore Boulevazd consists of two travel lanes in each direction. Near the southbound Bayshore Boulevard approach to the Sister Cities Boulevazd /Oyster Point Boulevazd intersection, southbound Bayshore Boulevard widens to five lanes to accommodate right-fuming, through, and left-turning traffic. SURROUNDING L4ND USES North San Bruno Mountain State and County Park, a 2,064acre regional open space preserve, extends uphill from the Terrabay project site and encompasses the prominent landform which separates South San Francisco from Brisbane farther north. The State of California owns 298 acres, and San Mateo County owns 1,766 acres, including the southeast ridge above the Terrabay project site. The County operates the entire area, all unincorporated, as asingle park. The park is within the San Bruno Mountain Habitat Conservation Plan (HCP) planning azea (see 2.2 Project Background. The Terrabay Woods East subarea is immediately contiguous to County parkland. Elsewhere, land owned by the project sponsor and located between the Terrabay site development area and land currently owned by the County has been offered for dedication (but not yet accepted) or is proposed for dedication to San Mateo County to add to the park. South Existing residential neighborhoods are located south of the site, across Sister Cities Boulevard in the City's Paradise Valley planning subarea. 14 Neighborhoods include the Peck's and Paradise Valley subdivisions, southeast and southwest, respectively, of the Terrabay Phase II and III sites and predominantly are developed with single-family homes. 14 The adopted Zand Use, Circulation and Transportation Elements of the General Plan (as amended 1986) divides the City into 11 planning areas. Downtown (Planning Area 2) and Sign Hill, Paradise Valley, Parkway-Sterling (Planning Area 3) are located southeast and southwest, respectively, of the Terrabay project site (Planning Area 4). The Land Use background report prepared for the ongoing General Plan update redefines planning subareas and designates the area from the Terrabay site (north) to the top of Sign Hill (south) as the Paradise Valley /Terra Bay Planning Subarea 18 2.0 PROJECT DESCR/PTiON Terrabay Phase ll and Ill SE1R East Transportation uses separate the project site from the developed and developing Oyster Point and Gateway areas of South San Francisco, east of Bayshore Boulevard, U.S. 101, and the Southern Pacific Railroad tracks. (Planned transportation improvements in the immediate vicinity of the site are described farther below.) The Oyster Point area includes the Shearwater (hotel, commercial, and auto sales uses) and vacant Sierra Point sites nearest to the Terrabay Phase III site and the Oyster Point Marina and Business Park farther east of the project site adjacent to San Francisco Bay. The partly developed Gateway area is being further developed with office, research and development, and visitor services. West The Terrabay Phase I site, located west of the Phase II and III project sites, is devoted to the Terrabay Park and Terrabay Village residential developments. The 1996 Terrabay Specific Plan provided for construction on the Phase I site of 293 housing units (168 units in Terrabay Village and 125 units in Terrabay Park) and other uses (fire station, recreation center, linear park, streets, and infrastructure). As of December 1997, 130 Phase I units had been completed and occupied, and 156 were under construction or yet to be built. 15 Fire Station 5 was completed in 1992 on an approximately half-acre site at the South San Francisco Drive-Hillside Boulevard-Jefferson Street intersection and was dedicated to and accepted by the City of South San Francisco. When built, the Hillside Recreation Center, planned for athree-acre site east of the fire station, will consist of both indoor and outdoor facilities. (The recreation center site has been dedicated but has not been accepted yet.) Other facilities (and their status) include a water tank built to serve both the Phase I and II sites (dedicated to the California Water Services Company, the private water provider), linear park (dedicated but not accepted yet) located along Hillside Boulevard between the Hillside Recreation Center site (east) and Hillside Elementary school (west)(where a soccer field has been dedicated to and accepted by the South San Francisco Unified School District), and South San Francisco Drive (offered for dedication but not accepted). All other internal roadways have been retained in common (private) ownership for maintenance by homeowners' associations (HOAs). Four debris basins have been built on the Phase I site. EXISTING LAND USE DESIGNATION AND ZONING Land Use Designation The Terrabay Specific Plan, amended and extended by the City of South San Francisco in 1996, established four land use categories for designation on the Terrabay site -residential, commercial, community facilities, and open space - as follows: 16 15 FAX to Nichols • Berman and the Crane Transportation Group (IIR traffic analyst) from James Sweenie, Sterling Pacific (project sponsor's representative), February 9, 1998. Traffic counts of existing conditions were made in September and December 1997 to account for Terrabay Phase I as then built and occupied. See 4.4 Traffic and Circulation for a full description of existing and future conditions analyzed in this 1998 SEIR. 16 Terrabay Modified Specific Plan, January 22, 1998, Sunchase G.A. California I. This document, the proposed Specific Plan amendment, is a "redline" or "strikeout" document which shows the 1996 Terrabay Specific Plan and changes proposed by the pending application, enumerated by the amendment, and described in Section 2.3 Project Description. 19 ZO PROJECT DESCR/PT/ON Terrabay Phase /l and 111 SE1R Residential Single family detached residential unit Single family attached residential unit (townhomes) Terraced townhome units (multifamily) 17 Condominiums (multifamily) Commercial Office structure Health club Restaurants Hotel /seminar center High technology center Zoning District Open Space Dedicated public open space Private open space maintained by HOA Dedicated HCP habitat azea Juncus ravine 18 Community Facilities (minimum uses) Childcare center 19 Tot lot(s) Recreation center complex Linear pazk Public street The project site is covered by the Terrabay Specific Plan District (Chapter 20.63) of the City of South San Francisco Zoning Ordinance. The Terrabay Specific Plan District establishes two zoning designations to apply exclusively on the project site and classifies the Phase II Terrabay site "Tertabay Residential District" and the Phase III site "Terrabay Commercial District". The Terrabay Specific Plan identifies permitted uses and development parameters for both districts. 17 "Multifamily" refers to multi-unit residential structures, not multi-family units, and is a type of single family attached housing. 18 The Juncus Ravine is a separate 157-acre parcel located west of the Hillside Elementary School which was owned by the original project sponsor (see Section 2.2 Project Background, below) who dedicated the pazcel to San Mateo County for inclusion in the San Bruno Mountain State and County Park as permanent public open space. Terrabay Draft EIR, op. dt., and Terrabay Specific Plan and Development Agreement Draft SEIR, op..cit. 19 'I~e developer paid an in lieu fee of $750,000, accepted by the South San Francisco City Council, September 25, 1996. 20 2.2 PROJECT BACKGROUND TERRABAY SITE The current application for development of the Terrabay Phase II and III sites is the most recent proposal for phased implementation of the previously approved Specific Plan for the Terrabay project site. The existing Terrabay Specific Plan originally was adopted by the City of South San Francisco and San Mateo County in 1982 and was extended and amended most recently in 1996. These activities were part of a larger planning process which encompassed all of San Bruno Mountain, the impetus for which was the 1973 Crocker Hills project. A brief chronology is presented below. 20 1973 Visitacion Associates proposed the Crocker Hills development project on San Bruno Mountain in San Mateo County. The 1,244-acre unincorporated site consisted of six development areas, including the South Slope (Terrabay) area. 1974 The Technical Advisory Committee established by San Mateo County examined the project, and Visitacion Associates revised the project in response Committee input. 1975 The County prepared a fiscal analysis and EIR on the entire project. Of the six areas studied, residential and commercial development was assumed to occur on 125-acres of the 480-acre South Slope (Terrabay) area. 1976 The County Board of Supervisors approved a General Plan Amendment limiting development to three areas -the Northeast Ridge, Brisbane, and South San Francisco (South Slope / Terrabay) Planning Areas. 1976 After County approval of the project, habitat was found on parts of San Bruno Mountain for the Mission Blue (Plebeius icariodes missionensis) and San Bruno Elfm (Callophrys mossii bayensis) butterflies. Later in 1976, the U.S. Fish & Wildlife Service (USFWS) designated the butterflies as "endangered" under the Endangered Species Act of 1973 (ESA). 1978 The USFWS proposed the callippe Silverspot (Speyeria callippe callippe) butterfly for listing as endangered under the ESA (in 1978 and again in 1994). 1980 The County commissioned biological studies of the butterflies to prepare a habitat conservation plan (HCP). The HCP was formulated to protect and perpetuate the butterflies by simultaneously preserving and improving some habitat and allowing limited development. 1981 The City of South San Francisco and San Mateo County adopted a Letter of Understanding for joint review and approval of development proposed on the South Slope (Terrabay) site. Zo Draft Environmental Impact Report for the Terrabay Dnelopment Project (1982 EIR), op. cit., and Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension (1996 EIR), op. cit. 21 2.0 PROJECT DESCRIPTION Terrabay Phase ll and 111 SE1R 1981 W.W. Dean and Associates submitted a preliminary concept plan for the site. After review and revision, the City and County approved the South Slope Concept Plan and required preparation of a Specific Plan and EIR. - 1982 The USFWS and County adopted the San Bruno Mountain Habitat Conservation Plan (HCP) for the HCP planning area which covers and exceeds the South Slope (Tenrabay) site. 1982 The County certified the EIR (1982 EIR), and the City and County jointly adopted the Terrabay Specific Plan. 1983 The City added the Ten:abay Specific Plan District to the zoning ordinance, annexed the 200- acre development area of the Terrabay site, and adopted a Development Agreement. The USFWS also issued a limited development permit for the HCP planning area under Section 10(a) of the ESA. 1985 The USFWS amended the HCP to allow repair of landslides above the Phase I project site. 7988 The City and W.W. Dean and Associates executed the Development Agreement. 1989 The City approved a Precise Plan and Vesting Tentative Subdivision Map for the Phase I (Terrabay Park and Terrabay Village) site. 1990 The project sponsor filed the Final Subdivision Map for Phase I and, between 1989 and 1992, began construction activities, including grading of about 80 acres of the entire site and installation of infrastructure required for Phase I development. 1995 SunChase G.A. California I, Inc., the current project sponsor, acquired the site and requested extensions from the City of the Terrabay Specific Plan, Development Agreement, and Phase I development approvals. The City extended the expiration dates until 1997 and required preparation of a Supplemental EIR (1996 SEIR). 1996 The City certified the final 1996 SEIR, extended Terrabay Specific Plan and Development Agreement, and approved completion of Phase I. The 1996 SEIR examined Phase I of Precise Plan level of detail, including site-specific aspects of residential development, but assessed Phases II and III at Specific Plan level of detail involving a conceptual development program and acknowledging that subsequent environmental review would be required on Precise Plans for Phases II and III. 1997 With Phase I construction underway, the project sponsor submitted a Modified Specific Plan (the proposed Specific Plan amendment) and Precise Plans to refine the Phase II residential development project and redefine the commercial development components of the Phase III site. The City required the preparation of a new Supplemental EIR (this 1998 SEIR) to evaluate the proposed changes compared with the project analyzed in the 1996 SEIR. 1997 The Callippe Silverspot received listing as endangered by the USFWS under the ESA in December 1997. PLANNED TRANSPORTATION IMPROVEMENTS A number of interrelated transportation projects planned in the vicinity of the U.S. 101 Oyster Point interchange by the City of South San Francisco and California Department of Transportation (Caltrans) are closely connected with the Terrabay site and proposed development due to their proximity to the site. Preliminary consideration and conceptual studies of these facilities predate 22 2.0 PROJECT DESCRIPTION Terrabay Phase ll and Ill SEIR certification of the 1996 SEIR on the Terrabay project, although planning, design, and construction of individual components of these transportation improvements have proceeded at different rates. The traffic analysis (4.4 Transportation and Circulation) describes these facilities further, but the summary presented below updates recent progress in order to provide context for the Project Description. This discussion identifies elements associated with the project due to location and future operations and distinguishes between improvements which are independent of the Terrabay project and those which are proposed as part of the project covered by this 1998 SEIR. Oyster Point Interchange The City began construction of this U.S. 101 interchange in 1993 and completed this project in 1996. It provides northbound on-, southbound on-, and northbound off- ramps and also connects land located east and west of the freeway via the Oyster Point Boulevard over-crossing. The west end of the over-crossing forms one leg of the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevard intersection and is located at the southeast comer of the Terrabay project site. Freeway access at the Oyster Point interchange presently is limited to the east end of the over-crossing via Dubuque Avenue. Traffic originating west of the freeway must travel through the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard / Oyster Point Boulevard intersection to reach north- and southbound freeway on-ramps. Northbound traffic on U.S. 101 destined for areas west of the freeway similarly must travel through the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevard intersection after exiting the freeway. Southbound traffic on U.S. 101 destined for areas east or west of the freeway must use the existing U.S. 101 Bayshore Boulevard exit ("scissors ramp") and, if eastbound, cross the freeway at Oyster Point Boulevard. An EIR was prepared and certified on the interchange before implementation. Flyover The flyover is an approved elemt'nt of overall Oyster Point interchange improvements which still is planned for implementation. Work to update this project's design is presently underway to meet new standards Caltrans adopted since it was initially designed. The flyover is intended to provide a direct connection for traffic traveling southbound on U.S. 101 to land east of the freeway. This tnaneuver would divert traffic from the existing southbound U.S. 101 Bayshore Boulevard exit (the "scissors ramp") and the Oyster Point Boulevard over-crossing. The City of South San Francisco is the sponsor of the flyover project and is responsible for its eventual implementation. Environmental review for the flyover was performed as part of the Oyster Point Interchange Project Report approved by Caltrans in 1990 and is not repeated by this 1998 SEIR. Hook Ramps The hook ramps constitute part of the proposed project examined in this 1998 SEIR, together with the Terrabay Phase II and III private development project The hook ramps would replace and reconfigure the existing southbound U.S. 101 Bayshore Boulevard exit (the "scissors ramp") and add a new southbound freeway entrance. This entire project would be confined to the west side of U.S. 101 (the west side of the freeway). The project, defined in more detail below (see the Project Description), would consist of a southbound U.S. 101 off-ramp (Ramp "A") to a new signalized "T" intersection with Bayshore Boulevard opposite the Terrabay Phase III project site and a southbound U.S. 101 on-ramp (Ramp "B") from Bayshore Boulevard to the fieeway mainline. It primarily would serve southbound traffic originating in Brisbane and simplify freeway access by allowing direct vehicle access onto the freeway before reaching the Oyster Point interchange. The City of South San Francisco is the sponsor of the hook ramps project to be funded by the Terrabay project sponsor and the City. Project implementation would require an encroachment permit from Caltrans for construction within the U.S. 101 right-of--way. Bayshore Boulevard Realignment Design of the hook ramps' terminus at Bayshore Boulevard would require the realignment of a segment of this roadway. This, too, constitutes part of the project 23 ZO PROJECT DESCRIPTION Terrabay Phase Il and 111 SE/R examined in this 1998 SEIR and also is defined in more detail in the Project Description (below). The terminus, as designed, would encroach into the right-of--way of Bayshore Boulevard. In order to provide adequate space to accommodate both the terminus and traffic operations on Bayshore Boulevard, a 2,000-foot segment of Bayshore Boulevard would be relocated west of the existing alignment onto the Terrabay Phase III project site. North of the hook ramp terminus, the rebuilt roadway would curve west onto the Terrabay site. South of the terminus, the relocated road segment would curve back to the existing alignment of Bayshore Boulevard. The Cities of South San Francisco and Brisbane are discussing which will be the sponsor of the Bayshore Boulevard realignment project to be funded by the Terrabay project sponsor. and local public funds. Project implementation would require approval by the City of Brisbane in whose jurisdiction the existing Bayshore Boulevard alignment is located. 24 2.3 PROJECT DECR/PT/ON The Terrabay II and III project application examined in this document requests City approval of the following: • Amendment of the Terrabay Specific Plan of 1996 21 • Approval of a Precise Plan for the Phase II Tetrabay site • Approval of vesting tentative and final subdivision maps for the Phase II and III sites • Amendment of the Terrabay Speck Plan District in the Municipal Code, Zoning • Amendment of the Development Agreement originally approved in 1988 and extended in 1996 • Approval of Covenants, Conditions, and Restrictions (CC&Rs) for all Phase II and III site components • Design review for Phase II • Grading permits for the Phase II and III sites Those entitlement requests are described below in relation to the project sponsor's objectives, accompanying development concept modifications, and project phasing. The project examined in this SEIR also includes proposed roadway improvements, although implementation would be funded by the Terrabay project sponsor, SunChase G.A. California I, Inc., and local public funds. 22 PROJECT OBJECTIVES The Terrabay site owner and project sponsor is SunChase G.A. California I, Inc., of Phoenix, Arizona. SunChase is represented by Sterling Pacific Management Services Company, also of Phoenix, Arizona, the marketing, management, and development arm of SunChase. Independent housing construction companies would buy parcels, once subdivided, and build out the Phase II site. SunStream would build single-family attached units proposed for the Tetrabay Commons and Point neighborhoods, and Centex Homes would build single-family detached units proposed for the Terrabay Woods neighborhood. Individual developers similarly would buy and build out Phase III parcels. 23 As of February 1998, speck commercial developers had not been identified. The proposed 1998 Specific Plan Amendment contains the following goals and objectives (new text is italicized and deleted text is t):2a 21 In order to distinguish between these documents, the 1998 SEIR (this SIIR) refers to them as the 1996 Terrabay Specific Plan and proposed 1998 Specific Plan Amendment. This SEIR also refers to previously completed environmental documents by date, including the 1982 EIR prepared for San Mateo County and the 1996 Supplemental EIR (1996 SEIR) prepazed for the City of South San Francisco. A complete bibliography is presented in Chapter 7.0 Appendix. 22 See 2.5 Administrative Actions for a list of all permits and approvals required for both the private development and public roadway projects. 23 The project sponsor does not propose to develop the Phase III site and lease buildings to tenants but potentially would build to suit purchasers of Phase III parcels. FAX to Nichols • Berman from James Sweenie, op. cit., October 1, 1997. 24 Terrabay Modified Specific Plan (proposed 1998 Speci, fic Plan Amendment), SunChase G.A. Califortua I, Inc., January 22, 1998, pages 9-10. 25 2.0 PROJECT DESCRIPTION Terrabay Phase /I and 111 SEIR • Help reduce the general housing shortage in the Bay Area and in San Mateo County by providing a variety of new housing units. • Provide economic growth and employment opportunities in northern San Mateo County and the City of South San Francisco. • Provide a range of public and private services and facilities in the Specific Plan Areas. • Reduce environmental impacts and preserve open space through use of a compact development design. • Assure sufficient revenues to City of South San Francisco to offset de~elep~e~ city service costs through early on development of the hotel, restaurant, and ' retail pads, and office uses. • Blend the development in to the undulating slopes of San Bruno Mountain by concentrating the development in the ravines and leaving the knolls largely intact. • Minimize the impact of south slope development on the San Bruno Mountain Park and Habitat Conservation Plan (HCP) area by providing an open space zone between the development and the park and special buffer zone adjacent to the HCP azea. • Preserve the archaeological site through cover and seal measures as set forth in the [1996] SEIR, and establish a park that explains the significance of the site to northern California. • inimi7P development traffic impacts on roadways through project sponsor construction or participation in the construction of roadway improvements, signalization, and transportation system management projects (TSM). TSM elements will include combinations of improvements on the site and system management techniques which will encourage use of alternative transportation modes. • Protect the HCP azea and County park habitat and minimize water usage through a carefully planned landscape plan utilizing non-invasive and drought resistant species common to San Mateo County. • Reduce impact of development on South San Francisco neighborhoods by construction of a traffic buffer and providing a buffer zone park adjacent to Hillside Boulevard. • Frovide water, sewer, storm, and energy utilities to service the project. • Conserve energy by constructing all units in compliance with the energy conservation standards set forth in Title 24 of the California Administrative Code. • Increase South San Francisco's access to the recreational opportunities of San Bruno Mountain park through the provision of trail heads and trails to the pazk properties. • Provide community services and facilities, including: firehouse, recreation center, pazks, tot lots, play field, and a fee for child caze and / or library facilities all of which will minimize impacts on existing community facilities and expand community services in South San Francisco.* * Amended per City Council Resolution No. 139-96 dated September 1996. 26 2.0 PROJECT DESCRIPTION Terrabay Phase /l and 111 SE/R PROJECT COMPONENTS 25 The project proposes residential development on the Phase II Terrabay site, a commercial development program for eventual construction on the Phase III site, construction of streets and pazking facilities, installation of public facilities and utilities, and creation of pazk and landscaped areas within the site development azea. The project also provides for protection of the site's habitat conservation azea outside (uphill from) the Phase II and III site development azeas. Associated roadway improvements proposed as part of the project analyzed by this SEIR include construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevazd. These development components aze summarized in Exhibit 2.3-I, presented on the following page, and aze described below. (Acreages in Exhibit 2.3-1 are rounded in the text.) Residential Development The 65-acre development area of the Phase II residential site consists of three general geographical neighborhoods. They in tum are divided into four subazeas. 26 Located from east to west along South San Francisco Drive, the neighborhoods (and subareas) aze as follows: Terrabay Point Terrabay Commons Terrabay Woods (Woods East and Woods West) The Precise Plan proposes construction of 348 housing units in the combined Phase II residential area. These units would be distributed among the subazeas as follows: Terrabay Point (181 units), Terrabay Commons (32 units), and Terrabay Woods (135 units). Exhibits 2.3-2a through 2d on the following pages present proposed land uses and Precise Plan site plans for the Phase II neighborhoods. The Precise Plan proposes development of Terrabay Point and Commons with single-family attached housing units (duplexes and triplexes) and Terrabay Woods with single-family detached units. Eroposed housing is summarized in Exhibit 2.3-3 by subarea and type. (Squaze footages in Exhibit 2.3-3 are rounded in the text.) Project implementation would result in construction of approximately 823,520 square feet of residential development, as follows: Attached Duplex Units would range in size from about 2,110 to 2,360 squaze feet (an average of approximately 2,290 square feet per unit) and would account for about 162,960 squaze feet (20 percent) of Phase II residential development. Each duplex structure would consist of two side-by-side units (not stacked units) with a common wall. Building footprints would range from about 2,740 to 2S This description of development components relies on maps, plans, and reports submitted to the City of South San Francisco as part of the formal applications for approval of the proposed Specific Plan Amendment and Precise Plan. Where the project sponsor's representatives have provided additional information in letters or conversations but that information is not yet reflected in the pending application materials, it is referenced in footnotes. 26 The proposed 1998 Specific Plan Amendment and Precise Plan for the Phase II site define what previously were designated as five subareas into four subareas. Prior plans identified the Terrabay Point, Terrabay Commons East, Terrabay Commons West, Terrabay Woods East, and Terrabay Woods West subareas. The Precise Plan combines the Terrabay Point and Terrabay Commons East subareas and designates the combined subarea Terrabay Point. The Precise Plan retains Terrabay Cotnmons West (as Terrabay Commons) and Terrabay Woods East and Terrabay Woods West (unchanged). 27 Exhibit 2.3-1 Land Use Summary a Land Use Summa Develo ed Area Undevelo d Total Area Phase 11 Terraba Residential Site Residential Lots 26.1 0.0 26.1 Private Street Ri ht-of-Wa 12.5 0.0 12.5 Private Common Area 23.1 0.0 23.1 HCP en S ace 0.0 3.1 3.1 Phase II Subtotal 61.7 3.1 64.8 Phase 111 Ten-aba Commercial Site Commercial Lots 30.9 0.0 30.9 Private Street Ri ht-of-Wa 1.0 0.0 1.0 Private Common Area 3.4 0.0 3.4 Archaeolo 'cal Site ` 2.0 0.0 2.0 Phase III Subtotal 37.3 0.0 37.3 Total Ten'aba Site 99.0 3.1 102.1 Hook Ram sand Ba hore Boulevard Reali nment Site Hook Rams 3.5 0.0 3.5 Ba shore Boulevard 11.0 0.0 11.0 Trans ortation Site Subtotal 14.5 0.0 14.5 Total SE/R Pro'ecf Site 113.5 3.1 116.6 Phase 11 Breakdown 'Develo ed Area Undevelo ed 'fota/ Area Ten-aba Point Residential Lots 10.2 0.0 10.2 Private Street Ri t-of-Wa 4.6 0.0 4.6 Private Common Area 9.1 0.0 9.1 HCP en S ace 0.0 0.3 0.3 Subtotal 23.9 0.3 24.2 Tenaba Commons Residential Lots 1.7 0.0 1.7 Private Street Ri t-of-Wa 1.3 0.0 1.3 Comm n Area 4.5 0.0 4.5 HCP n S ace 0.0 0.7 0.7 Subtotal 7.5 0.7 8.2 Terraba Woods East Residential Lots 9.7 0.0 9.7 Private Street Ri t-of-Wa 4.7 0.0 4.7 Private Common Area 4.7 0.0 4.7 HCP n S ace 0.0 2.1 2.1 Subtotal 19.1 2.1 21.2 Terraba Woods West Residential Lots 4.5 0.0 4.5 Private Street Ri t-of-Wa 1.9 0.0 1.9 Private Common Area 4.8 0.0 4.8 HCP en S ace 0.0 0.0 0.0 Subtotal 11.2 0.0 11.2 Total Residential Site 6i.7 3.1 64.8 In acres, rounded. Terrabay Phase 11 Residential Land Use Summary, Brian Kangas Foulk (BKF), January 23, 1998, Area Calculations for Terrabay (Development Areas), BKF, September 26, 1997 (revised February 20, 1998), Terrabay Resubdivision of Parcels 1 & 2, op. cit., Sheets S and 6, May 1990, and Vesting Tentative and Final Subdivision Map, BKF, January 15, 1998. Habitat Conservation Plan (HCP) area to be reviewed by Thomas Reid Associates (City, County, and USFWS HCP monitoring consultant, called the Plan Operator by the Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan) and ultimately to be dedicated to San Mateo County. 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Q'~~ ~ _. ~~ N N y ~ n ~.,, rnWcl:~ c~cai.n~n~iviV Terrabay Phase 11 and 111 SE/R Exhibit 2,3-3 Precise Plan Housing Summary Subarea Detached Duplex Triplex Total Point 0 64 117 181 Commons 0 8 24 32 Woods 135 0 0 135 Total Housin 135 72 141 348 Type /Plan Number of Units Size (square feet) Bedrooms Bathrooms Terraba Point lex Plan A ° 28 2,112 4 3.0 lex Plan B ° 28 2,390 4 3.0 Du lex Plan C 8 2,362 4 3.0 Tti lex Plan A ` 39 2,045 3 3.0 Tri lex Plan B 39 2,027 4 3.0 Tri lex Plan C 39 2,255 4 3.0 Point Subtotal 181 units 685 bedrooms Terraba Commons lex Plan A ° 4 2,112 4 3.0 lex Plan B ° 4 2,390 4 3.0 lex Plan C 0 2,362 4 3.0 Tri lex Plan A ` 8 2,045 3 3.0 T ' lex Plan B 8 2,027 4 3.0 Tri lex Plan C 8 2,255 4 3.0 Commons Subtotal 32 units 152 bedrooms Terraba Woods East Detached Plan 1 19 2,378 4 2.5 Detached Plan 2 23 2,465 4 3.5 Detached Plan 3 25 2,858 5 3.5 Detached Plan 4 24 3,024 5 3.5 Woods East Subtotal 91 units 413 bedrooms Tenaba Woods West Detached Plan 1 16 2,378 4 2.5 Detached Plan 2 8 2,465 4 3.5 Detached Plan 3 10 2,858 5 3.5 Detached Plan 4 10 3,024 5 3.5 Woods West Subtotal 44 units 196 bedrooms Total Housing 348 units 1,446 bedrooms Source: The Dahlin Group, January 15, 1998 (revised February 20, 1998) a Duplex Plans Aand B = downslope design. The January 15, 1998 Precise Plan shows 2,112-square foot Plan As and 2;390-square foot Plan Bs. The project sponsor's consultants reversed these sizes February 20, 1998 to 2,390-square foot Plan As and 2,112-square foot Plan Bs without revising the Precise Plan architectural drawings to show the changes. b Duplex Plan C = upslope design. c Triplex Plan A =lower unit. d Triplex Plans Band C =upper side-by-side units stacked over lower (Plan A) triplex unit. 33 2.0 PROJECT DESCRIPTION Terrabay Phase II and 111 SE1R 3,680 square feet for upslope and downslope units, respectively, and result in total building coverage by all 36 duplex buildings of 128,860 square feet (59 percent of lot area). Individual duplex units would provide four bedrooms and three bathrooms. The proposed Precise Plan illustrates two downslope plans and one upslope plan. Downslope duplex buildings are designed as two-story 31- foot high structures (maximum height ), and upslope duplex buildings are designed as three-story 35- foot buildings (maximum height), including individual garages providing two indoor parking spaces for each unit. 27 Attached Tiip/ex Units would range in size from about 2,030 to 2,260 square feet (an average of approximately 2,110 square feet per unit) and would account for about 298,070 square feet (36 percent) of Phase II residential development. Triplexes would consist of three-unit buildings with two side-by-side upper units stacked over a lower unit. Each three-unit building would have a footprint of 3,360 square feet, and the 47 separate triplex buildings would cover about 157,780 square feet (57 percent of lot area). One-third of triplexes (47 units) would provide three bedrooms and three bathrooms, and two-thirds of triplexes (166 units) would provide four bedrooms and three bathrooms, depending on floor plan (three plans are ident~ed). Triplex buildings are designed as four-story 45- foot high structures (maximum height), including individual garages providing two indoor parking spaces per unit. Fire sprinklers would be installed in all attached triplex units. Detached Units would range in size from about 2,380 to 3,020 square feet (an average of approximately 2,680 square feet per unit) and would account for a total of about 362,490 square feet (44 percent) of Phase II residential development. Building footprints would range from about 1,240 to 1,880 square feet per unit and result in total building coverage by all 135 single-family detached units of 214,840 square feet (42 percent of lot area). About half of single-family detached units would provide four and two-and-one-half to three-and-one-half bathrooms (66 units), and' 69 units would provide five bedrooms and three-and-one-half bathrooms, depending on floor plan (four plans are identified). The three-story units are presently designed as 35-foot high structures (maximum height), including two to three indoor garage parking spaces. Fire sprinklers would be installed in 17 detached units in the Woods East subarea which would be located farther than 150 from a turnaround approved by the South San Francisco Fire Department. 28 Exhibit 2.3-4 presents a summary of designs details for both attached and detached housing units ident~ed by the Precise Plan. All units would be sold to owner-occupants, including duplex and triplex condominiums (no rental housing). The applicant estimates a residential population of approximately 726 people at buildout and full occupancy of the Tetrabay Point, Commons, and Woods neighborhoods. 29 27 See the subsection on Streets and Parking, below, for a complete description of all residential, visitor, and commercial parking. 28 Terrabay Project, South San Francisco, California, Letter to Allison Knapp, City of South San Francisco, from Janine O'Flaherry, Brian Kangas Foulk (project sponsor's engineer), January 25,1998. 29 Letter to Nichols • Berman (EIR consultant) from James Sweenie, Sterling Pacific Management Company, op. cit., November 6, 1997. 34 2.0 PROJECT DcoCR~P i SON Terrabay Phase Il and 111 SE1R Exhibit 2.3-4 Residential Lot and Building Summary Attached Units Duplex Plan A-B a .Duplex Plan C a Triplexes Terraba Commons and Point Lot dimensions (width-de [h) 60-102 feet 64-81 feet 60-98.5 feet Lot size 6,200 s uaze feet 5,184 s ware feet 5,910 uaze feet Front setback ` 15 feet 17 feet 6-9 feet Reaz setback 13 feet 15 feet d Side setbacks 4 + 4 feet 4 + 4 feet 7.5 + 7.5 feet Buildin Foo rint ` 3,684 feet 2,744 feet 3,357 feet Buildin Covera a 59 ercent 53 ercent 57 ercent Gara e s aces 2 s aces 2 s aces Z s aces Hei ht a 31 feet 35 feet 45 feet Stories 2 3 4 Unit Size • Plan A 2,112 s uaze feet 2,045 s ware feet • Plan B 2,390 s uaze feet 2,027 s uaze feet • Plan C 2,362 s uaze feet 2,255 s uaze feet Bedrooms • Plan A 4 3 • Plan B 4 4 • Plan C 4 4 Detached Units Floor Plan 1 Floor Plan 2 Floor.P/an 3> Floor Plan 4 Terraba Woods Lot dimensions' 40-70 feet 40-88 feet 50-88 feet 50-88 feet Lot size 2,800 s uaze feet 3,520 s ware feet 4,400 s uaze feet 4,400 s uaze feet Front setback 8-17 feet' 15-17 feet 15-17 feet 15-17 feet Rear setback 15 feet 15 feet 15 feet 15 feet Side setbacks 4.5 + 4.5 feet 4 + 5 feet 5 + 5 feet 5 + 5 feet Buildin Foo rint 1,243 s uaze feet 1,347 s uaze feet 1,875 s uaze feet 1,881 s uaze feet Buildin Covera a 44 ercent 39 ercent 43 ercent 43 rcent Gara e s aces 2 s aces 2 s aces 3 s aces 3 s aces '" Hei ht ` 35 feet 35 feet 35 feet 35 feet Stories 3 3 3 3 Unit Size 2,378 square feet 2,465 square feet 2,858 s uaze feet" 3,024 s uaze feet" Bedrooms 4 4 5 " 5 " Source: The Dahlin Group, January 15, 1998 (revised February 20, 1998) a Plans A-B would be oriented downslope, and Plan C is an upslope design. As noted above, the January 15, 1998 Precise Plan shows 2,112-square foot Plan As and 2,390-square foot Plan Bs. The project sponsor's consultants reversed these sizes February 20, 1998 to 2,390-square foot Plan As and 2,112-square foot Plan Bs without revising the Precise Plan architectural drawings to show the changes. b Lot widths would vary, but minimum dimension of upslope duplex lots would be 64 feet. c Garage setbacks would vary 15 to 17 feet from front property lines and be 18 feet either from the face of the curb (where no sidewalk is adjacent to the street) or from the inner edge of the sidewalk (where present), but some facade features would be closer to the front property line than 17 feet. d Triplex buildings would front on two streets resulting in two "front" yards / "front" setbacks but no "rear" yards / "rear" setbacks. (Entrances to one triplex unit would be from a lower elevation street and to two triplex units would be from an upper elevation street). e Building footprint regardless of number or arrangement of units per building. For instance, two side-by-side duplex units equal the building footprint given above. Exhibit 2.3-4 Footnotes Continued on the Following Page 35 2.0 PRGUECT DESCR/PTIOh Tenabay Phase !I and !!I SE1R Exhibit 2.3-4 -Continued Residential Lot and Building Summary f Two (2) garage spaces each per attached unit in individual two-car garages (two garages apiece in duplex buildings and three garages apiece in triplex buildings). Dimensions of garage spaces would be ten feet wide by 20 feet deep (10x20) or larger, in conformance with City parking standards. Two additional spaces per unit would be provided outdoors on driveway aprons. Dimensions would measure eight feet wide by 15 to 17 feet deep (8x15-17) on each unit's lot, although adjacent curbs and / or sidewalks, where present, would extend those depths beyond the property lines of private lots. g 1996 Specific Plan building height limit is 30 feet for single-family detached units (and "townhomes") and 45 feet for attached units. Proposed Precise Plan drawings illustrate 35-foot detached units and uphill duplex buildings, 31- foot downhill duplex buildings, and 45-foot triplex buildings. h Total floor area of entire unit (versus footprint of one floor, as shown above). i Depths would vary, but minimum depths are shown, while widths are standard as shown. j The Precise Plan shows eight- to 15-foot front setbacks to structures and 17- to 18-foot setbacks to garage doors (thus 17- to 18-foot driveway apron lengths) from property lines. The outside faces of curbs and, where present, sidewalks increase these setbacks one to four feet from travel lanes of adjacent streets. k Two (2) ten-foot wide by 20-foot deep spaces (10x20) and one (1) ten-foot wide by 18-foot deep space (10x18). Although three spaces would be provided, one would be substandard 1 The City requires provision of a three-car garage for a five bedroom housing unit and / or a 2,500-square foot unit. The City standard for athree-car garage is 30-feet wide and 20 feet deep, free and clear of any obstructions. Proposed garages for both Floor Plans 3 and 4 fall would short of the City requirement. Floor Plan 3 proposes garages measuring 30 feet wide by 18 to 20 feet deep (18 feet deep for one space and 20 feet deep for two spaces), and Floor Plan 4 proposes garages measuring 29 feet four inches (29' 4") wide and 20 feet deep, eight inches narrower than the City's standard. m Two (2) ten-foot wide by 20-foot deep spaces (10x20) and one (1) nine-foot four-inch wide and 20-foot deep space (9'4^z20), as described immediately above. n Units with five bedrooms or more and / or in excess of 2,500 square feet in size require provision.of three-car garages pursuant to the City's Zoning Ordinance. 36 1.Ur'riWtCi UcoUHlh'i~UN Terrabay Phase /l and 111 SE1R Comparison with 1996 Specific Plan The proposed Precise Plan differs from the 1996 Terrabay Specific Plan in number, type, and density of units on the Phase II site. 30 Number of Units The 1996 Terrabay Specific Plan provides for construction of a total of 432 housing units in the Terrabay Point, Commons, and Woods neighborhoods compared with 348 units proposed by the Precise Plan, an 84-unit reduction from the 1996 Terrabay Specific Plan. Exhibit 2.3-5 compares the proposed Precise Plan with the prior 1982 and 1996 Specific Plans for both the Phase I and Phase II residential sites. Exhibit 2.3-5 Breakdown by Subarea' Number of 1982 1996 - 1998 Units S ecific Plan S ecific Plan Precise Plan Phase I (not covered b this EIR) Villa a 181 168 165 Park 136 125 125 Subtotal 317 293 29p b Phase lI (covered this EIR) Point 170 181 181 ` Commons 58 47 32 Woods 200 204 135 ` Subtotal 428 432 348 Total I & 11 745 725 638 a a Proposed 1998 Specific Plan Amendment. b Completion of 130 Phase I units and construction of another 156 units results in a total of 286 Phase I units (and a total of 634 Phase I and II units). FAX to Nichols • Berman and the Crane Transportation Group from James Sweenie, op. cit., February 9, 1998. c Breakdown of Housing Units by Neighborhood, Mark Day, The Dahlin Group (project sponsor's architect), FAX to Nichols • Berman, January 20, 1998. d Terrabay Point now refers to the combined Terrabay Point and Terrabay Commons East neighborhoods as described in prior planning and environmental documents. Terrabay Commons now refers to the Terrabay Commons West neighborhood. The 1982 Specific Plan distribution of units is adjusted above to reflect the redesignations. However, it provided for 99 Point units, 129 Commons units, and 200 Woods units for a total of 428 housing units. Type of Units 1996 Terrabay Specific Plan housing types for the Phase II residential site include "townhomes", "terraced units", and "condominium units", all typically classified as single-family attached housing 31, whereas the proposed Precise Plan calls for construction of both single-family attached (213 units) and detached (135 units) housing on the Phase II residential site. About 61 percent of proposed units would be attached, and 39 percent of Phase II residential units would be detached. Another difference between the 1996 and 1998 plans is that the proposed Precise Plan would provide larger housing units than envisaged by the 1996 Terrabay Specific Plan. Exhibit 2.3-6 compares unit types and sizes of adopted and proposed plans. 30 Completion of Phase I residential development will result in 286, as noted in Exhibit 2.3-5, seven fewer units than permitted by the approved 1996 Terrabay Specific Plan which allows development of up to 293 units on the Terrabay Phase I site (168 and 125 units in Terrabay Village and Park, respectively). FAX [o Nichols • Berman and the Crane Transportation Group, from James Sweenie, op. cit., February 9, 1998, providing the number of units completed and occupied and those yet to be built. 31 The 1996 Terrabay Specific Plan provided for both attached and detached units on the Phase I residential site. 37 t.urrtiwcl.~ UCJC.f-(IYIIUIV Terrabay Phase l1 and l/l SE'1R Exhibit 2.3-6 Comparison of Unit Types and Sizes Subarea 1982 :1996 1998 S ecific Plan S ecific Plan Precise Plan Unit T e Point Condo Units Condos SF ° Attached ' Commons Terraced Units Condos SF ° Attached Woods Townhome SF ° Detached SF ° Detached Unit Size ` Point n /a 1,000-2,200 2,027-2,390 Commons n /a 550-1,500 2,027-2,390 Woods n /a 1,200-1,800 2,378-3,024 a SF =single-family. b Single-family attached duplex and triplex units. c Square feet except where not available (n / a). Density of Development Available environmental and planning documents do not estimate density consistently for comparison. Nevertheless, the 1996 Terrabay Specific Plan anticipated a residential density of 6.0 units per gross acre (745 units on the Phase I and II sites' 126.5-acre development azea) and 7.2 units per net acre (428 units on the on the 59.9-acre Phase II site). 32 The proposed 348-unit Precise Plan would result in a density of 6.0 units per acre within the 58.1-acre Phase II site and 13.1 units per acre within the 26.5-acre residential lot azea of the Phase II site. Exhibit 2.3-7 Comparison of Residential Densities Units?Acre 1982 1996 1998 S clfic Plan S ecific Plan Precise Plan Gross Density 5.4 ° 6.0 4.6 Net Densi - 7.2 ` 5.4 ` a 745 units on 139-acre Phase I and II site,1982 EIR. 6 745 units on 126.5-acre Phase I and II site (5.96 units per acre, rounded), 1996 SEIR. c 428 units on 59.9-acre Phase II site,1996 SEIR. d 638 units (or 634 units) on a 139-acre Phase I and II site, Nichols • Berman. On a 126.5-acre Phase I and II site, gross density would be 5.0 units per acre. e 348 units on 64.8-acre Phase II site, Nichols • Berman. Within the 64.8-acre Phase II site, residential lots would account for 26.1 acres, resulting in an actual net density of 13.3 units per acre. Commercial Development The 37-acre development azea of the Phase III commercial site comprises the east leg of the Terrabay project site adjacent to Bayshore Boulevard. It consists of seven proposed commercial parcels on about 31 acres (Parcels A-G), common open space and a proposed pazk on approximately five acres, and about one acre of internal roadway (Exhibits 2.3-8a and 2.3-Sb). The commercial development program is discussed immediately below. Other Phase III land uses are discussed in the respective subsections (Common Area and Open Space and Streets and Parking). 32 Gross density normally refers to total site area (such as the development areas of the Phase I and II sites), and net density normally refers to residential lots (without area devoted to streets, developed open space, and other non-residential land uses). 38 0 m OD ~' ~i 0 c x Z m g x v N ,~, _ ~ ' •• •. :~h iii ~i ~`li v~'~~Lrl~• • • • • • • %:r= rrr ~`~ ~/ I ='r~;i v _;;:. ; ~ .; ,,,; ., ,,, ~ ~' ~' i ,; :,~r~ '~,'i .. ~;c?. ;,~;,:: ~ ~:• -, ;;;; ~ .„ _,,;`` _~,~ ~,~,:.. 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I~ ~ ~ I i 1 i/1 i y v .~ ,Y Q ~' `• N ~' 2.0 PROJECT DESCRIPTION Terrabay Phase 11 and 111 SE1R The Precise Plan contains a proposed development program (which identifies land uses and maximum buildout by parcel) and engineering drawings (which show azeas proposed to be graded and locations of underground infrastructure facilities) but no architectural drawings, as provided for the Phase II residential site. 33 Details about commercial development would not be available until individual developers /operators submitted applications to the City for their specific projects on a parcel-by- parcel basis. The proposed development program anticipates construction of 283,000 to 343,000 square feet of commercial space, including three hotels, four to six restaurants, retail space, and office space on about 16 acres of the Phase III commercial site (see Exhibit 2.3-9). 34 Exhibit 2.3-9 Commercial Development Summary° -Acres Developmentb Land Use Height° Land Use Summa Hotels (3) 21.2 235,000-280,000 380-600 rooms 250 Restaurants (4) 3.66 12,000-18,000 450 seats 70 Retail (3) 3.57 6,000-10,000 service retail 70 Mixed Use 2.45 30,000-35,000 retail, restaurant, office 70 Total Commercial 30.88 283,000-343,000 Parcel Summa Parcel A 3.57 6,000-10,000 Three (3) service retail uses 70 Parcel B 5.07 85,000-100,000 One (1) 120- to 200-room hotel 250 Parcel C 9.35 75,000-90,000 One (1) 130- to 200-room hotel 250 Parcel D 1.80 4,000-6,000 One (1) 150-seat restaurant 70 Parcel E 1.86 8,000-12,000 Three (3) restaurants (300 seats total) 70 Parcel F 2.45 30,000-35,000 Mixed-use retail, restaurant, office 70 Parcel G 6.78 75,000-90,000 One (1) 130- to 200-room hotel 75 Total Commercial 30.88 283,000-343,000 Source: Brian Kangas Foulk, January 25, 1998 (revised by Nichols • Berman, February 26, 1998) a Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. b Square feet. c Maximum building height in feet. The 1998 Specific Plan Amendment proposes maximum heights of up to 250 feet for hotels on the northern end of the Phase III site. Hotels on the southern end would be restricted to 75 feet in height. The maximum height for all other commercial structures would be 70 feet. d Not defined. The project sponsor estimates that these land uses would employ approximately 780 people. 33 The project sponsor characterizes the pending application as an "initial Precise Plan" which identifies "pad locations, the infrastructure for those pads, and the anticipated use for those pads". The sponsor further indicates that "Supplemental Precise Plans will then be filed subsequent to approval of this [application) when individual commercial users of the pads have been contracted with and their building designs and particular uses are to be reviewed and approved [sicl". Proposed 1998 Specific Plan Amendment, page 6. 34 Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. 41 2. ~ PROJECT DESCRIPTION Terrabay Phase 11 and 111 SE1R As an alternative to the commercial development concept presented in Exhibit 2.3-9, the Precise Plan provides that each parcel could be developed with offices. 35 This could result in as much as 343,000 square feet of office space, if fully developed with that use instead of hotel, retail, and restaurant uses. Hotels The proposed Precise Plan would devote about 21 acres to the three hotel sites (Parcels B, C, and G). It indicates that a combined total of 235,000 to 280,000 square feet of hotel space would be built in separate structures and that hotels would provide 120 to 200 rooms each (up to 600 rooms altogether). The Pazcel B hotel would consist of 85,000 to 100,000 square feet of space on a 5.07-acre site and is proposed as a 120- to 200-room hotel. 36 The Parcel C and G hotels each would consist of 75,000 to 90,000 square feet of space on 9.35- and 6.78-acre sites, respectively, and would be developed with 130- to 200-rooms each. Hotel buildings would not exceed 250 feet in height. The Precise Plan does not identify other details about hotels or specific developers /operators. Nevertheless, hotels would operate 24-hours per day and could employ a combined total of 405 workers throughout each day. 37 Restaurants The proposed Precise Plan designates about 3.7 acres on two sites specifically for restaurants (Parcels D and E) for about 18,000 square feet of restaurant development. The Parcel D restaurant would consist of 4,000 to 6,000 square feet of building area and accommodate approximately 150 seats. Parcel E would be developed with three separate restaurants of about 2,600 to 4,000 square feet each (for a total of 8,000 to 12,000 square feet of Parcel E restaurant space). Additional restaurants could be provided as part of mixed-use development on Parcel F. 38 The proposed Precise Plan amendment would permit a maximum height of 70 feet per commercial building, including restaurants. Two "medium tum-over Denny's type and two higher quality type restaurants" are anticipated, and no fast food restaurants are proposed for the site. 39 Depending on individual operators, restaurants could serve patrons from 6:00 AM to 10:00 PM and could employ a combined total of approximately 90 people. 40 Retail The Precise Plan proposes three service retail uses on the 3.57-acre Pazcel A accounting for a total of 6,000-10,000 square feet of development. Additional retail space could be provided as part of 35 ~~ 36 Actual hotel developers /operators would determine building specifications in applications when made to the City. If approved by the City, the proposed 1998 Specific Plan Amendment would identify the maximum number of hotel rooms which could be built. 37 Letter to Nichols • Berman from James Sweenie, op. cit., November 6, 1997. The applicant's cstimate assumes 0.75 employee per hotel room and an average of 180 rooms per hotel (540 rooms altogether). The proposed range of 120-200 rooms per hotel (360-600 total rooms) could result in 270-450 hotel workers on the Phase III commercial site at buildout. 38 The proposed Precise Plan does not quantify how much additional restaurant space would be provided on the mixed-use Parcel F. However, a City staff review of the proposed parking supply indicates that Parcel F could accommodate one . 3,760-square restaurant and 27,750 square feet of retail (or office) area without exceeding parking requirements of the Zoning Ordinance. 39 Letter to Nichols • Berman from James Sweenie, op. cit., November 6, 1997. ~ Ibid The applicant assumes 1.0 employee per 200 square feet of restaurant, retail, and office space and estimates a total employment of 375 restaurant, retail, and office workers for a combined 75,000 square feet of those uses on the Phase ID commercial site at buildout. (The Precise Plan development program proposes a combined total of 63,000 square feet of restaurant, retail, and office uses which, assuming one employee per 200 square feet, could result in 315 employees.) 42 2.0 PROJECT DESCRIPTION Terrabay Phase 1l and 111 SE1R mixed-use development on Parcel F. Retail buildings could be up to 70 feet high. Depending on actual retailers (assumed to be service retail, travel, or specialty uses), tenants could operate between 9:00 AM and 9:00 PM and could employ a total of about 50 people. 41 Mixed-Uses The proposed Precise Plan shows a total of 30,000-35,000 square feet of mixed-use development on the 2.45-acre Parcel F. Mixed uses could include office, restaurant, or retail development. Such development would be constructed in two- to three-story buildings up to 70 feet high. The applicant expects that two to four office tenants would occupy the proposed space, providing professional services or support for major area employers, that they would operate between 8:00 AM and 6:00 PM five days a week, and that approximately 175 people would be employed as office workers. 42 Comparison with 1996 Specific Plan The 1996 Terrabay Specific Plan and proposed Precise Plan contain different development concepts for the Phase III commercial site. 1996 Terrabay Specific Plan development components include a 400-room 18-story hotel, 268,000-square foot high technology "trade center", 57,500-square foot condominium office building, 18,000-square foot health club, and 150-seat 5,000-square foot restaurant (in addition to two hotel restaurants). Uses for which the 1996 Terrabay Speciftc Plan defined building area account for 348,500 square feet. The 18-story hotel would increase that azea to a total, as calculated by the applicant, of 669,300 square feet. 43 Hotels Compared with the 1996 Terrabay Specific Plan (one 400-room hotel), the proposed Precise Plan would increase the number of hotels (a total of three hotels) and hotel rooms (up to 600 could be proposed and built). Restaurants The proposed Precise Plan would increase the number of restaurants (four) compared with the 1996 Terrabay Specific Plan (three, including two hotel restaurants). Other Commercial Uses The proposed Precise Plan would eliminate the high technology "trade center" and health club previously provided by the 1996 Terrabay Specific Plan, potentially would permit up to 343,000 square feet of offices compazed with 57,500 square feet covered by the 1996 Terrabay Specific Plan (but, if fully developed with offices, without any of other hotel or commercial uses proposed by the Precise Plan), and would provide up to 45,000 squaze feet of specialty retail not envisaged by the 1996 Terrabay Specific Plan. Streets and Parking Access to the Phase II residential site would be via South San Francisco Drive at, respectively, its existing and new connections with Hillside Boulevard and Sister Cities Boulevazd. Access to the Phase III commercial site would be from Bayshore Boulevard. No roadway connection is proposed between the Phase II residential and III commercial sites. Other on- and off-site roadway improvements covered by this EIR include construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevazd in the vicinity of the Terrabay and hook ramp sites. 41 Ibid. 42 Ibid. 43 Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. 43 2.0 PROJECT DESCRIPTION Terrabay Phase ll and 111 SEIR Residentia/Streets South San Francisco Drive is an existing roadway built during implementation of the Terrabay Phase I Park and Village projects. It forms the north leg of the Hillside Boulevard- Jefferson Street intersection at the entrance to the Phase I residential site where it is fully operational. Inside the Phase I residential site, South San Francisco Drive does not provide public access east of the Hillside Recreation Center site. In 1989, the South San Francisco Drive alignment was graded and paved east from the Hillside Recreation Center site into the Phase II residential site, parallel to and north of Sister Cities Boulevard, for use by construction trucks canrying fill material to and from the proposed Terrabay Woods subarea and construction activities on the Phase I site. Approval and implementation of Phase II residential development would involve completion of South San Francisco Drive. It would be widened from Terrabay Park in the Phase I site to its "T" intersection with Sister Cities Boulevard. This intersection, located between the Terrabay Commons and Point neighborhoods, can ently is signalized but would begin accommodating fuming movements with project generated traffic. South San Francisco Drive would provide access to "minor roads" and "neighborhood lanes" serving all Terrabay Point, Commons, and Woods development. South San Francisco Drive would be dedicated to the City as a public street with appropriate traffic control signage and markings in place as required by the City's Fire Department. The "minor roads" and "neighborhood lanes" would remain private streets, owned and ~ maintained by each neighborhood's homeowners' association (described further below). The Point and Commons neighborhoods are proposed to be "gated communities". `~ South San Francisco Drive would have a 36-foot curb-to-curb paved width within a 60-foot right-of- way (ROW) and no on-street parking or driveway curb cuts. It would be developed with two 13-foot wide travel lanes (one in each direction) and two five-foot wide bike lanes (one in each direction). The Precise Plan proposes paved 25- and 30-foot wide private street cross-sections within'38-, 40-, and 43-foot rights-of--way within the residential neighborhoods. 45 Twenty-five-foot wide streets would provide a 25-foot wide two-way travel width and no parking, and 30-foot wide streets would provide a 22-foot wide two-way travel width plus an additional eight feet for parking on one side. The Precise Plan proposes maximum street grades of 12 to 15 percent on some uphill roadway segments and maximum grades of six percent through intersections. Dead-end streets in the Terrabay Commons and Woods neighborhoods would provide angled hammerhead turn-around areas designed according to South San Francisco Fire Department criteria to allow three-point toms by fire trucks. An 80-foot diameter col-de-sac in the Terrabay Point neighborhood would also facilitate toms. 46 The Precise Plan would provide four-foot wide sidewalks on one side of roadways serving housing units and bike lanes on South San Francisco Drive only. It would retain one trail connection to San Bruno Mountain State and County Park on the Phase I site (near the boundary of the Phase I and Phase II residential sites) and proposes a second trailhead at the north end of the Phase III commercial site instead of a trail at the boundary of the Phase II and Phase III sites previously shown by the 1996 `~ Letter to Nichols • Betman from James Sweenie, op. cit., November 6, 1997. 45 Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. Rights-of--way would include the paved travel ways, parking (where provided), and sidewalks (where provided) and would cover the entire area between front yard property lines of residential lots. 46 Ibid. 44 2.0 PtiGLECT DcoCRiPT~UN Terrabay Phase 1l and 11l SE/R Terrabay Specific Plan. The Precise Plan's proposed design of the Terrabay Point neighborhood would relocate the Phase II boundary in relation to the Phase III site. As currently proposed the former trailhead would now be confined inside the Terrabay Point neighborhood and would not be accessible to the public (due to proposed gating). 47 The project sponsor proposes to coordinate the location of the Phase III site trailhead with San Mateo County staff and to date has only identified a trail and trailhead conceptually. Commercial Streets Approval and implementation of Phase III commercial development would involve construction of three entrances into the site from Bayshore Boulevazd (two signalized intersections with divided on-site legs and one right-turn in /right-turn out entrance /exit) and an internal roadway connecting the entrances, commercial development parcels, and associated parking. The Precise Plan proposes 50-foot curb-to-curb paved cross-sections at signalized site entrances (with two lanes in each direction separated by raised medians) and a 25-foot paved cross-section on the internal connector street (with one travel lane in each direction and afour-foot wide sidewalk on one side). All parking would be provided off-street, in surface lots or "terraced" parking structures (see below). All Phase III streets would be private. (Improvements to public roadways -the Hook Ramps and Bayshore Boulevard Realignment -are described below.) The Precise Plan provides for maximum roadway grades of 12 to 15 percent (six percent through intersections) and would retain the transportation system management (TSM) provisions of the 1996 Specific Plan. Hook Ramps and Bayshore Boulevard Realignment Hook Ramps The hook ramps project would involve reconstruction of the existing southbound off-ramp from U.S. 101 to Bayshore Boulevazd and construction of a new southbound on-ramp from Bayshore Boulevard to U.S. 101. The southbound off-ramp (Ramp "A") would diverge from the freeway mainline at the existing off- ramp (980 feet north of the planned southbound Oyster Point interchange "flyover" exit) and continue 1,000 feet to a new "T" intersection on Bayshore Boulevard. The off-ramp would consist of one travel lane for 500 feet from where it would diverge from the U.S. 101 mainline and then would widen to two lanes. One lane would provide right-turns only onto northbound Bayshore Boulevard, and one would accommodate left-runs only onto southbound Bayshore Boulevard. The new intersection would be signalized. The southbound on-ramp (Ramp "B") would extend from the new signalized Bayshore Boulevard "T"' intersection, immediately south of the off-ramp junction, for a distance of 2,000 feet to the southbound freeway mainline. The on-ramp would consist of two lanes at the Bayshore Boulevard intersection entrance and would narrow to one lane before merging with the freeway mainline. Signalization of the new Bayshore Boulevazd "T" intersection would permit traffic on both northbound and southbound Bayshore Boulevard to use the on-ramp. Ramp metering equipment and a high occupancy vehicle (HOV) bypass lane would be included in the hook ramps project. 47 Ibid. 45 2.0 PRQIECT DESCRIPTION Terrabay Phase I! and l11 SE1R The new Hook Ramps /Bayshore Boulevard intersection would be located between the two signalized entrances proposed to the Terrabay Phase III commercial site. 48 The realigned Bayshore Boulevard cross section at this intersection would consist of one northbound lane for both through and right- tuming traffic (onto Ramp `B"), two southbound through lanes, and one southbound left-turn lane onto the southbound on-ramp (Ramp "B"). Construction of the hook ramps would entirely replace the existing "scissors ramp" southbound exit from U.S. 101 to Bayshore Boulevard. Once complete, the hook ramps would be dedicated to the State of California to be owned and maintained by Caltrans. The hook ramps would also extend Caltrans' right-of--way into the City of Brisbane's jurisdiction which currently covers the segment of Bayshore Boulevard contiguous to and between the existing U.S. 101 right-of--way and the Terrabay Phase III commercial site. Bayshore Boulevard Realignment This part of the project. would involve relocation of a 2,000-foot segment of Bayshore Boulevard to an alignment located, at its farthest, 140 feet west of the existing roadway. Construction of the hook ramps would require the realignment of Bayshore Boulevard in order to provide sufficient land area to accommodate the off- and on-ramps. The new alignment would follow a long curve connecting the existing alignment remaining in the vicinity of the two new signalized entrances to the Terrabay Phase III commercial site. The roadway cross section would accommodate through traffic lanes and turning lanes in different configurations according to location but would consist primarily of two northbound and two southbound lanes. These are summarized from north to south in Exhibit 2.3-I0. Pavement width would vary from approximately 46 to 90 feet. ' Exhibit 2.3-10 Bayshore Boulevard Segments Segment a _ , .Northbound . Southbound Middle Terrabay Entrance 2 lanes (i through lane dropped 2 through lanes Intersection north of intersection) 1 left-turn lane (into Terrab~:v) 1 ri ht-turn lane (into Terraba ) Hook Ramp Intersection 1 through /right-turn lane 2 through lanes 1 throu h lane 1 left-turn lane (onto Ram `B") Southern Terrabay Entrance 2 through lanes 2 through lanes Intersection 1 left-turn lane (into Terrabay 1 ri t-turn lane (into Terraba ) a All three intersections would be signalized. Parking Full implementation of the proposed Precise Plan would provide 1,760 spaces on the Phase II residential site and 809 spaces on the Phase III commercial site, as described below and summarized in Exhibits 2.3-I1 and 2.3-I2. Residential Parking would include garage parking, driveway apron parking, and additional parking in designated bays. The proposed Precise Plan would provide two garage spaces and two apron spaces 48 The northern signalized Terrabay Phase III commercial site entrance would be located approximately 600 feet north of the new Hook Ramps /Bayshore Boulevard intersection (between proposed Terrabay Parcels D and E). The southern signalized Phase III site entrance would be located approximately 300 feet south of the new Hook Ramps /Bayshore Boulevard intersection (between proposed Terrabay Parcels F and G). (The right-turn in /right-turn out entrance would be located farther north on Bayshore Boulevard, between proposed Parcels A and B.) 46 t.u rrY(J,icC:~ Ucal:rtrrnUrv Terrabay Phase /l and 111 SEIR Exhibit 2.3-11 Parking Supply Summary Phase /l Point Commons Woods Total Number of Units 181 32 135 348 Gara e S aces /Unit 2 2 2-3 " Gara a Subtotal 362 64 339 765 Drivewa Aron /Unit 2 2 2-3 A ron Subtotal 362 64 339 765 On-Street Guest Spaces ° 134 23 73 230 On-Street Subtotal 134 23 73 230 Total Parkin 858 751 751 1,760 Phase Ill Hotel Resfauranf Retail Mixed--Use Units ` 380-600 rooms 12,000-18,000 SF 6,000-10,000 SF 30,000-35>000 SF S ace /Unit 1 /room 1 / 300 SF 1 / 200 SF 1 / 250 SF `. S ecific Plan Rate 380-664 140-210 30-50 120-178 Pro osed Parkin Su 1 450 159 SO ISO Pro"ected Em to ees 405 90 50 175 Total Parkin 809 s aces 9 Total Em to ees 720 em to ees Source: The Dahlin Group, January 15, 1998 a Floor Plans 1 and 2 (66 units) would provide two-car garages (for 132 indoor spaces) and two-car driveway aprons (for 132 outdoor spaces), and Floor Plans 3 and 4 (69 units) would provide three car garages and aprons (for 207 and 207 spaces, respectively). Floor Plans 3 and 4 both propose five bedrooms each. The City parking requirement for a five bedroom and / or 2,500-square foot home is a three car garage. Dimensions of all garage and apron spaces are shown in Exhibit 2.3-I2. As presently proposed, dimensions would be substandard. b Dimensions of parallel parking spaces would be eight feet wide by 20 feet deep (8220). The City standazd is eight-and- one-half feet wide by 20 feet deep (8.5x20), one-half-foot wider than proposed c Rooms and square feet (SF). d Assumes airport-related hotels for which the City requires one space per room. The Ciry's parking requirement for non- airport-related hotels is 1.1 space per room (660 spaces if the maximum 600 rooms were built in non-airport-serving hotels). e Includes office, restaurant, and retail uses not shown in the respective restaurant and retail columns. The parking rate shown assumes all offices, although a 30,000-square foot specialty retail store could require 150 spaces (one space per 200 square feet) plus additional parking for the remaining 5,000 square feet of building arra, if developed on this parcel. f Letter to Nichols • Berman from James Sweenie, op. cit., November 6, 1997. g Does not account for potential shared parking but shows maximum number of spaces proposed 47 z.urrrcvcG~ uc~c;nirr~uw Tenabay Phase /l and /ll SE/R Exhibit 2.3-12 Residential Parking Dimension Summary a Attached Units Gara e S aces A ron S aces Du lexes Number Dimensions Number Dimensions Plan A (downslo e) (32 uniu) 2 ¢araee s aces 20x20-22 2 a ron aces 16x15 Plan B(dawnslo e) (32 uniu) 2 Qara e s aces 20x20-22 2 s aces 16x15 Plan C (u slo e) (8 uniu) 2 ears e s aces 22.5x20 2 a ron s aces 16x17 Tri lexes Number Dimensions Number Dimensions Plan A (u slo e) (47 uniu) 2 oara e s aces 20x21.5 2 a ron aces 16x17 Plan B (downslo e) (47 uniu) 2 Sara e s aces 20x23 2 a ron aces 16x 15 Plan C (downslo e) (47 riniu} 2 ara e s aces 23x23 2 a ron s aces 16x15 Detached Units Gars e S aces A ron S aces - Woods Number Dimensions Number Dimensions Plan 1 (35 uniu) 2 ara e s aces 19x21 ` 2 a ron s aces 16x17 Plan 2 (31 uniu) 2 ara e s aces 20x20 2 a ron s aces 16x18 Plan 3 ` (35 uniu) 3 garage spaces 30x18-20 ` 3 apron spaces 26x18 Plan 4`(34 uniu) 3 ara e s aces 29x20 ` 3 a ron s aces 26x18 Source: Precise Plmi, Part 1 Architecture, The Dahlia Group, January 15, 1998. a Parking space dimensions for new garages required by the City of South San Francisco's Zoning Ordinance (Section 20.74.110(c)) are ten feet wide by 20 feet deep (10x20) and by the Terrabay Specific Plan District for standard cars (Section 20.63.070(d)(1)) are nine feet wide by 20 feet deep (9x20). Driveway aprons of Plan A and B downslope duplexes (64 uniu) provide 15 feet of the required 18-foot depth within the property line with three feet extending into the ROW to the face of the curb. Driveway aprons of Plan C upslope duplexes (eight units) provide 17 feet of the required 18-foot depth within the property line with one foot extending into the ROW to the face of the curb. Driveway aprons of Plan A upslope triplexes (47 units) provide 17 feet of the required depth on individual lots with one foot on within the ROW to the back of the sidewalk and beyond that afour-foot sidewalk Driveway aprons of Plan B and C downslope triplexes (94 units) provide 15 feet of the required 18-foot depth within the property line with three feet extending into the ROW. c The proposed parking width of 19 feet, eight inches falls short of the Cirys 20-foot requirement. d The driveway apron is one foot short of the City requirement. e The City requires provision of a three-car garage for a five bedroom home and / or a 2,500-square foot home. The City standard for athree-car garage is 30-feet wide and 20 feet deep, free and clear of any obstructions. Both proposed garages for Floor Plans 3 and 4 fall short of the City requirement. Floor Plan 3 proposes garages measuring 30 feet wide by 18 to 20 feet deep, and Floor Plan 4 proposes garages measuring 29 feet four inches (29' 4") wide and 20 feet deep, eight inches narrower than the City's standard. f Although three spaces would be provided, one would be substandard, measuring ten feet wide by 18 feet deep (10x18). Nichols • Berman conversation with Mark Day, The Dahlia Group, January 30, 1998. 48 2.0 PROJECT DrSCRIP i iON Terrabay Phase 11 and 111 SEIR per attached duplex and triplex unit in Terrabay Commons and Point (852 garage and apron spaces combined for the 213 attached units), two to three garage sees (three-caz garages with substandard dimensions) and two to three apron spaces per detached unitin Terrabay Woods depending on floor plan (678 spaces for the 135 detached units), and an additional 230 on-street guest spaces on the Phase II residential site. The resulting parking ratios would be 4.74 spaces per attached and 5.56 spaces per detached unit. 49 Commercial Parking The proposed Precise Plan would establish ratios of spaces per hotel room and per square foot of other commercial land uses on the Phase III site as summarized below: 50 • One space per hotel room • One space per 200 squaze feet of retail area • One space per 80 square feet restaurant space 51 • One space per 300 square feet of office space Based on these ratios, the Precise P, lan would provide 809 pazking spaces to supply the commercial development program envisaged. The actual number of spaces ultimately required would depend on the amount of development proposed by individual developers on a pazcel-by-parcel or project-by- project basis. The actual number also would depend on the extent to which pazking would be "shared" among commercial uses should uses, ultimately developed generate demands for parking at different times of day. 52 None of the proposed parking supply is identified for employee use. 53 The Precise Plan indicates that all parking spaces would be provided at grade in surface lots except on Parcel C. The 156 spaces the Plan envisages for a hotel on Parcel C would be provided in a "decked or garage parking" structure. A City staff analysis concluded that either 450 hotel rooms, 16,480 square feet of restaurant (assuming 50 percent of the floor area parked at one space per 200 square feet and 50 percent -customer area - at one space per 50 square feet), 10,000 square feet of retail, and 27,750 square feet of mixed used /retail /office (assuming an average of one space per 250 square feet) or 242,700 square feet of office could be accommodated in conformance with the 809-space parking supply proposed by the Precise Plan. According to the Precise Plan, additional decked or 49 Terrabay Project, South San Francisco, California, Lettet to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. 50 Ibid. 51 g~~ on one space per 50 square feet of customer seating area and one space per 200 square feet for other restaurant space (kitchen, storage, restrooms, etc.), Ibui 52 The project sponsor has indicated that "cross-parking easements" would be provided as a "convenience feature" although full parking would be proposed for each building, Letter to Nichols • Berman from James Sweenie, op. cit. However, the Plan does not identify any rates to calculate shared parking requiremenu or establish a methodology to estimate overlap for the hotel, retail, restaurant, and offices uses proposed. 53 At a rate of one space per employee of any type, people wot~irtg on-site would account for 89 percent of spaces proposed, leaving 11 percent of the proposed supply for visitors (hotel guests, restaurant patrons, shoppers, etc.). See 4.4 Traffic and Circulation for an analysis of the adequacy of the proposed parking supply. 49 2.0 PROJECT DESCRIPTION Terrabay Phase 11 and ll! SE/R garage parking facilities may be incorporated at other pads [than on Parcel C] if a higher number of parking spaces is needed (e.g., if the final land use is primarily office)". 54 Comparison with 1996 Specific Plan The 1996 Specific Plan, indicated that Phase II residential parking would be provided at [he rates of 2.25-2.75 space per attached duplex or triplex unit in Terrabay Commons and Point and 4.25 spaces per detached unit in Terrabay Woods. These rates included both garage spaces for residents and outdoor spaces in parking "bays" for visitors. Applied to the 213 attached and 135 detached units proposed by the Precise Plan, these rates would result in the need for 162 and 388 spaces in the Terrabay Commons and Point neighborhoods and 574 spaces in Terrabay Woods for a total of 1,124 spaces in the combined Phase II residential site compared with 1,760 spaces provided by the proposed Precise Plan. The proposed Precise Plan would reduce the commercial parking supply compared with the 1996 Specifzc Plan. The 1996 Specific Plan provided for 1,254 pazking spaces on the Phase III commercial site (and calculated that City standards required 1,538 spaces for the uses then proposed) compared with the 809 spaces currently proposed. Common Area and Open Space Nearly 29 acres within the combined Phase II and III site development azeas would be landscaped and reserved as common azea (private open space), including the two-acre archaeological site proposed as a pazk and pazking facilities, and another three acres of the Phase II site would be dedicated to San Mateo County as public open space Common Area Common area on the Phase II residential site would account for 23 acres of land not otherwise devoted to private residential lots or to internal circulation. 55 Common azea would consist of a linear park, "master association slope", and Commons and Point landscaped areas and would be owned and maintained by the future homeowners' associations (see Properly Owners' Associations and CC&Rs, below). The proposed Precise Plan provides landscaping plans for the common areas. The linear pazk would be located along the perimeter of the Phase II site. In the Terrabay Point neighborhood, it would be located between residential development and Sister Cities Boulevard. From Terrabay Commons to Terrabay Woods West, the linear park would be located between South San Francisco Drive and Sister Cities-Hillside Boulevazd and developed with a walkway for pedestrians. Landscaping would include trees, shrubs, and groundcover species (see Exhibit 2.3-13) and would be fully irrigated. "Master association slopes" aze proposed in the Terrabay Commons and Woods neighborhoods. These landscaped slopes would be located between the rear yard property lines of residential lots and South San Francisco Drive. The slopes would provide visual but not usable open space. Commons and Point landscaped areas are proposed in breaks between housing groups or at the intersections of "minor roads" and "neighborhood lanes" and would provide wallcway connections for pedestrians. Landscaping of both "master association slopes" and Commons and Point landscaped areas would include trees, shrubs, and groundcover and would be fully irrigated (see Exhibit 2.3-I3). 54 Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. 55 Sheet 11 of the Terrabay 11 & III Vesting Tentative Subdivision Map and Preliminary Grading Plan indicates that the size of common open space Lot K in Terrabay Woods would be 3.27 acres, and Sheet 13 of indicates that the size of Lot K would be 3.33 acres. 50 t.u rnwc~ i uco~.n~r ~ wiv Terrabay Phase Il and 111 SE/R Exhibit 2.3-13 Landscaping Plan Plant Lisf a Trees Shrubs Groundcover Arbutus menaesii tnadrone Cupressus macrocarpa Monterey cypress Metrosideros ezcelsus New Zealand Christmas Tree Pines halepensis Aleppo Pine Platanus acerifolia 'Columbia' London plane tree Quercus agrifolia coast live oak Tristania conferta Brisbane boz Acacia redolens no common name Ceanothus 'dark star' no common name Ceanorhus thysiflorus `snow flurry' wild lilac Heteromeles arbutifolia toyon Melaleuca nesophilla pink melaleuca Myoporum pacificum no common name Rahapiolepis indica 'tiara' white India hawthome Rahapiolepis indica `Springtime' pink India hawthome Arctostaphylos u. 'emerald carpet' maraanita Baccharis pilularis coyote bush Ceanothus griseus horizontalis earrnel creeper Hypericum calycinum St. Johnswort Rosa californica wild rose Master Association Slopes Cupressus macrocarpa Monterey cypress Metrosideros excelsus New Zealand Christmas Tree Pines halepensis Aleppo pine Platanus acerifolia 'Columbia' London plane tree Quercus agrifolia Coast live oak Aescuhrs cornea brioti cape chestnut Maytenus boaria `green showers' mayten tree Pines halepensis Aleppo pine Papules fremontii Fremont cottonwood Pyres calleryerana 'chanticleer' flowering P~ Rhos lances African sumac Aesuclus californica California buckeye Arbutus unedo 'compacts' St[awbeny tree Arctostaphylos d 'Howard McMinn' Mar>'?aita Ceanothus 'dark star' wild lilac Ceanothus thysiflorus 'snow flurry' Wild lilac Heteromeles arburifolia Toyon Myrica californica no common name Rhamnus californica coffeeberry Sambucus mexicana ao common Warne Westringia rosmarinifolius no common name Arctostaphylos d 'Howard McMinn' rnanzanita Arbutus unedo 'compacts' dwarf strawberry tree Buxus m japonica 'green beauty' Japanese boxwood Ceanothus 'dark star' wild lilac Crntaurea cuuraria dusty miller Cistus ladanifer crimson-spot rockrose Cistus purpurus orchid roclQOSe Cistus skanbergii rockrose Dietes isidioides fortrright lily Erigonum arborescens Santa Cruz Island buckwheat Erigonum latifolium red buckwheat Hemerocallis hyrbird daylily Heteromeles arbuttfolia rayon Kniphof=a uvana red Got poker I.eptospermum s. 'ruby glow' New Zealand tea tree I.igusttum japonicum 'tezanum' Japanese privet Mahonia pinnata no common name Nandina domesdca heavenly bamboo Pinosposum eugeniordes no common name Raphiolepis indica 'clam' white India hawthome Westringia rosmariniformis no common name Arctostaphylos u. 'emerald carpet' Matr~anita Ceanothus griseus horizontalis earmel creeper Rosmarinus officinalis rosemary nretostapnyws u. emerara carper manTanita Trachelospetmum jasminoides star jasmine Romarinus ofj~cinalis rosemary Vines & Espaliers Bignonia violacea violet trumpet vine Macfadyena unguis-cati cat's claw Podacarpus gracilior fern pine Pyres kawakamii evergreen pear Source: Nevis Landscape Architecture and Planning a The Habitat Conservation Plan (HCP) does not allow some of the proposed species due to their invasive nature. Victoria Harris, Thomas Reid Associates (the City, County, and USFWS HCP monitoring consultant), June 3, 1998. 51 2.0 PROJECT DESCRIPTION Terrabay Phase /l and 111 SE/R The approximately five acres of common area on the Phase III commercial site would include "master association slopes" and a proposed pazk. Slopes would extend along the eastern site boundary adjacent to Bayshore Boulevard. The park would be located between Parcels E and F and would include part of an archaeological site which has been mapped to cover two acres in size. 56 The Precise Plan proposes to place an engineering geotextile on the existing surface of the archaeological site, cover the textile with approximately two feet of fill material (termed a "workable surface"), install a subdrain system in the workable surface, and place and compact additional fill material, for a total of five to 25 feet of material over the geotextile. The Precise Plan proposes to landscape the park, develop it with interpretative elements, and deed it to a university or other non-profit institution. The Plan proposes that the commercial property owners' association (see below) would maintain the park. 57 Open Space The proposed Precise Plan would designate 3.1 acres of Habitat Conservation Plan (HCP) open space azea within the Phase II residential site's development areas (downhill from the unincorporated HCP area of the Terrabay site and from the San Bruno Mountain State and County Pazk). HCP open space includes azea on spur ridges which separate neighborhoods and on upper slopes of the site's development areas. The Precise Plan contains an HCP Restoration Plan for the HCP open space areas to be implemented after grading and slope stabilization activities. The HCP Restoration Plan would primarily cover on- site HCP open space but also would extend onto some off-site HCP open space where the proposed limits of grading would occur beyond the Terrabay development azea boundary. Grading (described below) and subsequent restoration would extend beyond the Terrabay development area boundary of both the Phase II and III sites (and of all neighborhoods). The purpose of the HCP Restoration Plan would be to control erosion, create fire breaks between San Bruno Mountain open space and the Terrabay development areas, and restore or recreate habitat critical to protected butterfly species. 58 The HCP Restoration Plan consists of techniques to prepare the site (to test and augment soil), identifies plant materials and seeding activities (including the use of seeds gathered from San Bruno Mountain), and describes short-term monitoring and long-term maintenance requirements (including eradication of invasive plant species). After restoration, the HCP open space would be dedicated to San Mateo County as permanent open space upon completion of respective residential and commercial development. 56 This archaeological site, CA-SMa-40, is fully described and analyzed in 4.9 Cultural Resources. The Vesting Tentarive Subdivision Map indicates that proposed Pazce1226 would be 2.02 acres in size, part of which would be designated as a park and part is proposed as private easements for parking and utilities, although other application materials - Park at San Bruno Mountain Indian Mullen, Terrabay, South San Francisco, op. cit., July 1997 -propose designating a 2.5-acre park at the site. The archaeological site itself is two acres in size. 57 Park at the San Bruno Mountain Indian Mullen, Terrabay, South San Francisco, California describes landscape and interpretive elements proposed to be developed on top of the "working surface", including native plane, a crush rock path, granite boulders, and signs. 58 The Habitat Conservation Plan Restoration Plan is fully described and analyzed in 4.3 Biology. 52 2.0 PROJECT DcSCRIPTiON Terrabay Phase 11 and Ill SE1R Public Facilities and Utilities Project implementation would involve construction of water, sewer, and storm drainage facilities and installation of utilities (gas, electricity, telephone, and cable television facilities) as originally provided by the 1996 Specific Plan. Water Water supply would be delivered throughout the Phase residential II site via eight-inch diameter water lines installed in roadway rights-of-way. Service would be provided to each unit from its fronting street. Although the Precise Plan does not illustrate the water delivery system within the Phase III commercial site, on-site distribution is proposed to generally follow the internal roadway network and be extended to individual buildings as pazcels aze developed. 59 Sanitary Sewer On the Phase II residential site, wastewater would be collected from most lots by six- inch diameter sanitary sewers proposed to be located in roadway rights-of--way. For downslope lots which would not extend through to streets, sanitary sewers are proposed along reaz yazd property lines in easements (48 lots) or would extend through adjacent "master association slopes" to downhill connections in South San Francisco Drive (43 lots). 60 Sewer laterals would connect to the public sewer system either duectly or via a private gravity flow collection system. On the Phase III commercial site, aten-inch diameter sanitary sewer would be built across proposed development parcels, rather than along the internal roadway right-of--way, and would flow from north to south. Individual parcel developers would extend laterals to serve new buildings as constructed. At the archaeological site located between Parcels E and F (CA-SMa-40), the sanitary sewer is proposed to be installed above the existing surface in fill material (the proposed "workable surface"). Farther south, the proposed sanitary sewer would be constructed in the right-of--way of Bayshore Boulevazd, as realigned, and would connect to existing wastewater facilities located at the Bayshore Boulevard / Airport Boulevard /Sister Cities Boulevazd /Oyster Point Boulevard intersection. Stormwafer Drainage Implementation of Phase I residential development involved initial construction of shared storm drainage facilities on parts of the Phase II residential site, including a major trunk line, subarea collection lines, culverts, inlets, and concrete-lined V-ditches. Development of the Phase II site would involve installation of six debris basins and local collection and conveyance facilities to be connected to the previously built trunk line. Six debris basins aze proposed on the Phase II site, including two in the Point, one in the Commons, and one in the Woods West subazeas. Two other debris basins aze proposed in the Woods East subarea within the proposed "limits of 59 Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flahetty, op. cit., January 25, 1998. 60 The Precise Plan shows rear yard easements for proposed Point lots 1-28, Woods East lots 39-50, and Woods West lots 374. (A single sanitary sewer accommodating all proposed Point lots would cross the linear park to connect to areawide wastewater facilities.) The Precise Plan appears to show (and the Vesting Tentative Subdivision Map shows) downhill connections across "master association slopes" from proposed Commons lots 1-4, Woods East lots 1-19, and Woods West lots 1-20. 53 2.0 PROJECT DESCRIPTION Terrabay Phase ll and 111 SE/R grading" but on County land outside the site development area. include open two- to three-foot wide concrete-lined ditches neighborhood development areas, 12-inch diameter subsurface rights-of--way (augmented by roadway surface v-ditches) or swales. 62 61 Additional new facilities would at grade azound the perimeters of storm drain lines installed in street rear-yard easements, and rocked Development of the Phase III site would involve construction of four debris basins, two of which would be located upslope from proposed Parcel C (one northwest and one southwest of the commercial parcel) and six proposed ston~nwater collection lines and associated feeder lines ranging in diameter from 15 to 36 inches. 63 They include Lines H and I in the north, Line F-G in the middle (draining the two detention basins), and Lines A and B-C-D-E in the south parts of the site. Additional stormwater drainage facilities would be installed on individual pazcels with development of buildings, pazking, and landscaped areas and would be connected to Lines A through I, as appropriate. Proposed Lines A through I would connect to existing pipes and ditches which drain east to San Francisco Bay under Bayshore Boulevazd and U.S. 101. Surface flows from the realigned Bayshore Boulevard would drain to facilities located west of U.S. 101 and also would be directed under the freeway to the Bay. Utilities Joint energy and communications trenches would be constructed in roadway rights-of--way on both the Phase II and III sites for installation of electricity, gas, telephone, and cable television distribution facilities and extension to individual housing units and commercial buildings, as developed. In Phase II neighborhoods, connections to units would be made from fronting streets. No residential structures would lie built within the 150-foot wide PG&E power line right-of--way ~ on the Phase II site which crosses the Tetrabay Commons neighborhood (and contains six electric power transmission lines and an abandoned gas transmission line). Private streets and pazking in on-street pockets would be developed within the right-of--way under the power lines. No commercial structures would be built within the 40-foot wide San Francisco water pipeline easement 65 which crosses the northern end of the Phase III site between proposed Parcels A and B, although the internal roadway would be constructed over the easement near the right-turn in / right- turn out site access. The California Water Services Company pump station surrounded by the Phase III commercial site would remain in place. 61 According to BKF, the Precise Plan proposes six debris basins, as described above. However, the Precise Plan Grading Plan only shows headwall /retaining wall structures at two locations in the Point neighborhood and one in the Commons, without labeling them as debris basins. Precise Plan Grading Plan and Terrabay Project, South San Francisco, California, Letter to Allison Knapp, City of South San Francisco, from Janine O'Flaherty, op. cit., January 25, 1998. 62 Stormwater drainage facilities would be located in the same easements proposed for Point lots 1-28, Woods East lots 39- 50 and Woods West lots 37-44 to accommodate sanitary sewers. 63 According to BKF, the Precise Plan proposes four basins on the Phase III site. However, BKF's drainage report and plan sets only show two basins. Tenabay Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, op. cit., January 25, 1998. ~' PG&R Co. Tower Line Right Of Way (174 O.R. 153)(179 O.R. 426x185 O.R. 43). Terrabay Resubdivision of Parcels 1 & 2 Recorded in Volume 53 of Parcel Maps at Pages 82-83, Records of San Mateo County, op. cit. 65 City and County of San Francisco Pipe Line Easement (670 O.R. 173). Ibid 54 ~.Urriv~c~.~ L)CJl.l1/f'IIV~V Terrabay Phase 11 and ll1 SE/R The Precise Plan and Vesting Tentative Subdivision Map acknowledge the presence of other easements on the Phase III site, including the San Mateo County Drainage Easement and Cal Water ten-foot wide Water Main Easement, but indicate that the precise locations of several are "undeterminable". 66 Construcfion Activities and Project Phasing The Precise Plan contains grading plans, estimates the quantities of earthmoving, and identifies retaining wall location, height, and length for both the Phase II and III sites. Grading would be carried out for slope stabilization and site preparation and primarily would occur within the designated development azeas, although the mapped limits of grading would extend upslope into HCP open space azeas at specific locations. Grading Implementation of the Precise Plan would involve grading to stabilize slopes and prepare the site to install public facilities and utilities, build roadways and parking, and develop structures. The Precise Plan grading plan, showing the azea proposed to be disturbed, is presented in Exhibits 2.3-I4a through 2.3-I4c. 67 Grading would occur in locations previously disturbed by "rough" grading and also in parts of the site not previously disturbed by past grading operations. Some grading would extend beyond the development areas of both the Phase II and III sites, resulting in disturbance to 0.69 and 0.11 acres of the project site located on HCP open space uphill from the existing HCP fence. These azeas would be restored at completion of grading according to the project sponsor's HCP Restoration Plan and subject to review and approval by Thomas Reid Associates. 68 Phase II and III site development, construction of the hook ramps, and realignment of Bayshore Boulevard would result in cutting of approximately 1,224,000 cubic yazds of material and filling of 786,000 cubic yards of material (see Exhibit 2.3-I~. Of that total, Phase II residential site grading would involve approximately 854,000 cubic yazds of cut and 478,000 cubic yazds of fill for a net excess of 366,000 cubic yazds of material not used on-site which would need to be exported for reuse or disposal elsewhere. 69 Phase III commercial site grading would involve approximately 360,000 cubic yards of cut and 250,000 cubic yazds of fill for an excess of 85,000 cubic yards requiring off-site reuse or disposal. 66 These include the Crocker Estate Company and Spring Valley Water Company Pipe Line Easement (390 OR 139), Spring Valley Water Works Pipeline Easement (54 deeds 189), Spring Valley Water Works Pipeline Easement (37 deeds 356), City and County of San Francisco Pipeline Easement (887 OR 276), and City and County of San Francisco Main Easement (702 O.R. 352). Terrabay Phase 11 & 111 Vesting Tentative Map and Preliminary Grading Plan, January 15, 1998. 67 Site disturbance by grading for site preparation and landslide repair is described and analyzed in 4.I Geology, Soils, and Seismicity. Secondary effecu of grading on hydrology, biology, and other site conditions are addressed in the respective sections in Chapter 4 of this of this 1998 SE'IR. 68 Restoration would be subject to review and approval for HCP conformance by Thomas Reid Associates (the City, County, and USFWS HCP monitoring consultant). The project sponsor reportedly is preparing plans to demonstrate that proposed grading of the Phase II and III, combined with a relocation of the existing HCP fence, would result in a net increase in HCP land to be dedicated for inclusion in San Bruno Mountain County Park. However, application materials currently do not reflect an HCP fence change. 69 prior plans for Phase II site development envisaged use of excess fill material on the Phase III site, but the grading plan for the Phase III site would also produce an excess of fill, thus making both the Phase II and III sites net exporters of fill. Terrabay Project, South San Francisco, California, Letter to Allison Knapp from Jan O'Flaherty, op. cit. 55 2.0 PROJECT DESCnrr~TlON Terrabay Phase /l and !ll SE/R An off-site location for reusing or disposing of excess material has not been identified. However, excess material removed from the Phase II site would be transported to a receiving site via South San Francisco Drive and Sister Cities Boulevazd and from the Phase III site via Bayshore Boulevazd. Beyond those points, the haul route would not be known until the destination is identified. After grading, finished cut or filled slopes on either the Phase II or III sites would have maximum slopes of 2:1 (horizontal distance to vertical rise), except in rock cut areas where maximum slopes would be 1.5:1.70 According to the Precise Plan, other exceptions include 1.5:1 slopes in soils on the Commons and Woods East subareas of the Phase II site and on the Phase III site. 71 Retaining Walis Retaining walls with heights ranging from less than four feet to 16 feet would be built on the Phase II residential site along or at ends of streets, at the debris basins, as debris deflection walls, and, in the Woods neighborhood, as property line retaining walls (of less than four to eight feet high). Retaining walls with heights ranging from less than four feet to 20 feet would be built on the Phase III commercial and Bayshore Boulevazd realignment sites. Phase III walls would be located on the private internal roadway, at the debris basins, and for debris deflection. Exhibit 2.3-16 summarizes proposed retaining wall heights by location in approximate linear feet. Phasing The project sponsor currently proposes to commence grading of both the Phase II and III sites immediately upon City approval, if approved, of the pending application and granting of necessary permits, and has identified a target date of June 1998 to begin implementing the project. On the Phase II site, the project sponsor proposes to complete site preparation, install roadways and facilities, and transfer lots in the Commons and Woods West neighborhoods by October 1998 for subsequent residential construction. Two residential developers would build housing units, SunStream in the Point and Commons neighborhoods and Centex Homes in the Woods neighborhood. Housing development is estimated to take place through two, possibly three, construction seasons. Completion and full occupancy of proposed residential development could occur by approximately the year 2000 or 2001.72 70 Ibid. 71 According to Eric McHuron (EIR geologist). 4.1 Geology, Soils, and Seismicity presents an analysis of proposed slopes. 72 This 1998 SEIR uses three horizon years to analyze traffic impacts -- years 2000, 2010, and 2020. The 2000 and 2010 time horizons were identified to analyze the Terrabay project, together with cumulative areawide development, and the year 2020 time horizon was selected for Caltrans' review of the hook ramps. These periods and the reasons for selecting [hem are described in detail in 4.4 Traffic and Circulation. 56 l.: r y r g~ ~;~• + ,r A f . ~' ~ (/ 1 i %, I r I ~ it 1 . 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'r ~ "' ~ !• IIiI~~~~I;~1I, I~ •, : ',rl' •,~ :,:) i ~' ,' l i,j liil lilt / r' ~, ~ i / ~ t ~ ! :t ''I 1''11!, I 1 1 11 ~ I jll 1 ~ 1/ lI Y''', (~ ' ~r'I~. _.... .. ... .. ..,_ , 11 ! 1' 1' l I I !,~ ~ F .. ..., a y 0 3 '. ~o- a N w v 2.0 PROJECT DE~CRIPT~ON Terrabay Phase lI and 111 SEIR Exhibit 2.3-15 ing Volumes a Cutting Filling Net b Shrink (Expand) ` Export (Import) d Phase Il Terraba Residential Site Point 573,000 275,000 298,000 (11,000) 309,000 Commons 66,000 14,000 52,000 2,000 50,000 Woods East 94,000 147,000 (53,000) (15,000) (68,000) Woods West 121,000 42,000 79,000 4,000 75,000 Total Phase II 854,000 478,000 376, 000 366,000 Phase 111 Terraba Commercial Site Total Phase III 360, 000 250,000 110, 000 25, 000 85, 000 Hook Ram sand Ba hore Boulevard Hook Rams 9,000 8,000 1,000 1,000 0 Ba shore Boulevard 1,000 50,000 (49,000) (5,000) (54,000) Total Roadw 10, 000 58, 000 (48, 000) (6, 000) (54, 000) Total 1,224, 000 786,000 438,000 397, 000 Source: Brian Kangas Foulk, February 20, 1998, and Parikh Consultants, Inc. (project sponsor's geotechnical consultant) a Estimated quantities in cubic yards. Terrabay Project, South San Francisco, Californra, Letter to Allison Knapp from Jan O'Flaherty, op. cit., January 25, 1998 (revised February 20, 1998). 4.1 Geology, Soils, and Seismicity presents an analysis of proposed site grading. b Excess of cut to fill without parentheses; (additional need for fill with parentheses). c Shrinkage and (bulking) or expansion of materials shown with and (without) parentheses, respectively. Assumes eight percent solid shrinkage of fill, thus decreasing the amount to be exported and two percent bulking of cut material. Terrabay Project, South San Francisco, California, op. cit., January 25, 1998 (revised February 20, 1998). d Ibid Exhibit 2.3-16 Retaining Walls a < 4 Feet 4-8 Feet &t2 Feet t2-16 Feet 16-2Q Feet Phase 11 Terraba Residential Site Site Retainin Wal ls • Point 180 170 40 20 0 • Commons 200 290 150 80 0 • Woods East 2,050 1,370 350 10 0 • Woods West 790 200 0 0 0 Side Yard Pro a Lines • Woods East 6,540 20 0 0 0 • Woods West 3,000 200 0 0 0 Phase 111 Terraba Commercial Site Commercial Site 780 240 150 90 110 Ba shore Boulevard Roadwa ROW 1,800 490 750 600 90 Source: Brian Kangas Foulk (revised February 20, 1998) a Approximate length in linear feet of retaining walls with the height ranges given in vertical feet. b Site retaining walls, including walls at private streets, debris basins, and debris deflection walls. c Retaining walls within the realigned public road right-of--way (ROW). Depending on the exact location of Caltrans' future ROW, some of the retaining walls identified for the Bayshore Boulevard realignment may be located in Caltrans' ROW. 60 2.0 PROJECT DESCRIPTION Terrabay Phase 11 and Ill SE/R As of February 1998, the project sponsor had not identified developers to build commercial uses on the graded Phase III site. 73 The schedules for developing any of the seven commercial parcels would depend on when purchasers buy pazcels and obtain approvals from the City for their projects, in addition to the time required for site development. In the absence of a development schedule, this SEIR assumes buildout of the proposed commercial land uses by the year 2000 for analysis purposes, although the actual timing of development currently is only speculative. Property Owners' Associations and CC&Rs Approval of Tentative and Final Subdivision Maps for the Phase II and III sites would create residential and commercial development parcels plus additional land devoted to streets, parking, parks, and open space uses. Individual purchasers would own their respective residential units or commercial sites, and, except for land to be dedicated to public or quasi-public entities (such as for public streets or open space), remaining land would remain private and owned in common by "property owners' associations". As part of project implementation, the project sponsor would establish property owners' associations and finalize covenants, conditions, and restrictions (CC&Rs) to provide for long-term operation and maintenance of commonly owned land and facilities. The project sponsor proposes to establish two separate homeowners' associations for Phase II residential neighborhoods and a "master" association for the entire Phase II residential site. A commercial property owners' (or building owners') "master" association would be formed for the Phase III site. Of the homeowners' associations, one would be for Terrabay Woods, and the second would be for the combined Terrabay Commons and Points neighborhoods. 74 The homeowners' associations would own and maintain common area within the respective neighborhoods' development area, including private streets. 75 The overall "master" association for the Phase II site would own and maintain common open space area in all the residential neighborhoods, such as the linear park and "master association slopes". The building owners association for the Phase III site would own and maintain common area, including private streets and "master association slopes", and would maintain the park proposed on the azchaeological site (CA-SMa-40). Owners of individual commercial parcels would be responsible for maintaining their property. The property owners' associations would have long-term responsibility for administering and enforcing CC&Rs for their respective azeas and for maintaining common azeas (private roadways and parks). Membership in the property owners' associations would be mandatory with purchase of a residential unit or commercial parcel and would involve payment of requisite fees to operate the associations and maintain common azeas. The property owners' associations would be created and funded pursuant to California law covering such entities and would be managed professionally. CC&Rs, when adopted, would impose legally binding commitments on future property owners. Conditions contained in the CC&Rs would be a perpetual part of a property deed and would be transferred with the sale and resale of property to a new owner. Provisions of the CC&Rs would 73 The existing Development Agreement between the City and project sponsor requires implementation of the Phase III commercial project before construction on the Phase II residential site. The currently proposed sequence of development would necessitate the Development Agreement amendment requested by the pending application. 74 Letter to Nichols • Berman from James Sweenie, op. cit., October 1, 1997. 75 Letter to Nichols • Berman from James Sweenie, op. cit., November 6, 1997. 61 2.0 PROJtG~ DESCRIPTION Tetrabay Phase ll and Ill SE/R supplement and be in addition to the requirements of the City's zoning ordinance and any conditions of project approval. As of February 1998, the project sponsor had not submitted draft articles of incorporation for the property owners' associations or draft CC&lts to the City. PROJECT ENTITLEMENTS The project application requests a number of approvals from the City, including approval of a Precise Plan for the Phase II site, Vesting Tentative and Final Subdivision Maps for both the Phase II and III sites, Covenants, Conditions, and Restrictions for both sites, design review of Phase II site development, and grading permits for both sites. 76 The present application also requests the three required amendments to previous approvals summarized below. Specific Plan Amendment The proposed Speci, fic Plan amendment consists of changes to the Terrabay Specific Plan text, accompanying exhibits, and supplemental maps, as amended in 1996. These changes would be required in order to achieve consistency between the currently proposed Precise Plan for the Phase II site and the previously approved Terrabay Specific Plan. The amendment also contains changes to the Phase III site development concept described by the Terrabay Specific Plan but not yet defined in a Precise Plan. ~~ On the Phase II site, changes relate to the number of housing uniu and specific residential development components proposed (street and parking standards, building characteristics of housing units, such as floor area, heights, setbacks, etc.). On the Phase )>li site, changes relate to a different mix and intensity of commercial land uses (deleting some, adding some, and modifying other uses to be retained from the approved Terrabay Specific Plan). The specific changes are described in the previous pages of this Project Description, and the actual language of the proposed amendment is contained in the 1998 Specific Plan Amendment, an edited ("redlined") version of the Terrabay Specific Plan. 78 The amendment is required because proposed project refinements contained in the Precise Plan changed the Phase II site development concept from that approved in the Terrabay Specific Plan. State planning law requires precise plans to be consistent with applicable specific plans while 76 Permits and approvals required by other agencies are identified at the end of this chapter (see 2S Administrative Actions). ~~ The hierarchy of public plans from general plan to specific plan to precise plan represents increasing refinement and a progression of greater more site-specific detail about individual development projects. These steps eventually lead to approval of site development and building permits and aze established by the City's Municipal Code. The Phase III site development concept currently is described in a specific plan level of detail. The project sponsor describes application materials as providing "horizontal precise plan" information and seeks approval of an "initial Precise Plan" for the Phase III site on the basis of that information, further proposing that "Supplemental Precise Plans" would be forthcoming in the future for Phase III site parcels. The Municipal Code has no provision fora "horizontal precise plan", "initial Precise Plan", or "Supplemental Precise Plan" and contains specific project application requirements for City consideration of a precise plan. 78 The 1998 Specific Plan Amendment is part of the project file and can be examined at the Planning Division, Ciry Hall, 400 Grand Avenue, South San Francisco during normal business hours. 62 2.0 PROJECT DESCRIPTION Terrabay Phase ll and 111 SE/R providing additional detail. The amendment is required for the Phase III site to accurately reflect the proposed development concept as now revised and to provide the basis for subsequent preparation of a Precise Plan. According to the project sponsor, the Precise Plan for the Phase II site alters the Terrabay Specific Plan concept in response to market demand for different housing products than the types previously approved for the project. The Phase III site development concept similarly was altered in response to changes in the South San Francisco market and also to lower the intensity of development in an effort to reduce project-generated peak hour traffic. Zoning District Amendment This proposed amendment consists of changes to Section 20.63, Terrabay Specific Plan District, of the City of South San Francisco Municipal Code. These changes would be necessary to comply with State law which requires consistency between public plans and zoning. According to State law, inconsistency between a plan and zoning due to an amendment of the plan must be corrected by amending the zoning ordinance. Thus, the amendment is designed to achieve consistency between the currently proposed Precise Plan development concept for the Phase II site and provisions of the Terrabay Specific Plan District, as previously adopted. The amendment also changes District provisions to enable development of the Phase III site as now defined by the Specific Plan Amendment. The actual language of the proposed amendment reflecting the changes described above is presented in the Modified Terrabay Specific Plan District, an edited version of the Terrabay Specific Plan District. Development Agreement Amendment This proposed amendment would revise the Developmens Agreement Ordinance to bring the existing agreement into conformance with the Terrabay Specific Plan and Terrabay Specific Plan District, as altered by approval of the two amendments described above. The proposed amendment would allow the City Council to authorize development of Phase II prior to development of Phase III if certain criteria are met. The existing ordinance provides for the simultaneous development of Phases II and III. City approval of the 1996 Terrabay Specific Plan extended the time period the Plan was valid for ten yeazs (until yeaz 2007). According to the 1996 Terrabay Specific Plan, approved Precise Plans lapse after five years if the City has not issued a building permit and / or construction has not commenced or proceeded with due diligence. 63 2.4 CUMULATIVE DEVELOPMENT EIRs are required to assess the effects of implementing a proposed project under existing environrriental conditions and under anticipated "cumulative" conditions. The State CEQA Guidelines require that, for an adequate discussion of cumulative impacts, the EIR must provide: • A list of past, present, and reasonable anticipated future projects producing related or cumulative impacts, including those projects outside the control of the lead agency or A summary of projections contained in an adopted general plan or related planning document which is designated to evaluate regional or areawide conditions Cumulative development assumptions were identified for consideration in this SEIR's focused analyses, primarily to assess the combined effects on local and areawide traffic from buildout of the Terrabay site together with other area development. Cumulative effects involved in consideration of other environmental factors are more discrete and individualized and are described separately, below. The major areawide land use assumptions used to conduct the 1998 SEIR analyses included: • Completion and occupancy of Terrabay Phase I residential development in South San Francisco • Development of the East of 101 area of South San Francisco according to assumptions which update the land use concepts contained in the East of 101 Area Plan • Development west of U.S. 101 in South San Francisco • Buildout of Brisbane according to the City's most intense General Plan land use scenario TERRABAY PHASE l BUILDOUT As of December 1997 when traffic counts were taken for this 1998 SEIR, 130 Phase I units had been completed and occupied, and, according to the project sponsor, 156 units were under construction or yet to be built. The cumulative assumptions identified for this SEIR include completion and occupancy of the remaining 156 units. EAST OF 101 AREA The East of 101 area refers to the predominantly commercial and industrial land located east of the U.S. 101 freeway within the City of South San Francisco. This area consists of four distinct subareas, including East of 101, Gateway, Oyster Point, and South Airport. The combined cumulative development assumptions used for this area in the SEIR are shown in Exhibits 2.4-1a and 2.¢Ib. City Planning Division staff identified the land uses and intensities shown for consistent use by several concurrent traffic analyses. Those include both this 1998 SEIR's traffic analysis and separate analyses conducted for the City and Caltrans on roadway improvements associated with the U.S. 101 Oyster Point Boulevard interchange "flyover" and Bayshore Boulevard hook ramps. 79 79 Traffic Operations Report for U.S. 101 /Bayshore Hook Ramps, CCS Planning and Engineering, Inc., February 1998. 64 2.0 PROJECT DESCR1PT10N Terrabay Phase ll and 111 SEIR WEST OF 101 AREA In South San Francisco west of U.S. 101, a number of specific projects have been approved or are anticipated. In addition, some redevelopment and development will occur in the future along the El Camino corridor and at the planned Hickey BART station. 80 BR/SBANE GENERAL PLAN BUILDOUT The City of Brisbane General Plan contains land use assumptions for aten-year time horizon (by yeaz 2004) and thereafter (beyond the ten-year period), with no specific buildout date identified and according to different of development scenarios. 81 Potential development upon buildout varies widely according to the different land use scenarios. The most intense, "Scenario K", could result in construction of 4,200,000 square feet of new building area in the Baylands. This 1998 SEIR's cumulative analyses assume the Scenario K land uses shown in Exhibits 2.¢Ia and 21.4-1b. OTHER REGIONAL GROWTH Additional development outside South San Francisco (and Brisbane) expected to occur during the time horizons identified for this 1998 SEIR would influence cumulative impacts attributable to the Tetrabay Phase II and III project. Such regional growth would contribute incrementally to azeawide ttaffic conditions and would result in increased traffic volumes, deterioration of service levels, longer peak periods, and concomitant changes in traffic patterns. In order to account for background traffic increases, this 1998 SEIR used a growth factor of two percent per year. This additional traffic is projected to travel eastbound on Hillside Boulevard from Daly City to U.S. 101. 8o This 1998 SEIR does not assume redevelopment projects previously identified by the City for the D Camino corridor which currently considered inappropriate there but assumes an increment of growth, as further described in 4.4 Tfaj~c and Circulation. 81 Mark Crane, Crane Transportation Group (SIIR traffic analyst), conversation with Carol Nelson, Planing Director, City of Brisbane, January 28, 1998. 65 2. u r'r~(~JECT DESGr~IPTIc:~ r Terrabay Phase Il and Ill SE1R Exhibit 2.41 a Year 2000 Cumulative Development Project Land Use Size South San Francisco - East of 101 Area a Bay West Cove Auto nation 20 acres Hotel 615 rooms Brittania Biotech R & D 127,000 s uare feet Ham ton Inn Hotel 100 rooms Gatewa Lot 9 Office 201,000 s uare feet Athena R & D 55,000 s uare feet Heidelber Site Hotel 280 rooms Gatewa Lot 2C Hotel 112 rooms Gatewa Lot 2B Office 50,000 s uare feet Trammel Crow R & D 105,000 s uare feet Point Grand Business Park Office 154,000 s uare feet MRF Office 14,500 s ware feet Light Industrial 100,000 s care feet Genentech Additional Em to ees 195 em to ees South San Francisco -West of i01 Chestnut Estates Sin le-famil detached residential 80 units Heather Heio is Sin le-fatnil detached residential 34 units El Camino Corridor Redevelo went Variety of uses. Does not include BART station b Year 2000 Brisbane Zone 1 Sierra Point Office 352,400 s uare feet Hotel 600 rooms Restaurant 8,000 s uare feet Zone 3 Southwest Bayshore Retail 4,300 s uare feet Office 1,200 Trade Commercial 7,400 s ware feet Zone 4 Brisbane Acres Sin le-family detached residential 5 units Zone 5 Central Brisbane Single-famil detached residential 38 units Sin le-famil attached residential 16 townhouse units Zone 8 Crocker Park Health club 2,500 s uare feet Retail outlet 2,500 s uare feet Restaurant 3,000 s uare feet Warehouse /Office 164,452 oss square feet ` Zone 9 Northeast Ridge Sin e-fatnil detached residential 87 units Sin le-famil attached residential 268 townhouse units Sin le-famil attached residential 214 condo / a artment units Zone 10 Northwest Ba shore Trade Commercial 168,000 s uare feet Zone 12 Baylands Ba lands retail 450,000 s uare feet Education / R & D 200,000 s uare feet a Route 101 Bmshore Hook Ramps PSR /PR Draft Traffic Operations Report, February 2, 1998, CCS Planning & Engineering, "Potential Development and Traffic Generation South San Francisco" (Table 6). b Crane Transportation Group (1998 SEIR traffic consultant), February 1998. c Brisbane 1993 General Plan, Trajj4c & Circulation Technical Memorandum, `°Trip Generation, 10-Year Development Scenario, Pti Peak Hour" (Table 9B). d As of February 1998, one completed and four yet to be built. e Cif the 164,152 gross square feet, approximately 41,000 (plus or minus 25 percent) would be office space. f As of February 1998, 27 completed and 187 yet to be built. 66 2.0 PRQ/ECT DESCRIPTION Terrabay Phase /l and UI SE/R Exhibit 2.41 b Year 2001 to 2010 Cumulative Development Project Land Use Size ' South San Francisco - East of 101 Area a Bay West Cove Retail 209,660 care feet Hotel 610 rooms Brittania Biotech R & D 43,000 s uaze feet Gatewa Lot 9 Office 201,000 s uaze fee[ Gatewa Lot 2B Office 50,000 s uaze feet King Ventures Hotel 165 rooms Office 20,000 s uaze feet Raiser Or anization Hotel 400 rooms Harbor Wa Parcels Office 225,000 s uaze feet Gallo Li ht Industrial 57,000 s uaze feet Maniaz Li ht Industrial 131,000 s uaze feet Fuller O'Brien R & D 296,000 s uaze feet Genentech Additional em to ees 650 em to ees South San Francisco - West of 101 El Camino Corridor Redevelo went Area Variety of uses. Includes Hickey BART station Summerhill Homes Sin le-famil detached residential 160 units Brisbane Zone 1 Sierra Point Retail 42,000 s uaze feet Office 1,294,590 s uaze feet Hotel 500 rooms Zone 3 Southwest Bayshore Retail 30,700 s uaze feet Office 2,300 s uaze feet Trade Commercial 59,100 s uaze feet Zone 4 Brisbane Acres Sin le-famil detached residential 205 units Zone 5 Central Brisbane Sin le-famil detached residential 101 units Zone 10 Northwest Ba shore Trade Commercial 60,000 s uaze feet Zone 12 Baylands Retail 1,550,000 s uaze feet Office 500,000 s uaze feet R & D /Educational 490,000 s uaze feet Restaurant 75,000 s uaze feet Hotel 2,000 rooms a Route 101 Bayshore Hook Ramps PSR / PR Draft Traffic Operations Report, February 2, 1998, CCS Planning & Engineering, `Potential Development and Traffic Generation South San Francisco" (Table 6). b Crane Transportation Group (1998 SEIR traffic consultant), February 1998. c Brisbane 1993 General Plan, Traffic & Circulation Technical Memorandum, `°Trip Generation, 10-Year Development Scenario, PM Peak Hour" (Table 9B). 67 2.0 PROJECT DESCRIPTION Terrabay Phase ll and !!1 SE/R 2.5 ADMINISTRATIVE ACTIONS The proposed project would require multiple development permit applications from the City of South San Francisco and a number of other responsible agencies, all identified below. From the City'of South San Francisco, the following approvals must be received before any aspect of the project described in this 1998 SEIR can be implemented: • Approval of the proposed 1998 Terrabay Specific Plan Amendment to reflect the revised development program, including land uses and development standards envisaged on the Phase III site, and development standards, including residential building design, provision of parking, and utility specifications for the Phase II site, presented by and consistent with the proposed Precise Plans. • Approval of the proposed Precise Plan for construction of attached duplexes, attached triplexes, and detached housing units (a total of 348 units), development of internal roadways and parking, and installation of utilities on the Terrabay Point, Commons, and Woods neighborhoods on the Phase II project site. • Approval of Vesting Tentative and Final Subdivision Maps for the Phase II and III sites to create 294 parcels, comprised of 2S4 residential parcels (47 parcels each developed with three triplex units, 72 parcels each developed with one duplex unit, and 13S parcels each developed with one detached unit), seven commercial parcels, seven commonly-owned parcels for internal circulation, and 26 commonly-owned parcels for landscaping and open space. • Approval of an amendment to the Tertabay Specific Plan District in the Municipal Code (Zoning) in conformance with the 1998 Terrabay Specific Plan Amendment, including to sections 20.63.030(x), 20.63.OS0(a), 20.63.070(d)(1), 20.63.080(A)(1) and (B)(3), 20.63.120(E)-(1), and 20.63.140. • Approval of an amendment of the Development Agreement originally approved in 1988 and extended in 1996 to represent changes in the land uses proposed in 1998 and changes in project phasing. • Approval of Covenants, Conditions, and Restrictions (CC&Rs) for all Phase II and III site components. • Design review by the Design Review Board (DRB) with respect to architecture and landscaping. The DRB is an advisory body to the City's Chief Planner. • Grading permits for the Phase II and III sites. • A fording of compliance with the HCP as required by the original U.S. Fish and Wildlife Service (USFWS), San Mateo County, and City of South San Francisco HCP agreement and imposition 68 2.0 PROJECT DESCR/PT/ON Terrabay Phase I/ and /ll SE/R of conditions required by the agreement and Section (l0a) Permit of the Federal Endangered Species Act (FSA). 82 The City of South San Francisco cannot take action to approve, conditionally approve, or deny any of these pending requests until the City Council certifies the Fina11998 SEIR as complete in compliance with the California Environmental Quality Act (CEQA). The City's environmental review procedures before cert~cation of the SEIR involve the following steps: • This Draft 1998 SEIR is being circulated publicly for review and comment_ • The City Planning Commission will hold a public hearing(s) at which time individuals can comment on the adequacy of the Draft 1998 SEIR (see I.4 Introduction). • The Final 1998 SEIR -consisting of all comments received on the Draft 1998 SEIR together with responses to those comments -will be circulated publicly for review. • The City Planning Commission will hold a public hearing(s) on the adequacy (the completeness) of the 1998 SEIR for decision-making purposes. • When the Planning Commission is satisfied that the Final 1998 SEIR is complete, it will recommend that the City Council "certify" the Fina11998 SEIR. • The City Council will hold a public hearing(s) to certify the Fina11998 SEIR. During Planning Commission consideration of the 1998 SEIR, it also will consider the merits of the project and ultimately will recommend certification of the EIR and action on the project. Then the City Council will certify the 1998 SEIR, consider the merits of the project, and approve, conditionally approve, or deny the applications listed above. Although the Commission and Council, each in turn, can consider the EIR and project merits simultaneously, no final action can be taken on the permit applications until after the City Council certifies the EIR. The City will follow its normal notification and hearing procedures for both Planning Commission and City Council action. The following responsible.. agencies have discretionary jurisdiction and approval authority for the activities involved in implementing various aspects of the project. They would use this 1998 SEIR to make their decisions about the project and permits they have authority to grant. • City of Brisbane (Bayshore Boulevard relocation and hook ramp construction within the existing City boundary) • California Department of Transportation (Caltrans) encroachment permit (hook ramps construction within the right-of--way of a State highway) • California Department of Fish and Game (CDFG) (State-listed special status species and wetlands) 82 Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan and Nichols • Berman conversation with Victoria Harris, Thomas Reid Associates, op. cit., February 1998. , 69 20 PROJECT DESCRIPTION Terra6ay Phase /l and 111 SE1R • San Francisco Bay Regional Water Quality Control Board (RWQCB) approval of a Stormwater Pollution Prevention Plan (SWPPP) incorporating "best management practices" (BMPs) to control erosion from the project. _ • Bay Area Air Quality Management District (BAAQMD) • U.S. Army Corps of Engineers (Corps) (wetlands) • U.S. Fish & Wildlife Service (USFWS) (Federal-listed special status species) as reviewed for compliance with the HCP by Thomas Reid Associates (the USFWS, City, and County HCP consultant /Plan Operator). Compliance reports submitted to the USFWS (plus the CDFG and County) must identify: 83 The final location of the HCP fence The project's proposed restoration plan Relevant CC&R sections (such as those relating to pesticide use) San Mateo County Airport Land Use Commission with respect to project compliance with the County Airport Land Use Plan. 83 Ibid. 70 --3.0 SUMMARY OF FINDINGS 3.0 SUMMARY OF F1ND/NGS This section summarizes the findings of this 1998 SEIR. It highlights the project's effects and identifies the alternatives studied. The proposed project includes residential development on the Terrabay Phase II site, a commercial development concept for the Terrabay Phase III site, and redevelopment of existing and development of new transportation facilities on the west side of U.S. 101. The Terrabay project proposes immediate development of 348 housing units (72 attached duplexes, 141 attached triplexes, and 135 detached units) on the Terrabay Phase II site and future construction of 343,000 squaze feet of commercial building area on the Terrabay Phase III site. The project application consists of requests to amend the existing Terrabay Specific Plan and Terrabay Specific Plan District in relation to both the Phase II and III sites, approve a new Precise Plan for the Terrabay Phase II site, and associated actions (approval or amendment of vesting tentative and final subdivision maps, development agreement, CC&Rs, design review, and grading permits): The U.S. 101 southbound hook ramps and Bayshore Boulevard realignment project proposes reconstruction of the existing southbound off-ramp (scissors ramp), construction of a new southbound on-ramp, both connecting U.S. 101 and Bayshore Boulevard, and the relocation and reconstruction of a segment of Bayshore Boulevard along an alignment west of the existing roadway on the Terrabay Phase III site. Approval of the Phase II development project would result in grading, road building, and installation of utilities by the project sponsor and site owner, SunChase G.A. California I, Inc., beginning immediately followed by home building by Centex Homes (135 detached units) and SunStream (213 attached units) commencing in October 1998. Completion and full occupancy is expected by approximately year 2000 or 2001. Approval of the Phase III development concept would result in immediate grading of building pads by SunChase for eventual development by future purchasers of individual commercial parcels. The timing of commercial development is not known, but this 1998 SEIR analyzes combined buildout of the Terrabay Phase II and III sites under both year 2000 and 2010 conditions. All aspects of the proposed project are described in 2.3 Project Description. Exhibit 3.0-I, presented at the end of this chapter, summarizes the project's environmental effects. A detailed discussion of the impacts in found in Chapter 4.0 Environmental Setting, Impacts, and Mitigation Measures. The following levels of significance were used to identify impacts in the summary table (Exhibit 3.0-I) and elsewhere in this 1998 SEIR: Significant Unavoidable Impact (SU) A significant (or potentially significant) impact which cannot be avoided with mitigation. These include impacts which could be partly mitigated but could not be reduced to aless-than-significant level. When the symbol "SU" is used, it indicates that the impact would be sign~cant both before and after mitigation. (A potentially significant impact is identified when not enough information is known to determine if the impact would be significant.) ~i 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SEIR Significant Impact (S) A significant (or potentially significant) impact which can be mitigated to ales-than-sign~cant level. The symbol "S" denotes that the impact would be significant before mitigation but that mitigation would be effective in reducing the magnitude of impact to a less-than-significant level (LTS). (As noted above, a potentially significant impact is identified when not enough information is known to determine if the impact would be significant.) Less-than-Significant Impact (LTS) A change or effect directly or indirectly attributable to the project which would not exceed the threshold(s) of significance. When the symbol "I.TS" is used, it indicates that the impact would not be significant and would not require mitigation, although mitigation could decrease less-than-significant project effects even further (or avoid such effects altogether). Each topical analysis in Chapter 4 lists the thresholds and criteria used to determine significance of impact. 3.1 SIGNIFICANT UNAVOIDABLE IMPACTS The 1998 SEIR ident~es the following significant unavoidable (SL1) impacts which could not be eliminated to reduced to aless-than-significant level through mitigation measures required by the SEIR. The impacts are described in detail in Chapter 4. Numbers in the margin refer to the Chapter 4 impact discussions and also are crossed referenced with Exhibit 3.0-1. 4.4-13 Year 2020 Hook Ramps Impact on Freeway Mainline 4.4-14 Year 2020 Hook Ramps Impact on Freeway Ramps 4.5-3 Changes in Regional Long-Term Air Quality 3.2 SIGNIFICANT IMPACTS The 1998 SEIR ident~es the following significant (S) (or potentially significant (PS)) impacts which could be reduced to ales-than-significant level by implementing mitigation measures required by the SEIR. These impacts also are described in detail in Chapter 4, according to the numbers in the margin, and presented in Exhibit 3.0-I. 4.1-2 Slope Stability /Erosion 4.1-3 Landsliding and Debris Slides 4.1-4 Rockslides and Rock Falls 4.1-5 Art~cial Fill 4.1-6 Secondary Effects of Seismic Shaking 4.1-7 Hook Ramps and Bayshore Boulevard Realignment 4.2-1 Stormwater Drainage Patterns and Flooding (streets) 4.2-2 Stormwater Drainage Patterns and Flooding (yards) (potentially significant) 4.2-3 Stormwater Drainage Patterns and Erosion and Sedimentation 4.2-4 Flooding (commercial site) (potentially significant) 4.2-5 Stormwater Drainage Patterns and Flooding (commercial site with hook ramps) (potentially significant) 4.2-6 Erosion and Sedimentation (concrete to earth-lined channels) 4.2-7 Erosion and Sedimentation (unnecessary grading) 4.2-8 Erosion and Sedimentation (regrading) ~z 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SEIR 4.2-9 Erosion and Sedimentation (unprotected roadways) 4.2-10 Erosion and Sedimentation (facility connections) 4.2-11 Erosion and Sedimentation (commercial site debris basin) (potentially significant) 4.3-1 Vegetation Removal, Wildlife Habitat Loss, and Landscape Compatibility 4.3-2 Impacts on Special-Status Species . 4.3-3 Loss of Jurisdictional Wetland Habitat 4.4-1 Yeaz 2000 Base Case plus Phases II + III Freeway Impacts 4.4-2 Year 2010 Base Case plus Phases II + III Intersection Impact 4.4-3 Year 2010 Base Case plus Phases II + III Intersection Impact 4.4-4 Year 2010 Base Case plus Phases II + III Freeway Impact 4.4-5 Year 2010 Base Case plus Phases II + III Ramp Impacts 4.4-6 Roadway Width 4.4-8 Residential Parking Dimensions 4.4-9 Overflow Parking 4.4-10 Potential Commercial Parking Supply Shortfalls 4.4-12 Potential Storage Distance Deficiencies Between Intersections 4.5-1 Short-Term Construction Impacts (potentially significant 4.6-1 Construction Noise Impacts 4.6-2 Land Use Compatibility Impact 4.7-4 Impact on Police Communications 4.8-1 Soil Contamination by Aerially Deposited Lead 4.9-1 Damage to CA-SMa-40 4.9-2 Indirect Impacts on CA-SMa-92 (potentially significant) * 4.4 Traffic and Circulation indicates that the severity of Impacts 4.4-1, 4.4-4, and 4,4-5 could be reduced to less-than-significant levels with implementation of mitigation measures identified by this 1998 SEIR. The mitigation measures would require reduction of the proposed development, in some cases up to 85 percent. However, without mitigation, the impacts would remain significant and unavoidable. 3.3 LESS-THAN-SIGNIFICANT IMPACTS As discussed in the Introduction, the City determined the scope of the 1998 SEIR through a process beginning with preparation of an Initial Study /Environmental Checklist which identified a number of topics for analysis in this SEIR. Responses to the Notice of Preparation (NOP) further refined the scope of the SEIR, as did comments made during the public scoping meeting and workshop held for the SEIR. The following topics were selected for analysis, but, upon closer examination, their effects were found to be less-than-significant (I..TS). This list only includes effects of the project which would require no mitigation whatsoever and excludes significant effects which could be reduced to less-than-significant levels through mitigation. (Those impacts aze listed in 3.2 Significant Impacts, above). 4.1-1 Grading 73 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SE/R 4.47 Turnarounds 4.411 Pedestrian and Bicycle Access and Trailhead Access and Parking 4.5-2 Changes in Local Long-Term Air Quality 4.6-3 Traffic Noise Impacts 4.6~ Traffic Noise Impacts from the Hook Ramps 4.7-1 Impact of Residential Development on Police Services 4.7-2 Impact of Commercial Development on Police Services 4.7-3 Combined Project Impact on Police Services 4.7-5 Traffic Impact on Police Response Times 4.7-6 Police Impact from Cumulative Development 4.7-7 Impact on Brisbane School District 4.7-8 Impact on Jefferson Union High School District 4.7-9 Impact on South San Francisco Unified School District 4.7-10 Cumulative School Impacts 4.8-2 Effect of EMF on Future Residents 3.4 ALTERNATIVES EVALUATED This 1998 SEIR examines the following five alternatives (Chapter 5, Alternatives to the Proposed Project): • The mandatory No Development Alternative assesses no development at this time and continuation of existing environmental conditions but does not foreclose development in the future. • The Existing Specific Plan Alternative evaluates buildout according to the 1996 Specific Plan, including development of 432 housing units on the Phase II site (181 Point, 47 Commons, and 204 Woods units) and 669,300 square feet of commercial use on the Phase III site (268,000 square feet of high technology, 57,500 square feet of office, 18,000 square feet of health club, and 5,000 square feet of restaurant space and a 400-room hotel). • The Phase ll Reduced Residential Development Alternative assesses construction of 316 housing units on the Phase II site (181 Point and 135 Woods units) and landscaping and development of previously graded parts of the Commons as a park. It does not assess the Phase III commercial site. • The Phase 111 Reduced Commercial Development Alternative examines development of 293,000 square feet of hotel, mixed-use, restaurant, and retail uses on 14 acres of the Phase III site, preservation of the archaeological site (CA-SMa-40), and construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevard. It does not assess the Phase II residential site. • The Phase /l/ Permanent Open Space Alternative assumes purchase of the Phase III site, permanent preservation, protection, and management of the archaeological resources, and, 74 3.0 SUMMAr?Y Or FfND~NCiS Terrabay Phase 11 and 11! SE1R possibly, low-impact trail use elsewhere on the site. It does not assess the Phase II residential site. The analyses conclude that a combination of the No Development Alternative on the Phase II site and the Phase III Permanent Open Space Alternative would be the environmentally "superior alternative". Of the development alternatives analyzed, implementation of the Phase II Residential and Phase III Commercial Development Alternatives would be environmentally superior. 3.5 AREAS OF CONTROVERSY The Impact Overview identifies areas of controversy and issues to be revolved. These include impacts on archaeological resources, impacts on biological resources, and geologic hazards (see 6.5 Areas of Controversy and Issues to Be Resolved). 75 Exhibit 3.ar Summary of Impacts and Mitigation Measures Impact a Mitigation Geology, Soils, and Seismicity 4.1-1 Grading Construction of the Phase II and III No measures would be required for grading per se within projects would require excavation of 57 additional acres of previously graded parts of Phase II and III site development natural lands. This grading would expose areas to erosion, areas. Moreover, grading which would not extend beyond decrease the stability of the bedrock and sediment cover, and the 50-foot minor boundary adjustment limit and 9.31-acre cause differential settlement in fills over drainages. The uphill of the HCP fence would comply with the Agreement impact of grading of new areas could not be avoided without with Respect to the San Bruno Mountain Area Habitat redesigning the project and reducing the size of development Conservation Plan, as required by the Terrabay Specific areas. Grading as proposed without mitigation would result Plan District, and, therefore, would not necessitate in significant erosion, slope instability, differential additional mitigation. In order for the project to be deemed settlement, and secondary impacts. LTS in compliance and to constitute ales-than-significant impact: • All grading plans and operations in the Terrabay Specific Plan District shall be in compliance with the provisions of the San Bruno Mountain Area Habitat Conservation Plan (Title 20 of the South San Francisco Zoning Code Section 20.63.020). In order to meet this requirement, disturbed land within this minor boundary adjustment limit shall be replaced through in-kind restoration. • No development proposal which requires a permit or an approval of any sort to be issued by any local, State, • or Federal agency may be approved by the City until proof of such other permit, license, or approval is on file in the Department of Community Development (Title 20 of the South San Francisco Zoning Code Section 20.63.250). Reducing the extent of grading involved in project implementation would help balance cut and fill operations and the need to export excess fill material for disposal (or reuse) at another location. Measures to mitigate direct erosion, slope stability, and differential settlement impacts are presented below (see Mitigation Measures 4.1-2 through 4.1-5), and measures to mitigate indirect traffic, air quality, and noise impacts are presented in the respective analyses. 4.1 2 Slope Stability/Erosion Cuts greater than ten (a) In order to reduce slope stability impacts to less-than- feet high, cuts in soil for proposed slopes with grades steeper significant levels, the project's proposed grading plans shall than 2:1 (horizontal:vertical), or cuts with bedrock grades be revised to incorporate the following: steeper than 1.5:1 could erode until vegetation is re- ' Slopes shall be laid back to provide grades no steeper established. These engineered slopes can erode locally, as experienced in Phase I where substantial grading was than 2:1 in soil and 1.5:1 in rock except in areas where completed during a drought and then abandoned during a rock is highly fractured and acts like soils in which period of above average rainfall. Proposed cut slopes, case slopes shall be laid back farther, rock bolts shall especially in soil, need to be protected from erosion before be installed, or retaining walls shall be constructed. In the rainy season. Unless a comprehensive winterization plan addition, subsurface drainage shall be installed. is implemented before the onset of winter rains, the erosion • Intermediate benches and accompanying drainage shall from the unvegetated slopes would be significant S be designed at vertical intervals of about 30 feet. a LTS = Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 76 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and /!I SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures /mpact a Mitigation Geology, Soils, and Seismicity -- Continued 4.1-2 Slope Stability/Erosion (continued) Perimeter type A-ditches shall be provided above cut slopes. • Slope and groundwater monitoring instruments (inclinometers, piezometers) shall be installed at the tops of cuts to monitor slope stability. If slopes cannot be laid back without encroaching beyond the 50-foot buffer (and in excess of 9.31 acres) in the HCP area, alternative mitigation to the above criteria include revising proposed grading plans to modify site design. Such modifications shall incorporate one or all of the following measures: • The location and / or height of retaining walls shall be shifted or raised. Retaining walls higher than ten feet shall not be designed as poured in place structures but shall provide step backs or cribs planted with vegetation and built with rough stone or earth colored materials. The project sponsor shall submit plans for retaining wall design for walls higher than ten feet for City review. • Grades of the site streets shall be increased wherever possible to reduce grading into the hill but in no case exceed 15 percent. Grades between 12 and 15 percent shall require approval by the City Engineer, as provided by the Terrabay Specific Plmt District. • Development shall be limited to lower site elevations to contain grading within development areas, thus reducing the total development area (and amount of development which could be accommodated). This measure tnay eliminate the uppermost four triplex lots (12 units) currently proposed in the Commons neighborhood or individual lots at street ends of any of the hammerheads proposed in Woods East. (b) As previously stipulated for Phase I, the City shall withhold building permits for development of lots located downhill of cut slopes until the slopes have experienced at least one average winter season. (c) As automatically required by the Regional Water Quality Control Board (RWQCB) and City of South San Francisco, all exposed slopes and surfaces (graded pads) shall be winterized before October 15 of the year. The Phase II and III winterization programs shall include such measures as: • Waddles, hydroseeding, silt fences, straw bales, and berms shall be placed around pads with contained (i e) dischar es. a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 77 3.0 SUhIhIRRY OF F/ND~hu Ten'abay Phase ll and 111 SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Geology, Soils, and Seismicity -- Continued 4.1-2 Slope Stabi/ity/Erosion (continued) • Streets shall be swept before (and truck access should be limited during) major storms. • Sandbag check dams shall be placed along gutters, and straw mats should be placed over storm inlets. • The grading site(s) shall be inspected prior to and durin¢ maior storms. 4.1-3 Landsliding and Debris Slides Landslides and debris slides are present within and above site development areas of the Phase II and Phase III sites. Without mitigation, continued movement would have significant impacts on proposed development. Large-scale grading operations likely would be necessary to repair unstable azeas. In addition to deep-seated landslides, the site has experienced impacts from shallow debris slides. Landslide repair techniques, similaz to those used during Phase I grading, would be necessary during grading proposed for the Phase II and III sites. If mitigation measures, including drainage, removal, deflection and / or retention structures, setbacks, debris basins, etc., aze not taken, future debris slides would have a significant impact on proposed development. S 4.1-4 Rockslides and Rockfalls Past cuts into the sandstone bedrock along the southern end of San Bruno Mountain often initiated major rockslides, such as large historic rockslides present north and northeast of the Phase III development area. Grading plans for the Phase II (Point) and III sites propose significant cutting into the sandstone bedrock along the southern end of San Bruno Mountain. As of February and March 1998, specific rock slope stability analyses had not been performed for the high rock slopes (a) The Precise Plan and Vesting Tentative Map grading plans shall be revised to incorporate the following: • Measures to mitigate active slide areas located in the Commons neighborhood and Phase III site and to mitigate cuts into active slides shall be incorporated into the project and include removing material, buttressing, and building retaining walls. • Locations shall be shown of all deflection and retaining walls as determined necessary by the City's Consulting Geologist. • Implementation shall include installation of monitoring instruments (inclinometers, piezometers). Measures shall adhere to the City's grading requirements listed in Impact 4.1-2 and can be achieved by using techniques listed in Mitigation Measure 4.1-2(a), including installation of slope stability monitoring instruments. (b) The project's Covenants, Conditions, and Restrictions (CC&Rs) shall establish and provide for implementation of a Slope Maintenance Plan by the project's Property Owners Associations (Owners Associations). The project sponsor shall provide initial funding for the Slope Management Plan, and the Property Owners Associations shall fund long-term implementation after receiving title to their respective private open space lands. At a minimum, the Slope Maintenance Plan shall provide for monitoring and maintenance of engineered slopes, perimeter drainage, debris slide retention, and deflection structures. (a) Project plans shall be revised to incorporate the specific measures identified by the detailed rock slope stability analysis of the orientation and spacing of rock defects and inspection of individual rock outcrops conducted by the project sponsor's geotechnical consultant. The revised plans shall identify individual measures or combinations of measures proposed for each rock slope, outcrop, and source azea to mitigate rockslide and rockfall impacts. Among measures for consideration are one or more of the following: a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 78 3.0 SUMMARY OF FINDINGS Tenabay Phase ll and Ill SE/R Exhibit 3.0-7 Summary of Impacts and Mitigation Measures Impact a Mitigation Geology, Soils, and Seismicity -- Continued 4.1-4 Rockslides and Rockfalls (continued) proposed on the Terrabay Point and Phase III sites, and application materials had not identified proposed mitigation. In addition, rock outcrops on and above the site pose potential hazards from rockfalls, especially if triggered by groundshaking in an earthquake. S Rockslide measures: • Flatter slopes shall be graded with benches, drainage ditches, and access for maintenance. • Rock anchors shall be installed. • Subdrains shall be constructed. • Geotechnical mitigation and revegetation shall be coordinated, possibly through design of benched terracettes. • Slope monitoring instrumentation shall be installed (inclinometers, piezometers etc.). Rockfall measures: • Loose rocks shall be scaled off, • Netting shall be placed around features to encapsulate and prevent material from moving. • Simple retention structures (fences) shall be built below outcrops and above cut slopes. (b) The project sponsor shall include annual inspection of outcrops before each rainy season and after significant seismic shaking in the Slope Maintenance Plans (i.e., CC&Rs) identified in Mitigation Measure 4.1-3(b) for implementation by the respective Property Owners Associations. The City shall review, modify as necessary, and anarove the CC&Rs. 4.1-5 Artificial Fil/ Differential settlement from placement of deep fill, unconsolidated fill, or artificial fill at variable thicknesses can damage structures, roadways, and utilities developed on or in the fill material. Compression from placement of fill on the archaeological site would damage those resources (a direct archeological impact) and potentially disruptor damage facilities developed in or on the fill (an indirect geologic impact). S (a) The Precise Plan shall be revised to indicate the measures proposed to mitigate differential settlement impacts expected from development in Terrabay Point on areas of deep or varied fills. These techniques shall be evaluated and used on a case-by-case basis and, when selected and implemented, shall be monitored to determine their effectiveness. One or a combination of the following approaches shall be incorporated into project plans: • Cuts shall be over-excavated to provide benches in the fill. • Rock 5ll shall be used in the deepest parts of canyons. • Fill shall be surcharged with excess material to accelerate settlement. • Development of areas most sensitive to settlement shall be postponed for a construction season. • The rate of settlement shall be monitored and development (including utilities, curbs, gutters, etc.) delayed until the rate of movement is within acceptable limits of the engineered structures. • Structures shall be placed on deep pier foundations. • Fill over the archeological site shall not be placed on a scarified or benched surface. a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 79 3.0 JUMhIAr~ r Gr ~utiviNGJ Terrabay Phase ll and 111 SEIR Exhibit 3.0-1 Summary ctf Impacts and Mitigation Measures Impact a Geology, Soils, and Seismicity -Continued 4.1-5 Artificial Fi/I (continued) 4.1-6 Secondary Effects of Seismic Shaking Given site geologic conditions, hazards to people or property from groundshaking (including liquefaction, lurching, and lateral spreading) could be mitigated to levels deemed acceptable in a seismically active region through compliance with Uniform Building Code standards and measures required to address other potential impacts on development. S 4.1-7 Hook Ramps and Bayshore Boulevard Realignment Construction of the proposed hook ramps and realignment of Bayshore Boulevard adjacent to [he Mitigafion • Construction activity on the archeological site shall be limited to small construction equipment. Measures selected shall be evaluated through monitoring of reference points, and development of the site, including roadways and utilities, shall be delayed until the amount of future settlement reaches an acceptable level, approximately one-half inch across the triplex lot. (b) The Precise Plan shall provide drainage both around the archaeological site to maintain depressed groundwater levels and under the cap to divert potential sewer leakage. During project implementation, care shall be taken to properly install a subdrain under the cap. This drain would prevent infiltration of rainwater and landscape irrigation from the Park from percolating through the site. The project sponsor's archaeologist shall be present during installation of project drainage facilities at the archeological site. Relocation of the sanitary sewer to the internal roadway right-of--way would eliminate the potential of puncturing the cap placed over the archaeological site. Stability analyses shall be conducted on representative slopes based on seismic loading and anticipated groundwater conditions to evaluate the need (if any) for special mitigation measures over and above standard engineering of the slopes in order to mitigate potential impacts on development from seismically induced landsliding and rockslidins. If the stability analysis identifies the need for special mitigation, Mitigation Measures 4.1-3 and 4.1-4 shall be revised to incorporate the additional seismic measuresrequired. These could include one or more of the following: • Keyways for fills shall be placed.through soft soils. • Flatter slopes shall be graded with benches. • Rock anchors shall be installed. • Subdrains shall be constructed. • Retaining walls shall be built to minimize fill over sensitive areas. • Buildings shall be designed in conformance with Uniform Building Code (UBC) Zone 4 and City standards. • Rockfalls shall be mitigated by removal, encapsulation, or fences (Mitigation Measure 4.1-4(a)). The following measures shall be requtred to mitigate impacts from construction of the hook ramps and Bayshore Boulevard realignment: a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 80 3.0 SUMMARY OF F1NDlNGS Terrabay Phase 1l and 111 SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Geology, Soils, and Seismicity -- Continued 4.1-7 Hook Ramps and Bayshore Boulevard Realignment (continued) Phase III Terrabay site would result in significant impacts, including erosion from removal of native vegetation; cutting into bedrock and cover sediments, filling over cover sediments (including soft compressible soils), and fill encroachment onto the azchaeological site. These impacts would require mitigation similar to measures identified for the Phase III site. S An erosion control plan shall be prepared and implemented during project construction in compliance with Regional Water Quality Control Boazd and City of South San Francisco requirements. The plan shall be implemented before the winter rainy season (by no later than October 15) and shall include such measures as: a Waddles, silt fences, straw bales, and bem~s shall be placed where the ground has been exposed by grading. Truck movements shall be limited during major storms. Sandbag check dams shall be placed along ditches, and straw mats should be placed over storm inlets. The site shall be inspected prior to and during major storms. • Engineered fill shall be surcharged to accelerate compaction before construction of roadway facilities in order to reduce potential impacts from settlement and avoid potential impacts from differential settlement. • Weak cover soils shall be over-excavated and replaced with benched and drained engineered fill. • Drainage shall be provided along the seepage azeas in the alluvial fan cover sediments. • Retaining walls shall be built to minimize the amount of fill over weak soils in the vicinity of the archaeological site. Hydrology and Drainage 4.2-1 Stormwater Drainage Patterns and Flooding Some of the streets proposed for construction on the Phase II site would be drained by concrete V-channels aligned between street travel lanes and pazking bays. This design would promote the occasional clogging of the channel with debris and induce minor flooded conditions along the central portion of the roadway. This would be a potentially significant impact. PS 42-2 Stonnwater Drainage and Flooding One percent slopes proposed for residential yards and rear yazd drainage swales in Phase II neighborhoods would allow sediment deposition in the swales, thus creating opportunities for nuisance flooding of rear yard or side yard areas. This would be a potentially significant impact. PS All street configurations shall incorporate this standard curb and gutter design with crowned roadway. Thus, currently proposed Phase II street configurations 1, 3, 4, 6, 7, and 9 shall be redesigned to eliminate the off-set drainage channel concept. Vesting Tentative Map and Preliminary Grading Plan Sheet 3 shall be amended to provide minimum rear yard and side yazd drainage Swale slopes of two percent in the Phase II development area in conformance with UBC standards. In addition, the conditions of project approval shall include appropriate oversight and / or controls on backyard paving a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 81 3.0 SUMMAr=rY OFFINDINGS Terrabay Phase ll and Ill SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Hydrology and Drainage -- Continued 4-2-2 Stormwater Drainage and F/oodit (continued) 4.2-3 Stormwater Drainage Patterns and Erosion and Sedimentation Absence of drain inlets on cut benches would permit runoff to flow onto an unprotected hillslope which could trigger hillslope erosion in the form of gully incision. This would be a significant impact. S by residents. These controls shall be included in the project's Covenants, Conditions, and Restrictions (CC&Rs) and enforced by the respective Homeowners Associations for each neighborhood The proposed grading plan shall be revised to provide for grading of the bench identified in the Commons neighborhood in order to direct runoff flows toward the inlet to the debris basin. 4.2-4 Flooding Benched concrete lined drainage channels on the Phase III site would convey surface drainage to a sump inlet with headwall not linked to the adjacent street storm drain system. This ultimately could cause some minor street flooding and would constitute a potentially significant impact. PS 4.2-5 Stormwater Drainage and Flooding Construction of the new U.S. 101 freeway access ramps in the vicinity of the existing southbound exit (scissors ramp) would occur in steepened soils also subjected to occasional ponding upslope of the 48-inch roadway culvert on the Phase III site. Ramp construction in the absence of proper upslope interception of shallow spring and seep dischazge could impair the stability of the freeway embankment. This would be a potentially significant impact. PS 4.2-6 Erosion and Sedimentation Higher velocity flows from steep concrete-lined channels into earth-lined ditches would erode and could also exceed the capacity of the downstream earthen reach. This would be a significant impact. S 4.2-7 Erosion and Sedimentat/on Unnecessary grading for culvert installation in the Woods East neighborhood would constitute a significant impact. S 4.2-8 Erosion and Sedimentation Regraded Commons neighborhood roadways left unpaved after project implementation could erode and generate downstream sedimentation. This would be a significant impact. S Vesting Tentative Map and Preliminary Grading Plan Sheet 17 shall be amended to included missing stone drain link in the storm drain design. Implementation of Mitigation Measure 4.2-5 would also be required as explained below. The project sponsor and City shall complete and implement proper geotechnical investigation of subsurface seepage conditions in the vicinity of the new freeway ramps. This could include borehole logging in the vicinity of the earthen ditch specified in the Vesting Tentative Map and Preliminary Grading Plan (Sheet 17), at the lower end of proposed commercial I..ot 220 (Pazcel F). If positi6ned at the proper elevation, this ditch could alleviate potential seepage pressures in the freeway ramp embankment. Vesting Tentative Map and Preliminary Grading Plan (Sheet 17) shall be revised to change the benched earthen channel segment to a rocked or concrete-lined channel. The channel also shall be redesigned with a higher capacity to accommodate some entrained sediments and rocky debris conveyed from the upstream concrete segment. Vesting Tentative Map and Preliminary Grading Plan Sheets 8 and 9 shall be revised to eliminate the storm drain segment in Woods East proposed on the contour bench of Lots G and J from the drainage and grading plan design. The existing dirt access roads aze located entirely within the limits of proposed grading. Therefore, both roads shall be removed According to the City Fre Marshall and the project sponsor's engineer, none of the roadways outside of paved subdivision streets would be required for fire access. In addition, where no regrading is proposed, the original hillslope topography shall be restored with no installation of artificial drainage facilities. Within the proposed slope regrading area, the regraded slope shall be slightly amended to allow for the roadway elimination. All regraded and restored hillslope areas shall be subjected to appropriate a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU = Significant Unmitigable 82 3.0 SUMMA~YOFF/ND/NGS Terrabay Phase ll and 111 SE1R Exhibit 3.a~ Summary of Impacts and Mitigation Measures Impact a - Hydrology and Drainage -- Continued 4.2-8 Erosion and Sedimentation (continued) 4.2-9 Erosion and Sedimentation Retaining unprotected roadways in the Point neighborhood after project implementation could yield substantial sediment volumes. This would be a significant impact. S 4.2-1 D Erosion and Sedimentation Drainage facility connections omitted from 171ots proposed in the Point neighborhood could result in localize erosion and downstream sedimentation if left unprotected. This would be a significant impacK. S 4.2-11 Erosion and Sedimentation Design of the southern Phase III debris basin and its diversion Swale could result in significant deposition of sedimentation which would reroute water discharge around or over the deposited material and trigger downslope erosion. This would be a potentially significant impact. PS Mitigation erosion control measures in conformance with an approved Stormwater Pollution Prevention Plan (SWPPP), as previously required by the 1996 SEIR. Two options are available to mitigate this erosion impact. With approval and monitoring by the San Bntno Mountain HCP coordinator, the applicant shall remove the entire length of any roadway which would daylight within the proposed limits of project grading. This option would include restoring original hillslope topography, revegetating restored slopes using native species, and implementing erosion control methods. This is the preferred option. The applicant shall regrade and maintain the existing unpaved roadways to protect them against erosion using fortified shoulder drainage ditches and frequent water bar construction. This is the inferior option. If this option is selected, the City shall require long-term monitoring by the entity overseeing debris basin performance. The first option would require an extension of the Stotmwater Pollution Prevention Plan (SWPPP) for the project which the 1996 SEIR previously required as a mitigation measure. Expansion of the SWPPP would consist of the designation of Best Management Practices (BMPs) for erosion control in the restored hillslope areas. This could include broadcast straw or other surface erosion protection, seeding or planting of native grasses and forts, and stockpiling of amendments to applied topsoil Vesting Tentative Map and Preliminary Grading Plan Sheets 15 and 16 shall be revised to add transitional storm drain links between outlet drains from proposed Point Lots 167B- 1758 to Line A. The project shall be revised to provide for installation of a third debris basin at the base of the steep reach of the middle channel. The retaining wall proposed as part of the project to extend north and south to the adjacent debris basins shall be redesigned to accommodate debris and water overflow from the new central basin. Inclusion of the third basin would reduce the collective long term costs of sediment / debris basin maintenance at the three sites through its more hydraulically efficient delivery characteristics. a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 83 3.0 SUMMARY OF FINDINGS Terrabay Phase 1l and 111 SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures I Impact a Mitigation Biology 4.3-1 Vegetation Removal, Wildlife Habitat Loss, (a) Areas of native freshwater marsh and riparian natural and Landscape Compatibility Grading associated with communities in the Phase III portion of the site shall be project implementation would require removal of existing vegetation and associated wildlife habitat in azeas proposed for development. Loss of non-native grassland would not be considered significant, but impacts on native freshwater marsh and riparian habitat and remnant stands of native grasslands would be significant. Proposed landscaping and restoration of graded slopes appear to be compatible with open space designations on parts of the site, but without a salvage component to the proposed restoration plan anticipated impacts would continue to be significant. S preserved to the greatest extent possible given the difficulty of recreating these natural community types and their importance as a source of surface water and protective cover for wildlife. Of greatest importance is the perennial spring at the southern edge of proposed Parcel C on the Phase III site which provides a permanent source of drinking water for wildlife. Preservation and in-kind replacement of these wetland-related habitat types shall be considered as part of the midgadon plan called for in Mitigation Measure 4.3-3(a). If preservation is determined to be infeasible, any replacement mitigation shall provide for creation of a permanent spring which replicates the flows from the perennial spring on the site. The replacement spring shall be located adjacent to the County open space lands to ensure accessibility to terrestrial wildlife populations on San Bruno Mountain. (b) The proposed Restoration Plan for the project shall be revised to include an additional component which provides for salvage of native plant material that otherwise would be eliminated as a result of grading and development Salvage shall be performed during the optimum period necessary to ensure plant survival, generally in the fall and early spring months, with material stored in a temporary growing area if necessary and eventually transplanted onto slopes where restoration is to occur following final grading and soil preparation. Any plant salvage operation shall be restricted to the limits of final grading to prevent the further loss of native species in permanent open space areas. (c) Any pedestrian trails linking the site with the open space lands of San Bruno Mountain preferably shall follow the alignment of existing fire trails to minimize disturbance to vegetative cover and shall avoid areas of native grasslands, freshwater seeps, and larval host plants for callippe silverspot butterfly. Final pedestrian trail alignments shall be approved by the Habitat Conservation Plan coordinator. 4.3 2 Impacts on Special-Status Species Except for callippe silverspot butterIIy and mission blue butterfly, no impacts on populations of other special-status plant and animal species area anticipated. While the San Bruno Mountain Habitat Conservation Plan (HCP) fully addresses potential impacts of anticipated development on mission blue, amendments to the HCP would be necessary for the recently listed callippe silverspot. Further loss of suitable habitat for callippe silverspot on the site would be a significant impact. S The project sponsor shall be required to fulfill the landowner / developer obligations identified by the San Brtoto Mountain Habitat Conservation Plan with respect to the site. If San Mateo County does not obtain an amended inadental take permit which includes callippe silverspot butterfly, the project must be redesigned to avoid all larval host plants. If the permit is amended to include callippe silverspot, the landowner shall incorporate any new permit conditions into the project. The following measures also shall be implemented to further minimize potential impacts of the project on the callippe a LTS =Less-than-Significant PS =Potentially Significant S = Significant SU =Significant Unmitigable 84 Ex3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase 1l and lp SE1R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Biology -- Continued 4.3-2 Impacts on Special-Status Species (continued) • project plans shall be redesigned to avoid disturbance to and development of areas supporting populations of the larval host plant (Viola pedunculata) to the greatest extent possible. Of particulaz concern is the population containing more than 1,000 plants in the northeastern comer of the Phase III site. IIimination of development in the vicinity of proposed Parcel A and a pazt of Pazcel B on the Phase III site would preserve the lazgest population and minimize impacts on the callippe silverspot • The proposed Restoration Plan shall be revised to include a component to salvage and transplant existing larval host plants and adult nectar plants (especially natives such as Monardella) which otherwise would be lost due to grading and development. Salvage material shall be used as part of a propagation program to reestablish larval host plants and adult nectar plants on restored slopes and in additional grassland habitat where they currently are absent. • Signs shall be prepared, in cooperation with the San Mateo County Pazks Department and HCP coordinator, and installed along trails and other appropriate locations warning park users against illegal activities (such as poaching). • Appropriate dust control measures shall be implemented as a component of the project's sedimentation and erosion control plans in order to minimize construction-generated dust (as required by Mitigation Measures 4.1-2(c) and 4.5-1). Measures shall include frequent watering of graded area, equipment, and haul roads to minimize dust and control its dis rsal. 4.3-3 Loss of Jurisdictional Wetland Habitat (a) The proposed project shall be redesigned to avoid Implementation of the project as proposed would eliminate jurisdictional wetland habitat to the maximum extent feasible. approximately two acres of jurisdictional habitat, including Of greatest concern is the freshwater seep habitat on the Phase areas of sensitive freshwater seeps, riparian habitat, and the ~ site particulazly the perennial spring at the southern end of perennial spring on the site. This loss of jurisdictional proposed parcel C. Grading and other disturbance shall be wetland habitat would be a significant impact of the project restricted within a minimum of 50 feet of the spring, and the S area shall be incorporated into proposed private open space lands of Parcel C to be preserved and maintained by the master building owners association established for the Phase III site. (b) If complete avoidance of jurisdictional wetlands is not feasible, a wetland mitigation plan shall be prepared by the ro'ect s nsor's wetland consultant to rovide for their . a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 85 Ex3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and ll/ SEIR Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Biology -= Continued 4.3-3 Loss of Jurisdictional Wetland Habitat replacement. The plan should provide for in-kind replacement (continued) of any wetlands lost as a result of development, preferably located on the Phase III site. The plan shall include the following details: • All plantings to be used as part of any replacement mitigation shall be restricted to native wetland, riparian, and adjacent upland species found on the site. • Site preparation and revegetation procedures, planting design, implementation schedule, and funding sources shall be defined to ensure long-term management of the overall wetland mitigation plan. • Performance criteria, maintenance and long-term management responsibilities, monitoring requirements, and contingency measures, if performance standards and mitigation goals are not met, shall be specified. Replacement habitat shall be monitored for a minimum of five years until all success criteria are met. • Before issuance of any grading or building permit for the project, the mitigation plan shall be reviewed and approved by the U.S. Army Corps of Engineers, California Department of Fish and Game, and Regional Water Quality Control Board subject to their authority under Section 404 of the Clean Water Act, Section 1603 of the California Fish and Game Code, and Section 401 Certification, respectively. (c) A detailed erosion and sedimentation control plan shall be prepared and implemented during construction on the site. The plan shall contain detailed measures to control erosion of stockpiled earth and exposed soil, minimize consttuction- generated dust, provide for revegetation of graded slopes before the first rainy season following construction, and specify procedures for monitoring •of the plan's effectiveness. The revegetation component of the plan shall be consistent with the revised Restoration Plan. Traffic and Circulation 4.4-1 Year 2000 Base Case p/us Phases ll + l/l The project sponsor shall reduce the amounts of Freeway Impacts Phase II and III traffic combined would development proposed within the Phase II and Phase III increase volumes by more than one percent on segmenu of sites and / or shall assist with funding for regional circulation U.S. 101 freeway already operating unacceptably at LOS F. system improvements. Based upon the freeway segments S receiving the biggest significant impact due to the project, • Southbound: north of the off-ramp to Bayshore Phase II + III trip generation would need to be reduced at Boulevard (AM=1.25 percent / PM 2.43 percent least 64 percent. increases), from the new Ba shore Boulevard on-ram a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 86 Ex3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SElR Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Traffic and Circulation -- Confinued 4.4-1 Year 2000 Base Case plus Phases 11 t 111 Freeway Impacts (continued) to the Dubuque on- ramp (PM=2.45 percent increase) and south of the Dubuque on-ramp (AM=1.66 percent increase) (Segments 1, 3 and 4 in Exhibit 4.4-2). • Northbound: from the Grand Avenue on-ramp to the Dubuque off-ramp (AM=1.71 percent / PM=2.76 percent increases), from the Oyster Point on-ramp to the Bayshore Boulevard off-ramp (PM=1.60 percent increase) and north of the Bayshore Boulevazd off- ramp (AM=1.65 percent / PM=1.75 percent increases) (Segments 5, 7 and 8 in Exhibit 4.4-2). Phase II and III traffic would change operation from LOS E to an unacceptable LOS F: Northbound: from the Oyster Point northbound on- ramp to the Bayshore Boulevard northbound off-ramp during the AM peak period (Segment 7 in Exhibit 4.4- 2). Southbound: from the Oyster Point southbound on- ramp to the Grand Avenue interchange during the PM Weak period (Seement 4 in Exhibit 4.4-2). 4.4-2 Year 2010 Base Case plus Phases II + l1l Intersection Impact AM peak hour Base Case operation plus project traffic would change operation from an unacceptable LOS E to an acceptable LOS D at the Sister Cities Boulevard /Bayshore Boulevazd /Airport Boulevard / Oyster Point Boulevard Intersection (a beneficial impact), but acceptable LOS D PM peak hour operation would change to an unacceptable LOS F. S The project sponsor shall provide a fair share contribution towazds restriping the southbound (Bayshore Boulevazd) intersection approach (to provide an exclusive right, a shared through / right, a through, and two left rum lanes) and construction of exclusive right-turn lanes on the eastbound (Sister Cities Boulevard) and westbound (Oyster Point Boulevard) intersection approaches. This latter measure would require widening of the Oyster Point Boulevard freeway overpass. Although individual intersection analyses would not necessarily indicate a need to widen the Oyster Point overpass, preliminary evaluation of coordinated operation between both the Bayshore /Oyster Point and Dubuque /Oyster Point intersections indicates the need for additional storage on the overpass. Based upon total traffic growth to 2010, the project's fair share contribution would be 21 percent of the improvement costs. 4.4-3 Year 2010 Base Case plus Phases ll t !II Intersection Impact Project Phase II + III traffic would change 2010 AM peak hour operation at the Oyster Point Boulevazd /Dubuque Avenue / U.S. 101 Northbound On- Ramp Intersection from an unacceptable LOS E to an acceptable LOS D (a beneficial impact) but would change acceptable PM peak hour LOS D operation to an The project sponsor shall provide a fair share contribution towards construction of a second exclusive right-turn lane on the westbound (Oyster Point Boulevard) approach and a second exclusive left-turn lane on the northbound (Dubuque Avenue) intersection approach. Both measures would require widening existing structures. Based upon total traffic growth to 2010, theproject's fair share contribution would a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 87 F.x3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase Il and l1l SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Traffic and Circulation -- Continued 4.4-3 Year 2010 Base Case plus Phases ll + 111 be five percent of the improvement costs. Intersection /m act (continued) unacce table LOS F. S 4.4-4 Year 2010 Base Case plus Phases Il and I/I Project sponsors shall reduce the amounts of development Freeway /mpact Phase II and III project traffic combined proposed within the Phase II and Phase III sites and / or shall would increase Base Case volumes by more than one percent assist with funding for regional circulation system on U.S. 101 freeway segments already operating improvements. Based upon the freeway segment receiving unacceptably at LOS F. S the biggest significant impact due to the project, Phase II + • Southbound: north of the off-ramp to Bayshore ~ trip generation would need to be reduced at least ~9 Boulevard (AM=1.10 percent / PM=2.09 percent percent. increases), from the new Bayshore Boulevard hook on- ramp to the Dubuque on-ramp (PM=2.19 percent increase) and south of the Dubuque on-ramp (AM=1.48 percent / PM = 2.00 percent increases) (Segments 1, 3 and 4 in Exhibit 4.4-2) • Northbound: from the Grand Avenue on-ramp to the Dubuque off-ramp (A,M=1.50 percent / PM=2.41 percent increases) from the Oyster Point on-ramp to the Bayshore Boulevard off-ramp (AM=1.34 percent / PM=1.39 percent increases) and north of the Bayshore Boulevard off-ramp (AM=1.46 percent / PM=1.51 percent increases) (Segments 5, 7 and 8 in Exhibit 4.4-2). 4.4-5 Year 2010 Base Case plus Phase /I + I/! Ramp The project sponsor shall reduce Phase II and III Impacts Phase II + III development combined would development trip generation. Approximately an 85 percent increase PM peak hour Base Case over-capacity operation by reduction in Terrabay trip generation would be required to 6.8 percent on the Northbound On-Ramp from Oyster Point reduce the project traffic impact to less than a 1 percent Boulevard. S increase. Alternatively, the sponsor shall provide a fair share contribution towards construction of a second on-ramp lane connection to [he U.S. 101 freeway. Based upon total traffic growth to 2010, the project's fair share contribution would be 12 ercent of the im rovement costs. 4.4-6 Roadway Width While roadways would conform The following mitigation will be required: to adopted standards, narrow 22-foot wide roadways raise . The Precise Plan shall be revised to provide minimum safety concerns, not for through movements but for 25-foot wide travelways on residential roadways interference with or by curbside activities. S (containing one 12.5-foot lane in each direction) in order to facilitate activities such as backing out of driveways and to improve safety and convenience for drivers exitin vehicles arked on-street. 4.4-7 Turnarounds Angled, hammerhead, and cul-de-sac No mitigation would be required. turnarounds proposed for the Phase II site would accommodate fire trucks. LTS 4.4-8 Residential Parking Dimensions Although the The parking dimensions for parallel parking, garage, and Precise Plan would conform to minimum arkin su 1 drivewa a rons shown on the Precise Plan shall be revised a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 88 Ex3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and l1l SE1R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Traffic and Circulation -- Continued 4.48 Residential Parking Dimensions (continued) to comply with Specific Plan and other applicable City requirements, dimensions of some spaces would be standazds. substandard. S 4.49 Overflow Parking Although the Precise Plan The Precise Plan shall be revised to provide overflow would conform to minimum pazking supply requirements, it pazking, consisting of six to eight spaces, within each does not provide for overflow pazking for use by visitors residential neighborhood. These spaces can be provided by attending parties or special events. S enlarging cul-de-sac bulbs, paving areas at the ends of hammerhead turnarounds, or eliminating one to two housing units adjacent to the street end (hammerhead or cul-de-sac). If housing units are eliminated, on-site parking should be monitored at regular intervals. If it is found that the amount of overflow parking provided is not required, then one or both of the remainin units could be constructed. 4.410 Potential Commercial Parking Supp/y The project sponsor or individual subsequent developers Shortfalls The currently proposed maximum Phase III shall submit pazking plan(s) for each of the proposed Parcels development concept would not provide sufficient parking A through G as pazt of an overall Phase III site Precise Plan for the types and amount of development presently or parcel-by-parcel Precise Plans to demonstrate compliance envisaged. S with minimum requirements and / or that shazed pazking would be adequate to accommodate uses proposed. The total amount of development proposed shall be reduced, if necessary, to an intensity which also can accommodate its r uired azkin su ly. 4.411 Pedestrian and Bicycle Access and No mitigation would be required. Trailhead Access and Parking Sidewalks, bike lanes, and a new trail would be provided with project implementation, but the project currently does not s ecificall rovide trailhead azkin .LTS 4.412 Potential Storage Distance Deficiencies Interconnected and coordinated signal operation and flow Between Intersections Queues would exceed available between these four closely spaced intersections along storage capacity at three to six intersections, depending on Bayshore Boulevazd shall be provided in order to preclude analysis methodology. S storage deficiencies. Due to right-of--way limitations along Bayshore Boulevard, provision of dual left-tum lanes is not considered feasible on the northbound approaches to the Terrabay Phase ID site driveways or on the southbound approach to the U.S. 101 southbound hook on-ramp. Also the northbound left-turn lane on the approach to the Terrabay North Access could not be lengthened without shortening the southbound left-tum lane on the approach to the U.S. 101 southbound on-ramp. Traffic volumes and queues shall be monitored at these intersections as development occurs on the Terrabay site to determine if the turn lane lengths and signal timing should be adjusted. 4.413 Year 2020 Hook Ramps Impact on Freeway No mitigation is feasible other than not constructing the Mainline Traffic from the new on-ramp would increase project. AM and PM eak hour volumes b more than one ercent on a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 89 Ex3-2.doc 3. C SUMMARY OF FINDINGS Terrabay Phase ll and 111 SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Traffic and Circulation -- Continued 4.4-13 Year 2020 Hook Ramps Impact on Freeway Mainline (continued) the U.S. 101 Freeway Southbound Mainline from the new southbound buttonhook on-ramp to the southbound on-ramp from Dubuque Avenue, a segment about 3,500 feet long that would already be experiencing unacce table LAS F o eration. SU 4.4-14 Year 2020 Hook Ramps Impact on Freeway No mitigation is feasible other than not to construct the Ramps Increased traffic due to the hook ramp project project. would increase AM peak hour off-ramp volumes by more than one percent at the diverge of the Southbound U.S. 101 Freeway Off-Ramp to Bayshore Boulevard where diverge traffic flow operation would already be an unacceptable LOS F. SU Air Quality 4.5-1 Short-Term Construction Impacts Dust The Bay Area Air Qualiry'~ianagement District (BAAQMD) generated during construction periods could result in both recommends the following measures for large construction health and nuisance effects. Although temporary, this would areas located near sensitive receptors. The BAAQMD be a significant impact. PS typically determines the level of significance based on the control measures implemented. These measures constitute all feasible control measures, with the addition of a disturbance coordinator to monitor compliance with the control measures and respond to neighborhood complaints. The disturbance coordinator shall be retained by the City and paid for by the project sponsor. The following controls shall be implemented throughout the construction area: • All active construction azeas shall be watered at least twice daily and more often when conditions warrant. T1us measure would reduce emissions by at least 50 percent. • All trucks hauling soil, sand. and other loose materials shall be covered, or all [rucks shall be required to maintain at least two feet of freeboard. • All unpaved access roads and pazking azeas at construction sites shall be paved, watered three times daily, or treated with (non-toxic) soil stabilizers. • All paved access roads, parking azeas, and staging areas at construction sites shall be swept daily (with water sweepers). • Streets shall be swept daily {with water sweeper) if visible soil tnaterial is carried onto adjacent public streets. • Inactive construction areas (previously graded areas inactive for ten da s or more) shall be h droseeded or a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 90 Ex3-2.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SE1R Exhibit 3,0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Air Quality 4.5-1 Short-Term Construction Impacts (continued) treated with (non-tonic) soil stabilizers. • Exposed stockpiles (dirt, sand, etc.) shall be enclosed, covered, watered twice daily, or treated with (non- toxic) soil binders. • Traffic speeds on unpaved roads shall be limited to 15 miles per hour (mph). • Sandbags or other erosion control measures shall be installed to prevent silt runoff to public roadways. • Disturbed areas shall be replanted with vegetation as quickly as possible (within one month of the disturbance). • Wheel washers shall be installed for all exiting trucks, or the tires or tracks shall be washed off all trucks and equipment leaving the site. • Excavation and grading activity shall be suspended when winds (instantaneous gusts) exceed 25 mph and cause visible clouds to extend beyond the construction site. Activities shall be suspended until the disturbance coordinator decides that the emissions from _ construction activities would be controlled (such as through additional watering or installation of wind fences). This measure could reduce dust emissions by up to 80 percent. • Wind breaks shall be installed, or trees /vegetative wind breaks shall be plant on windward sides(s) of construction areas, if conditions warrant, to prevent visible dust clouds from extending beyond the site. • The area subject to excavation, grading, and other construction activity shall be limited at any one time. • A disturbance coordinator, retained by the City and paid for by the project sponsor, shall be designated to be responsible for monitoring compliance with dust control measures and to respond to neighborhood concerns regarding air pollutant emissions (primarily dust) during constnrction. The project sponsor and coordinator shall be responsible for operating a neighborhood "hotline" for neighbors to voice com lainu re ardin¢ air uali durin construction. 4.5-2 Changes in Local Long-Term Air Qualify No mitigation would be required. Carbon monoxide levels attributable to traffic substantially affected by the project would be below State and Federal ambient air quality standards. This would be a less-than- si~nificant im act_ LTS a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 91 Ev-3.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SElR Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Air Quality -- Continued 4.5-3 Changes in Regional Long-Term Air Qualify Direct and indirect emissions of air pollutants associated with full buildout of the project could interfere with the efforts within the region to attain ozone and PM10 air quality standards. Thus, while the incremental change between the currently and previously proposed Phase II and III projects would be less-than-significant, the cumulative impact of full Terrabay project development (Phases I, II, and III) would exceed standards tightened since examination in the 1982 EIR and 1996 SEIR. SU Air pollutant emissions which would be regionally significant could be reduced from motor vehicles through a reduction in vehicle trips, vehicle miles traveled, and reduced traffic congestion. The following measures either are included in the project design or shall be implemented by the project sponsor to reduce regionally significant air pollutant emissions. • Coordinated traffic signals shall be installed to provide more efficient levels-of-service at intersections substantially affected by project traffic. The project includes roadway improvements to Sister Cities Boulevard which have already been constructed. Additional intersection improvements are proposed along Bayshore Boulevard as part of Phase III. This measure could reduce total year 2000 project emissions by ten (10) pounds per day of ROG, seven (7) pounds per day of NOx, and one (1) pound per day of PM~o. The U.S. 101 southbound freeway off ramp shall be reconstructed and a new U.S. 101 on ramp shall be constructed (the "hook ramps"). This measure would allow direct access on to the freeway, eliminating emissions associated with congestion at local intersections which provide access to southbound U.S. 101. This measure could reduce total year 2000 project emissions by five (5) pounds per day of ROG, sox (6) pounds per day of NOx, and seven (7) pounds per day of PM~o. Efficient transit service shall be provided to Caltrain, BART, the airport, and major employment centers. In the future, it is likely that BART and Caltrain would provide the most efficient access to downtown San Francisco, San Francisco International Airport, and other major employment centers along the Peninsula. It is difficult to assess the reduction in pollutants from this measure. However, a reduction in vehicles trips of at least three percent seems reasonable to expect. As a result, this measure could reduce total year 2000 project emissions by six (6) pounds per day of ROG, seven (7) pounds per day of NOx, and six (6) pounds per day of PM~o. Bus shelters, easy pedestrian access, and bicycle lanes shall be provided in the project design to facilitate alternative modes of transportation. This measure a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 92 Ex3-3.doc 3.0 SUMMARY OF FINDfNGS Terrabay Phase ll and 1!I SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation ' Air Quality -- Continued 4.5-3 Changes in Regional Long-Term Air Quality could reduce total year 2000 project emissions by ten (continued) (10) pounds per day of ROG, 12 pounds per day of NOx, and 11 pounds per day of PM~o. • Use of public trattsit at Phase III commercial development shall be provided and promoted. For instance, Caltrain and bus schedules could be made available to hotel patrons. Shuttles to the airport and other major trip attractors could provide a good alternative to single occupant car use. This measure, although difficult to assess, could reduce total year 2000 project emissions by six (6) pounds per day of ROG, seven (7) pounds per day of NOi, and six (6) pounds per day of PM~o- • Fireplaces shall be equipped with certified wood burning fireplace inserts which meet Federal emission standards. It is difficult to assess the overall effectiveness of this measure due to the infrequent use of fireplaces. However, the measure would reduce PM~o emissions from fireplaces by up to 90 percent. • The applicant proposes to include outdoor electrical outleu and natural gas subs to avoid the use of gasoline-powered landscape equipment. This would provide a minor reduction in overall emissions of ozone recursor air ollutanu. Noise 4.6-1 Construction Noise Impacts During The following measures shall be required to reduce the construction periods, noise levels would be elevated outride project's short-term construction noise impacu to a less-than- existing homes located across Hillside Boulevard and Sister significant level: Cities Boulevard from the Phase II residential development. . Noise-generating construction activities, including This would constitute a significant short-term impact. S truck traffic going to and from the site for any purpose, and maintenance and servicing activities for construction equipment, shall be limited to the hours stipulated by the City's Noise Ordinance which are 8:00 AM to 8:00 PM on weekdays, 9:00 AM to 8:00 PM on Saturdays, and 10:00 AM to 8:00 PM on Sundays. • All equipment used on the project site shall be adequately muffled and maintained. All internal combustion engine-driven equipment shall be fitted with intake and exhaust mufflers which are in good condition. Use of good mufflers with quieted compressors on all non-impact tools should result in a maximum noise level of 85 dBA when measured at a a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 93 F.x3-3.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and 111 SEIR Exhibit 3.P-1 Summary of lmpacfs and Mitigation Measures Impact a Mitigation Noise -- Continued 4.6-1 Construction Noise Impacts (continued) distance of 50 feet. • Powered conswction equipment shall be turned off when not in use. • Stationary noise-generating conswction equipment shall be located as far as possible from nearby residences. • Blasting noise control measures used in Phase I, including line drilling, time delayed charges, and blasting mats, shall be used in Phase II and III where blasting is required. Blasting shall be restricted to the hours of 8:00 AM to 5:00 PM. • A project construction supervisor shall be designated as a "noise disturbance coordinator" who would be responsible for responding [o any local complaints about conswction noise (as was done for Phase I site development). The disturbance coordinator shall ~ determine the cause of the noise complaints (such as ~ starting too early, bad muffler, etc.) and shall require implementation of reasonable measures warranted to correct the problem. The telephone number of the disturbance coordinator also shall be posted cons icuously at the conswction site. i 4.6-2 Land Use Compatibility Impact Proposed uses In order to reduce potential noise and land use compatibility in Phase II and Phase III would be exposed to noise levels impacts to a less than-significant-level, the project sponsor which would exceed those considered satisfactory for the shall retain a qualified Acoustical Engineer to prepare a intended uses. S detailed acoustical analysis and mitigation plan pursuant to i Title 24 of the California Code of Regulations. The report shall be submitted to the Ciry for review and approval before ~ issuance of building permits. The report shall include a detailed acoustical analysis of noise reduction requirements and specifications for each project phase, in accordance with land use /noise level compatibility standards established by the State and set forth in the City's Noise Element. The identified noise reduction requirements and specifications then shall be included in the siting or design of individual housing units or hotels: • Noise levels in backyards of homes proposed adjacent to and overlooking the Sister Cities Boulevard-Hillside Boulevard corridor and Sister Cities Boulevard / Oyster Point Boulevard intersection shall be mitigated with a noise barrier. The proposed upsloping geometry to a graded building pad would provide an excellent opportunity to mitigate with a property line barrier. Calculations based on the Precise Plan adin¢ laps a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 94 Ex3-3.doc 3.0 SUMMARY OF F1ND/NGS Terrabay Phase ll and 111 SE/R Exhibit 3.O-T Summary of Impacts and Mitigation Measures Impact a Mitigation Noise -- Continued 4.6-2 Land Use Compatibility Impact (continued) indicate that asix-foot high barrier measured above the rear property line elevation would be appropriate at locations shown on Exhibit 4.6-7. To be effective, the barrier must be constructed airtight over its face and at the base and have a minimum surface weight of three pounds per square foot. Suitable materials include wood, masonry block, precast masonry, or precast concrete panels. If the barrier is constructed of wood, a post and panel or board and batten construction method should be used to eliminate sound leaks. • Forced air mechanical ventilation shall be provided pursuant to residential building sound insulation requirements so windows may be kept closed at the discretion of building occupants to control noise. Additional building sound insulation treatments (such as sound rated windows and doors) would likely be required in parts of the Point neighborhood and for the hotels overlooking U.S. 101. • The interior CNEL shall be reduced to a level of 45 dB or less to conform with City General Plan and State Building Code requirements. The noise analysis also shall include adequate consideration of aircraft noise to achieve the FAA's recommended maximum single- event noise level of 55 dBA in bedrooms of housing units and also shall be applied to proposed hotel rooms. 4.6-3 Traffic Noise Impacts Traffic-generated noise No mitigation would be required. _ would not increase ambient noise levels measurably on existing neighborhood streets or roadways which would provide access to the project site. This impact would be less- than-si 'ficant. LTS 4.6-4 Traffic Noise Impacts from the Hook Ramps No mitigation would be required. Traffic-generated noise from the proposed hook ramps would not change noise levels noticeably at any noise- sensitive land uses. This impact would be less than si 'ficant. LTS 4.7-1 Impact of Residential Development on Police No mitigation would be required. Services The 1998 Precise Plan proposes 84 fewer housing units than the 1996 Specific Plan. However, larger three-, four-, and five-bedroom units currently are proposed compared with smaller two-, three-, and four-bedroom units previously proposed. The South San Francisco Police Department is concerned that this difference would result in a larger residential population on the Phase II site with a ro ortionate increase in demands for olice services. The a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable 95 Ex3-3.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and !ll SE/R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Services -- Continued 4.7-1 Impact of Residential Development on Police Services (continued) future Phase II site population would not be expected to change staffing requirements by one full officer position. The 0.2- to 0.3-officer difference would be considered ales-than-si ~ficant im act. LTS 4.7-2 Impact of Commercial Development on Police No additional mitigation would be required beyond project Services Proposed commercial development would sponsor provision of a new police vehicle as previously generate 367 additional calls for service per year and require required. the combined effort of 0.91 officer. Prior environmental review did not address the impact of commercial development separately from the entire three-phased project which was determined to require 3.0 additional officers. The 1982 EIR and 1996 SEIR assumed heavy reliance on use of private security on the Phase III site to minimize impacts on the South San Francisco Police Department. Although prior EIRs did not separate the demands for commercial development, in view of the estimated need for less than one new officer position for the Phase III site alone, the impact would be considered ales-than-significant. This is because it still would not result in a physical impact, such as the re uirement for a new atrol vehicle. LTS 4.7-3 Combined Project Impact on Police Services No mitigation would be required. The combined effect of Terrabay Phase II and III development according to the 1998 Precise Plan could be interpreted to require one additional police position (0.91 position) which still would represent ales-than-significant im act. LTS 4.7-4 Impact on Police Communications The Phase The developer of the first building constructed on the III site is located in a communications shadow formed by Terrabay Phase III site shall install relay equipment suitable San Bruno Mountain which would inhibit police and fire to facilitate police and fire communications between the radio transmissions to and from emergency service vehicles transmitter and land located behind San Bruno Mountain, if on patrol on [he site or farther east of U.S. 101. The South required to do so by the South San Francisco Police San Francisco Police Department will require the first Department as a condition of approval. Equipment installed project developed within the shadow, whether on the Phase shall meet South San Francisco Police Department III site or elsewhere, to install required relay equipment. S specifications. If such equipment is installed on another project constructed before development proceeds on the Terrabay Phase III site, no additional mitigation would be r uired. 4.7-5 Traffic Impact on Police Response Times No mitigation would be required. Congestion causing delays in future traffic conditions with the project would be expected at two intersections at the Oyster Point interchange but not before the year 2010. Unconstrained conditions elsewhere would off-set potential future delays, thus not affecting police response times si 'ficantl .LTS a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU=Significant Unmitiaable 96 Ex3-3.doc 3.0 SUMMARY OF F/NDIhGS Terrabay Phase ll and 111 SE1R Exhibit 3.a1 Summary of Impacts and Mitigation Measures Impact a Mitigation Services -- Continued 4.7-6 Police Impact from Cumulative Development Substantial cumulative development by the year 2010 would greatly increase the number of calls for service to the South San Francisco Police Department and could require an estimated 5.4 to 6.2 additional police positions plus two additional police vehicles. While these cumulative impacts would be significant, the incremental contribution of Terrabay Phase II and III development would not be "considerable", thus less-than-significant for the purposes of CEQA. LTS 4.7-7 Impact on Brisbane School District Development of 213 duplex and triplex uniu in the Terrabay Phase II Point and Commons neighborhoods and creation of an estimated 720-780 jobs on the Phase III site would add about 85-88 new studenu to Brisbane School District (BSD) schools. This number would be fewer than the 90 students preciously estimated to be generated by the Terrabay project. approximately 85-88 new students would contribute incrementally to capacity constraints, but class size reductions are affecting school capacity more profoundly than increased enrollments attributable to new development. LTS 4.7-8 Impact on Jefferson Union High School District Fewer but larger Point and Commons uniu proposed by the Precise Plan would generate virtually the same number of studenu to Jefferson Union High School District schools (21 studenu) as estimated from more but smaller uniu previously proposed by the Specific Plan (22 studenu). LTS 4.7-9 Impact on South San Francisco Unified School District Development of 135 housing uniu in the Terrabay Phase II Woods neighborhood would add about 45- 61 studenu to South San Francisco Unified School District (SSFUSD) schools, including about 11-27 students in Grades K-5, 15 students in Grades 6-8, and 19 smdenu in Grades 9- 12. This number would be fewer than the 103 studenu preciously estimated from the former 204-unit Terrabay Woods part of the Phase II project. This also is the same elementary school enrollment increase as estimated by the SSFL.`SD (11 studenu). LTS 4.7-10 Cumulative Impacts Schools Substantial residential and non-residential development could increase Brisbane School District and Jefferson Union High School District enrollments by an uttknown number of students by year ?010, although the Terrabay Phase II and III share of studenu would not be defined as "considerable". Planned development within the South San Francisco Unified School No additional mitigation would be required of the Terrabav Phase II or III project than identified by Mitigation Measure 4.7-4 and the 1982 EIR / 1996 SEIR. The prior EIRs required funding provision of a separate new fully-staffed beat (1982 EIR) to consist of three officer positions and one new patrol vehicle /1996 SEIR). Implementation of Brisbane School District efforts to cam' out iu class size reduction policy -when facility improvemenu (and funding sources to make them) have been identified -will mitigate the impact of decreasing elementary school capacity. Such efforts would accommodate studenu originating from development of the Terrabay Phase II or III site at Brisbane Elementary School. and no additional mitigation would be required. No mitigation would be required. No mitigation would be required. No mitigation would be required. a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU=Significant Unmitigable 97 Ex3-3.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase lI and Il/ SE1R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Public Services -- Continued 4.7-i0 Cumulative Impacts Schools (continued) District has been taken into account by district plans for J elementary school enrollments. L.TS Hazards 4.&1 Soil Contamination by Aerially Deposited Lead Construction of the hook ramps and realignment of Bayshore Boulevard would occur in a project area where levels of aerially deposited lead potentially could exceed thresholds established by Federal and / or State regulations defining hazardous wastes. Lead levels within the Caltrans right-of--way could exceed criteria of afive-year variance for Caltrans projects which allow reuse and containment of contaminated soils on-site in specific circumstances. Such levels of contamination would require special handling by construction workers to remove and dispose of excavated soils at a Class 1 landfill. S (a) The City shall complete the lead testing program for total lead concentrations authorized for the project area in order to characterize site soils. If levels do not exceed State criteria defining a hazardous or designated waste, no additional mitigation would be required. If levels exceed State thresholds listed in Exhibit 4.8-I ,Mitigation Measure 4.8- 1(b) shall be required. (b) If the preliminary environmental investigation is inconclusive or identifies total lead concentrations in excess of State criteria, the City shall perform, at a minimum, supplemental citric acid waste extraction (WE'1~ tests to identify soluble lead levels and determine whether soils within Caltrans' right-of--way could be reused without further regulation in project fills in compliance with Caltrans' variance. If found appropriate to be used on-site, Mitigation Measure 4.8-1(d) shall be required. If not capable of reuse on-site or if located outside Caltrans' right-of--way, Mitigation Measure 4.8-1(c) shall be required. (c) If the supplemental analysis program identifies levels in excess of State criteria, the Ciry shall remove, transport, and dispose the contaminated soil at a Class 1 (or 2) landfill which is licensed and operated to accept hazardous (or designated) waste. (d) If project area soils containing permissible levels of lead are to be reused on-site, the City shall comply fully with all the conditions, limitations, and other requirements specified by the DTSC variance for Caltrans projects. The following measures include some but all of the variance's requirements: • The lead-contaminated shall be placed a minimum of two feet above the maximum water table elevation and covered with at least one foot of clean soil. • Lead-contaminated soil shall not be moved outside the specified corridor boundaries. Any lead-contaminated soil which cannot be buried and covered within the Caltrans right-of--way shall be managed as a hazardous waste (see Mitigation Measure 4.8-1(c)). • Lead-contaminated soil shall not be buried in areas where it will be in contact with groundwater, surface a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmi[igable 98 Ex3-4.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase A and 111 SElR Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Hazards -- Continued 4.8-1 Soil Contamination by Aerially Deposited Lead (continued) 4.8-2 Effect of EMF on Future Residents Residential development of the Commons West site would not expose residents to unusual magnetic field levels or, in the absence of California State or Federal standards, levels which government entitles outride California regulate. LTS water, or plants. Lead-contaminated soil shall only be buried and covered in locations protected from erosion and storma-ater run-on and run-off and shall not be buried within ten feet of culverts or locations subject to frequent R•orker exposure. • Lead-contaminated soil shall be buried and covered in a manner which will prevent accidental or deliberate breach of the asphalt, concrete, and / or cover soil. • Excavated contaminated soil shall be stockpiled and managed on a daily basis according to the variance, including no stockpiling in environmentally sensitive areas. All field work to drill test borings and perform subsequent excavations on the site during project implementation shall be conducted in compliance with a site safety plan which meets requirements contained in [he Occupational Safety and Health Guidance Manual to protect field crew and construction workers' health. These measure shall include monitoring and exposure standards as provided by the variance. They also shall include required worker training in advance of implementation. Although the proximity of electric power lines to proposed housing units would not be expected to result insignificant impacts requiring mitigation, the August 1997 PG&E report reviewed by this SEIR makes two recommendations. The first corresponds with 1996 SEIR mitigation. These are to: • Include an advisory disclosure statement on all deeds of properties Rithin the Commons West subarea of the site that the subject property is located near power lines and purchasers should be aware that there is ongoing research on the potential health effects associated with magnetic fields which exist wherever there is electric current • Remind potential buyers that PG&E can and will, upon request, provide infom~ation on EMF and the current state of ongoing research on the potential health effects of EMF. Archaeology 4.9-1 Damage to CA-SMa-40 Placement and compaction of eight to 23 feet of fill would inseparably damage and probably would destroy the integrity of cultural materials and features present on a site acknowledged to be (a) A data recovery program for CA-SMa-40 should be carried out before any fill is placed on the site or commercial development activities occur there with the goal of completely recording the current condition of CA-Shia-40. a LTS =Less-than-Significant PS =Potentially Significant S =Significant SL' =Significant Unmitigable 99 F.x3-4.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase ll and Ill SEIR Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Archaeology-- Continued 4.9-1 Damage to CA-SMa-40 (continued)an extremely This mitigation program, recommended by Holman & important resource under CEQA and believed to be eligible Associates (hence interpreted to be proposed as part of the for listing on the National Register of Historic Places. This applications pending Ciry approval), should be accompanied would be a significant impact. S by long-term post-construction monitoring of site compression after placement of fill, as well as monitoring of subsequent development at any location within 30 meters (100 feet) of the mapped boundary of CA-SMa-40. The data recovery program should include: 6 • Mitigative data recovery excavations. • Data analysis. • Curation of recovered materials. • Report(s) preparation. • Post-fill compression study. The proposed data recovery program is intended to "allow CA-SMa-40 to be understood in the regional archaeological context and to contribute to anthropological understanding of the development and history of human habitation in the Bay Area, specifically, and Central California and Western North America". The program proposes to address the following research topics: • Geo-archaeological landscape reconstruction. • Environmental change and human adaptation (and related environmental questions). • Prehistoric chronology. • Culture history. • Coastal settlement patterns and economic models. • Local, regional, and wider cultural /social relationships. • Population increase, resource utilization intensification, and changes in cultural patterns. (b) As an alternative to Mitigation Measure 4.9-1(a), the project should be revised to prevent significant impacts on CA-SMa-40 and to preserve the archaeological site through a combination of site planning to avoid damage to this resource and permanent protection by establishing a conservation easement. ... The CA-SMa-40 site should also be protected by a permanent conservation easement or dedicated to San Bruno Mountain County Park. These measures would preclude the need to place extensive fill on CA-SMa-40 and eliminate Impacts 4.9-1 and 4.9-2 (below) attributable to the project approach. ... Variations of Mitigation Measure 4.9-1(b) are possible as long as the basic remise of site reservation is maintained and the need for a LTS =Less-than-Significant PS =Potentially Significant S =Significant SU =Significant Unmitigable b See 4.9 Archaeology for additional description of this measure. 100 Ex3-4.doc 3.0 SUMMARY OF FINDINGS Terrabay Phase 11 and l/1 SE1R Exhibit 3.0-1 Summary of Impacts and Mitigation Measures Impact a Mitigation Archaeology -- Continued 4.9-1 Damage to CA-SMa-40 (continued) 4.9 2 Indirect Impacts on CA-SMa-92 Increased recreational trail use on the archaeological site could result in impacu to the resource. The magnitude of impact is not known at this time but would depend on property ownership and associated issues of preservation methods and resource management. L:~ntil the project addresses such issues, the impact is considered potr.adally significant. PS site destroying fill compaction and compression is eliminated. One suggested variation comes from the Native American community which recommends that the site location be controlled and managed by the Costanoan / Ohlone themselves. Environmental documents and archaeological reports of this nature ofren defer to Native American sensibilities but seldom consider a full partnership in the actual control of the cultural resource. Perhaps there is a viable management alternative in this recommendation. b (c) In the event that the Ciry elects to adopt Mitigation Measure 4.9-1(a) instead of requiring Mitigation Measure 4.9-1(b), Mitigation Measure 4.9-1(a) should be revised to incorporate the following additional provisions: • CA-SMa-92 should be investigated to determine its relationship to CA-SMa-40 and thus provide adequate documentation for the two sites and determine their cultural and temporal relationship. • The sanitary sewer proposed to cross CA-SMa-40 should be relocated to the west side of the intental access road right-of--way and, if required for operation, pumping facilities should be installed. CA-SMa-92 should be protected from damage resulting from increased use in and around the archaeological site area. The following measures would mitigate potentially significant impacts on this archaeological site: • The project sponsor and County should agree on a trailhead location, and the County should connect the [railhead to other trails in the park via a route which would avoid CA-SMa-92. This measure may include relocating any existing trails or routes which impinge on the archaeological site. • The project sponsor should "cap" CA-SMa-92 with a shallow layer of fill to retard the erosive nature of human visitation and help maintain the integrity of the site as a potentially important and unique archaeological resource. This should be completed before County accepts dedication of the parcel which CA-SMa-92 is located. a LTS =Less-than-Si~ificant PS =Potentially Significant S =Significant SU =Significant Unmidgable 101 Ex3-4.doc 4,0 ENVIRONMENTAL SETTING, IMPACTS, AND MITIGATION MEASURES 4.0 ENVIRONMENTAL SETTING, IMPACTS, AND M1T/GATION MEASURES This chapter contains an analysis of each environmental topic identified by and subsequent to the City's scoping process for this 1998 SEIR (Initial Study /Environmental Checklist, Notice of Preparation, scoping meeting, working session, etc.) described in 1.0 Introduction. Environmental topics addressed in this chapter include: • 4.1 Geology, Soils, and Seismicity 4.6 Noise • 4.2 Hydrology and Drainage 4.7 Public Services • 4.3 Biology 4.8 Hazards • 4.4 Traffic and Circulation 4.9 Archaeology • 4.5 Air Quality Sections 4.1 through 4.9 of this chapter describe existing environmental conditions as they relate to each specific topic, identify potential impacts from implementing the project, and present mitigation measures required to reduce significant adverse impacts to ales-than-significant level. Where relevant, cumulative impacts of project buildout combined vzth other growth elsewhere in the immediate site vicinity or surrounding study area are analyzed, as discussed in 2.4 Cumulative Development. FORMAT OF TOP/CAL ANALYSES Existing conditions aze described in the respective "setting" sections. These descriptions summarize information compiled during the study process to prepare this 1998 SEIR (see I.3 Information Used to Prepare the EIR). Conditions described are those relevet to the focus of the 1998 SEIR in order to provide a basis for assessing and understanding the impacts of the project as now proposed. Background materials used in this 1998 SEIR are referenced in footnotes and listed in the appendices (see 7.3 Bibliography). Standards used to evaluate the magnitude of impacts are listed in the "significance criteria" subsections for each topic analyzed. Under the California Environmental Quality Act (CEQA), a significant effect is defined as a substantial or potentially substantial adverse change in the environment -namely, in any of the "physical conditions within the azea affected by the project including land, air, water, minerals, flora, fauna, ambient noise, and objects of historic or aesthetic significance". The State CEQA Guidelines (Guidelines) direct that the significance of impact be determined on the basis of scientific and factual data. The significance criteria were derived from the following main sources -the Guidelines, City of South San Francisco General Plan and other City policies and requirements (such as zoning), and the professional standards and practices of the technical analysts who conducted the EIR evaluations. The "impacts and mitigation" subsections identify three types of environmental effects from implementing the project: Significant Unavoidable Impact (SU) A significant (or potentially significant) impact which cannot be avoided with mitigation. These include impacts which could be partly mitigated but could not be reduced to ales-than-significant level. When the symbol "SU" is used, it indicates that the impact would be significant both before and after mitigation. (A potentially significant i o2 4.0 ENV/RONME~:,L SETTING, IMPACTS & MITIGATION MEASURES Terrabay Phase ll and 01 SEIR impact is identified when not enough information is known to determine if the impact would be significant.) • Significant Impact (S) A significant (or potentially significant) impact which can be mitigated to aless-than-significant level. The symbol "S" denotes that the impact would be significant before mitigation but that mitigation would be effecti~•e in reducing the magnitude of impact to a less-than-significant level (I,TS). (A potentially significant impact is identified when not enough information is known to determine if the impact would be significant.) • Less-than-Significant Impact (LTS) A change or effect directly or indirectly attributable to the project which would not exceed the threshold(s) of significance. When the symbol "LTS" is used, it indicates that the impact would not be signiftcant and would not require mitigation, although mitigation could decrease less-than-significant project effects even further (or avoid such effects altogether). A significant effect on the environment is defined as a substantial or potentially substantial adverse change in the physical conditions which exist in the area affected by the proposed project. According to the Guidelines The determination of whether a project may have a significant effect on the environment calls for careful judgment on the part of the public agency involved, based to the extent possible on scientific and factual data. An ironclad definition of significant effect is not possible because the significancae of an activity may vary with the setting. All impacts are numbered consecutively by topic. Significant unavoidable (SU) and significant (S) impacts are followed by measures required to reduce the magnitude of impact. No mitigation measures are required for less-than-significant impacts (LTS), although additional measures may be capable of further reducing environmental effects identified. (Implementation of any additional measures is voluntary, not mandatory.) Mitigation measures also are numbered to correspond to the respective impacts. For each significant unavoidable (SU) impact identified in the Final SEIR, the City would be required to adopt Findings of Fact and a Statement of Overriding Considerations explaining the reasons for approving the project (if approved) despite the impacts identified. 103 4.1 GEOLOGY, SO/LS, AND SE/SM/CITY GEOLOGY, SOILS, AND SEISMICITY- THE SETTING This section describes the project's impacu related to soils, geology, and seismicity. The 1982 EIR first presented these issues and their impacu, and the 1996 SEIR focused on the changes since the 1982 EIR. 84 This 1998 SEIR briefly presents existing conditions and focuses on changes since the 1996 SEIR. Environmental Impact Planning Corporation prepared the soils and geology analysis for the 1982 EIR, Harlan Tait Associates developed the 1996 SEIR analysis, and McHuron Geosciences prepared this 1998 SEIR analysis. Eric McHuron, Ph.D., has been a consultant for the City of South San Francisco since the original Terrabay Phase I grading in 1989. He served as the engineering geologic reviewer for the City as the Chief Geologist of Roger Foott Associates (1989-1992) and as President of McHuron Geosciences (1995-present). Topography As shown on Exhibits 2.1-I and 2.1-2, the Terrabay site is located on the lower flanks of San Bruno Mountain. Site topography varies from gently rolling hills and alluvial / colluvial valleys to fairly steep ridgelines. The overall elevation of the mountain, in the site vicinity, varies from sea level to about 1,050 feet. Elevations within the Terrabay site development areas vary from about ten to 15 feet (in lower parts of the Phase III commercial site) to about 360 feet (in the upper parts of perimeter cut slopes in the Woods East and Woods West neighborhoods on the Phase III residential site). The main ridgeline of San Bruno Mountain trends northwest with numerous spur ridges and drainages which trend approximately perpendicular. These spur ridges divide the site into ten drainages. Of primary importance to the site are the topographical swales (hollows) along the spur ridges. These hollows are sources of potential debris slides. These debris slides and alluvial processes have formed gently sloping depositional terraces which grade into the lower elevations of the site. The upper parts of these terraces commonly are incised by the active drainages which form alluvial fans on the lower part of the mountain. During the time between the 1982 EIR and 1996 SEIR, approximately 80 acres of the site were graded as part of Phase I development. This grading took place in 1989-1990 and included the grading for Sister Cities Boulevard and South San Francisco Drive. Four permanent (concrete) debris basins were constructed on the Phase I site, and five temporary (earthen) siltation basins were constructed on Phase II and western part of the Phase III sites. This grading involved cutting slopes up to 80 feet high and placing fills up to 60 feet deep and, as noted below, included grading of the Point. Most Phase I grading occurred on the Phase I site (in the Village and Park neighborhoods)(about 60 acres of which approximately 18 acres include the landslide R and D repairs and other areas designated as open space). However, the rough grading plans for Phase I also permitted placement of 84 Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, August 1982 (1982 EIR), and Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Euension, R'agstaff and Associates, January 1996 (1996 SEIR). 104 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase /l and 111 SE1R excess fill material in part of the Phase II site. 85 Under this provision approximately 18 acres in Woods East, Woods West, and Commons East (now Point) neighborhoods of the Phase II site received fill. 86 Excess material from Landslide R and D mitigation was placed as engineered fill in the Woods East neighborhood. In Woods West, topsoil stripped from the Phase I site was stockpiled, and some excess material from Phase I grading (mainly from Landslide R mitigation) also was stockpiled as non-engineered fill. In addition to the fill, approximately 15 acres of the Phase II site were graded for slopes associated with construction of Sister Cities Boulevard, South San Francisco Drive, and the siltation basins and staging area (Commons West) which included grading in the Point. Since preparation of the 1996 SEIR, additional fill has been placed in the Woods East neighborhood. This material consists of excess material from the Area D Landslide repair, placed as engineered fill, and foundation excavations from structures in Phase I, stockpiled asnon-engineered fill. The 1998 Precise Plan for Phase II and the Specific Plan amendment for Phase III generally are similar to eazlier plans for the Commons, Woods East, and Woods West neighborhoods. Each neighborhood would occupy a valley between spur ridges. The 1998 Precise Plan would merge the Point and former Commons East neighborhoods and proposes significant filling of the ravine in the western part of the Phase III commercial site which was not envisaged in 1982. The plans call for grading of an additional 25 acres on the Phase II and 28 acres on the Phase III sites (see Exhibits 4.1-1a through 4.I-Ic. In addition, proposed construction of the U.S. 101 southbound hook ramps, not covered by the previous Ellis, would affect the Phase III site. The Phase III grading plan proposes to accommodate realignment of Bayshore Boulevard by moving commercial development pazcels farther west into the base of the mountain. Bedrock Geology Two major bedrock types are present at the site (see Exhibit 4.I-2). The northern and eastern parts of the site are underlain by Franciscan sandstone (greywacke). This unit has variable bedding, is massive to highly fractured, and generally is hard strong erosion-resistant rock not affected by major fault zones. In contrast, the western part of the site is underlain by Franciscan melange. This unit consists of highly sheared shale, siltstone, some graywacke, chert, and metamorphic rocks which have been subjected to tectonic mixing. The contact separating these two major units is the Hillside Fault (see Seismicity, below). 87 This fault trends northwest-southeast, traverses Terrabay Pazk, passes through Woods West, and trends pazallel to and just north of South San Francisco Drive. Along the ridges and spurs, the depth to bedrock is fairly shallow (less than a few feet). However, in the hollows between the spurs and in some of the lower parts of the alluvial terraces, the depth to bedrock increases from a few feet to as deep as 60 feet. The bedrock surface is covered by various types of sediments (see Exhibit 4.I-2). 85 Stage I Grading, Unit 3 Terrabay Woods West, Rough Grading (Drawing C-7) and South San Francisco Drive-Hillside Boulevard Extension, Rough Grading (Drawing C-8), Terrabay Development, South San Francisco, CREM, April 17, 1989. 86 Prior plans referred to the Commons East and Commons West neighborhoods. As described in 2.3 Project Description, the Precise Plan has combined the area formerly known as Cotnmons East with the Point. The resulting neighborhood areas currently are referred to the Point and Commons. 87 Preliminary Geologic Map of the San Francisco South Quadrangle and Pan of the Hunters Point Quadrangle, California, M.G. 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(p \ r'<. ~ ~~ / s .., ,vj)jl e \ (( ` I ~ A N ~~ "i. FJt~t,~~+'-~. ,' , .:: _:._,.. ..-. ~>~~ ~:~_.'._~, ~:•J 1i f :~~.~'~~ ~~ ..:F'`'/"~;,t:"'• '` ~1111~ tI~I~- • ' ii ~ ~ ~ at ~ ..~ // see ~I ~..1 r ,. ~m~.' . ~,/ <~r~ t,4' ' } .,. "'^w., , t , .~ \ ~~ ~~.~ ~r I:.. Q ;! { .,Al t~ } ~ •w r t+,1 ~,::. ~ ~y ~, ! ' ' 1 , ~, , SC Q „ ~ ,~ ~ /` ~ r '~ ; D Y?. Q .. SL Dr 'r F ,ry "'' (' .I ~ I J, i, S` ` ~ i ~ X,r- "• ~•ti ,~'. ~ ~ r'(J: •` 1 ~ bi. ~ ~t p y'1r 1, i I t,,, ,r. '~,.,,~ , ` . ~ P SeaA 11 it .. . .~'. ,~ .~..•• ~~ra I a ;~ ' -,. r ` , D ' ' ',:~ I ~t ~ -~ 1 _ t ~~. l . _ ~ t , wf ,I. ~:,'rr,.. r' %~ ... , . ,,b ~. (~ ~' G A v C N 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase 1l and 111 SEIR Cover Sediments The bedrock is overlain by cover materials derived from weathering, colluvial creep, debris slides, windblown sand, landslides, alluvial deposition, bay mud, and man-made fill. These sediments vary widely in texture from predominately fine-grained with some larger clasts (colluvium, debris slides, and landslides), clean fairly uniform silty sand (dune sand), and predominately coarse-grained material in a clayey matrix (debris slides, alluvium). During Phase I grading, up to 60 feet of cover sediments were found above buried erosional-valleys cut into the bedrock. These sediments vary in age from Holocene (last 10,000 years) to late Pleistocene (175,000 to 10,000 years ago). The Holocene sediments commonly are tan to dazk brown, and the Pleistocene sediments are reddish-brown in color. These older sediments have been leached of most of their nutrients and calcium. 88 These older sediments are predominately clayey and are susceptible to erosion and gullying frilling and "badlands" topography) unless a stable mat of vegetation is established. Excellent exposures of these older sediments were formed during Phase I grading. This grading cut through the alluvial and debris fan terraces traversing the site from the uplands. Examples of these terrace sediments can be found in the cuts along Skycrest Drive (Phase n, along the Sister Cities Boulevazd (near Hillside Boulevard), around the cuts in the Point and Commons neighborhoods (Phase In, and the old "quarry" in the western side of the Phase III site. The Phase II and III sites also contain areas of artificial fill. This fill consists of non-engineered stockpiles of topsoil (Woods East, Woods West), non-engineered soils from Phase I grading and landslide repairs (Woods West), and engineered fill from Phase I landslide repair (Woods East). In addition to these sediment types, the Phase III site also contains deposits of organic material and shells (archeological site), bay mud (along Bayshore Boulevard), and artificial fill from tunnel excavation through the southeast nose of San Bruno Mountain. The tunnel was excavated for relocating San Francisco's Crystal Springs water pipeline which was exposed by landsliding and widening of Bayshore Boulevard. The 1982 EIR described site soils as "part of the Gaviota eroded Rockland association generally found on steep slopes containing numerous exposures of bedrock". The 1996 SEIR described site soils using the Soils Survey of San Francisco and San Mateo Counties revised by the U.S. Soil Conservation Service in 1991.89 According to the 1991 Survey, the soils developed on bedrock, colluvium, and alluvium in the site vicinity consist of the Barnabee-Candlestick Complex, Candlestick Variant loam, and Orthents. The 1996 SEIR describes these soils as follows: Barnabee-Candlestick Complex This soil type generally occurs on the upper slopes of the site and is characterized by gravely sandy loam which is highly susceptible to slippage (landsliding, debris sliding) when wet. Runoff is rapid to very rapid, and erosion potential is high to very high. Candlestick Variant Loam This soil type occurs on the lower slopes and swales of the site and is characterized by loam to clayey loam which has a moderate shrink-swell potential. On gentle slopes, runoff is slow to medium, and the hazard of erosion is slight to moderate. On steep slopes, runoff is rapid, and the hazard of erosion is high. 88 Eric McHuron conversation with Dave Kaplow (project sponsor's Habitat Conservation Plan (HCP) consultant), 1998. 89 The U.S. Soil Conservation Service (SCS) subsequently has been renamed and is called the Resource Conservation Service. 110 4.1 GEOLOGY, SO/LS, AND SEISMICITY Terrabay Phase /I and III SEIR Orthents This soil type consists of soils which have been cut and filled for development. It has highly variable characteristics because of the differences in the type and amount of fill material used. Runoff is rapid to very rapid, and erosion potential is very high. Seismicity The project site is located in a region of high seismicity, as is the rest of the Bay Area. The sources of this seismicity are known active faults, including the San Andreas (approximately three miles southwest), the San Gregorio fault (approximately ten miles southwest), the Hayward fault (approximately 15 miles northeast), and the Calaveras fault (approximately 27 miles northeast). According to the U.S. Geological Survey (USGS), the probability of a large (magnitude 7.0 or greater) earthquake along the San Francisco Peninsula segment of the San Andreas fault zone is estimated to be 23 percent over the 30-year period from 1990-2010. 90 Overall, the total probability that one or more large earthquakes will occur in the San Francisco Bay region during the same time period is estimated to be 67 percent. No known active faults are located within the Terrabay site. The current Alquist-Priolo Earthquake Fault Map for the USGS San Francisco South Quadrangle shows that the nearest active fault is the San Andreas. Two inactive faults are located closer to the site..The San Bruno fault zone is located about 1.5 miles southwest of the site, and the Hillside fault (which separates the Franciscan sandstone from the Franciscan melange) traverses the site. During Phase I grading, the Hillside fault was exposed in several places ('Terrabay Park) where it was overlain by Pleistocene sediments. Examination of these locations did not reveal any evidence of fault movement within the cover sediments. Therefore, the Hillside fault is not active (that is, it has not moved within the last 11,000 years). Mapping by Roger Foott Associates during excavation for the subsurface canyon drains underlying the fill found no evidence that it had moved in the last 80,000 years (Pleistocene age dune sands of the Colma formation covering the fault trace). Although the Hillside fault is not an active fault, it is significant in relation to landsliding at the site. Landslides and Debris Slides The 1982 EIR and 1996 SEIR identified a large number of landslides on the site. These landslides vary from fairly shallow colluvial soil slumps and debris slides to deep-seated failures. Most of the deep-seated failures occur within the Franciscan melange bedrock and are present in the Phase I and western part of the Phase II (Woods West) sites. During the investigation for the 1996 SEIR, Harlan Tait Associates reviewed 1993 stereo-pair aerial photographs, conducted a site inspection in September 1995, reviewed the geotechnical reports completed for the site since 1982, and reviewed the new and revised geologic information pertaining to the site to develop the 1996 SEIR's Geologic Map. 91 These previous studies have been updated for the 1998 SEIR with the results of additional test pits and geologic mapping (see Exhibit 4.1-2). 90 probabilities of Large Earthquakes in the San Francisco Bay Regiorz, California, U.S. Geological Survey Working Group, U.S. Geological Survey Circular 10532, 199Q 91 Figure 29, Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, op. cit. 111 4.1 GEOLOGY, SO/LS, AND SEISMICITY Terrabay Phase 1l and 111 SEIR Several deep-seated landslides underlain by Franciscan melange were identified on the Phase I site. In the original geotechnical report, these landslides were designated by letter (Area A, B, C, D, R, etc.). 92 Some landslides also are present on the Phase II (Point, Commons, Woods West) and III sites. Because the bedrock type under the Phase II and III sites is predominately Franciscan sandstone, the dominant mechanism for downslope movement is shallow colluvial creep and debris slides rather than deep-seated landslides. Colluvial creep forms areas of fairly shallow landsliding, as seen in the Point. Debris slides initiate from the colluvial-filled swales (hollows) between the ridge spurs. These debris slides are mobilized during periods of high intensity rainfall which follow antecedent storms that saturate the ground. With groundwater at ground level, soil turns to liquid and flows downslope. The movement will create a scar of one or two feet at the headscarp and a depositional zone below. 93 Debris slides were initiated on San Bruno Mountain during the January 4-S, 1983 storm event and recently during the February 2 and 6, 1998 storms. Exhibit 4.I-2 shows the location of the scars from the earlier debris slides and the debris slides which mobilized in February 1998. Based on their location on the mountain, these debris slides either enter the drainages which traverse the site or deposit their slide material on the alluvial terraces and debris fans in the lower parts of the site. These debris slides can mobilize very lazge boulders and rock debris. During the January 4-5, 1983 storm event, boulders and debris traversed the Phase I site and destroyed some homes across Hillside Boulevard. Large boulders from older debris slides aze exposed along the incised terrace in Woods East. In the eastern part of the Phase III site, boulders also can be seen on the surface of the active debris fan. Rockslides and Rockfalls In addition to the landslides and debris slides discussed above, parts of the site have been subjected to rockslides and rockfalls. Five test pits were excavated into the sandstone early in December 1997. Examination of the rock outcrops and test pits excavated into the bedrock indicates that the sandstone is thinly bedded to massive, has been folded into many different orientations, and is cut by numerous fractures. All of these features can contribute to the rock defects of the sandstone. 94 Most of these pits were located in zones of significant seepage from groundwater weeping through the fractures and bedding. Therefore, the combination of .rock defects and seepage may have caused the bedrock failures (as rockslides) when undercut for grading. High cut slopes proposed by grading would also be subjected to seismic forces during significant earthquakes. The largest rockslide identified near the site is located just outside the northeastern boundary of the Phase III site. This slide occurred in an area above the road cut for Bayshore Boulevard. A stone- faced retaining wall has been placed to support the failure, and some excavation is present above the slide, perhaps to help unload the top of the rockslide. Other azeas of rockslides are visible along the southern elevations of San Bruno Mountain along Bayshore Boulevard in Brisbane. 92 Geotechnical Feasibility Study, Phase 1, South Slope San Bruno Mountain, South San Francisco Area, San Mateo County, California, PSC Associates, Inc., April 1982, and Geotechnical Feasibility Study, Phase 11, South Slope San Bruno Mountain, South San Francisco Area, San Mateo County, California, PSC Associates, Inc., May 1982. 93 Compared with a debris slide, rockslides occur when undercutting, such as for construction, results in failure. 94 Supplemental Subsurface F_rploration (Test Pits), Terrabay Project, South San Francisco, Parikh Consultants, Inc., January 1998, op. cit. 112 4.1 GEOLOGY, SOILS, AND SEISMlC1TY Terrabay Phase 11 and 111 SEIR The potential for rockfalls was identified during grading for Phase I. During engineered mitigation of the Area C Landslide (Terrabay Village), numerous boulders were found within the landslide mass. These boulders were from rock outcrops at the top of the landslide. Over time, boulders from the outcrops had moved downhill and become incorporated in the landslide deposits. Geologic mapping for the Phase II and III sites identified similar potential source azeas. Because the predominant bedrock type in the Phase II and III sites is Franciscan sandstone, many more potential rockfall source areas exist than on the Phase I site. These areas are identified on Exhibit 4.1-2. Most of the potential rockfall sources are located above proposed development areas within HCP lands. However, examination of the surface materials below these potential source areas reveals numerous boulders which had moved downslope during previous rockfall events. Seepage and Groundwater Another important factor in the stability of the site and the proposed grading is seepage and groundwater. Observations during past winters and the springtime indicate that groundwater and surface seepage are important factors in the stability of both natural and cut slopes of the developed azea. Based on seepage observations and groundwater measurements taken from Area D Landslide instrumentation (Terrabay Park), groundwater neaz the apex of the debris fan rose up to 16 feet after a significant rainfall. In addition, a zone of significant spring /seepage activity was noted along the trace of the Hillside fault. This spring activity was interpreted to be related to groundwater within the more permeable and fractured Franciscan sandstone of the uplands, encountering the less permeable fault zone and Franciscan melange on the downhill segment of the fault. During an early 1998 site visit, a spring with an estimated flow of five gallons per minute was noted in the talus slope along the Hillside fault between the Commons and Woods East neighborhoods (see Exhibit 4.1-2). Seepage also has been noted in several of the hollows between the spur ridges and near the intersection of the colluvial slopes with the depositional terraces which grade out of the mountain. Some of the seepage zones have vegetation indicative of shallow moisture (such as Juncos and Scirpus). These zones are discussed in more detail in 4.3 Biology. GEOLOGY, SOILS, AND SEISMICITY - SIGNIFICANCE CRITERIA A geologic impact of the project would be significant if: • It has a potential to kill or injure people or damage residential structures. • It has a potential to damage or disrupt critical infrastructure. • It is subject to major landsliding, debris slides, or steep slopes. • Differential settlement adversely affects engineered structures. • The site is subjected to secondary seismic hazazds (liquefaction, lurching, lateral spreading, etc.). • Fill over the archeological site causes significant damage due to settlement and groundwater leaching. • Grading generates secondary impacts of dust and noise. 113 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase ll and ll! SEIR Site disturbance, such as through grading, encroaches into area more than 50 feet uphill form the Habitat Conservation Plan (HCP) fence or more than 9.31 acres of HCP land. 95 GEOLOGY, SOILS, AND SE1SMlCITY-IMPACTS AND MITIGATION MEASURES E/R Peer Review The project sponsor's civil engineer, Brian Kangas Foulk (BKF) prepared grading plans for the Precise Plan and Vesting Tentative Map for both the Phase II and III sites. Preparation of the plans involved an iterative process including input from the sponsor's geotechnical consultant, Parikh Consultants, Inc., and review and comment by City staff and consultants. The sponsor's consultants continued revising proposed grading plans after submittal to the City of January 15, 1998 application materials -those used for this 1998 SEIR's project description and topical environmental analyses. As of February and March 1998 when 1998 SEIR's geology, soils, and seismicity analysis was conducted, the sponsor's consultants. were making further revisions to plans proposed as part of the Precise Plan and Vesting Tentative Map. When fmal revisions are submitted to the City, the revised project may avoid impacts and / or incorporate mitigation measures which meet or exceed the criteria identified by this 1998 SEIR. In the meantime, this 1998 SEIR's geology, soils, and seismicity analysis reflects the project proposed as of January 15, 1998. Focus of Analysis Based on input during the 1982 EIR, the 1996 SEIR, and public meetings associated with the Phase II and III project, several issues have been raised regarding the geotechnical aspects of the project. These topics are listed below and are the focus of this 1998 SEIR's analysis: • Mass grading disturbing native vegetation • Stability of cut slopes (soil and bedrock) • Differential settlement of fills (over canyons, cut /fill transitions, and weak soils) • Erosion control / winterization / revegetation • Surface runoff from slopes and building pads • Debris basins (sizing /maintenance /overflow) .. • Landslide mitigation (potential for encroachment on the HCP area) • Mitigation of potential debris slides /flows and rock falls • Maintenance of cut slopes, erosion control, perimeter drainage, and debris basins • Seismic shaking • Noise and dust control during construction (see 4.5 Air Quality and 4.6 Noise) • Cut /fill balance • Effects of fill over the archeological site (also see 4.9 Archaeology) 95 ps described below (see Impact 4.1-1), the Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan permits encroachment onto (and requires restoration of) up to ten acres of Habitat Conservation Plan (HCP) land within a 50-foot minor boundary adjustment limit of the site development areas. Implementation of Phase I affected 0.69 acre of this total, leaving 9.31 acres for implementation of Phases II and III. Nichols • Berman conversation with Victoria Hams, Thomas Reid Associates (City, County, and U.S. Fish & Wildlife Service HCP consultant), March 30, 1998. 114 4.1 GEOLOGY, SOILS, AND SEISMIC/TY Terrabay Phase ll and 111 SE1R IMPACTS AND MITIGATION MEASURES Impact 4.1-1 Grading Construction of the Phase lI and 111 projects would require excavation of 57 additional acres of natural lands. This grading would expose areas to erosion, decrease the stability of the bedrock and sediment cover, and cause differential settlement in fills over drainages. The impact of grading of new areas could not be avoided without redesigning the project and reducing the size of development areas. Grading as proposed without mitigation would result in significant erosion, slope instability, differential settlement, and secondary impacts. LTS Proposed grading for the Phase II and III sites would have a significant impact on the existing topography of the site and a significant secondary effect on the vegetation growing on the site. Approximately 25 acres on the Phase II site and seven acres on the Phase III were graded as part of Phase I activities. The grading plan proposes the additional cutting and filling of 29 acres on the Phase II site and 28 acres on the Phase III site. Thus, prior and proposed grading would affect a combined ± 89 acres (54 acres on the Phase II and 35 acres on the Phase III sites). Perimeter cuts along the hillside boundary of site development areas would reduce the overall stability of the soil and rock masses in the cut slopes. These cuts would remove existing vegetation cover and expose materials to erosional processes. They would place proposed development closer to zones of known and potential geological hazards (landslides, debris slides, rockfalls, and groundwater seepage). While some grading would be performed to prepare pads for proposed development, other grading would be involved in mitigating known geologic hazards (such as landsliding, debris slides, rockfall, etc.). Although the extent of proposed grading is generally understood, some unforeseen conditions may be exposed during grading which would require additional corrective action (such as over- excavating landslide material, installing subsurface drainage systems, laying back slopes in weaker materials, rock bolting, etc.). Site development would change the topography from current conditions. Site development could involve grading of about 1,250,000 cubic yards of material and may require two construction seasons. 96 Proposed grading would result in a net excess of material and require export and disposal of the excess material. The project sponsor's consultants estimate that about 397,000cubic yards of material would be exported from the site. 97 This estimate was reviewed independently for this 1998 SEIR, and, based on experience from Phase I grading, the amount of material to be exported may be greater. The acttial volume could be as much as 500,000 cubic yards. Export of excess fill material would result in secondary traffic impacts along the haul route to the disposal or reuse site with accompanying short-term air quality and noise impacts (see 4.4 Traffic and Circulation, 4.5 Air Quality, and 4.6 Noise). No specific disposal or reuse site has been identified, but sites currently needing significant quantities of fill include Ralston Avenue at U.S. 101 in Belmont and Avalon Canyon in Daly City. However, excess material removed from the Phase II site would be transported to a receiving site via South San Francisco Drive and Sister Cities Boulevard and from the Phase III site via Bayshore Boulevard. Beyond those points, the haul route (and impact along that route) would 96 According to the project sponsor, as noted in 2.3 Project Description, grading could take two, possibly three, seasons. It is possible that the grading proposed could be completed in two seasons. 97 Brian Kangas Foulk (project sponsor's engineer) and Parikh Consultants, Inc. (sponsor's geotechnical consultant). Minor grading projects typically involve several hundred to about 10,000 cubic yards. Movement of 100,000 cubic yards is commonly identified as significant because this quantity would generate a substantial number of truck trips and dust generation. 115 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase II and Ill SEIR not be lrnown until the destination is identified. Impacts generally would consist of increased traffic, dust, and noise levels during an intense period of construction. Grading activities would create secondary dust and noise impacts off-site (see 4.5 Air Quality and 4.6 Noise). Based on the experience in Phase I, most site grading can be completed by conventional ripping and scrapers. However, parts of the Phase II (Point) and III sites may require controlled blasting (also addressed in 4.6 Noise). The San Bruno Mountain Area Habitat Conservation Plan (HCP) which allows limited development on the mountain in exchange for landowner participation in a mountain-wide mitigation program provides for minor boundary adjustments when ultimately implementing the individual development projects. 98 For all three phases of the Terrabay project, the agreement permits encroachment onto (and requires restoration of) up to ten acres of Habitat Conservation Plan (HCP) land within a 50-foot minor boundary adjustment limit of the site development areas. Implementation of Phase I affected 0.69 acre of this total. Both disturbance and restoration would be subject to review and approval for HCP conformance by the City, County, and USFWS HCP monitoring consultant. 99 Mitigation Measure 4.1-1 No measures would be required for grading per se within previously graded parts of Phase II and III site development areas. Moreover, grading which would not extend beyond the 50-foot minor boundary adjustment limit and 9.31-acre uphill of the HCP fence would comply with the Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan, as required by the Terrabay Specific Plan District, and, therefore, would not necessitate additional mitigation. In order for the project to be deemed in compliance and to constitute ales-than- significant impact: All grading plans and operations in the Terrabay Specific Plan District shall be in compliance with the provisions of the San Bruno Mountain Area Habitat Conservation Plan ('Title 20 of the South San Francisco Zoning Code Section 20.63.020). In order to meet this requirement, disturbed land within this minor boundary adjustment limit area shall be replaced through in-kind restoration. • No development proposal which requires a permit or an approval of any sort to be issued by any local, State, or Federal agency may be approved by the City until proof of such other permit, license, or approval is on file in the department of Community Development (Title 20 of the South San Francisco Zoning Code Section 20.63.250). Reducing the extent of grading involved in project implementation would help balance cut and fill operations and the need to export excess fill material for disposal (or reuse) at another location. Measures to mitigate direct erosion, slope stability, and differential settlement impacts are presented below (see Mitigation Measures 4.1-2 through 4.1-5), and measures to mitigate indirect traffic, air quality, and noise impacts are presented in the respective analyses. Significance after Mitigation Implementation of Mitigation Measure 4.1-1 would avert significant impacts because no development could proceed until the project complied with the Terrabay Specific 98 Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan, op. cit., and Nichols • Berman conversation with Victoria Harris, Thomas Reid Associates, op. cit. 99 The project sponsor reportedly is preparing plans to demonstrate [hat proposed grading of the Phase II and III combined with a relocation of the existing HCP fence would result in a net increase in HCP land to be dedicated for inclusion in San Bruno Mountain County Park. However, application materials currently do not reflect an HCP fence change. 116 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase 11 and ll! SEIR Plan District and San Bruno Mountain Area Habitat Conservation Plan. Thus, the result would be to reduce the impact to aless-than-significant level. Implementation of Mitigation Measures 4.1-2 through 4.1-5 would reduce adverse effects of erosion, reduced stability of cut slopes, and differential settlement. Responsibility and Monitoring Same as Mitigation Measures 4.1-2 through 4.1-5. lmpact4.1-2 S1opeStability/Erosion Cuts greater than ten feet high, cuts in soil for proposed slopes with grades steeper than 2: 7 (horizontal: vertical), or cuts with bedrock grades steeper than 1.5:1 could erode until vegetation is re-established. These engineered slopes can erode locally, as experienced in Phase I where substantial grading was completed during a drought and then abandoned during a period of above average rainfall. Proposed cut slopes, especially in soil, need to be protected from erosion before the rainy season. Unless a comprehensive winterization plan is implemented before the onset of winter rains, the erosion from the unvegetated slopes would be significant. S Cut slopes can be susceptible to slope stability problems. The initial cuts for Phase I were graded in 1989 and then lay idle while project implementation was delayed. During that time, two minor slope failures occurred on individual lots within the site, and about eight occurred on perimeter slopes. The slippages on the lots resulted primarily from ponded water and lack of attention and maintenance of winterization plans. The slippages on the perimeter slopes were located primarily at the interface between the bedrock and cover sediments and were related to seepage along this interface. Other slipouts were related to saturated soil slippage (seepage near Hillside fault) and from saturation of the cut slopes between the benches during the intense 1997-1998 winter storms. During preliminary design of the Phase II Precise Plan, the project sponsor's consultants undertook efforts to minimize the amount of grading in stability-sensitive sediment-filled hollows above the site. Efforts included designing narrower lots in place of wider ones, increasing street grades, and eliminating some proposed housing units. Examination of the Precise Plan, the Vesting Tentarive Map 1~, and the geologic conditions outlined by the Geologic Map and Geologic Summary Report 101 indicates that some of the proposed cut slopes would have grades of 1.5:1 in soils, would not contain intermediate benches, and would not have perimeter type A-ditches. In addition, while this 1998 SEIR was being prepared, the project sponsor's geotechnical consultant was analyzing the stability of representative cut slopes throughout the proposed Phase II and III site development areas. The results of these analyses were not available to review in the 1998 SEIR but would need to be reviewed and approved by the City before issuing a grading permit. The City of South San Francisco requires cut slopes no steeper than 2:1 in soils and 1.5:1 in bedrock, provision of benches at approximately 30 feet of cut, and placement of perimeter type A-ditches above cut slopes and V-ditches on benches. In addition, the City requires all fill slopes to have maximum grades of 2:1. These criteria were imposed for Phase I grading. The overall success of the slopes on the Phase I site confirms that the basic design requirements are sound. However, the isolated failures also emphasize the importance of slope design and the necessity of intermediate benches on cut slopes to act as buffers between potential slipouts and structures. 100 Precise Plan and Vesting Tentative Map and Preliminary Grading Plan, Brian Kangas Foulk, January 15, 1998. 101 Geologic Map and Geologic Summary Report, Terrabay Development Phase II & 111, South Slope San Bruno Mountain, San Mateo County, California, Parikh Consultants, Inc., September 1997. 117 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase ll and 111 SE/R In the ten years since the Phase I site was graded, the cut and fill slopes have been subjected to si~lificant winter storms, and some experienced erosion and gullying. The project sponsor's revegetation consultant, Pacific OpenSpace studied these slopes, and corrective measures (regrading, waddles, reseeding, hydromulch, and straw) were taken to revegetate eroded areas. This proactive approach w•as implemented in 1996 (after completion of the 1996 SEIR and restoration /mitigation of the Area D Landslide) and was further modified and improved before the 1997-1998 winter season. Mitigation Measure 4.1-2(a) In order to reduce slope stability impacts to less-than-significant levels, the project's proposed grading plans shall be revised to incorporate the following: • Slopes shall be laid back to provide grades no steeper than 2:1 in soil and 1.5:1 in rock except in areas where rock is highly fractured and acts like soils in which case slopes shall be laid back farther, rock bolts shall be installed, or retaining walls shall be constructed. In addition, subsurface drainage shall be installed. • Intermediate benches and accompanying drainage shall be designed with vertical intervals of about 30 feet or as recommended by the City Engineer. • Perimeter type A-ditches shall be provided above cut slopes. • Slope and groundwater monitoring instruments (inclinometers, piezometers) shall be installed at the tops of cuts to monitor slope stability. If slopes cannot be laid back without encroaching beyond the 50-foot Honor boundary adjustment limit (and in excess of 9.31 acres) in the HCP area, alternative mitigation to the above criteria include revising proposed grading plans to modify site design. Such modifications shall incorporate one or all of the following measures: • The location and / or height of retaining. walls shall be shifted or raised. Retaining walls higher than ten feet shall not be designed as poured in place structures but shall provide step backs or cribs planted with vegetation and built with rough stone or earth colored materials. The project sponsor shall submit plans for retaining wall design for walls higher than ten feet for City review. • Grades of the site streets shall be increased wherever possible to reduce grading into the hill but in no case exceed 15 percent. Grades between 12 and 15 percent shall require approval by the City Engineer, as provided by the Terrabay Specific Plan District. • Development shall be limited to lower site elevations to contain grading within development areas, thus reducing the total development area (and amount of development which could be accommodated). This measure may eliminate the uppermost four triplex lots (12 units) currently proposed in the Commons neighborhood or individual lots at street ends of any of the hammerheads proposed in Woods East. Mitigation Measure 4.1 Z(b) As previously stipulated for Phase I, the City shall withhold building permits for development of lots located downhill of cut slopes until the slopes have experienced at least one average winter season (about 20 inches of rain). Mitigation Measure 4.1-2(c) As automatically required by the Regional Water Quality Control Board (RWQCB) and City of South San Francisco, all exposed slopes and surfaces (graded pads) shall be winterized before October 15 of the year. The Phase II and III winterization programs shall include such measures as: Waddles, hydroseeding, silt fences, straw bales, and berms shall be placed around pads with contained (pipe) discharges. Streets shall be swept before (and truck access should be limited during) major storms. Sandbag check dams shall be placed along gutters, and straw mats should be placed over storm inlets. I18 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase U and ll! SE7R The grading site(s) shall be inspected prior to and during major storms. Significance after Mitigation Mitigation Measures 4.1-2(a), 4.1-2(b), and 4.1-2(c) aze intended to duplicate and improve on the measures used on the Phase I site to mitigate stabilize and winterize, graded slopes. While the measures used on the Phase I site have been successful overall during the past ten years, implementation of Mitigation Measures 4.1-2(a), 4.1-2(b), and 4.1-2(c) would be required to reduce stability and erosion impacts to less-than-significant levels. This is because the pending plans currently fall short in incorporating successful measures as listed in Mitigation Measures 4.1-2(a) and 4.1-2(c). The plans shall be revised to incorporate the principles enumerated in Mitigation Measures 4.1-2(a) and 4.1-2(c) in order to reduce the impacts from slope stability and erosion to aless-than-significant level. Mitigation Measure 4.1-2(a) contains alternative approaches which could result in secondary impacts. Such impacts relate to grading farther upslope of previously disturbed azeas in order to achieve flatter grades, including encroaching onto HCP lands. As discussed in relation to Impact 4.1-1, the Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan permits encFoachments within a 50-foot band and not exceeding ten acres. In Phase I, grading of 80 acres resulted in encroachment of 0.69 acre of the ten acres permitted. For this reason, this potential secondary impact is considered less-than-sign cant. Responsibility and Monitoring The project sponsor (and sponsor's consultants) shall be responsible for modifying the Precise Plan and implementing Mitigation Measures 4.1-2(a) and 4.1-2(c), and the City shall be responsible for implementing Mitigation Measure 4.1-2(b). Revised Precise Plans shall be subject to City review prior to issuing a grading permit. In addition, the sponsor's geotechnical consultant shall be required to be present on-site on a full-time basis to verify and modify, if necessary, the fmal grading plans. As with Phase I grading, the City shall also have an inspector to monitor the mass grading. After grading is complete, the sponsor's and City's inspectors shall continue to monitor slopes including the monitoring instruments until the slopes aze fumed over to the Homeowners Association. Impact 4.1-3 Landsliding and Debris S/ides Landslides and debris slides are present within and above site development areas of the Phase 11 and Phase 111 sites. Without mitigation, continued movement would have significant impacts on proposed development. Large-scale grading operations likely would be necessary to repair unstable areas. In addition to deep-seated landslides, the site has experienced impacts from shallow debris slides. Landslide repair techniques, similar to those used during Phase I grading, would be necessary during grading proposed for the Phase 11 and 111 sites. If mitigation measures, including drainage, removal, deflection and / or retention structures, setbacks, debris basins, etc., are not taken, future debris slides would have a significant impact on proposed development. S The project sponsor's geotechnical consultant has prepared three documents which address an understanding of current conditions and propose measures to mitigate the geotechnical and geological hazards identified at the site. 102 The geotechnical reports propose several measures to mitigate impacts from the presence of landslides on the site. These measures are similar to those used on Phase 102 Ibid., Supplemental Subsurface Exploration (Test Pits), Terrabay Project, South San Francisco, Parikh Consultants, Inc., January 1998 and Geologic and Geotechnical Impact and Mitigation Summary Report, Terrabay Development Phase 11 & III, South Slope of San Bruno Mountain, San Mateo County, California, Parikh Consultants, Inc., February 1998. 119 4.1 GEOLOGY, SOILS, AND SEISA.f/C/TY Terrabay Phase lI and Ill SE/R 1103 For example, in the Woods West neighborhood, mass grading is proposed to remove and replace landslide debris with benched, drained, engineered fill, similar to the Area C and R landslide repairs undertaken on the Phase I site. In the Point neighborhood, deflection and retaining walls are proposed to be built to buttress shallow slide material and retain future movement. However, no mitigation is proposed for landslides identified in the Commons neighborhood and Phase III site. Although Parikh Consultants identified an active slide area on the upper elevation of the Commons neighborhood, grading plans indicate cut slopes into these landslide areas of 1.5:1 and do not indicate any measures to mitigate the identified landslides. Both the project sponsor's and City's geotechnical consultants would monitor excavated slopes during site grading for evidence of conditions different than anticipated by the geotechnical reports. This approach is standard practice for grading and was successful in identifying additional conditions which required mitigation during Phase I development. In particular, the Area R landslide mitigation was changed from a series of drains to complete removal of slide material and replacement with keyed, drained, engineered fill. As shown by this example, the volume and areal extent of mass grading for landslide repair could be greater with project implementation than currently estimated. The environmental effects would include disturbance of larger areas of natural slopes, loss of more native vegetation, potentially intensified short-term air quality (dust) and construction noise impacts, and possible encroachment into the HCP area. The impacts of debris slides would also be significant unless mitigated. Examination of the project site reveals scars of debris slides which occurred during the January 4-5, 1983 storm and fresh debris slides which occurred during record rainfall in February 1998. These debris slides and potential debris slide areas are located on HCP lands above proposed development areas. Debris slides on San Bruno Mountain would follow existing drainageways across the site. Debris basins are proposed to be constructed in various drainages to retain debris. Most proposed debris basins would be located in existing drainages, as built in Phase I. However, debris basins proposed on the Phase III site would be located outside confined drainages, and concrete channels would be built into the basins. These lateral channels would have two percent grades and significant angle changes, both of which could cause debris to be deposited above the debris basins. These "lateral" channels and debris basins must be designed to ensure that they would perform their functions and mitigate the impacts of debris slides entering drainages. (Impact 4.2-11 also addresses Phase III site debris basin design.) Potential debris slides located directly upslope of proposed development would need different mitigation from that required for other types of landslides. Potential debris slide material can be removed through grading. This approach would increase the area impacted by grading and in some areas could involve grading onto HCP lands. Another approach would be to install a subsurface drainage system to dewater the soil mass. This approach also would require grading above the cut slopes of the site development area, including some HCP land. Potential impacts of debris slides also can be mitigated by construction of retention and / or deflection structures located upslope of perimeter cut slopes of the development areas. In relation to all these approaches, the HCP requires that the activities be confined within the 50-foot minor boundary adjustment limit and not exceed the remaining 9.31 acres of land which can be disturbed by development. Any encroachment be}•ond those areas would require an amendment of the HCP. The Precise Plan primarily proposes deflection and retention walls to mitigate potential debris slide hazards directly above the Phase II site. However, no mitigation measures are proposed for many 103 The project sponsor's geotechnical consultant, Parikh Consultants, previously was a Principal of PSC, the firm which completed the original geotechnical investigations for the proposed project. Gary Parikh also was responsible for inspecting on-site grading during Phase I. 120 4.1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase lI and 111 SE/R areas of potential debris flows. 104 Until incorporated in the Precise Plan and Vesting Tentative Map, lack of deflection and retaining walls would constitute a significant impact. Mitigation Measure 4.1-3(a) The Precise Plan and Vesting Tentative Map grading plans shall be revised to incorporate the following: Measures to mitigate active slide areas located in the Commons neighborhood and Phase III site and to mitigate cuts into active slides shall be incorporated into the project and include removing material, buttressing, and building retaining walls. Locations shall be shown of all deflection and retaining walls as determined necessary by the City's Consulting Geologist. Implementation shall include installation of monitoring instruments (inclinometers, piezometers). Measures shall adhere to the City's grading requirements listed in Impact 4.1-2 and can be achieved by using techniques listed in Mitigation Measure 4.1-2(a), including installation of slope stability monitoring instruments. Mitigation Measure 4.1-3(b) The project's Covenants, Conditions, and Restrictions (CC&Rs) shall establish and provide for implementation of a Slope Maintenance Plan by the project's Property Owners Associations (Owners Associations). 105 The project sponsor shall provide initial funding for the Slope Management Plan, and the Property Owners Associations shall fund long-term implementation after receiving title to their respective private open space lands. At a minimum, the Slope Maintenance Plan shall provide for monitoring and maintenance of engineered slopes, perimeter drainage, debris slide retention, and deflection structures. 106 Significance after Mitigation Geotechnical techniques are available to~ repair landslides and reduce potential impacts from movements of debris flow slides. These techniques are capable of successfully mitigating impacts. When incorporated into project plans, landslide repair, elimination or repair of potential debris slide source areas, and provision of additional retention and / or deflection structures would reduce this impact to ales-than-significant level. Responsibility and Monitoring The project sponsor and sponsor's consultants shall be responsible for incorporating Mitigation Measure 4.1-3(a) in the Precise Plan Grading-Plan and Mitigation Measure 4.1-3(b) in the project's CC&Rs. The sponsor's geotechnical consultant and City's inspector shall monitor mass grading on the Phase II and III sites. Any conditions not identified before grading, shall be mitigated during mass grading. The project sponsor's geotechnical consultant also shall monitor the instrumentation. If monitoring determines that mitigation is not working as designed, additional mitigation will be necessary, using the measures listed above, as approved by the City. As required by Mitigation Measure 4.1-2(b), slopes shall be monitored for at least one average winter 104 Eric McHuron conversation with Gary Parilch, February 19, 1998. This discussion indicated that several retention and / or deflection structures were omitted from project plans accidentally and are being incorporated into the Precise Plan Grading Plans. 105 The term "Property Owners Association" refers to proposed Homeowners Associations for residential neighborhoods, Master Association for the Phase II residential site, and a Master Association for the Phase III commercial site. 106 As of February 1998, the project sponsor had not submitted draft CC&Rs [o the City as required to accompany a Precise Plan. 121 4.1 GEOLOGY, SOILS, A..'JD SEISMICITY Terrabay Phase 11 and Ill SE1R season before releasing lots immediately below the slopes for development. After development, the site shall be monitored as part of the Slope Maintenance Plan similar to procedures used in Phase I. Impact 4.1-4 Rockslides and Rockfalls Past cuts into the sandstone bedrock along the southern end of San Bruno Mountain often initiated major rockslides, such as large historic rockslides present north and northeast of the Phase 111 development area. Grading plans for the Phase lI (Point) and 111 sites propose significant cutting into the sandstone bedrock along the southern end of San Bruno Mountain. As of February and March 1998, specific rock slope stability analyses had not been pen`ormed for the high rock slopes proposed on the Terrabay Point and Phase 111 sites, and application materials had not identified proposed mitigation. In addition, rock outcrops on and above the site pose potential hazards from rockfalls, especially if triggered by groundshaking in an earthquake. S Rockslides Five test pits were excavated into the sandstone early in December 1997. Examination of the rock outcrops and test pits excavated into the bedrock indicates that the sandstone is thinly bedded to massive, has been folded into many different orientations, and is cut by numerous fractures. All of these features can contribute to the rock defects of the sandstone. 107 Most of these pits were located in zones of significant seepage from groundwater weeping through the fractures and bedding. Therefore, the combination of rock defects and seepage may have caused the bedrock failures (as rockslides) when undercut for grading. High cut slopes proposed by grading would also be subjected to seismic forces during significant earthquakes. Mitigation for rockslides needs to start with an understanding of the potential risk. This risk is related to the orientation and spacing of rock defects. In areas where rock defects are deemed to be significant (where the rock would act more like a soil than bedrock), mitigation measures need to be taken. These measures include grading flatter slopes, installing rock anchors, and building subdrains. Graded slopes also would need to provide benches, with drainage ditches, and access for maintenance, but flatter slopes would encroach farther up hillside than slopes designed with steeper grades. Revegetation of graded slopes also can mitigate rockslide impacts. However, revegetation of 1.5:1 slopes cut into rock during Phase I grading has had limited success. Geotechnical mitigation and revegetation efforts for the Phase II and III sites need to be coordinated in order to be adequate. One approach could be through use of terracettes (small benches in the overall slope). Terracettes would help trap eroded material and aid in the establishment of vegetation. Once the vegetation has had a chance to become established, it would help stabilize slopes (and also help soften the visual impact of highly prominent cut slopes). Rockfalls Boulders up to several feet in diameter are present at the base of some of the st:.eper slopes where rock outcrops are located. These boulders are evidence of rockfalls. Along the Hillside fault zone, between the Commons and Woods East neighborhoods, these boulders form a talus slope. Rock outcrops located on and above the site provide the sources of these rocks and boulders ~j~hich become dislodged slowly (such as through weathering) or in sudden events (such as in an earthquake). Mitigation of individual rockfalls would require several different measures. Most sources of rockfall material are located on HCP lands. These potential source areas need to be examined further to evaluate the most appropriate method to mitigate the problem. Actual measures or combination of measures would vary from outcrop-to-outcrop, but potential mitigation methods include scaling, 107 Supplemental Subsurface Exploration (Test Pits), Terrabay Project, South San Francisco, Parikh Consultants, Inca, January 1998, op. cit. 122 4.1 GEOLOGY, SOILS, AND SEISM/C1TY Terrabay Phase 11 and 11! SE1R encapsulation (netting), rock anchoring, and building simple retention structures (fences) below outcrops and above cut slopes. The project sponsor's geotechnical consultant currently is reviewing specific mitigation methods to propose undertaking at each rockfall source area. Most measures are expected to involve fences outside the site development areas (farther uphill than the cut slope but below the HCP fence). Many of the anticipated fences would double as debris flow retention / deflection structures. Mitigation Measure 4.1-4(a) Project plans shall be revised to incorporate the specific measures identified by the detailed rock slope stability analysis of the orientation and spacing of rock defects and inspection of individual rock outcrops conducted by the project sponsor's geotechnical consultant. The revised plans shall identify individual measures or combinations of measures proposed for each rock slope, outcrop, and source area to mitigate rockslide and rockfall impacts. Among measures for consideration are one or more of the following: Rockslide measures: • Flatter slopes shall be graded with benches, drainage ditches, and access for maintenance • Rock anchors shall be installed. • Subdrains shall be constructed. • Geotechnical mitigation and revegetation shall be coordinated, possibly through design of - benched terracettes. • Slope monitoring instrumentation shall be installed (inclinometers, piezometen etc.) . Rockfall measures: Loose rocks shall be scaled off. Netting shall be placed around features to encapsulate and prevent material from moving. Simple retention structures (fences) shall be built below outcrops and above cut slopes. Mitigation Measure 4.1-4(b) The project sponsor shall include annual inspection of outcrops before each rainy season and after significant seismic shaking in the Slope Maintenance Plans (that is CC&Rs) ident~ed in Mitigation Measure 4.1-3(b) for implementation by the respective Property Owners Associations. The City shall review, modify as necessary, and approve the CC&Rs. Significance after Mitigation After rockslides, individual outcrops, source areas have been visited and mitigation methods proposed, reviewed, and approved by the City, the significance of rockslide and rocl~all impacts would be reduced to aless-than-significant level. As discussed above in relation to other impacts, secondary impact of grading flatter slopes to mitigate rockslide, rockfall, or other geologic impacts would be to encroach uphill, disturbing the natural landform and native vegetation. By confming grading within the 50-foot and ten-acre area in compliance with the Agreement with Respect to the San Bruno Mountain Area Habitat Conservation Plan, the severity of secondary impact would not be significant. Responsibility and Monitoring The project sponsor shall be responsible for implementing rockfall mitigation measures before turning repaired slopes over to the respective Property Owners Associations for long term maintenance and monitoring -including both visual inspection and continuing to collect monitoring instrumentation data. The Property Owners Associations shall have long-term responsibility for implementing the project's Slope Maintenance Plans including monitoring of the outcrops to be inspected annually before each rainy season and after significant seismic shaking. 123 4. i GEOLOGY, SOILS, AND SEISMICIry Terrabay Phase 1! and 111 SEIR Impact 4.1-5 Artificial Fill Differential settlement from placement of deep fill, unconsolidated fill, or artificial fill at variable thicknesses can damage structures, roadways, and utilities developed on or in the fill material. Compression from placement of fill on the archaeological site would damage those resources (a direct archeological impact) and potentially disrupt or damage facilities developed in or on the fill (an indirect geologic impact). S Differential Settlement Differential settlement occurs when artificial fill is placed in a canyon, in an area which requires substantial differences in fill thickness, or across materials with variable strength properties (such as bay mud or non-engineered fill compared with stiff soils or bedrock). When engineered fill is placed under ideal conditions, the amount of expected settlement is about one percent. Therefore, in the Point neighborhood, where fill would cross a ravine and fill thickness would vary by about 50 feet, differential settlement of at least six inches would be expected. This anticipated settlement is especially important because the large footprint of the triplexes would span a zone of differential settlement. Without mitigation, structures (houses, sidewalks, streets) could experience excessive differential settlement, surface drainage of streets could be adversely affected, and gravity flow sewer lines might not operate properly. Differential settlement would also be expected if fill was placed over the existing stockpiles of non-engineered fill and topsoil in the Woods East and Woods West neighborhoods. Because these stockpiles would be removed prior to placement of benched and drained engineered fill, they would not represent a potential differential settlement impact. Many approaches are available to geotechnical engineers to minimize the impacts of differential settlement. These mitigation approaches include over-excavating to cut benched areas in the fill, using boulder rock fill in the deepest parts of canyons, surchazging fill with excess material, postponing development in azeas most sensitive to settlement for a construction season (then monitoring the rate of settlement and delaying development until the rate of movement is within acceptable limits), and placing structures on deep pier foundations. These techniques need to be evaluated and used on a case-by-case basis. For example, material graded on the Point /Commons area could be used to surcharge fill placed in the part of the Point which straddles the ravine during which time installation of utility lines and fine grading could be delayed for a construction season. In the meantime, construction could occur elsewhere in Point and Commons on areas located on cut slopes or where the depth of fill would be more uniform. Archeological Site Placement of fill over the archeological site would also result in settlement impacts. 108 The archeological site is up to ten feet thick and consists of loosely compacted shell and organic material. Shell fragments are touching shell fragments (in grain to grain contact) in the site. When fill is placed on the site, it would consolidate and settle. In addition to settling, the shell fragments are fragile and would be crushed at the grain-to-grain contacts. The amount of fill proposed on the site would. vary from about five to 22 feet, with five to ten feet over the thickest part of the archeological site. The project sponsor's geotechnical consultant estimates that the amount of settlement and crushing within the mound could be as much as one foot (ten percent). 109 This amount of settlement within the archeological site would be significant. The standard approach for placing engineered fill would be to strip the site of organic material and then scarify and bench the fill into the native materials. While the destructive effect on archeological materials is mainly a cultural resources issue (and is discussed in 4.9 Archaeology), settlement of fill also could affect utilities 108 Also see 4.9 Archaeology for a description of the archaeological site CA-SMa-40, an analysis of impacts attributable to the project, and measures recommended by the project sponsor's and SEIR's archaeologists to mitigate those impacts. 109 Eric McHuron conversation with Gary Parikh, February 19, 1998. 124 4. 1 GcOLOGY, SOILS, AND SEISMICITY Terrabay Phase 11 and 111 SEIR placed in or under the material. For example, settlement of the sanitary sewer proposed across the archeological site could damage the facility and, in turn, cultural resources. In addition, capping of the site would also affect moisture conditions in the archeological site. If groundwater is allowed to build up and flow through the site, shells could dissolve. Water sources could include elevated groundwater, rain, landscape irrigation, and leaks in the sanitary sewer line proposed across the archeological site. The Precise Plan presents no detailed design of on-site or perimeter drainage or of the proposed cap. Mitigation Measure 4.1-5(a) The Precise Plan shall be revised to indicate the measures proposed to mitigate differential settlement impacts expected from development in Terrabay Point on areas of deep or varied fills. These techniques shall be evaluated and used on a case-by-case basis and, when selected and implemented, shall be monitored to determine their effectiveness. One or a combination of the following approaches shall be incorporated into project plans: • Cuts shall be over-excavated to provide benches in the fill. • Rock fill shall be used in the deepest parts of canyons. • Fill shall be surcharged with excess material to accelerate settlement. • Development of areas most sensitive to settlement shall be postponed for a construction season. • The rate of settlement shall be monitored and development (including utilities, curbs, gutters, etc.) dela}~ed until the rate of movement is within acceptable limits of the engineered structures. • Structures shall be placed on deep pier foundations. • Fill over the archeological site shall not be placed on a scarified or benched surface. • Construction activity on the archeological site shall be limited to small construction equipment. Measures selected shall be evaluated through monitoring of reference points, and development of the site, including roadways and utilities, shall be delayed until the amount of future settlement reaches an acceptable le~-el, approximately one-half inch across the triplex lot. Mitigation Measure 4.1-5(b) The Precise Plan shall provide drainage both around the archaeological site to maintain depressed groundwater levels and under the cap to divert potential sewer leakage. During project implementation, care shall be taken to properly install a subdrain under the cap. This drain would prevent infiltration of rainwater and landscape irrigation from the Park from percolating through the site. The project sponsor's archaeologist shall be present during installation of project drainage facilities at the archeological site. Relocation of the sanitary sewer to the internal roadway right-of--way would eliminate the potential of puncturing the cap placed over the archaeological site. Significance after Mitigation Implementing the mitigation and monitoring measures listed in Mitigation Measure 4.1-5(a) would reduce the differential settlement impacts to less-than-significant levels. Implementing Mitigation 4.1-5(b) by installing drainage below the cap, similar to the capping of hazardous waste sites, would also reduce moisture impacts to less-than-significant levels. Implementation of Mitigation Measure 4.1-5(b) would avert potential long-term impacts due to settlement and resulting maintenance required for the sanitary sewer. Potential impacts from puncturing the cap could be avoided by relocating the sewer to the internal roadway right-of--way. Responsibility and Monitoring The project sponsor's geotechnical consultant shall be responsible for identifying the measure or combination of measures listed in Mitigation Measure 4.1-5(a) to incorporate into project plans for City review and approval. The sponsor's geotechnical consultant shall be responsible for implementing the measure(s) selected and monitoring settlement rates. i ~.s 4.1 GEOLOGY, SOILS, AND SE/SM/CITY Terrabay Phase ll and 111 SE1R Impact 4.7-6 Secondary Effects of Seismic Shaking Given site geologic conditions, hazards to people or property from groundshaking (including liquefaction, lurching, lateral spreading) could be mitigated to levels deemed acceptable in a seismically active region through compliance with Uniform Building Code standards and measures required to address other potential impacts on development. S The project site would be subjected to seismic shaking some time during the life of development there, as will occur elsewhere in the San Francisco Bay Area. Geotechnical investigation of the site has not revealed any evidence of soil conditions which might be susceptible to the secondary effects of seismic shaking (liquefaction, lurching, lateral spreading, etc.). Design of structures would be required to comply with Uniform Building Code (UBC) Seismic Code (Zone 4) standards and City standards. Nevertheless, seismic shaking can trigger landslides, rockslides, and rockfalls without mitigation of those potential hazards. Mitigation Measure 4.1-6 Stability analyses shall be conducted on representative slopes based on seismic loading and anticipated groundwater conditions to evaluate the need (if any) for special mitigation measures over and above standard engineering of the slopes in order to mitigate potential impacts on development from seismically induced landsliding and rocksliding. If the stability analysis identifies the need for special mitigation, Mitigation Measures 4.1-3 and 4.1-4 shall be revised to incorporate the additional seismic measures required. These could include one or more of the following: • Keyways for fills shall be placed through soft soils. • Flatter slopes shall be graded with benches. • Rock anchors shall be installed. • Subdrains shall be constructed. • Retaining walls shall be built to minimize fill over sensitive areas. • Buildings shall be designed in conformance with Uniform Building Code (UBC) Zone 4 and City standards. • Rockfalls shall be mitigated by removal, encapsulation, or fences (Mitigation Measure 4.1-4(a)). Significance after Mitigation Implementation of Mitigation Measure 4.1-6 would reduce the potential secondary effects from seismic shaking to aless-than-significant level. Responsibility and Monitoring The applicant's geotechnical consultant shall be responsible for analyzing the engineering analyses of proposed slopes, also to be reviewed and approved by the City before granting grading permits. City building inspectors shall be responsible for reviewing and approving the seismic design of proposed structures as a routine response to building permit applications. Impact 4.1-7 Hook Ramps and Bayshore Boulevard Realignment Construction of the proposed hook ramps and realignment of Bayshore Boulevard adjacent to the Phase Ill Terrabay site would result in significant impacts, including erosion from removal of native vegetation cutting into bedrock and cover sediments, filling over cover sediments (including soft compressible soils), and fill encroachment 126 4. 1 GEOLOGY, SOILS, AND SEISMICITY Terrabay Phase 11 and 111 SE/R onto the archaeological site. These impacts would require mitigation similar to measures identified for the Phase 111 site. S The geotechnical consultant for the hook ramps project, CH2MHill, has completed geotechnical borings for other roadway improvements in the vicinity of the ramps 11o but plans to initiate speck additional studies for the hook ramps in the near future. 111 gases on the existing information and an understanding of conditions on the adjacent Ten-abay Phase III site, conditions on the hook ramps and Bayshore Boulevard realignment site predominantly consist of existing fill for Bayshore Boulevard over a thin Iayer of Bay Mud and then alluvial cover sediments. The thin layer of Bay Mud has already undergone consolidation over the years. Because construction of the hook ramps is planned where the present Bayshore Boulevard is located, Bayshore Boulevard would be realigned onto native material (bedrock, colluvial, alluvial fan, soft clayey soils). The existing grade of the scissors ramp and Bayshore Boulevard alignment would be raised by placing artificial fill along the proposed alignments. Finished grades for the hook ramps and Bayshore Boulevard realignment have been deternuned ir. relation to design requirements of the Oyster Point interchange flyover. The flyover is also proposed in the immediate vicinity and would permit southbound L"'.S. 101 movements to the developing area directly east of the freeway. The hook ramps have been designed to a higher finished grade elevation than the present scissors ramp to provide required clearance for the flyover. The Bayshore Boulevard realignment similarly would be raised in order to make a transition with the hook ramps and with the Terrabay Phase III site. This filling would place up to fi~~e feet of material over the native materials, including the southern boundary of the archaeological site. If placing five feet of material on the archaeological site would not be acceptable for cultural resource reasons, alternatives include building a retaining wall to support the realigned roadway segment through this part of the site or constructing the western edge of this realigned roadway segment on piers to provide a bridged causeway or flyover which would be cantilevered over the site. ' Mitigation Measure 4.1-7 The following measures shall be required to mitigate impacts from construction of the hook ramps and Bayshore Boulevard realignment: An erosion control plan shall be prepared and implemented during project construction in compliance with Regional Water Quality Control Board and City of South San Francisco requirements. The plan shall be implemented before the winter rainy season (by no later than October 1 ~) and shall include such measures as: Waddles, silt fences, straw bales, and berms shall be placed where the ground has been exposed by grading. Truck movements shall be limited during major storms. Sandbag check dams shall be placed along ditches, and straw mats should be placed over storm inlets. The site shall be inspected prior to and during major storms. Engineered fill shall be surcharged to accelerate compaction before construction of roadway facilities in order to reduce potential impacts from settlement and avoid potential impacts from differential settlement. 110 Foundation Report for Southbound Flyover at 0}~ster Point Boulevard, CH2hiHill, 1997, and Borings Logs B-1 and B- 4 Oyster Point Interchange and Grade Separation, CH2MHill. 111 Eric McHuron conversation with Ana Demorest, CH2MHi11, March 16, 1998. 127 4.1 GEOLOGY, SOILS, AND SE/SMIC/TY Terrabay Phase 11 and 111 SE/R Weak cover soils shall be over-excavated and replaced with benched and drained engineered fill. Drainage shall be provided along the seepage azeas in the alluvial fan cover sediments. Retaining walls shall be built to minimize the amount of fill over weak soils in the vicinity of the archaeological site. Significance after Mitigation Implementation of Mitigation Measure 4.1-7 would reduce the impacts of constructing the hook ramps and realigning Bayshore Boulevard to aless-than-significant level. Responsibility and Monitoring The project sponsor's geotechnical consultant shall be responsible for analyzing the engineering analyses of the proposed grading and mitigation measures, for review by Caltrans, the City of South San Francisco, and City of Brisbane before granting grading permits. Caltrans and City inspectors shall be responsible for monitoring construction and post-construction performance of the improvements. t 2a 4.2 HYDROLOGYAND DRAINAGE HYDROLOGYAND DRAINAGE -THE SETTING Background This section describes the project's potential impacts on drainage, on- and off-site flood hazard:, and related aspects of hillslope erosion and downstream sedimentation. The project's impacts on water quality are not reexamined by this 1998 SEIR assessment because these impacts were discussed in the Draft and Final 1996 SEIR and are not expected to change as a result of the currently proposed project. The section contains an overview of the existing hydrologic system altered from natural conditions by initial site grading and drainage modifications implemented on Phase II and Phase III lands in anticipation of approved development. (All required debris basin and storm drainage facilities en the Phase I site have already been built.) It also describes changes in the project since preparation of the 1996 SEIR and assesses the currently proposed project's impacts on both previously installed permanent drainage facilities and other local hydrologic and drainage characteristics. Regional Setting Exhibit 4.2-1 shows the Phase II and III sites and their tributary watersheds. The four contiguous sub- watersheds drain the Phase II site, and three principal sub-watersheds drain the Phase III site. The Phase II site sub-watersheds encompass a combined area of approximately 508 acres and extend from South San Francisco Drive north to the ridge of San Bruno Mountain, upslope from the site boundary. The slopes of these sub-watersheds face south except for the eastern part of the Point neighborhood where about nine acres face east. Before initial grading in 1982, those slopes wer: part of the southernmost sub-watershed on the Phase III site. This change resulted in a cross-basin diversion, although both Phase II and III lands discharge to the same outlet in San Francisco Bay-. The sub-watersheds where the Phase III site is located cover 182 acres on the eastern flank of San Bruno Mountain. From the ridgeline above the site, these sub-watersheds drain to outlets along Ba~-shore Boulevard, in the vicinity of the existing southbound U.S. 101 off-ramp (the "scissors ramp"). Runoff from the four Phase IIsub-watersheds eventually discharges into the Terrabay Trunk Storm Drain (TTSD) constructed in 1989 to facilitate development of Terrabay Phase I and II sites (see Exhibit 4.2-2). The TTSD conveys runoff from Phase I and II lands east along Sister Cities Boulevard to a concrete box culvert under U.S. 101, just north of the intersection with Bayshore Boulevar. At the eastern edge of the freeway, this box culvert discharge enters a concrete lined drainage channel which extends east for roughly 100 feet before turning sharply to the north, parallel to the Public Storage facility. The north-trending segment of channel continues for approximately 2,000 feet to its outlet at the northwestern corner of the dredged access channel serving the Oyster Point marina, in San Francisco Bay. Runoff from the three principal Phase III sub-watersheds collects along the western shoulder of Bayshore Boulevard and enters one of three reinforced concrete pipe (RCP) culverts which convey flows under Bayshore Boulevard and U.S. 101. According to Caltrans staff these culverts are not 129 Legend: - -Tributary Watershed Boundary ~ Project Boundary Source: Clearwater Hydrology Exhibif 4.2-1 Regional Location and Watershed Map II~!'i i . ''~ . ~ t'i I~ j C n .. ?~~I}, `~ • I1 1 i o+! O i /, ~ / ~. ~ ~\ /: ,.. ,'~>< , y f ~ 1 \' !l . er J~jJ :~ 1,'•, / ~ ~ '~ / l l ~ ` •~ , . 1 ~ ~ to { /// , i \ Il 'Tl '; `tt ~l ' \ \ \ ~ rf I ~1 ' 1,~I !r r ., is ,... 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"FF++ C ~. :: , ; . ... , ..~ m 1 ~,,, ... ..: l' JI ~ ''. ^ T i ~ ' , O .. _ `~ ~. m ~ ~ ~ a ~p•a ~'^-~n5 t 1 ~ ~ .,~f .~ •; < y ~. ~.. t N 7 ~~ d t , ~, , {t , :~ '~'~ C O' H 'N 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase 11 and 111 SE1R linked to the box culvert (connected to the TTSD), and all culverts discharge into the lined channel located parallel to the northbound lanes of U.S. 101. 112 , Current Land Use and Local Hydrology The lower colluvial slopes of the Phase II site development area were graded into terraces in anticipation of site buildout. Temporary drainage facilities, including a network of concrete-lined V- ditches, culverts, and four sediment basins for control of downstream sedimentation were constructed in 1989 in association with installation of the TTSD. The sediment basins are located just upslope of South San Francisco Drive and are fitted with slotted riser pipe spillways. The easternmost basin in the Point development area also features a spillway with ananti-vortex hood constructed of rebar. Except for the larger Woods East sediment basin, which drains a much larger sub-watershed, inflow to the basins is via overland flow and gullied access roadways. Inflow to the Woods East sediment basin initially is intercepted 300 feet farther upslope near the base of the steeper reach of the tributary drainageway and enters a 42-inch RCP culvert. This culvert also accepts some locally diverted roadway drainage collected from the adjoining southwest-facing hillslopes. Rocks have been placed at the culvert outlet at the sediment basin for energy dissipation. The sediment basin is fitted with two riser pipe spillways and twin emergency overflow weirs. Mid- February 1998 site inspections identified recent weir overflows which probably occurred during severe rainstorms in early February. Some severe erosion, debris flow, and slump failure activity was evident during the mid-February 1998 site inspections. Significant gully erosion was observed along sections of the earthen access roads on mid- and lower-slopes of the Phase II site. Despite the presence of extremely steep channel gradients and the transport of occasional debris flows, the upper undisturbed reaches of Phase II drainages appear relatively stable. In some cases (such as the principal Woods East drainage), extensive riparian willow growth occurs in the lower portions of these channel reaches. The south-facing slope of the easternmost Phase II sediment basin in the Point has eroded into a "badlands"-type topography (bluffs dissected by gully incision). Elsewhere on the Phase II site, two slope failures were evident during the February site inspections. One involves the west-facing upper -grace slopes in the Commons neighborhood where significant recent erosion has occurred. This failure appears to be related to poor hydraulic conditions at the entrance to a small diameter polyvinyl chloride (PVC) drain pipe conveying runoff downslope between terraces. The second failure involves the south-facing slope of the sediment basin in the western part of the Woods East neighborhood which has suffered a massive slump failure. A poorly protected roadway culvert outfall and excessive recent rainfall /runoff combined to induce large-scale gullying and the pronounced slump failure. While unsightly, the slump material affecting the Woods East basin is contained within the sediment basin, and the outlet works continue to function satisfactorily. At some point, however, reductions of basin depth and storage volume could lead to short-circuiting of flows through the basin. This would decrease the efficiency of settling processes operating to retain sediments in the basin storage pool and would increase suspended sediment concentrations in basin outflow. The main inlet to this sediment basin consists of a 150 foot- long rocked spillway which was in an undisturbed condition at the time of 112 Clearwater Hydrology (1998 SEIR hydrologist) conversation with Jx Peterson, Caltrans Staff Ene neer, Hydraulics Section, District 04, February 1998. 13'_ 4.2 HYDROLOGY AND DR,4/NAGS Terrabay Phase l/ and 111 SE/R the mid-February 1998 inspections. The spillways, now serving the temporary sediment basins, would be removed as site development proceeds. All Phase II site sediment basin outflows enter the roadside storm drain system along South San Francisco Drive. This system also accepts local roadway runoff and conveys the combined flows to the TTSD via curbside drain inlets. As noted above, the TTSD dischazges to a Caltrans-maintained box culvert under U.S. 101. Prior grading of the Phase III site is significantly less extensive than on the Phase II site. However, the combined effects of grading disturbance and slope failures on upper watershed lands and the resulting deposition of colluvial /alluvial fan material downslope have produced a melange of drainage patterns out of synch with the pre-disturbance topography. The most radical grading occurs as earthen roadway construction at the base of the steep hillslopes of San Bruno Mountain. In addition, a large spoil pile was created at the former confluence of the south and north forks of the northern sub-watershed. This mound of material appeazs stable, and runoff from the north fork of the upper drainage flows along a roadway shoulder upslope of the mound to join with the south fork drainage. As noted in the description of Phase II conditions, surface runoff from nine acres of the southern Phase III sub-watershed has been diverted south, out of the original watershed. The upper portion of this sub-watershed has also been altered by the grading. Runoff from the upper and mid-reaches of the drainage has been diverted farther north in an excavated earthen channel. Toward the natural northern boundary of the sub-watershed, the earthen channel enters an 18-inch corrugated metal pipe (CMP) culvert which conveys runoff northeast and across the local drainage boundary to a protected outlet along the western shoulder of Bayshore Boulevard. This culvert discharge joins with local highway runoff and additional runoff from the middle Phase III sub-watershed in a topographic depression characterized by winter ponding and dense willow growth. Once the ponding capacity is reached, runoff proceeds to the entrance of a 48-inch RCP culvert, the southern of three roadway culverts which convey Phase III runoff under Bayshore Boulevard and U.S. 101 into the lined drainage outlet channel to the east. The culvert entrance is located just south of the existing scissors ramp exit off southbound U.S. 101. A 30-inch RCP culvert is located farther north along the west shoulder of Bayshore Boulevard. This culvert conveys local Bayshore Boulevard runoff and a diverted portion of runoff from the northern Phase III sub-watershed under the roadway and freeway to the lined drainage outlet channel. The cross-basin diversion represented by the northern sub-watershed inflow is the second diversion made by prior grading on the site. The northernmost roadway /freeway culvert conveying site watershed runoff is a 36-inch RCP located farther upslope along Bayshore Boulevard and north of the 30-inch culvert. Its position places its dischazge point near the ultimate outlet of the lined drainage channel, east of the freeway and just west of the Oyster Point marina. The culvert entrance is heavily fortified with sacrete (wetted concrete bags laid onto the slope for slope stabilization) headwall and sidewalls. Due to excessive deposition of debris flow material and other coarse-grained deposits upslope and south of the culvert entrance, runoff from the principal drainage (south fork) in the northernmost sub-watershed is conveyed downslope in numerous shallow channels, rather than in abetter-defined single channel. The bulk of this south fork runoff is diverted south toward the shoulder of Bayshore Boulevard and eventually to the 30-inch RCP culvert inlet. Only the local runoff from portions of the upslope spoil mound and hillslope runoff at the northern end of the Phase III site reach the 36-inch culvert inlet. 133 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase ll and /ll SE/R As in the Phase IIsub-watersheds, the upper undisturbed reaches of natural drainage channels are relatively stable and, in some instances, support good stands of willow growth. However, once the channels ford disturbed lands and local channel inflow is concentrated along roadway margins (or some times down the middle of the roadways), discontinuous gully processes aze activated, and sediment yields are increased. This has magnified the more natural accumulation of debris flow material (colluvium) and alluvial deposits along the middle and lower elevation reaches of the drainages. The resulting deposition of sediments has heightened the alteration of local drainage patterns and increased the likelihood of cross-basin overflows. Groundwater The 1996 SEIR noted the well drained nature of site soils under average rainfall conditions. In wet years, such as 1998, the steep hillslopes, underlying geology, and high rainfall- intensities can trigger debris flows in the upper watershed areas. Similarly, the mid-slope colluvium and alluvial deposits generate significant spring and seep discharges during wet years and / or prolonged rainstorms in areas where underlying fractured sandstone comes in contact with the harder Franciscan melange unit (see 4.I Geology, Soils, and Seismicity). Early and mid-February 1998 site inspections revealed large- scale spring and seep activity extending nearly the entire length of the Phase III site's middle and lower slopes. 4.3 Biology further discusses the potential correspondence of this perched groundwater and seasonal wetland and other sensitive plant species. Flooding The temporary conveyance facilities and downslope sediment basins have been adequate thus far to forestall significant flooding on the Phase II site. Moreover, the TTSD has functioned without problems during the nine years it has been in service. On the Phase III site, some minor flooding was observed in February 1998 just upslope of the 48-inch culvert entrance and along the western shoulder of Bayshore Boulevard. At the time of site inspections for the 1998 SEIR, roadway maintenance crews had excavated a number of small water drainage ditches inland from the shoulder toward the lower-lyiiig azeas adjacent to the 30- and 48-inch culvert entrances. These ditches served to drain off water ponded along the roadway shoulder which otherwise would present a safety hazard to motorists. Joint Powers Agreement for Facilities Maintenance On June 23, 1983 the City of South San Francisco and the County of San Mateo adopted a Joint Exercise of Powers Agreement for Maintenance of Catchment Basins on San Bruno Motattain (JPA). The agreement was intended to establish a joint authority to maintain catch (debris) basins, their appurtenances, and their surface delivery facilities (such as concrete lined ditches), as identified by the Terrabay Specific Plan, and to provide a common method of funding such maintenance, including associated liability and administrative costs. 113 Since its establishment in 1983, the JPA Governing Boazd has approved the design of the debris basins and has overseen their construction. The County recently indicated a desire to disband the JPA and assume full responsibility for the outlined maintenance. However, unresolved issues involving funding of the required maintenance have delayed the adoption and implementation of any new agreements on facilities maintenance. 114 113 Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996, and Final Supplemental Environmental Impact Report for the Terrabay Speciftc Plan and Development Agreement Extension-Responses to Commenu, Wagstaff and Associates, October 1996 (1996 SEIR). 114 Clearwater Hydrology conversation with Richard Harmon, Senior Engineer, City of South San Francisco Department of Public Works, February 1998. 134 4.2 HYDROLOGY AND DRA/NAG= Terrabay Phase !I and 1!I SElR HYDROLOGYAND DRAINAGE -SIGNIFICANCE CRITERIA In accordance with the State CEQA Guidelines for EIRs, the proposed project would have a significant hydrologic impact if it: • Decreased absorption (infiltration) rates which produced computable increases in either the volumes or rates of surface runoff and, in turn, exceeded the capacity of downstream storm drain systems or natural channels to transport the stormwater without harmful erosion, sedimentation, or flooding for all rainstorm magnitudes up to the design storm rainfall (ten-year, 100-year rainstorm). • Altered channel alignments, the course of floodwaters, or exposed people or property to water related hazards such as flooding during rainstorms with recurrence intervals of ten to 100 years. depending on the appropriate design storm. • Increased off-site peak flow rates in excess of the capacity of downstream hydraulic structures. • Resulted in hillslope or channel erosion which, directly or indirectly, would produce excessive soil loss, habitat degradation, property loss, or reductions in the capacity of downstream channel reaches and / or hydraulic structures via sedimentation. Accepted technical guidelines and practices employed by registered civil engineers in the State of California also were used to identify impact and determine their significance. HYDROLOGY AND DRAINAGE -IMPACTS AND MITIGATION MEASURES The setting section described drainage and sediment facilities present on and around the site. Some of these facilities are temporary and would be removed and / or replaced during proposed grading. Other facilities, including some of the upslope v-ditches, Bayshore Boulevard / U.S. 101 culverts, and storm drain segments along South San Francisco Drive, would remain in place to serve the project. Potential hydrologic and drainage impacts of both types of facilities are assessed below, and appropriate mitigation measures are presented. Currenf Phase ll and Phase 111 Project Descriptions Phase II site development would involve installation of debris basins and storm drain lines. Those lines would connect the basins and residential drainage systems with the existing storm drain system along South San Francisco Drive and with the Terrabay Trunk Storm Drain (TTSD). New drainage facilities would include open two- to three-foot wide concrete-lined ditches at grade around the development area perimeter, eight- to 12-inch subsurface storm drains installed along rear yard lot lines, variable diameter storm drain segments installed in roadways, and street gutters installed either on both sides of driving lanes (at curbs) or in the middle (single gutter) between the driving lanes and parking bays. Debris basins would be located at the upper margins of the site development areas to trap and divert failed hillslope debris away from housing units and streets (Exhibit 4.2-3 shows basin locations). 135 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase 11 and 111 SEIR These would include two in the Woods East, and one in the Woods West neighborhoods. 115 The two Woods East debris basins would be constructed within the proposed "limits of grading" but on County land outside the site development area. Additional retaining walls would be built at some of the debris basins in order to shield downslope housing units from potential debris basin overflow. Implementation of the proposed Precise Plan would eliminate temporary drainage facilities installed during initial grading operations undertaken for Phase I. These facilities include all the sediment basins and their appurtenances (spillways, inlet structures, etc.) and numerous concrete-lined V- ditches. Most of the existing earthen roadways outside of the site development areas would be left in their existing condition or re-graded to accommodate the new slope grading along the upslope margins of the development areas. Phase III site development would include construction of two debris basins (both on proposed Parcel C) and six principal storm drain lines with associated secondary laterals. 116 Lines A through E would serve the southern part of the Phase III site and discharge to the existing 48-inch culvert under Bayshore Boulevard / U.S. 101. Lines F and G would serve the central part of the site and discharge to the 30-inch culvert under Bayshore Boulevard / U.S. 101. Lines H and I would serve the northern part of the site and drain to the existing 36-inch culvert under Bayshore Boulevard / U.S. 101. All of the proposed storm drain alignments provide for the planned ~-idening of Bayshore Boulevard and construction of the U.S. 101 southbound hook ramps. According to Caltrans hydraulic design staff, the three existing RCP culverts under Bayshore Boulevard and U.S. 101 were sized to accommodate ultimate buildout of the Terrabay site or other development(s) within the tributary watersheds. i 17 At the northern end of the Phase III site, the Precise Plan grading plan proposes eliminating the existing spoil mound and restoring the original alignments of the north and south forks of the northernmost drainage channel. While the amount of grading required to accomplish this topographic restoration would be significant, it would be considered beneficial from a hydrologic standpoint, assuming the drainage restoration was designed and implemented by an engineering hydrologist and restoration contractor(s) experienced in such work. E/R Peer Review of Storm Drainage Design The project sponsors civil engineer, Brian Kangas Foulk (BKF), designed the storm drainage facilities for the Terrabay Phase II and III sites. BKFs project design infom~ation is presented in Storm 115 According to the project sponsor's engineer, three other debris basins are proposed as part of the project, including two in the Point neighborhood and one in the Commons neighborhood. While the Precise Plan Grading Plan shows headwall /retaining wall structures, they are not labeled as such. Thus, Exhibit 4.1-3 designates these potential basin sites as "proposed debris basins". Precise Plan Grading Plan, Brian Kangas Foulk, January 15, 1998 and Terrabay Project, South San Francisco, California, Letter to Allison Knapp, City of South San Francisco, from Janine O'Flaherty, Brian Kangas Foulk, January 25, 1998, op. cit. 116 According to Brian Kangas Foulk (BKF), the project sponsor's engineer, the Precise Plan proposes four basins on the Phase III site. However, BKF's drainage report and plan sets onl}~ show ta~o basins. Terrabm Project, South San Francisco, California, Letter to Allison Knapp from Janine O'Flaherry, Brian Kangas Foulk, January 2~, 1998. 117Clearwater Hydrology (1998 SEIR hydrologist) conversation with Joe Peterson. op. cit. 137 4.2 HYDROLOGY AND DRA/NAGS Terrabay Phase 11 and 111 SE/R Drainage Report-Collection System and Debris Basins. 118 Design criteria for both the storm drain system and debris basins were based on previously established standards cited in documentation by the prior civil engineering consultant, CREM. This documentation was appended to the BKF report and was reviewed by the 1998 SEIR hydrologist. CREM / BKF designated the 100-year rainstorm as the design rainstorm for the TTSD and sub-trunk systems. Sub-trunk systems on the Phase II site include minor system lines which would connect interior networks with the trunk line and on the Phase III site include principal storm drain Lines A through I. All other lateral drain segments are designed for the ten-year rainstorm. This is in conformance with accepted municipal engineering design practice. BKF applied the Rational Method to compute peak storm drain dischazges from delineated tributary sub-watersheds. These sub-watersheds are smaller in size than the sub-watersheds referred to in the setting section because the delineated areas used in storm drain design correspond to numerous drain inlets where runoff is collected. Runoff coefficients for discharge computations were selected to accommodate the use of the Rational Method. Previous peak discharges were computed using the Santa Barbara Unit Hydrograph Method. To match the design discharges computed using the former method, the runoff coefficient for open space areas was increased from 0.40 to 0.50, while the impervious land usage was set at 50 percent of the development area. Independent calculations by the 1998 SEIR hydrologist based on the tabulated values in Exhibit 2.3-1 of this EIR indicated actual impervious surface coverage of 39 percent and 18 percent, respectively, on the Phases II and III sites. Thus, the BKF assumption represents a conservative design element. Other hydrologic and hydraulic design criteria cited in the BKF report include the following: • Rational Method rainfall intensities obtained using Chart K, Zone B, Sub-zone 2 of the Caltrans District 4 intensity /duration /frequency curves • An initial time of concentration estimate for runoff of five minutes • Runoff coefficients determined by area weighting using 0.95 for impervious areas and 0.50 for open space /grassed areas • Mannings roughness coefficient of 0.0012 used for 42-inch and lazger reinforced concrete pipe and 0.013 for smaller diameter pipe • Junction loss coefficient of 0.5 used for straight through manholes Assumed maximum outfall water surface elevation of 13.95 feet at the outlet of the Caltrans box culvert east of U.S. 101 which is the downstream connection with the TTSD _ Of the above design criteria, only the assumed Mannings coefficient values could be somewhat underestimated. The values selected apply to clear water flowing in smooth reinforced concrete pipe. In field situations and even in the presence of upslope debris basins which would trap a good proportion of incoming alluvial sediments, the actual roughness coefficient is higher due to the entrainment of sediment in the pipe discharge. This effect would be more pronounced in smaller laterals with mild slopes, such as the proposed rear yard drains with one percent slopes. 118Storm Drainage Report-Collection System and Debris Basins, Brian Kangas Foulk, December 13, 1997. 138 '~ I . ~ ~ ~I' 1 ~~ 1 I '~'~ , I I , ~ I I~ ~I . ;Iyl i1ll I G' ~~ ~~ ;~V;I i • iii I ;, ~ I~ I.~ ... i I 'i~ I` ~ (I ': i I ;'j '~ I~ , I. 7~ I I I I r ~ i~ ~ ~ I ,' ~~, r! I~~~ ,~o. 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C ,, r 0 r .~. ~., ~ ~-. /~ 1f 11 ~ r 1 ~~ - ~' ~' ~ '~ Y I It ( ~~~`\ •`~ :. } / u /I~~~ ~ I.I. _. ~ . ,, 1 ,~1 ~ ~- \~ _ ~ l ~. ~.. .` ,i=.,r,..,~.~1 ~. ~-. ~ ~~11 1.1i// 1 ~itll)I~I~I~ rt11 .. .. 1 A, 1~, ~ ~ ~ f`~ ~ r ~illl~' ~~~ If'I ~. '` ` ~ ` ~ '~` - , ~~; ~~.~` ~ ~ ~~.. ~ (~ ~.~e ~ ~ iii irfl i I ODD "\_ ~ ~ ~~ "-r-_ t~~ ~. '-. 11~~~ 1. __.,,~ Q y~ ', .~' r -• ~w 4.2 HYDr~OLOGY AND DRAINAGE Terrabay Phase 11 and 111 SE/R The TTSD was originally designed in 1983 based on a total watershed area of 492.6 acres and an impervious surface area of 51.2 acres. Subsequently, BKF conducted an independent check of the tributary watershed area and determined the total area to be 499 acres. With the adjustments made in assumed impervious surface coverage and the open space runoff coefficient to facilitate the change in analytical methodologies (Santa Barbara LJH Method to Rational Method), the current design configuration represents an increase in total watershed area of nine acres (comprised of the part of the Point diverted to the Phase II system) and a decrease in the impervious surface area estimate relative to the original CREM analysis. The resulting design storm discharge at the system outlet was consequently increased by nine cubic feet per second (9 cfs), from 612 to 621 cfs. This is a 1.5 percent increase over the prior TTSD design estimate. BKF hydraulic computations indicate that this discharge can be successfully passed through the system with a maximum pipe surharge of 6.3 feet at the outlet (tailwater controlled) and 3.6 feet in the TTSD. The resulting minimum freeboard to the rim elevation is 2.8 feet. This is satisfactory, and the minor increase in project peak flow should not cause any diminution in system performance. As noted above, the three cross-roadway /freeway culverts (the 48-, 30- and 36-inch diameter culverts) installed by Caltrans were designed based on the assumption of full buildout of the upstream tributary watersheds. Furthermore, the currently proposed project represents a reduction in the percentage of developed area within project site watersheds tributary to the freeway culverts. Therefore, the impervious surfaces and increased peak flow rates which would accompany project Phase II and III construction would not result in a significant impact on downstream drainage structures for the 100-year design rainstorm. Debris basin design standards BKF assumed in its Storm Drainage Report mere extracted from CREM's 1989 report, Updated Compilation of Documents Pertaining to Terraba}• Development Catch Basins. 119 B~• applied the methodology presented in CREM's document for computing required debris basin sediment /water storage volumes and basin geometries in the current design of the additional basins proposed on the Phase II and III sites. lmpacf 4.2-1 Stormwater Drainage Patterns and Flooding Some of the streets proposed for construction on the Phase 11 site would be drained by concrete V-channels aligned between street travel lanes and parking bays. This design would promote the occasional clogging of the channel with debris and induce minor flooded conditions along the central portion of the roadway. This would be a potentially significant impact. PS Normal curb and gutter construction and crowned roadways promote efficient evacuation of accumulating roadway runoff to curbside drain inlets. Although normal roadwa~~ design details are proposed for some Phase II street segments, the Vesting Tentative Map and Preliminary Grading Plait (Plan Sheet 2) shows the off-set drainage concept on segments 1, 3, 4, 6, 7, and 9 in the Woods East and West neighborhoods. These roadway segment cross-sections would consist of two travel lanes (one in each direction) plus a parking bay on one side. Drainage V-channels would be located on the travel lane side of the parking bay, not the curb side. Concentration of roadway drainage and wash water drainage in summer would tend to accelerate road deterioration because the wet surface would be in frequent contact with mo~-ing vehicles. An 119 Compilation of Documents Pertaining to Terrabay Development-Debris Basin Facilities, Carro:i /Resources Ene neering and Management (CREM), September 1988. 139 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase Il and I!I SE/R additional drawback of this design would manifest during future resurfacing activities because roadways are paved with asphalt. Either the central channels would be overlain and begin to lose their definition, or the homeowners would be required to spend higher sums to reconstruct the center concrete drainage channels than necessary when drainage is routed to curbs. Mitigation Measure 4.2-1 All street configurations shall incorporate this standard curb and gutter design with crowned roadway. Thus, currently proposed Phase II street configurations 1, 3, 4, 6, 7, and 9 shall be redesigned to eliminate the off-set drainage channel concept. Significance after Mitigation Implementation of Mitigation 4-2-1 would reduce the impact on drainage and flooding to aless-than-significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for redesigning roadway drainage in the Woods East and West neighborhoods for review and approval by the City Planning and Public Works Departments before filing of the Final Subdivision Map and granting of grading permits for Phase II development. The homeowners associations (HOAs) to be established for these neighborhoods would be responsible for monitoring and lonb term maintenance of private roadways and drainage facilities. 120 Impact 4 2-2 Stormwater Drainage and Flooding One percent slopes proposed for residential yards and rear yard drainage swales in Phase ll neighborhoods would allow sediment deposition in the swales, thus creating opportunities for nuisance flooding of rear yard or side yard areas. This would be a potentially significant impact. PS Construction of one percent slopes proposed for residential yards and rear yard drainage swales in Phase II neighborhoods would be difficult to achieve. This is because grade control to such a tight accuracy is a difficult construction feat. As a result, the Uniform Building Code (i7BC) specifies a minimum slope of two percent for such features. 121 Moreover, such flat slopes would not permit flushing of sediment carried in surface water, would result in gradual accumulation of sediments which eventually would block evacuation of surface flows, and could lead to localized ponding or flooding. Public Works Department staff members have documented several instances where residents of the Phase I site have paved over large portions of their backyards. This has led to an obliteration of intended lot drainage patterns and drainage problems. 122 Mitigation 42 2 Vesting Tentative Map and Preliminary Grading Plan Sheet 3 shall be amended to provide minimum rear yard and side yard drainage Swale slopes of two percent in the Phase II 120 As of February 1998, the project sponsor had not submitted draft Codes, Covenants, and Restrictions to the City for review. 121 Uniform Building Code, Section 3315.4 "Drainage and Terracing", State of California, 1994. This section of the UBC states that building pads must have minimum two percent slopes unless three exemptions provisions are met. The second exemption specifies that proposed, adjacent slope heights must be less than ten feet. This provision of the section is not met by the project. The third of these regarding adjacent hillslopes cites a minimum 10:1 (horizontal:vertical) slope face. The hillslope grades adjacent to proposed residential lots on the project site are steeper than this maximum. 122 Clearwater Hydrology conversation with Richard Harmon, op. cit., March 1998. 140 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase /l and 111 SE/R development area in conformance with UBC standards. In addition, the conditions of project approval shall include appropriate oversight and / or controls on backyard paving by residents. These controls shall be included in the project's Covenants, Conditions, and Restrictions (CC&Rs) and enforced by the respective Homeowners Associations for each neighborhood. 123 Significance after Mitigation Implementation of Mitigation Measure 4-2-2 would reduce the impact on drainage and flooding to ales-than-significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for redesigning rear and side yard grading and associated drainage to comply with UBC requirements. The City Planning and Public Works Departments would review and approve revisions before filing of the Final Subdivision Map and granting of grading permits for Phase II development. Impact 4.2-3 Stormwater Drainage Patterns and Erosion and Sedimentation Absence of drain inlets on cut benches would permit runoff to flow onto an unprotected hillslope which could trigger hil/slope erosion in the form of gully incision. This would be a significant impact. S The Vesting Tentative Map and Preliminary Grading Plan (Plan Sheet 10) for the Commons neighborhood indicates that a benched drainageway above the 300-foot contour on the graded east- facing slope would convey hillslope runoff to the southwest. Part of the bench would not be supported by any drain inlet. Thus, runoff would flow off the southwest end of the bench and onto an unprotected hillslope. This could trigger hillslope erosion in the form of gully incision. Mitigation Measure 4.2-3 The proposed grading plan shall be revised to provide for grading of the bench identified in the Commons neighborhood in order to direct runoff flows toward the inlet to the debris basin. Significance after Mitigation Implementation of Mitigation Measure 4.2-3 would reduce the impact on Stormwater drainage and erosion and sedimentation to ales-than-significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for revising the grading plan to direct surface runoff to the Commons debris basin. The City Planning and Public Works Depamnents would review and approve revisions before filing of the Final Subdivision Map and granting of grading permits for Phase II development. Impact 4.2-4 Flooding Benched concrete lined drainage channels on the Phase 111 site would convey surface drainage to a sump inlet with headwall not linked to the adjacent street storm drain - system. This ultimately could cause some minor street flooding and would constitute a potentially significant impact. PS The .Vesting Tentative Map and Preliminary Grading Plan for the Phase III site shows benched concrete lined drainage channels conveying surface drainage to a sump inlet with a proposed headwall but without a storm drain link to the adjacent street storm drain system. In the absence of this link, flows eventually would overtop the sump area and flow out onto the adjacent street. Eventually the 123 As of February 1998, the project sponsor had not submitted draft CC&Rs to the City. 141 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase ll and UI SE/R sump would fill with sediment transported both from the natural drainageway upstream of the concrete gutter reach (southern approach) and hillslope runoff onto the earthen ditch (southern approach). The resulting sediment-laden and the street overflow then could be accompanied by sediment. The resulting sediment-laden street overflow then could clog drainage facilities proposed for the internal roadway and cause some minor street flooding. While the street overflow could produce a local nuisance flooding condition, it would be unlikely to create downslope overflow onto the archeological site because a second drain inlet is proposed for the opposite (east) gutter as well. Mitigation Measure 4.2-4 Vesting Tentative Map and Preliminary Grading Plan Sheet 17 shall be amended to included missing storm drain link in the storm drain design. Implementation of Mitigation Measure 4.2-5 would also be required as explained below. Significance after Mitigation Implementation of Mitigation Measures 4.2-4 and 4.2-6 (below) would reduce related flooding and erosion and sedimentation impacts on the Phase III site to a less-than- significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for revising the project plans to add the storm drain link on the Phase III site. The City Planning and Public Works Departments would review and approve revisions before filing of the Final Subdivision Map and granting of grading permits for Phase III development. Impact 4.2-5 Stormwater Drainage and Flooding Construction of the new U.S. i0i freeway access ramps in the vicinity of the existing southbound exit (scissors ramp) would occur in steepened soils also subjected to occasional ponding upslope of the 48-inch roadway culvert on the Phase Ill site. Ramp construction in the absence of proper upslope interception of shallow spring and seep discharge could impair the stability of the freeway embankment. This would be a potentially significant impact. PS Depending on the local subsurface geology, upslope seepage and spring discharge might not be intercepted by roadside drainage ditches on the Phase III site. An embankment lacking in property subsurface drainage could be subject to slope seepage failures and require future maintenance. Mitigation Measure 4.2-5 The project sponsor and City shall complete and implement proper geotechnical investigation of subsurface seepage conditions in the vicinity of the new freeway ramps. This could include borehole logging in the vicinity of the earthen ditch specified in the Vesting Tentative Map and Preliminary Grading Plan (Sheet 17), at the lower end of proposed commercial Lot 220 (Parcel F). If positioned at the proper elevation, this ditch could alleviate potential seepage pressures in the freeway ramp embankment. _ Significance after Mitigation Implementation of Mitigation Measure 4.3-5 would reduce this potential impact on Stormwater drainage and flooding to aless-than-significant impact. Responsibility and Monitoring The City sponsored a subsurface geologic investigation for the hook ramps which included the drilling of boreholes to provide detailed geotechnical information for use by its civil engineering consultant to undertake the final engineering design. 142 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase 1l and 111 SE/R Impact 4.2-6 Erosion and Sedimentation Higher velocity flows from steep concrete-lined channels into earth-lined ditches would erode and could also exceed the capacity of the downstream earthen reach. This would be a significant impact. S The proposed Vesting Tentative Map and Preliminary Grading Plan (Sheet 17) shows an earthen ditch located contiguous to and north of the Phase III sump area described in Impact 4.2-4. It would convey surface runoff from the hillslope areas and debris overflow zone, the latter consisting of a retaining wall and steep concrete channel. Higher velocity flows through the steeper concrete-lined section of channel would tend to erode the downstream earthen reach. Sediments and rocky debris carved from the upstream concrete segment also could reduce the capacity of the earthen channel and result in overflows. Mitigation Measure 4.2-6 Vesting Tentative Map and Preliminary Grading Plan (Sheet 17) shall be revised to change the benched earthen channel segment to a rocked or concrete-lined channel. The channel also shall be redesigned with a higher capacity to accommodate some entrained sediments and rocky debris conveyed from the upstream concrete segment. Significance After Mitigation Implementation of Mitigation Measure 4.2-6 (together with Mitigation Measure 4.2-4, above) would reduce this flooding and erosion and sedimentation impact to a less- than-significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for revising plans and specifications for the Phase III site. The City Planning and Public Works Departments would review and approve revisions before filing of the Final Subdivision Map and granting of grading permits for Phase III development. Impact 4.2-7 Erosion and Sedimentation Unnecessary grading for culvert installation in the Woods East neighborhood would constitute a significant impact. S The Vesting Tentative Map and Preliminary Grading Plan Sheet 9 shows a storm drain segment in the Phase II Woods East neighborhood which is proposed to be constructed upslope of the contour bench and would traverse parts of open space Lots G and J. Vesting Tentative Map and Preliminary Grading Plan Sheet 8 shows the existing ungraded topography and does not indicate the presence of any existing Swale or drainageway along this alignment which would warrant culverting. (A swale or other drainageway would be indicated by an upside-down v-shape configuration along adjacent contours.) The resulting grading to install a culvert would be unnecessary. Mitigation Measure 4.2-7 Vesting Tentative Map and Preliminary Grading Plan Sheets 8 and 9 shall be revised to eliminate the storm drain segment in Woods East proposed on the contour bench of Lots G and J from the drainage and grading plan design. Significance after Mitigation Implementation of Mitigation Measure 4.2-7 would reduce this erosion and sedimentation impact to aless-than-sign~cant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for revising the Sheets 8 and 9, and the City Planning and Public Works Departments would review the revisions before filing of the Final Subdivision Map and granting of grading permits for Phase III development. 143 4.2 HYD.40LOGY AND DRAINAGE Terra6ay Phase ll and 111 SEIR Impact 4.2-8 Erosion and Sedimentation Regraded Commons neighborhood roadways left unpaved after project implementation could erode and generate downstream sedimentation. This would be a significant impact. S Two existing dirt roads graded onto hillslopes adjoining the Commons neighborhood would be partly regraded with project implementation but left in an unprotected earthen condition. The regraded road segments would end at the eastern termini of proposed L and N Streets. Erosion of the unprotected roads during wet winters and / or significant rainstorms could yield substantial quantities of sediment onto L and N Streets. Mitigation Measure 4.2-8 The existing dirt access roads are located entirely within the limits of proposed grading. Therefore, both roads shall be removed. According to the City Fire Mazshall and the project sponsor's engineer, none of the roadways outside of paved subdivision streets would be required for fire access. 124 In addition, where no regrading is proposed, the original hillslope topography shall be restored with no installation of artificial drainage facilities. Within the proposed slope regrading area, the regraded slope shall be slightly amended to allow for the roadway elimination. All regl-aded and restored hillslope areas shall be subjected to appropriate erosion control measures in conformance with an approved Stormwater Pollution Prevention Plan (SWPPP), as previously required by the 1996 SEIR. Significance after Mitigation Implementation of Mitigation Measure 4.2-8 would reduce this impact on erosion and sedimentation to aless-than-significant level. Responsibility and Monitoring The project sponsor's civil engineer would be responsible for revising the project to incorporate these measures. The City Planning and Public Works Departments would review and approve revisions before filing of the Final Subdivision I~iap and granting of grading permits for Phase III development. Impact 4.2-9 Erosion and Sedimentation Retaining unprotected roadways in the Point neighborhood after project implementation could yield substantial sediment volumes. This would be a significant impact. S On the south-facing portion of the Point subazea, some existing dirt roads previously graded into the adjacent hillslopes would remain untreated and would continue to yield significant volumes of sediment through rill and gully erosion processes. This sediment would be discharged in runoff entering the storm drain system lateral upslope of open space Lot V. Mitigation 4.2-9 TR-o options are available to mitigate this erosion impact. With approval and monitoring by the San Bruno Mountain HCP coordinator, the applicant shall remove the entire length of any roadway which would daylight within the proposed limits of project grading. This option would include restoring original hillslope topography, revegetating restored slopes using native species, and implementing erosion control methods. This is the preferred option. 124 Clearwater Hydrology conversations with Laura Mapes, Fire Marshall, Ciry of South San Francisco Fire Department, and Jan O'Flahem. BKF, op. cit., March 1998. lag 4.2 HYDROLOGY AND DRAINAGE Terrabay Phase ll and lIl SEiR The applicant shall regrade and maintain the existing unpaved roadways to protect them against erosion using fortified shoulder drainage ditches and frequent water bar construction. This is the inferior option. If this option is selected, the City shall require long-term monitoring by the entity overseeing debris basin performance. The first option would require an extension of the Stormwater Pollution Prevention Plan (SWPPP) for the project which the 1996 SEIR previously required as a mitigation measure. Expansion of the SWPPP would consist of the designation of Best Management Practices (BMPs) for erosion control in the restored hillslope areas. This could include broadcast straw or other surface erosion protection, seeding or planting of native grasses and forbs, and stockpiling of amendments to applied topsoil. Significance After Mitigation Implementation of Mitigation Measure 4.2-9 would reduce this erosion and sedimentation impact to aless-than-significant level. Responsibility and Monitoring The applicant's civil engineer shall revise the Vesting Tentative Map and Preliminary Grading Plan to reflect the option required by the City as a condition of project approval. The City Planning and Public Works Departments would be responsible for reviewing the Final Subdivision Map for compliance before filing and granting of a grading permit. The City shall consider requiring long-term monitoring (such as by the entity overseeing debris basin performance) as a mitigation measure shall it require the second mitigation option. Impact 4.2-10 Erosion and Sedimentation Drainage facility connections omitted from 17 lots proposed in the Point neighborhood could result in localize erosion and downstream sedimentation if left unprotected. This would be a significant impact. S Vesting Tentative Map and Preliminary Grading Plan Sheets 15 and 16 do not show transitional storm drain links from proposed Point neighborhood Lots 167B to 175B. Links would be necessary to discharge piped rear yard stormwater drainage and convey it downslope to storm drain Line A. The absence of storm drain linkage could result in localized erosion and downstream sedimentation if outlets were left unprotected and / or supporting transitional storm drain links were -not provided. Although this may be an oversight of the plan, it should be corrected. Mitigation Measure 4.2-10 Vesting Tentative Map and Preliminary Grading Plan Sheets 15 and 16 shall be revised to add transitional storm drain links between outlet drains from proposed Point Lots 167B-175B to Line A. Significance after Mitigation Implementation of Mitigation Measure 4.2-10 would reduce this impact on erosion and sedimentation to aless-than-significant level. - Responsibility and Monitoring The applicant's civil engineer would be responsible for revising the project and Vesting Tentative Map and Preliminary Grading Plan, and the City Planning and Public Works Departments would be responsible for reviewing the Final Subdivision Map for compliance before filing and granting of a grading permit. 145 4.2 HYDROLOGYAND DRAINAGE Terrabay Phase 11 and Ill SE/R Impact 4.2-11 Erosion and Sedimentation Design of the southern Phase 111 debris basin and its diversion swale could result in significant deposition of sedimentation which would reroute water discharge around or over the deposited material and trigger downslope erosion. This would be a potentially significant impact. PS Potential sediment and debris inflows would be routed to the southern Phase III site debris basin by a concrete Swale connecting the basin to a steep undisturbed channel farther upslope. A severe bend at the top of the concrete Swale (just downstream from the undisturbed channel reach) may not be capable of accommodating viscous debris flows. At the very least, massive deposition of debris and sediment at this juncture would require frequent (and costly) maintenance which could only be accomplished during the dry, summer season. At most, diversion of debris potentially emanating from the steep upper channel would create significant opportunities for sediment deposition at the juncture of the natural reach and concrete diversion swale. Such deposition would reroute water discharge around or over the deposited material and trigger downslope erosion. Mitigation Measure 4.2-11 The project shall be revised to provide for installation of a thud debris basin at the base of the steep reach of the middle channel. The retaining wall proposed as part of the project to extend north and south to the adjacent debris basins shall be redesigned to accommodate debris and water overflow from the new central basin. Inclusion of the third basin would reduce the collective long term costs of sediment /debris basin maintenance at the three sites through its more hydraulically efficient delivery characteristics. Significance after Mitigation Implementation of Mitigation Measure 4.2-11 would reduce the impact on erosion and sedimentation to aless-than-significant level. Responsibility and Monitoring The applicant's civil engineer would be responsible for revising the project and Vesting Tentative Map and Preliminary Grading Plan to incorporate an additional debris basin, and the City Planning and Public Works Departments would be responsible for reviewing the Final Subdivision Map for compliance before filing and granting of a grading permit. ia6 4.3 BIOLOGY BIOLOGY -THE SETT/NG Background and Methods This section of the 1998 SEIR updates information on the biological resources of the site, re-evaluates potential impacts on sensitive resources, and identifies additional measures to mitigate adverse impacts of the project. Biological resources discussed in this section were identified through the review and compilation of existing information, including the previous 1982 EIR and 1996 SEIR, and conduct of supplemental field surveys. 125 The review and surveys provided information on common biological resources, the extent of sensitive natural communities, potential jurisdictional wetlands, and the distribution and habitat requirements of special-status species which have been recorded on or are suspected to occur in the vicinity of the Terrabay project site. Biological resources associated with the proposed hook-ramps also have been reviewed and incorporated into this assessment. The previous EIRs summarize information on general vegetation and wildlife, sensitive plant and animal species, and the project's relationship to the 1982 San Btuno Mountain Habitat Conservation Plan (HCP). The re-evaluation of issues examined in the 1996 SEIR reflected changes in the listing status of rare and endangered species known or suspected to occur on the site, changes in populations and distribution of these species, the possible presence of other species of concern on the site, and the relationship of on-site restoration activities to the HCP. Additional issues of concern were raised as part of the scoping process for this 1998 SEIR.' These issues included the potential for impacts on wetland resources, need for supplemental surveys for special-status plant species, confirmation of the absence of suitable habitat for California red-legged frog, changes in the status of the callippe silverspot butterfly, and questions concerning the adequacy of the proposed Restoration Plan for the project. Surveys conducted during prepazation of this 1998 SEIR included reconnaissance surveys to confirm conditions regarding general vegetation and wildlife resources described in the previous EIIts, systematic surveys for special-status plant species, a habitat suitability analysis for California red-legged frog and San Francisco garter snake, review of mapping of the larval host plant for the callippe silverspot and re-evaluation of potential impacts on this protected butterfly subspecies, and a peer review of a preliminary jurisdictional wetland delineation of the site conducted by the project sponsor's wetland consultant. Natural Community Types and Wildlife Habitat As described in the 1996 SEIR, grassland forms the predominate natural community on the site. The grasslands vary in floristic diversity as a result of differing topography, exposure, soil depth, and other factors. Other natural communities and vegetative cover on the site include freshwater marsh and riparian vegetation associated with seeps and drainages, areas of sparse soft-chaparral on hillsides with a primarily southern exposure, and ornamental landscaping along the freeway right-of--way, roadway 125 Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, 1982 (1982 EIR), and Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, 1996 (1996 SEIR). 147 4.3 BfOLOGY Terrabay Phase 11 and 111 SE/R frontages, and graded slopes. These various community types and associated wildlife species are summarized below. Grassland Non-native grassland dominates the more level parts of the site where development is proposed, generally below the 400-foot elevation. Grasslands in these areas are mostly composed of non-native annual grasses and forbs, including slender wild oat (Avena barbata), wild oat (A. fatua), ripgut brome (Bromus diandrus), Italian ryegrass (Lolium multiflorum), annual bluegrass (Poa annua), handing grass (Phalaris aquatics), black mustard (Brassica nigra), broad-leaf filaree (Erodium botrys), and plantain (Plantago spp.). Ruderal or weedy species composed of sweet fennel (Foeniculum vulgare), bristly ox- tongue (Picris echioides), and wild radish (Raphanus sativus) form dense stands in a number of locations, particularly where grading and other disturbance have eliminated native cover. The upper slopes and ridges of the site support a greater diversity of native species, forming open stands of valley needle grass grassland dominated by tufts of native purple needlegrass (Nassella pulchra) or dense clumps of wild rye grassland formed almost exclusively by blue wild rye (Leymus triticoides). Other native grass species found on the site include California melic grass (Melica californica), tufted hairgrass (Deschampsia cespitosa cespitosa), and California brome (Bromus carinatus carinatus). Native annual and perennial forbs also are found throughout the grasslands, such as California poppy (Eschscholzia californica), blue dicks (Dichelostemma capitatum), long-petal iris (Iris longipetala), soap plant (Chlorogalum pomeridianium), blue-eyed grass (Sisyrinchium bellum), yarrow (Achilles millefolium), mule ears (Wyethia angustifolia), purple owl's-clover (Castilleja ezserta ezserta), lupine (Lupinus spp.), and Johnny jump-up (Viola pedunculata). A few native shrub species are scattered throughout the grasslands, such as coyote brush (Baccharis pilularis), toyon (Heteromeles arbutifolia), California sagebrush (Artemisia californica), and oso bent' (Oemleria cerasiformis). These generally occur as individual plants, rather than dense stands or brushfields, and aze not considered a distinct community type. Except for the presence of special-status butterfly species found on San Bruno Mountain, wildlife use of the site is typical of grassland habitat throughout the San Francisco Bay region. The grasslands of the site aze contiguous with and contribute to the overall habitat value of the grasslands on San Bruno Mountain. They support a number of small mammals, reptiles, and birds which in turn serve as prey for larger predatory mammals and birds. Common species which occur on-site and in the surrounding grasslands include California vole, Botts pocket gopher, California ground squirrel, black-tailed hare, striped skunk, savannah sparrow, white-crowned sparrow, red-winged blackbird, western fence lizard, northern alligator lizard, gopher snake, and western rattlesnake. Predatory birds and mammals which forage in the grasslands of the vicinity include American kestrel, white-tailed kite, red-tailed hawk, turkey vulture, great-homed owl, gray fox, and long-tailed weasel. Freshwater Marsh and Riparian Scrub The seeps and drainages on the site support native species indicative of freshwater marsh and riparian plant communities. Freshwater marsh vegetation occurs azound the numerous seeps and springs in the proposed development area on the Phase III site, dominated by rushes (Juncos spp.), tall umbrella-plant (Cyperus eragrostis), water cress (Rorippa nasturtium-aquaticum), common monkeyflower (Mimulus guttatus), and sour dock (Rumex obtusifolius). Most of the stream channels on the site support a cover which is indistinguishable from the surrounding grasslands. Willow (Salix lasiolepis) occurs as scattered clumps in a number of locations, primarily along drainages in the proposed development area on the Phase III site, and freshwater marsh vegetation sometimes occurs along segments of the channels. The largest stand of willow on the site occurs as a 148 4.3 BIOLOGY Terrabay Phase 11 and 111 SE/R dense thicket larger than one acre in size along the western edge of Bayshore Boulevard, in the vicinity of the proposed hook ramps. The available surface water and dense cover associated with the marsh and riparian vegetation provide important resources to wildlife on this part of San Btuno Mountain. At least one of the seeps on the Phase III site appears to be a perennial spring and provides a source of drinking water for wildlife during the summer and fall months when other drainages have dried. Larger mammals and numerous bird species most likely use the dense willow as protective cover, perching and nesting locations, and areas of retreat during high temperatures and severe wind. Aquatic life observed in pools along the seeps and drainages included a few insects species and numerous tadpoles of Pacific tree frog and western toad. Ornamental Landscaping Landscaping has been planted along the freeway right-of--way where the proposed hook-ramps are proposed to be located, as groundcover plantings along South San Francisco Drive, and as a small grove of blue gum eucalyptus (Eucalptus globules) on the Phase III site. All of the species used in ornamental landscaping are non-native trees, shrubs, and groundcovers, and none is of particularly outstanding size or importance as habitat for wildlife. Most of the wildlife species associated with the landscaped areas are common to suburban habitat and ruderal grasslands. These include non-native birds such as European starling, English sparrow, and house finch. The eucalyptus trees on the site occasionally may be used as roosting and perch locations for raptors, but no nests were detected during the field surveys. Special-Status Species 126 Special-status species are plants and animals which are legally protected under the Federal and / or State Endangered Species Acts or other regulations, as well as other species which are considered rare enough by the scientific community and trustee agencies to warrant special consideration, particularly with regard to protection of isolated populations, nesting or denning locations, communal roosts, and other essential habitat. 127 Species with legal protection under the Endangered Species Acts often represent 126 Special-status species include designated rare, threatened, or endangercd and candidate species for listing by the California Department of Fish and Game (CDFG), designated threatened or endangered and candidate species for listing by the U.S. Fish and Wildlife Service (USFWS), species considered rare or endangered under the conditions of Section 15380 of the State CEQA Guidelines (such as those plant species identified on lists lA, 1B and 2 in the Inventory of Rare and Endangered Vascular Plants of California, California Native Plant Society, 1994), and possibly other species which are considered sensitive or of special concern due to limited distribution or lack of adequate information to permit listing or rejection for State or Federal status (such as those included on list 3 in the California Native Plant Society Inventory or identified as animal "Species of Special Concern" by the CDFG). 127 The Federal Endangered Species Act of 1973 (FESA) declares that all Federal departments and agencies shall use their authority to conserve endangered and threatened plant and animal species. The California Endangered Species Act of 1984 (CESA) parallels the policies of FESA and pertains to native California species. 149 4.3 BIOLOGY Terrabay Phase 11 and 111 SEIR major constraints to development, particularly when they are wide ranging or highly sensitive to habitat disturbance and where proposed development would result in a "take" of these species. 128 The previous EIRs contain information on special-status species suspected to possibly occur on the site at the time the reports were prepared. The 1996 SEIR contains information on ten plant species and seven animal species of concern considered to have the highest likelihood of occun ence on the site. Except for mission blue butterfly (Icaticia icarioides missionensis) and callippe silverspot butterfly (Speyeria callippe callippe), both of which have been observed on the site, the 1996 SEIR reported no other special-status species on the site. Information on plant and animal species of concern is reviewed below. Plant Species of Concern The 1996 SEIR conclusion, that no special-status plant populations occur on the site, was based on surveys conducted throughout San Bruno Mountain, rather than systematic surveys of the site itself. For this reason, supplemental surveys were conducted during preparation of this 1998 SEIR following CDFG guidelines to provide a conclusive determination of the absence of any populations of special-status plant species within the proposed development azea. 129 A list of 27 plant species of concern suspected to possibly occur on the site was compiled before initiating the field surveys (see Appendix 7.~. Systematic surveys were conducted on Mazch 30 and May 9, 1998 and focused on the proposed site development azea. All plant species encountered were identified to the degree necessary to determine possible rarity, and a comprehensive list prepared for the site (see Appendix ~ ~. No special-status plant species were encountered during the field surveys, and none is suspected to occur within the proposed development area. A small population of San Francisco wallflower (Erysimum franciscanum) was found in the large ravine at the southern edge of the Phase III site but was located outside the proposed limits of grading. This species has no Federal or State listing status under the Endangered Species Acts but is considered rare by the California Native Plant Society (maintained on list 1B of the Inventory) and is considered a Species of Concern by the USFWS. Animal Species of Concern The 1996 SEIR acknowledges the potential presence of four special-status butterfly species on San Bruno Mountain but concludes that essential habitat for other animal species of concern is not present on the site. Butterfly species of concern listed in the 1996 SEIR include mission blue and San Bruno elfin (Incisalia fotis bayensis), both Federally-endangered, bay checkerspot (Euphydryas editha bayensis) 128 The FESA defines "take" to mean "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect" a threatened or endangered species. The USFWS further defines "harm" to include the killing or harming of wildlife due to significant obstruction of essential behavior patterns (breeding, feeding, or sheltering) through significant habitat modification or degradation. The CDFG also considers the loss of listed species habitat as take, although this policy lacks statutory authority and case law support of the CESA. Two sections of FESA contain provisions which allow or permit "incidental take." Section 10(a) provides a method by which a state or private action which may result in take may be permitted. The project sponsor must provide the USFWS with an acceptable conservation plan and publish notification for a permit in the Federal Register. Section 7 pertains to a Federal agency which proposes to conduct an action which may result in take, requiring consultation with USFWS and possible issuance of a jeopardy decision. Under the CFSA, take can be permitted under Section 2081 of the Fish and Game Code. The project sponsor must enter into a habitat management agreement with the CDFG which defines the permitted activities and provides adequate mitigation. 129 Guidelines for Assessing Effects of Proposed Development on Rare and Endangered Plants and Plant Communities, California Department of Fish and Game, 1994. I50 4.3 BIOLOGY Terrabay Phase Il and 111 SEIR which is Federally-threatened 130 and callippe silverspot which previously was a Federal candidate but recently was listed as endangered. Other animal species of concern addressed in the 1996 SEIR include San Francisco garter snake (Thamnophis sirtalis tetrataenia), San Francisco forktail damselfly (Ischnura gemina), and burrowing owl (Athene cunicularia). Suitable habitat for San Francisco garter snake and San Francisco forktail damselfly is absent from the site, and these species have not been reported on San Bruno Mountain. Similarly, suitable habitat for bun owing owl also is generally absent from the site, and no owls were observed during evening surveys conducted in 1995. While most of the information presented in the 1996 SEIR regarding animal species remains accurate, this 1998 SEIR includes a supplemental detailed assessment of the potential impacts of the project on two species of concern, callippe silverspot and California red-legged frog (Rana aurora draytonii). The recent endangered status of the callippe silverspot raises concerns over the potential impacts of the proposed project on this subspecies and the adequacy of HCP provisions to address habitat loss. A supplemental assessment of potential impacts on callippe silverspot was performed during preparation of this 1998 SEIR. In addition, the 1996 SEIR does not address the potential for occurrence of California red-legged frog on the site, and, because marginal habitat for this frog was observed during initiation of this 1998 SEIR, supplemental surveys for this species also were conducted. The results of additional studies conducted for these two species are summarized below. callippe silverspot Butterfly The callippe silverspot (Speyeria callippe callippe) is endemic to the San Francisco Bay Area and was Federally-listed as endangered in December 1997. It is one of 16 subspecies of Speyeria callippe, a silverspot species which ranges from the Rocky Mountains to the Pacific coast. The local endangered subspecies is believed to formerly have been widespread throughout the grassland-covered hills of the San Francisco Bay Area but today is known only from San Bruno Mountain in San Mateo County and Joaquin Miller and Redwood Regional Parks in Oakland (Alameda County). The callippe silverspot occurs in grasslands where its sole larval foodplant, Johnny jump-up (Viola pedunculata), grows. Adults tend to congregate on prominent hilltops where they search for potential mates during the flight season (from about mid-May through early July). Because of the length of the flight season, adults visit several different plant species as nectar becomes available. These include mints (such as Monardella villosa) and thistles (such as Silybum marutnum and Cirsium vulgare and C. quercetorum). Adult callippe silverspot have been observed on the site during surveys initiated as part of the HCP process in 1981 and as part of annual monitoring since then. The larval foodplant of callippe silverspot is known to occur on the southeast ridge and other locations on San Bruno Mountain. Detailed mapping was prepared by the project sponsor's vegetation specialist, Dave Kaplow, in late January 1998 to provide a more accurate understanding of the distribution of Viola pedunculata on the site. 131 A supplemental assessment for callippe silverspot was conducted during preparation of this 1998 SEIR to confirm the accuracy of the host plant mapping by the project sponsor's vegetation specialist and update the evaluation of potential impacts associated with the proposed project No surveys for adult silverspots or mapping of nectar plants were attempted as part of the supplemental field effort. A copy of the supplemental assessment is contained in Appendix 7.4. 130 The 1996 SEIR notes that bay checkerspot has the potential to occur on San Bruno Mountain but has not been confirmed there in recent years. 131 Viola Pedunculata Survey, letter report and mapping to Sterling Pacific Management Services from Dave Kaplow, Pacific Openspace, Inc., February 5, 1998. 151 4.3 BIOLOGY Terrabay Phase ll and 111 SE/R Verification of the Viola pedunculata distribution on the site was performed on March 20, 1998 which indicated that the mapping by the project sponsor s vegetation specialist generally was accurate. Exhibit 4.3-1 shows the occurrence of Viola pedunculata on the site, together with estimates of the number of individual plants at each location. Determining population estimates of Viola pedunculata was difficult because of the ability of this species to reproduce vegetatively and form clumping, but estimates of the project sponsor's vegetation specialist were considerably fewer than those made during the 1998 EIR assessment. Based on the mapping effort, the largest population of Viola pedunculata occurs in the northeastern part of the Phase III site and contains more than 1,000 plants. Two smaller populations with about 300 plants occur on both sides of an intermittent drainage in the proposed Terrabay Commons neighborhood of the Phase II site. No host plants occur in the vicinity of the proposed hook-ramps. Ca/ifomia Red-Legged Frog This subspecies was Federally-listed as threatened in May 1996 and is considered a Species of Special Concern by the CDFG. 132 It typically is associated with freshwater ponds and streams which hold water through its metamorphosis period (generally in July or early August) and allow for successful breeding. The current distribution of red-legged frog in northern San Mateo County and San Francisco County is sporadic, including occurrences at Lake Merced, Lincoln Park, Golden Gate Park, the Presidio, the San Francisco International Airport, and the San Francisco County Jail facility in San Bruno. Attempts to locate this species at other locations in the vicinity of San Bruno Mountain, including surveys at a small seasonal wetland area along Bayshore Boulevard in Brisbane, have been unsuccessful. 133 Because of the presence of possible marginal habitat and fact that California red-legged frog had not been addressed in the previous EIIts, a survey was conducted to determine habitat suitability on the site. All wetlands within and adjacent to the site were surveyed to determine if habitat features necessary to support a resident population are present. On February 13, 1998, an initial survey of the site was conducted where potential breeding habitat was evaluated. These included three recently created detention basins, a small shallow series of interconnected pools within the flow channel of the perennial spring on the Phase III site, and the dense willow thicket along the Bayshore Boulevard frontage of the Phase III site. Due to the heavy rainfall and turbidity of the ponded areas, a supplemental survey was conducted on April 9, 1998. A copy of the survey report is contained in Appendix 7.4. The results and conclusion of the survey effort were that no larva or adult California red-legged frog were detected and that suitable spawning habitat necessary for successful reproduction is not present on the site. By early April, the detention basins either had lost most of their water or showed signs that they would not hold water for a sufficient duration to support a breeding population of the frog. Similazly, suitable breeding habitat within the willow thicket and the small pools in the eastern part of the Phase III site do not retain water long enough to support this species. Pacific tree frog tadpoles were discovered in the small pools of the drainage from the perennial spring on the Phase III site, but red-legged frog tadpoles were not observed. Wetlands Although defmitions vary to some degree, wetlands generally aze considered to be areas which are periodically or permanently inundated by surface or ground water and support vegetation adapted to life in saturated soil. Wetlands are recognized as important features on a regional and national level due to their high inherent value to fish and wildlife, use as storage areas for storm and flood waters, and water 132 Species of Special Concern generally have no legal protective status but are of concern to the CDFG because of severe decline in breeding populations in California. 133 The Status of the California Red-Legged Frog on the Lavine Property, Brisbane, California, Samuel McGinnis, 1997. 152 4.3 BIOLOGY Terrabay Phase ll and 111 SE/R recharge, filtration, and purification functions. The CDFG and U.S. Army Corps of Engineers (Corps) have jurisdiction over modifications to river banks, lakes, stream channels, and other wetland features. 134 The previous EIRs did not address the potential for occurrence of jurisdictional wetland habitat on the site. A wetland delineation appazently was prepared for the site by Hazding Lawson Associates in 1989, and a nationwide permit was issued by the Corps in April 1990 which authorized fill of less than one acre of jurisdictional habitat on the entire site. 135 However, because the nationwide permit has expired, because the original delineation was only partly available, and because conditions on the site may have changed since then, a new delineation was prepared for the project sponsor by Vicki Reynolds. 136 ~, peer review of Reynolds' preliminary wetland delineation was performed during preparation of this 1998 EIR. Wetlands and unvegetated "other waters of the U.S." associated with stream channels on the site were mapped by Reynolds using Corps methodology. Mapping prepared as part of the 1989 delineation was reviewed in the field during surveys on February 18 and March 17, 1998, and three additional wetland azeas were mapped by Reynolds. Reynolds estimated that potential jurisdictional wetlands occupy approximately 1.63 acres of the site, generally in the northern half of the Phase III site. These include freshwater marsh habitat associated with the perennial spring and numerous seeps and with the large willow thicket along Bayshore Boulevard. Reynolds estimated that an additional 0.24 acre of unvegetated "other waters of the U.S." occurs along stream channels, for a total of 1.87 acres of jurisdictional habitat on the site. Exhibit 4.3-I shows the extent of jurisdictional wetlands and stream channels mapped by Reynolds and additional potential jurisdictional habitat encountered on the site during the peer review for this 1998 SEIR. While Reynolds' delineation generally provides an accurate mapping of jurisdictional habitat, three small seep areas also appear to qualify as wetlands, and a narrow channel approximately 125 feet long occurs in the Phase III site. These additional potential wetland areas collectively encompass approximately 0.15 acre, and the unvegetated channel contains about 0.006 acre of jurisdictional habitat. Including these additional azeas with those mapped by Reynolds, a total of 2.026 acre of jurisdictional 134 Jurisdiction of the Cotps is established through the provisions of Seciion 404 of the Clean Water Act which prohibits the discharge of dredged or fill material into "waters" of the United States without a permit, including wetlands and unvegetated "other waters of the U.S.". The Corps uses three mandatory technical criteria (hydrophytic vegetation, hydric soils, and wetland hydrology) to determine whether an area is a jurisdictional wetland. All three of the identified technical criteria must be met for an area to be identified as a wetland under Corps jurisdiction, unless the area has been modified by human activity. Jurisdictional authority of the CDFG over wetland areas is established under Sections 1601-1606 of the Fish and Game Code which pertain to activities which would disrupt the natural flow or alter the channel, bed, or bank of any lake, river, or stream The Fish and Game Code stipulates that it is "unlawful to substantially divert or obstruct the natural flow or substantially change the bed, channel, or bank of any river, stream or lake" without notifying the Department, incorporating necessary mitigation, and obtaining a Streambed Alteration agreement. The Wetlands Resources Policy of the CDFG states that the Fish and Game Commission will "strongly discourage development in or conversion of wetlands ... unless, at a minimum, project mitigation assures there will be no net loss of either wetland habitat values or acreage". The Department also is responsible for commenting on projects requiring Corps permits under the Fish and Wildlife Coordination Act of 1958. 135 "Subject File No. 18052S91A", letter to W.W. Dean and Associates from Calvin C. Fong, Chief, Regulatory Branch, Department of the Army, Corps of Engineers, Apri120, 1990. 136 Preliminary Jurisdictional Determination Pursuant to Section 404 of the Clean Water Act, Terrabay Developmerzt Site, Vicki Reynolds, April 8, 1998. 153 4.3 BIOLOGY Terrabay Phase ll and Il! SE1R habitat occur on the site. The Corps eventually will verify the preliminary wetland delineation and determine the actual extent of jurisdictional habitat on the site as part of its permitting process. BIOLOGY -SIGNIFICANCE CRITERIA The State CEQA Guidelines (Guidelines) identify potentially significant environmental effects on biological resources. Those would result when a project: • Impacted a population or essential habitat of special-status plant or animal species. • Substantially interfered with the movement of any resident or migratory fish or wildlife species. • Substantially reduced habitat for fish, wildlife, or plants. In addition, although not specifically identified in the Guidelines as a potentiall~• significant impact, modifications to wetlands are of great concern to jurisdictional agencies due to the regional and national importance of these features. The cumulative adverse effect of seemingly minor changes to wetlands often can result in major damage to these resources through numerous individual alterations. Therefore, loss or substantial modification to existing wetlands also would be considered a potentially significant effect. A determination of the significance of project impacts for each of these potentially significant effects is based on a review of the biological resources on the project site and vicinity, application of professional experience, and, where available, through the use of guidelines established by trustee agencies. BIOLOGY- IMPACTS AND MITIGATION MEASURES Impact 4.3-7 Vegetation Removal, Wildlife Habitat Loss, and Landscape Compatibility Grading associated with project implementation would require removal of existing vegetation and associated wildlife habitat in areas proposed for development. Loss of non-native grassland would not be considered significant, but impacts on native freshwater marsh and riparian habitat and remnant stands of native grasslands would be significant. Proposed landscaping and restoration of graded slopes appear to be compatible with open space designations on parts of the site, but without a salvage component to the proposed restoration plan anticipated impacts would continue to be significant. S Vegetation Removal and Habitat Loss Implementation of the proposed project would disturb an estimated 102.1 acres of the site and an additional 14.5 acres along Bayshore Boulevard and the west side of the U.S. 101 corridor. Of that total, approximately 32 acres have been disturbed already through prior Phase I grading. Vegetation within the proposed limits of grading would be removed as part of landslide repair efforts and recontouring of the site to accommodate the proposed approach to development. Most of the affected vegetation would consist of non-native grasslands on the lower elevations of the site, together with the eucalyptus trees on the Phase III site and ornamental landscaping along the freeway right-of--way. Loss of this non-native vegetation would not be considered significant due its disturbed condition and relative abundance in surrounding pazklands. Smaller resident mammals and reptiles would be eliminated from areas encompassed by development, and birds and larger mammals would be displaced at least temporarily as development is implemented. 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(f~I S. ~l~x. ~ ~~. ~ ~ t~ I` V ' l r , ~ ~ ;1 Yr ( JJ! ` 1~•.'r ,{/ (1r ,. r r~ : i ' 7 , U t 1r~1 + ,,a ! ° ~ .~,\ ! .., lr ~ ~ \ \. / rJ /r ~ ~ .~ ~ ' 'e:~_ ~ r, \vt f ` \ \ /~. j ~, w \•. ~• ~~ i '" 1+Itrlr'',. h; ~r7 ~ , ~. ... ~ `~ ~ /f c.tla4/ ^'r...r 4 i,t ...` \' ,,\ !~ I11))!~~ _ ,~ ~ / ,, . ; ' . ` :, Y • - ~IIIr. • ~, "''t t, t tilttj~" rr+~ `~.. .....~: f ..... '~\ • ` ~r • x•,~ f1 ~< .t t) \ a .~'a"""', ~ ~~ \ \,,' rrf. . . ,. .. _. 7 ., , •. I ,,, ~.. i, ~ , r f` ~~'~~ I~(I 1 ~ ' ~~ -* J11~ ~t \ It ~~`:j \ ,` \ \~ ~S J ' ~ ~ t , • ~s ~ r. I 1 ...' ._ r i Tff., a' .. I . . I„ ,. i( t 1 ~ 11 i l . ~Q ~ ~; C :p y 4.3 BIOLOGY Terrabay Phase 1/ and 111 SEIR nesting substrate. Predatory mammals and birds would avoid the developed part of the site even after construction due to elimination of suitable foraging habitat. While the proposed project would affect local populations of wildlife species, restoration and open space provisions proposed on the site and as part of the HCP for San Bruno Mountain would minimize potential impacts. Thus, no new significant impacts on general wildlife resources would be anticipated. While the anticipated loss of non-native grasslands is not considered significant, removal of native wetland-related habitat and the perennial spring on the Phase III site would be significant. As can-ently proposed, development would eliminate all the native freshwater marsh and riparian vegetation, resulting in a collective loss of approximately two acres of these sensitive natural community types. These scattered seeps, springs, and thickets provide critical cover and surface water for wildlife on this part of the mountain, and their removal may be an unavoidable loss given the difficulty of recreating these natural habitat types as replacement mitigation. The loss of these native habitat types would be considered a significant impact requiring mitigation as called for below and discussed under Impact 4.3-3. In addition,.at least one pedestrian trail is proposed to provide a link between the developed part of the site and open space lands on San Bruno Mountain. Schematic project plans have depicted the pedestrian trail alignment in at least two locations on the Phase III site. The 1996 Specific Plan trail alignment followed the bottom of the lazge ravine in the southern part of the Phase III site which could have adversely affected native grasslands and possibly the population of San Francisco wallflower in the ravine. As currently proposed in the northeastern part of the Phase III site, the trail alignment would go straight up the hillside above Pazcel A and could adversely affect native grasslands and callippe silverspot host plants known to occur in this area. 137 The trail's currently proposed alignment most likely would contribute to severe erosion and on-going maintenance problems. Careful consideration of any trail improvements would be necessary to avoid sensitive native vegetation. Landscape Compatibility Proposed Landscape Plans for the project show the intended approach to landscaping azound buildings, along roadways and pazking areas, and on internal hillside slopes and include detailed lists of plant species to be used in landscaping. Landscaping throughout the developed part of the site would be composed of a mixture of both non-native and native species used in ornamental plantings, including a variety of trees, shrubs, and groundcovers (Exhibit 2.3-I3). No highly aggressive species are proposed in plantings near the interface with undeveloped hillsides, and no significant impacts due to landscape incompatibility would be anticipated. The project sponsors vegetation specialist has prepazed a proposed Restoration Plan for treatment of graded slopes at the interface between development and dedicated HCP open space areas. Restoration Plan specifications provide information on site preparation, erosion control and seed application, container plantings, maintenance, monitoring, success criteria, and remediation. Native species would be used exclusively in the restoration effort, with species selection and application rates dependent on slope and other variables. Based on the peer review conducted during preparation of this 1998 SEIR, the proposed Restoration Plan appears to provide a feasible approach to establishing native grassland cover on graded slopes, with appropriate contingency measures if success criteria are not met during the monitoring effort. The provisions in the proposed Restoration Plan related to eradication of perennial weeds and calling for minimum success criteria for native cover establishment should serve to address problems previously experienced with restoration efforts on the Phase I site. 137 Terrabay Phase III Commercial Land Use Plan, Exhibit 5-36, January 22, 1998. 156 4.3 BIOLOGY Terrabay Phase 11 and 111 SElR Although the proposed Restoration Plan generally appears adequate, it currently does not include a provision for salvage and transplant of scatxered native grassland plants which otherwise would be eliminated as a result of development. The non-native grasslands of the lower elevations of the site continue to support native perennial species in a number of locations which would be suitable for salvage and eventual transplanting onto restored slopes following grading and soil treatment. Salvage of native material would protect the genetic diversity of native plant species on the site and shorten the length of time for plant establishment as part of the restoration effort. These include larval and adult host plant species for special-status butterfly species, as well as other native perennial species which contribute to the overall habitat of the mountain. Salvaged plants also could be used as a source of propagation material for the container planting to be used in the Restoration Plan. Without an acceptable plant salvage component, the proposed Restoration Plan would be considered inadequate which would be a significant impact. Project-related grading would create suitable conditions for establishment of broom (Cyrisus spp.), sweet fennel, pampas grass, gorse, and other invasive species. Most of these non-native species already occur on the site, and, if their occurrence is not controlled, they tend to form dense thickets which out-compete and eventually replace grassland and herbaceous cover. The Restoration Plan proposed for the project includes provisions to prevent the establishment and spread of weedy species on open space slopes on the site, including the use of mowers, trimmers, and application of herbicides. Implementation of the proposed weed eradication effort should prevent the re-establishment of undesirable species on graded slopes and minimize the potential for spreading into permanent open space lands. Mitigation Measure 4.3-1(a) Areas of native freshwater marsh and riparian natural communities in the Phase III portion of the site shall be preserved to the greatest extent possible given the difficulty of recreating these natural community types and their importance as a source of surface water and protective cover for wildlife. Of greatest importance is the perennial spring at the southern edge of proposed Pazcel C on the Phase III site which provides a permanent source of drinking water for wildlife. Preservation and in-kind replacement of these wetland-related habitat types shall be considered as part of the mitigation plan called for in Mitigation Measure 4.3-3(a). If preservation is determined to be infeasible, any replacement mitigation shall provide for creation of a permanent spring which replicates the flows from the perennial spring on the site. The replacement spring shall be located adjacent to the County open space lands to ensure accessibility to terrestrial wildlife populations on San Bruno Mountain. Mitigation Measure 4.3-1(b) The proposed Restoration Plan for the project shall be revised to include an additional component which provides for salvage of native plant material that otherwise would be eliminated as a result of grading and development. Salvage shall be performed during the optimum period necessary to ensure plant survival, generally in the fall and eazly spring months, with material stored in a temporary growing area if necessary and eventually transplanted onto slopes where restoration is to occur following final grading and soil preparation. Any plant salvage operation shall be restricted to the limits of final grading to prevent the further loss of native species in permanent open space areas. Mitigation Measure 4.3-1(c) Any pedestrian trails linking the site with the open space lands of San Bruno Mountain preferably shall follow the alignment of existing fire trails to inimi~P disturbance to vegetative cover and shall avoid azeas of native grasslands, freshwater seeps, and larval host plants for callippe silverspot butterfly. Final pedestrian trail alignments shall be approved by the Habitat Conservation Plan coordinator. Significance after Mitigation Implementation of Mitigation Measures 4.3-1(a), 4.3-1(b), and 4.3-1(c) would ensure protection or replacement of sensitive natural communities and important wildlife habitat, reducing impacts to Iess-than-significant levels. ts~ 4.3 BIOLOGY Terrabay Phase 1l and 111 SElR Responsibility and Monitoring The project sponsor would be responsible for revising the Specific Plan grading plan and conceptual development plan for the Phase III site, revising the proposed Restoration Plan for the Phase II and III sites, and cooperating with the City, County, and HCP coordinator about trail location to connect the project site and San Bruno Mountain County Park. Salvaging should occur before grading is initiated but after grading permits are issued to prevent premature removal of plants. The City of South San Francisco and HCP coordinator would monitor compliance. Impact 4.3-2 lmpacfs on Special-Status Species Except for callippe silverspot butterfly and mission blue butterfly, no impacts on populations of other special-status plant and animal species area anticipated. While the San Bruno Mountain Habitat Conservation Plan (HCP) fully addresses potential impacts of anticipated development on mission blue, amendments to the HCP would be necessary for the recently listed callippe silverspot. Further loss of suitable habitat for callippe silverspot on the site would be a significant impact. S No special-status plant species or essential habitat for most of the special-status animal species of concern were encountered within the proposed development areas of the site, and no adverse impacts would be anticipated for these species. The small population of San Francisco wallflower detected in the lazge ravine in the southern part of the Phase III site is located well outside the proposed limits of grading, and no impacts would be expected on this population. Project implementation would result in both direct and indirect impacts on callippe silverspot. While extensive stands of Johnny jump-up occur in the permanent open space lands higher up the mountain, proposed grading would eliminate the remaining larval hostplants and adult foodplants within the development area of the site and, possibly, individual callippe silverspot butterflies as well. Indirect impacts to areas outside the proposed limits of grading also could occur as a result of construction- generated dust and equipment disturbance, particularly on lands immediately adjacent to the site. Because of the Federally-listed endangered status of this subspecies, these potential direct and indirect impacts would be considered significant under CEQA. The San Bruno Mountain HCP was adopted in 1982 to conserve and enhance as much of the remaining natural habitat on the mountain as possible, thereby protecting populations of mission blue and callippe silverspot butterflies, other special-status species, and the unique and diverse ecology of the mountain as a whole. An underlying premise of the HCP is that allowing limited development would enhance the butterflies' survival by making possible the transfer of neazly 800 acres of privately held lands to the public, by providing the funding source for the conservation and enhancement activities described in the HCP, and by mitigating the impacts of development through required compliance with provisions set forth in the HCP. Development approvals on the mountain required the issuance of a permit under Section 10(a) of the Endangered Species Act. The Section 10(a) permit authorizes the taking of some of the butterflies as a result of development with the understanding that implementation of the HCP provides the framework to ultimately enhance the overall survival of these protected species. Although the framework defined in the HCP included consideration of both the mission blue and the callippe silverspot, the Section 10(a) permit did not specifically allow for incidental take of callippe silverspot because it was not a listed species at the time. The loss of habitat for callippe silverspot on the site currently is illegal without a permit from the USFWS. Since development on the site was approved as part of the San Bruno Mountain HCP, an amendment to the existing incidental take permit would be the preferred approach to securing authorization from the USFWS. On March 11, 1998, a meeting was held between the project sponsor and USFWS to discuss the need to amend the incidental take permit to include the callippe silverspot. A summary of the meeting indicates that USFWS concerns relevant to the callippe silverspot include the need to post informational signs at trailheads into the park (to warn tss 4.3 BIOLOGY Terrabay Phase 11 and lIl SE/R poachers about violations associated with this illegal activity) and the acknowledgement that San Mateo County would need to propose this additional condition in the amendment to the permit (the HCP implementing agreement prohibits the USFWS from imposing additional mitigation measures). 138 Mitigation Measure 4.3-2 The project sponsor shall be required to fulfill the landowner /developer obligations identified by the San Bruno Mountain Habitat Conservation Plan with respect to the site. If San Mateo County does not obtain an amended incidental take permit which includes the callippe silverspot butterfly, the project must be redesigned to avoid all larval host plants. If the permit is amended to include callippe silverspot, the landowner shall incorporate any new permit conditions into the project. The following measures also shall be implemented to further inim;~P potential impacts of the project on the callippe silverspot: Project plans shall be redesigned to avoid disturbance to and development of areas supporting populations of the larval host plant (Viola pedunculata) to the greatest extent possible. Of particular concern is the population containing more than 1,000 plants in the northeastern corner of the Phase III site. Elimination of development in the vicinity of proposed Parcel A and a part of Parcel B on the Phase III site would preserve the largest population and minimize impacts on the callippe silverspot. The proposed Restoration Plan shall be revised to include a component to salvage and transplant existing larval host plants and adult nectar plants (especially natives such as Monardella) which otherwise would be lost due to grading and development. Salvage material shall be used as part of a propagation program to reestablish larval host plants and adult nectar plants on restored slopes and in additional grassland habitat where they currently are absent. Signs shall be prepared, in cooperation with the San Mateo County Parks Department and HCP coordinator, and installed along trails and other appropriate locations warning park users against illegal activities (such as poaching). Appropriate dust control measures shall be implemented as a component of the project's sedimentation and erosion control plans in order to minimize construction-generated dust (as required by Mitigation Measures 4.1-2(c) and 4.5-1). Measures shall include frequent watering of graded area, equipment, and haul roads to minimize dust and control its dispersal. Significance after Mitigation Compliance with the landowner /developer obligations of the HCP and implementation of these additional measures would mitigate potential adverse impacts on callippe silverspot to ales-than-significant level. Responsibility and Monitoring The project sponsor would be responsible for revising the Specific Plan grading plan and conceptual development plan, revising the proposed Restoration Plan, and posting trailhead signs in cooperation with the City, County, and HCP coordinator. The City of South San Francisco and HCP coordinator would monitor compliance. 138 San Bruno Mountain HCP: Section 10(a) Permit Amendment Regarding Callippe silverspot Butterfly, letter to James Sweenie, Sterling Pacific Management Service, from Robert D. Thornton, Nossaman, Gunther, Knox & Elliott, I.I.P, March 11, 1998. 159 4.3 BIOLOGY 7errabay Phase ll and 1Il SEIR Impact 4.3-3 Loss of Jurisdictional Wetland Habitat Implementation of the project as proposed would eliminate approximately two acres of jurisdictional habitat, including areas of sensitive freshwater seeps, riparian habitat, and the perennial spring on the site. This loss of jurisdictional wetland habitat would be a significant impact of the project. S Potential impacts to jurisdictional habitat would include direct loss of wetlands and stream channels by development and indirect changes associated with the increased potential for erosion and water quality degradation. Potential erosion and degradation of waters located downstream from the site may result from increased urban runoff volumes and degraded water quality associated with proposed development. Soils exposed during grading and construction would contribute to increase sediment loads, if adequate erosion control measures were not implemented. Increased urban pollutants (such as petroleum products from automobiles and fertilizers, herbicides, and pesticides associated with suburban development) may contribute to long-term degradation of water quality. Proposed development would eliminate all the remaining jurisdictional habitat on the site, including up to two acres of wetlands and approximately 0.25 acre of jurisdictional "other waters of the U.S." along the unvegetated stream channels. This would include the complex of freshwater seeps and the perennial spring on the Phase III site and the large willow thicket along the Bayshore Boulevard frontage. Loss of the lazge willow thicket would occur as a result of placing fill for the hook ramps. The loss of jurisdictional habitat on the site would be considered a significant impact of the project as currently proposed. Modifications to wetlands and other waters on the site would be subject to jurisdictional review and approval by the Corps, CDFG, and Regional Water Quality Control Board (RWQCB). Based on the estimated loss of almost two acres of jurisdictional habitat and more than 500 linear feet of stream channel, an individual permit would be required for the project. The preferred approach to mitigation is avoidance of any sensitive habitat which would include areas of freshwater seeps and willow riparian scrub. Where avoidance is not possible, creation of in-kind habitat, at a replacement ratio of from 2:1 to 3:1 (ratio of created habitat to lost habitat), typically is required when sensitive natural communities (such as freshwater mazsh and riparian habitat) are affected. While creation of replacement habitat for the willow scrub community type could be achieved successfully, it is questionable whether freshwater seeps and the perennial spring could be recreated, emphasizing the importance of preserving this habitat type to the greatest extent possible. Mitigation Measure 4.3-3(a) The proposed project shall be redesigned to avoid jurisdictional wetland habitat to the maximum extent feasible. Of greatest concern is the freshwater seep habitat on the Phase III site, particulazly the perennial spring ~t the southern end of proposed Pazcel C. Grading and other disturbance shall be restricted within a minimum of 50 feet of the spring, and the area shall be incorporated into proposed private open space lands of Parcel C to be preserved and maintained by the master building owners association established for the Phase III site. Mitigation Measure 4.3-3(b) If complete avoidance of jurisdictional wetlands is not feasible, a wetland mitigation plan shall be prepared by the project sponsor's wetland consultant to provide for their replacement. The plan should provide for in-kind replacement of any wetlands lost as a result of development, preferably located on the Phase III site. The plan shall include the following details: All plantings to be used as part of any replacement mitigation shall be restricted to native wetland, riparian, and adjacent upland species found on the site. ibo 4.3 BIOLOGY Tenabay Phase Il and 111 SE/R Site preparation and revegetation procedures, planting design, implementation schedule, and funding sources shall be defined to ensure long-term management of the overall wetland mitigation plan. Performance criteria, maintenance and long-term manasement responsibilities, monitoring requirements, and contingency measures, if performance standards and mitigation goals are not met, shall be specified. Replacement habitat shall be monitored for a minimum of five years until all success criteria are met. Before issuance of any grading or building permit for the project, the mitigation plan shall be reviewed and approved by the U.S. Army Corps of Engineers, California Department of Fish and Game, and Regional Water Quality Control Board subject to their authority under Section 404 of the Clean Water Act, Section 1603 of the California Fish and Game Code, and Section 401 Certification, respectively. Mitigation Measure 4.3-3(c) A detailed erosion and sedimentation control plan shall be prepared and implemented during construction on the site. The plan shall contain detailed measures to control erosion of stockpiled earth and exposed soil, minimize construction-generated dust, provide for revegetation of graded slopes before the first rainy season following construction, and specify procedures for monitoring of the plan's effectiveness. The revegetation component of the plan shall be consistent with the revised Restoration Plan. Significance after Mitigation Coordination with jurisdictional agencies and implementation of these measures would reduce impacts on wetland and surface water resources to ales-than-significant level. Responsibility and Monitoring The project sponsor would be responsible for revising the Specific Plan grading plan and conceptual development plan, formulating and implementing the Wetland Mitigation Plan, and preparing and implementing erosion and sedimentation control measures. The Corps, CDFG, and RWQCB would monitor compliance. 161 4.4 TRAFFIC AND CIRCULATION INTRODUCTION This section presents the analysis of circulation impacts from development of the Terrabay Phase D and III project and provision of new hook on- and off-ramps which would connect to Bayshore Boulevazd and serve southbound U.S. 101 freeway traffic. It first describes the existing transportation network in the City of South San Francisco in the immediate area of both projects, the potential circulation impacts due to the Terrabay project on this network, and measures required to mitigate the Terrabay development. It then describes potential impacts and measures required to mitigate the hook ramp project. Where relevant, parts of this section draw on the 1996 SEIR. Both the 1996 SEIR and 1998 SEIR traffic analyses were prepared by the Crane Transportation Group. For the analysis of the Terrabay project, local transportation system conditions are described for the following scenarios: • Existing (Fall 1997) • Year 2000 "Base Case" (anticipated future traffic conditions without the project) • Yeaz 2000 "Base Case plus Phase II Only" (anticipated future traffic conditions with 348 housing units -- 7.5 Appendix) • Yeaz 2000 "Base Case plus Phase III Only" (hotel, restaurant, office, and retail uses - 7.5 Appendix) • Year 2000 "Base Case plus Phases II and III" • Yeaz 2010 "Base Case" (anticipated future traffic conditions without the project) • Year 2010 "Base Case plus Phase II Only" (7.SAppendix) • Yeaz 2010 "Base Case plus Phase III Only" (7.SAppendix) • Year 2010 "Base Case plus Phases II and III" For yeaz 2000 and 2010 future yeaz scenarios, this analysis assumes the following conditions based on current development timing or specific project development proposals for the Terrabay site: • For all future year analyses, the southbound to eastbound U.S. 101 off-ramp flyover is assumed to be in operation (by year 2000). • For year 2000 or 2010 Base Case or Base Case plus Phase II analyses, the proposed southbound buttonhook on- and off-ramps connecting to Bayshore Boulevazd are not assumed to be in place. However, the existing southbound off-ramp connection to Bayshore Boulevard (the scissors ramp) is assumed to remain in operation. • For yeaz 2000 or 2010 analyses including Phase III development, the southbound hook ramps aze assumed to be constructed (as part of Phase III). • Roadway and intersection geometrics are assumed to remain the same from 1997 to 2010 for analysis purposes unless specifically stated otherwise in the text. All specific future roadway improvements needed as mitigation are presented after each impact. 162 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE/R In addition to the 2000 and 2010 environmental analysis for the Terrabay project, this traffic section also contains year 2020 environmental analysis for the proposed southbound hook ramps which would connect to Bayshore Boulevard (in approximately the same location as the existing southbound off- ramp). This analysis was conducted for the Project Study Report (PSR) and Project Report (PR) recently prepared for the hook ramp project. 139 The following scenarios were evaluated for year 2020 conditions: Total local area development (including Terrabay Phases I, II, and II)) with no hook ramps in place. Total local azea development (including Terrabay Phases I, II, and IIn with the hook ramps in operation. SETTING Circulation System Regional Freeway Access The network of freeways, arterial streets, and local streets serving the project area is illustrated on Exhibit 4.4-I and described below. U.S. Highway 101 (U.S. 101) is the principal freeway providing access to the project area. U.S. 101 has eight travel lanes through South San Francisco with auxiliary lanes provided between some interchanges. AcEess to U.S. 101 in the project area is provided by the Oyster Point Boulevazd interchange and by select on- and off-ramps connecting to Bayshore Boulevazd (to the north) and Airport Boulevazd and Grand Avenue (to the south). The Oyster Point interchange provides on-ramp connections to both north- and southbound U.S. 101, as well as a northbound off-ramp. The northbound off-ramp and southbound on-ramp connect to a common signalized intersection with Dubuque Avenue on the east side of the freeway, just south of the Dubuque Avenue connection to Oyster Point Boulevard. The northbound on-ramp extends north as the fourth leg of the signalized Oyster Point Boulevazd /Dubuque Avenue intersection. Southbound U.S. 101 traffic accesses the project azea via a stop sign-controlled off-ramp connecting to Bayshore Boulevard along the Terrabay Phase III site frontage. The southbound off-ramp is designed in a "scissors" configuration, including a two-way stop with northbound Bayshore Boulevazd. Southbound Bayshore Boulevard traffic is not stop sign-controlled at this location. Rather, it has a separate travel lane as does off-ramp traffic departing the all-way-stop intersection with northbound Bayshore Boulevard. A northbound U.S. 101 off-ramp to northbound Bayshore Boulevard is provided just north of the project azea. U-turns aze prohibited on northbound Bayshore Boulevard well into the City of Brisbane. - Local Roadway Network Hillside Boulevard is a four-lane roadway in the project area along the base of San Bruno Mountain. Hillside Boulevazd extends along the southern boundary of the project site at the site's western end. The roadway intersects the recently completed Sister Cities Boulevazd about one-third of the distance 139 Route 101 /Bayshore Boulevard Hook Ramps PSR /PR Traffic Operations Analysis, CCS Planning and Engineering, Inc., March 23, 1998. 163 '- ~ a ~7 am tQ W ~L C O Z a 0 C7 c 0 m r 0 a h c m H m c m U m U O 4.4 TRAFFIC AND CIRCULATION Terrabay Phase I/and 111 SE/R along the southern site boundary and then extends to the southeast as a two-lane roadway through a residential neighborhood towards downtown South San Francisco. It ends at an intersection with Linden Avenue which connects directly to Airport Boulevazd. Hillside Boulevazd has signalized intersections with Sister Cities Boulevard, Stonegate Drive, and Linden Avenue. Also, a new signal began operation in early May 1998 at the Chestnut Avenue intersection. 140 An all-way stop is provided at Lincoln Street. All other roadways aze stop sign-controlled on their approaches to Hillside Boulevazd. From just east of Lincoln Street to Sister Cities Boulevard, the new four-lane section of roadway with a raised median located immediately adjacent to the Terrabay site is designated the "Hillside Boulevard Extension". The two-lane roadway running just south and parallel to the extension (adjacent to single-family units on the south side of the street) is designated Hillside Boulevard. Hillside Boulevazd Extension has signalized intersections with Jefferson Street /South San Francisco Drive (the Terrabay Phase I site access) and Sister Cities Boulevard. Chestnut Avenue extends westerly from Hillside Boulevard. The roadway has four lanes near Hillside Boulevazd but narrows to two lanes in places where roadway widening has not yet occurred. Sister Cities Boulevard is a four-lane divided arterial roadway located along the southern Terrabay Phase II site boundary. It extends from its signalized intersection with Oyster Point Boulevazd / Airport Boulevard /Bayshore Boulevard on the east to its signalized intersection with Hillside Boulevard Extension /Hillside Boulevard on the west. The one intersection along Sister Cities Boulevard (with South San Francisco Drive) is about halfway between Oyster Point $oulevazd and Hillside Boulevazd. This intersection is signalized and, when fully operational, would provide access into the Phase II site. 141 South San Francisco Drive extends west from this Phase II intersection into the Phase I site where it is paved and intersects with Hillside Boulevard Extension at Jefferson Street. Bayshore Boulevard is primarily afour-lane arterial roadway extending north from South San Francisco into the cities of Brisbane and San Francisco on the west side of U.S. 101. South of Oyster Point Boulevard it continues through South San Francisco as Airport Boulevard and South Airport Boulevard. Adjacent to the eastern boundary of the Terrabay site, Bayshore Boulevard has two travel lanes in each direction, narrowing fo single travel lanes near its intersection with the U.S. 101 southbound off-ramp (scissors ramp). Airport Boulevard /South Airport Boulevard is a north-south arterial roadway located parallel to and west of U.S. 101. The roadway is four lanes wide in the project azea. Oyster Point Boulevard is a major arterial roadway extending east from the Airport Boulevard / Bayshore Boulevard /Sister Cities Boulevard intersection across the U.S. 101 freeway and Caltrain raih oad tracks into the East of 101 employment area. The freeway overpass has eight travel lanes and a narrow raised median. 140 Crane Transportation Group conversation with Dennis Chuck. City of South San Francisco Public Works Department. 141 The signal is in place and operating, but the Phase II site entrance (South San Francisco Drive) is not complete and is only used occasionally for construction vehicles. 165 4.4 TRAFFIC AND CIRCULATION Terrabay Phase /l and !ll SE/R Dubuque Avenue is a frontage road running along the east side of U.S. 101 from Oyster Point Boulevard south to Grand Avenue. It has two travel lanes along its entire length except from Oyster Point Boulevard to its intersection with the freeway northbound off-ramp /southbound on-ramp where up to eight lanes and a narrow raised median are provided. It has signalized intersections with Grand Avenue, the freeway ramps, and Oyster Point Boulevard. Study Intersections In order to evaluate the impacts of the Terrabay Phase II and III project, the AM and PM peak hour operations of 11 intersections were studied (ten signalized intersections and one stop sign-controlled intersection) -- see Exhibit 4.4-2. The 11 intersections are: Signalized • Hillside Boulevard Extension /Jefferson Street /South San Francisco Drive (Terrabay Phase I access) • Hillside Boulevard /Sister Cities Boulevard /Hillside Boulevard Extension • Sister Cities Boulevard /South San Francisco Drive (primary Tenrabay Phase II access) • Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard • Oyster Point Boulevard /Dubuque Avenue / U.S. 101 northbound on-ramp • Dubuque Avenue / U.S. 101 northbound off-ramp / U.S. 101 southbound on-ramp • Bayshore Boulevard /Terrabay Phase III northern access (proposed) 142 • Bayshore Boulevard /Terrabay Phase III southern access (proposed) 4 • Bayshore Boulevard /southbound U.S. 101 freeway on and off hook ramps (future) • Chestnut Avenue /Hillside Boulevard (signalized operation as of May 1998) All-way-stop controlled U.S. 101 southbound off-ramp /northbound Bayshore Boulevard Intersection Turning Movements Intersections, rather than mid-block roadway segments, are almost always the critical capacity controlling locations for a local circulation system. Both AM and PM peak period (7:00-9:00 AM and 4:00-6:15 PM) turn counts were conducted for this 1998 SEIR in late October 1997 at the Hillside Boulevard, Hillside Boulevard Extension, and Sister Cities Boulevard intersections to be analyzed in this study. 143 ~ addition, counts from early December 1997 at the intersections within the Oyster Point interchange were obtained from the traffic study being conducted to analyze operation of the proposed hook ramps along Bayshore Boulevard. 144 142 The proposed Phase III development concept provides for two signalized intersections with Bayshore Boulevard (the northern and southern entrances) and a third unsignalized right-turn-in /right-turn-out entrance located farther north on Bayshore Boulevard. This 1998 SEIR analysis focuses on the two signalized intersections. 143 Conducted by Crane Transportation Group (EIR registered traffic engineer) for the 1998 SEIR. 144 Draft Route 101 /Bayshore Boulevard Hook Ramps PSR /PR Traffic Operations Analysis, op. cit. 166 N a' +.. k w Q3 r_ C a a ~ C u ~~ m o C `o ~ o°p 'c o o~~ .. a... c y v ~ m .~ anyanbngnd _ m y o f ~ °' ~ E= 4 a, ~ ~. ~ v ~ m v' ~ ~ CG C C i. a, ~ o m~ o~ m '~ 2 O o ~' a S ~ m n v, a, ~' > _ O ;7 Z G Cl. cOm O O o a v~ O o> .:a t ~a C O Q ~ z a m G. 0 :~ c ~~ ~ V ~ O ~---4 ~ O ~ ~ o ..`~ zoo ~p ~ o ~J .~ ~ y ~~ ~ ~- 3 e o y ~ r __ _ _ ~~~ _ - •- c O O C O O cQ O L (Q o~~ o f ~., ~..,u, o~ E LL O ct m m ~ oo a Q.m yOC oq o y ~ ~~ Q v°~m0 v°~OiW~ - r°p'O v S n _ 000 = o ~ a = - ~ anyanbngnp~"""` _ y ~ qc oaC ~ .~ ~Ey ~~c °p _ a~ O ~~m Zi.O o~ ~ma ~'~ tom z~ m _ r ~~ ~ V O~' 200 ~ ..1 o ... _ _ o ,.., a v -..:.., ~~ m- ~~o. ~a~ - ~ma LL .°oer ° r m `m oo z Qm Q N Q ~ ~ ~. O hmm0 inO~iW~ ton00 dl .O V J y t O C :.. O ~ :. V mJ i N r N C ~ . ~ C Q ~L C O Z m N Z y am ~ U .a Q ~^ a 0 C7 C O 0 n c R H m C (9 U m U 3 O 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE/R Existing AM peak hour counts are presented in Exhibit 4.4-3, while existing PM peak hour counts are presented in Exhibit 4.4-4. Exhibit 4.4-5 shows existing lane striping at each analyzed intersection. Existing Operating Conditions Intersection Operation Level of Service Methodology Signalized Intersections Signalized intersection operation is graded using two different scales. The first scale employs a grading system called Level of Service (LOS) which ranges from Level A (indicating uncongested flow and minimum delay to drivers) to Level F (indicating significant congestion and delay on most or all intersection approaches). The Level of Service scale also is associated with an average vehicle delay tabulation at each intersection. 145 The vehicle delay designation allows a more detailed examination of the impacts of a particular project. Greater detail regarding the LOS /delay relationship is provided in 7.5 Traffic Appendix. Unsignalized Intersections Unsignalized intersection operation also is typically graded using the Level of Service A through F scale. LOS ratings for all-way-stop intersections are determined using a methodology outlined in Circular 209, the 1994 Highway Capacity Manual (HCM). 146 Under this methodology, all-way-stop intersections receive one LOS designation reflecting operation of the entire intersection. Average vehicle delay values also are calculated. Intersections where only side streets are stop-sign-controlled also are evaluated using the LOS and delay scale methodology outlined in the HCM. However, unlike si~alized or all-way-stop analyses (where the LOS and delay designations pertain to the entire intersection), the analysis of side street stop-sign-control computes LOS and delay designations for stop-sign-controlled approaches or individual turn and through movements rather than for the entire intersection. Unsignalized intersection analysis methodologies are described in 7.5 Appendix. City LOS Standards The City of South San Francisco considers Level of Service D (LOS D) to be the poorest acceptable operation for signalized and all-way-stop intersections and LOSE to be the poorest acceptable operation for unsignalized intersection turn movements. Intersection Levels of Service All signalized intersections analyzed for this study currently are operating at acceptable levels during both the AM and PM commute peak traffic hours (see Exhibit 4.4-v7. All operations are either LOS $ or C except for the Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard intersection where AM peak hour operation is LOS D. At the all-way-stop southbound off- ramp /Bayshore Boulevard intersection, operation is acceptable during both commute time periods (LOS D during the AM peak hour and LOS B during the PM peak hour). 145 1994 Highway Capaciry,~f,~sual (HCM) operations method. 146 Ibid., Circular 209, Transportation Research Board. 168 a a w W ~ m O ~~ ^ ~ ~~ m r r ~ ~/ '~ ~" ~ ~~ $ d ~ ~ ~ O °~ N n C ~ ~1 N o~ z ~' o t ~€ 0 0 0 o ~l ~ r ~ ~1~. r~ m * ~ I ~ ~n ~ ~ ~d ~ 4nO a mom ~ ~ c m _m N ~ ~n O 0 0 = ~ ~ ~ ~ ~ Z 0 m •_ ~ ~ ~• O O r ~ m ~~ r ~l~ re o ~ N .~ f ~. r ~ < -gym C Q1 O O O ~ ` r U y m y H ~ N ~ 1 • ~' t ~ ¢ ° -~ 0 °z ~~ w o m o t `~ de ~;aw N O 1 ~ N ~ . , ~ N a{ 0 ~ N W a = b l0 ~ v ~ 1O •- o ~ ~ ~ ~ ~ ~ (~ Q ~ ~ • T ~ ~ uosreyap ~ 1~ ° ~ b egi ° ~ ~ N a a L m -~- m _ \ yam/ ~ N N ~~ ~n i~ ~ ~ o_ ~a~ G 7 O C7 C O r N C m U m U 7 O a .~ t W ~-- o ~_ F m s{ ~~ ~G E A ~ D~d O ~ ~-~ N o -. m m t~ t~ o~ mo o m ~~ ~ ~~ o ~~ o Z ~ 1 4 r~ ~l~ r~ 2 ~ I ~ ~ .~' ~ ~~ an nyno m 0 0 ~~ N E ,~ ~ 0 r ~ ~ F ~ 2 ~ f- m c ---- a ~ e y m o E t ~' O m N O ~ ~ m E- W .~1~. r~ ,~ ~ ~ a .~ f ~. O -gym M ~ ~ N N ~ 0 ~ ~ U ~ ~~ o°~ y m y ~y t y o 1 o Q `e c ~ o ~ m ~- Na a0e O ~ o ~\\\5` O ~ N '~ 1 ~• ~ H m W 0 ~ a ~- °~ _ ,~ "~ Vj N ~ ~ ~'~ N am ~l~ r~ O ~~ N 117 O v \ 0 yam/ ~ m N ~O ~~ ~ ~ N f0 O G h 0 o ,~ N a 0 C7 c 0 r N H m C U m U O ~i a Z W a ~~ ~ ~ ~ ~ ~- m ~ ~, , ~~ C q ~ -0 , 1 a~ c~ a z~ ° r~ y ~ ._ z ° o ~ a en o E o= o y ~.` ~ ~ '••~ r~~°° ~ C~ ?.Qy tgOW W~ ' y~~~~ ~~ ~' ICI f -~ PM8 a~oy E8 ~ , -- 41 -~ m U m y ~Na ~`\\5`d0 ~ ~l~ ° tf~ m w m y m m ~, ¢ ~ ~ ~ ~ ~ uosia}{a~ ~ i F~ v \ .r `may/ ~~ ~~ 'Cn .~ (~ ~~ o m t~ z ~ 2O a - c y o E ra o= ~, o C CA _ ~, QQ O C/~ V] ~~ ~~L L ~L Z O Z a 0 C7 c 0 m r 0 a y C m C U m U 7 O 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SEIR Exhibit 4.46 Intersection Levels of Service Year 2000 Year 2010 -- Existing Base Case With Project phase I/ With Project Phase !ll With Project Phase l/+lll Base Case With project phase 11 With Project Phase Il! Wifh Project Phase l/+I!/ AM Peak Hour Hillside /Chestnut B-14.7° C-19.0 C-21.7 C-20.0 C-23.4 D-37.1 D-38.9 D-38.8 E-39.5 Hillside /Jefferson B-6.5° B-9.1 B-9.3 B-9.5 B-9.6 C-17.4 C-19.5 C-19.7 C-21.6 Hillside /Sister Cities B-8.8° B-10.8 B-11.1 B-11.4 B-11.9 C-16.4 C-17.7 C-18.7 C-20.4 Bayshore /Sister Cities / O ster Point / ~ rt D-28.3° C-23.1 C-24.8 C-22S D-23.7 E-42.6 E-45.9 D-32.3 D-39.2 Oster Point /Dubu ue B-14.0° C-17.1 C-17.5 C-16.6 C-16.9 E-44.9 E-49.2 D-38.5 D-39.5 Dubu ue/US 101 Rams B-9.2° B-14.3 B-14.7 B-10.1 B-I1.5 C-21.9 C-23.6 C-15.2 C-16.5 Bayshore / SB US 101 Off-Ram (All-Wav-Sto ) D-20.6" A-4.8 B-5.2 NA NA B-7.0 B-7.5 NA NA Sister Cities /Phase II Access NA NA B-7.9 NA B-8.0 NA B-I 1.7 NA B-12.8 Bayshore /Phase III North Access NA NA NA B-9.4 B-9.6 NA NA B-12.2 B-12.3 Bayshore / SB On-0ff Hook Rarn s NA NA NA B-11.9 B-12.0 NA NA C-19.6 C-19.7 Bayshore/ Phase III South Access NA NA NA B-8.4 B-10.4 NA NA B-8.8 B-11.4 PM Peak Hour Hillside /Chestnut B-9.2 ° B-11.6 B-14.0 B-12.4 C-15.2 B-14.8 C-16.1 C-16.1 C-20.0 Hillside /Jefferson B-5.6 ° B-6.9 B-7.0 B-7.2 B-7.3 B-13.2 B-13.9 C-15.4 C-19.6 Hillside /Sister Cities B-6.8 ° B-7.2 B-7.4 B-7.4 B-7.6 B-9.6 B-10.4 B-10.2 B-11.3 Bayshore /Sister Cities / ster Point / ~ ort C-18.6 ° C-19.0 C-21.2 C-25.0 D-24.3 D-35.6 E-42.2 F` F` Oster Point /Dubu ue C-16.5 ° C-20.4 C-21.2 C-22.4 C-24.9 D-36.8 E-44.4 F` F` Dubu ue / US 101 Rams B-8.4 ° B-11.4 B-12.4 B-10.6 B-11.4 D-34.9 D-35.8 C-18.9 C-22.9 Bayshore / SB US 101 Off-Ram (All-Wa -Sto ) g_9.2 s B-8.6 C-11.0 NA NA D-28.2 E-36.2 NA A Sister Cities / Phase II Access NA NA B-11.2 NA B-12.8 NA C-17.5 NA C-21.3 Bayshore /Phase III North Access NA NA NA B-8.5 B-9.7 NA NA B-9.1 B-9.7 Bayshore / SB On-0ff Hook Ram s NA NA NA C-13.5 C-16.0 NA NA D-29.0 D-35.8 Bayshore /Phase III South Access NA NA NA B-6.9 B-8.6 NA NA B-10.2 B-11.8 Source: Crane Transportation Group a Signalized Level of Service -Average Vehicle Delay (in seconds). b All-Way-Stop Levei of Service -Average Vehicle Delay (in seconds). c F =Delay greatcr than 60 seconds. Specific delay measttrements not provided by software for LOS F operation. terrabay\traffickt-4-6.doc 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SEIR Existing Signalization Requirements Traffic signals are used to provide an orderly flow of traffic through an intersection. Many times they aze needed to offer side street traffic an opportunity to access a major road where high volumes and / or high vehicle speeds block crossing or turn movements. However, they do not increase the capacity of an intersection (increase the intersection's overall ability to accommodate additional vehicles) and, in fact, often slightly reduce the number of total vehicles which can pass through an intersection in a given period of time. Signals also can cause an increase in traffic accidents if installed at inappropriate locations. There are 11 possible tests for determining whether a traffic signal should be considered for installation. These tests (called "warrants") consider criteria such as actual traffic volume, pedestrian volume, presence of school children, and accident history. Two or more warrants usually must be met before a signal is installed. This 1998 SEIR applies the test for Peak Hour Volumes (Urban Warrant #11). When Warrant #11 is met, there is a strong indication that a detailed signal warrant analysis covering all possible warrants is appropriate. The Caltrans Traffic Manual describes these rigorous analyses, and Warrant #11 is presented in 7.5 Appendix. 147 A signal warrant analysis was performed at the Bayshore Boulevard ,( U.S. 101 southbound off-ramp intersection -- the one unsignalized study intersection in South San Francisco not programmed for immediate signalization. Based on Caltrans Warrant #11 criteria, the Bayshore Boulevard / U.S. 101 southbound off-ramp intersection has volume levels approaching signal warrant criteria levels during the AM peak traffic hour but not during the PM peak traffic hour. The planned south- to eastbound off-ramp flyover (to be in operation by 2000 148) should significantly reduce volumes on the southbound off-ramp connection to Bayshore Boulevazd. Volumes then will be well below wan ant criteria levels at this location. Existing Freeway Operation AM and PM peak period counts of the U.S. 101 freeway at the Oyster Point interchange overpass were conducted for this 1998 SEIR in late October 1997. 149 Exhibits 4.4-3 and 4.4-4 present existing AM and PM peak hour volumes, respectively. Exhibit 4.4-2 shows the freeway segments analyzed for this study while Exhibit 4.4-7 shows that existing (Fall 1997) AM peak hour operation along the U.S. 101 freeway in the vicinity of the Terrabay site primarily is LOS E or F for southbound traffic flow and LOS D or E for northbound traffic flow. Exhibit 4.4-7 also shows that existing PM peak hour southbound operation primarily is LOS D, northbound operation primarily is LOS E, and one segment is LOS F. Levels of service were determined using procedures described by the HCM and assuming a free-flow speed of 65 miles per hour. 15o LOS E operation is the minimum acceptable condition for peak hour operation of U.S. 101 in South San Francisco set by the City /County Association of 147 Caltrans Traffic Manual, Chapter 9. 148 See Planned Transportation Improvements, below. 149 Crane Transportation Group, op. cit. 150 1994 Highway Capacity Manual, op. cit., Chapter 3. 173 Exhibit 4.47 U.S 101 Freeway Levels of Service ~ ~ Year 2000 Year 2010 US 101 Freeway ~ Existing With With With Base Case Base Case Base Case Segment Base Project Project Project Base + Project + Protect + Project Case Case phase /l Phase Ill Phase /I-!ll Phase 11 Phase !l1 Phase IHllI AM Peak Hour North ofSBOff-Ramp& ° NB Flyovct Off-Ramp to F/E F/E F/E F/E F/E F/F F/F F/F , F/F Bayshore , From Oyst,°r Point NB On- RamptoBayshoreNB E/E° F/E F/F F/F F/F F/F F/F F/F F/F Off-Ramp Ac the Oyster Point Overpass E/D° E/E E/E E/E E/E F/E F/E F/E F/E From Oyster Point Interchange to Grand Ave F/ E° F/ E F/ E F/ E F/ E F/ F F/ F F/ F F/ F Interchange PM Peak Hour North ofSBOff-Ramp Bt ° NB Flyover Off-Ramp to D/E E/F E/F E/F E/F F/F F/F F/F F/F Bayshore FromOyserPointNBOn- Ramp to Ba}5hore NB D/F° D/F D/F D/F D/F E/F E/F E/F E/F Off-Ramp At the Oysxr Point Overpass D/E° D/E D/E D/E D/E E/F E/F E/F E/F From Oyster Point ° Interchange to Grand Ave E/E E/F E/F F/F - F/F F/F F/F F/F F/F Interchange Source: Crane Transportation Group; Special Report 209, Transportation Research Board, 1994 Highwm• Capacin~ :Kanual Analysis Methodology. Freevs~ay Level of Service -- Southbound /Northbound. 4.4 TRAFFIC AND CIRCULATION Terrabay Phase 11 and !Il SEIR Governments. Segments with theoretically predicted LOS F operation were observed to have vehicle speeds ranging from 35 to 45 miles per hour. Also, locations with LOS F operation had volume levels just past the LOS E / F breakpoint. Existing Ramp Operation Based on the methodology contained in Circular 209 of the HCM, ramp capacities have been set at 2,100 vehicles per hour for diamond (slip) ramps and 1,900 vehicles per hour for any ramps with sharp curves (such as the southbound buttonhook ramps proposed to connect to Bayshore Boulevard). These capacities reflect LOS E operation, the same service level which is acceptable for freeway operation. Exhibit 4.4-2 shows the various freeway ramps analyzed for this study. Exhibit 4.4-8 shows that all ramps at the Oyster Point interchange currently are operating under capacity during both AM and PM peak traffic hours. However, traffic on the southbound off-ramp connection to Bayshore Boulevard occasionally backs up to the freeway mainline during the morning commute period. The AM peak hour LOS D (minimum acceptable) operation of the southbound off-ramp all-way-stop intersection with Bayshore Boulevard reflects the potential for occasional extended backups on the off-ramp approach. Existing Transit Service Local Bus Routes Bus transit service is provided to the project area by the San Mateo County Transit District (SamTrans). Exhibit 4.4-9 describes SamTrans routes serving the project site vicinity. Routes 7B and 24B travel along Bayshore Boulevard adjacent to the eastern site boundary, and Route 26H travels along the Hillside Boulevard Extension west of Jefferson Street, along Jefferson Street, and through the residential neighborhood south of Hillside Boulevazd. Route 26H also provides service from the vicinity of the Terrabay Phase I and II sites to the Colma BART station and to the Caltrain station. Route 7B provides service between the South San Francisco Caltrain station and the Terrabay Phase III site. Exhibit 449 Local SamTrans Bus Route Descriptions Route a Description ST 24B Local service along Bayshore Boulevard and Airport Boulevard between Daly City (Cow Palace), Brisbane, South San Francisco, and [he Tanforan Shopping Center. ST 7B Regional service along Bayshore Boulevard and Airport Boulevazd between downtown San Francisco (Transbay Terminal) and Redwood City. ST 26H Local service between the Tanforan and Serraznonte Shopping Centers along Mission Road, Hillside Boulevard, Hillside Boulevard Extension, Jefferson Street, Hemlock Street, and Linden Avenue. Source: Crane Transportation Group, SamTrans. a All three bus routes pass within 500 feet of the South San Francisco Caltrain Station. Route 26H also serves the Colma BART station. SamTrans service also provides and accepts inter-agency transfer passes to and from Santa Clara County Transit at shared bus stops, San Francisco Municipal Railway routes at selected points, and AC Transit routes at shared bus stops in Alameda, San Mateo, and Santa Clara counties. 175 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE1R Exhibit 4.48 Existing and Base Case Freeway Ramp Operation AM and (PM) a Peak Hour, Without and With Project Existing Base Case Base Case + Phase U Base Case + Phase l/l Base Case + Phase P~oiect Froject ll-ll Protect US 101 Capacity Ramp n Volume Under/Over Volume Under/Over ' Volume Under/Over Volume Under/Over Ca aci Ca ac Ca aci Ca aci Year 2000 SB Off- x,100 795 283 Under 295 Under NA ~ NA ~ NA ` NA ` Ramp to (535) (424) (Under) (494) (Under) Bayshore NB On- 2,100 9?5 1,156 Under ' 1,221 Under 1,2?5 Under 1,290 Under Ramp (2,600)° (1,130) (1,506) (Under) (495) (Under) (1,631) (Under) (1,656) (Under) from Oyster Point NB Off- 2,100 740 1,065 Under 1,221 Under 1,183 Under 1,199 Under Ramp to (490) (760) (Under) (1,531) (Under) (912) (Under) (994) (Under) Dubu ue SB On- 2,100 800 1,090 Under 1,071 Under 814 Under 894 Under Ramp (2,600)° (1,215) (1,747) (Under) (842) (Under) (1,498) (Under) (1,530) (Under) ftom Dubu ue SB On- 1,900 NA ` NA ` NA ` NA ` NA ` 345 Under 345 Under Ramp (416) (Linder) (416) (Under) from Bayshore (Phase III) SB Off- NA ` NA ` NA ` NA ` NA ` NA ` 400 Under 412 Under Ramp to (503) (fi)nder) (573) (Under) Bayshore I (Phase IID SB toEB 2,100 NA` 865 Under 865 Under 865 Under 865 Under Flyover - (445) (Under) (445) (Under) (445) (Under) (445) (Under) Off-Ram i Year 2010 SB Off- 2,100 795 333 Under 345 Under NA NA NA NA Ramp to (535) (659) (Under) (729) (Under) I Ba shore NB On- 2,100 925 1,589 Under 1,654 Under 1,653 Under 1,718 Under Ramp (2,600) (1,130) (2,191) (Over) (2,216) (Over) (?,316) (Over) (2,341) (Over) from Oyster Point NB Off- 2,100 740 1,520 Under 1,536 Under 1,648 Under 1,664 Under Ramp to (490) (1,240) (Under) (1,322) (Under) (1,396) (Linder) (1,478) (Under) Dubu ue SB On- 2,100 800 1,485 Under 1,565 Under 1,117 Under 1,203 Under Ramp (2,600)° (1,215) (2,402) (Over) (2,434) (Over) (2,036) (Under) (2,068) (Under) from Dubu ue SB On- 1,900 NA ` NA ` NA ` NA ` NA ` 445 Under 445 Under Ramp (563) (Under) (563) (Under) firom Bayshote (Phase IIn SB Off- NA ` NA ` NA ` NA ` NA ` NA ` 493 Under 502 Under Ramp to (810) Nnder) (880) (Under) Bayshore (Phase III) ~ 2'100 NA` 1,300 Under 1,300 Under 1,300 Under 1,300 Under Flyove (810) (Under) (810) (Under) (810) (Under) (810) (Under) Off-Ram Source: Crane Transportation Group; Special Report 209, Ttanspottation Research Board; 1994 Highx•ay Capacity Manual. a # = AM peak hour; (#) = PM peak hour. b Passenger car equivalents. Existing and base case volumes should be increased by about five percent to reflect truck traffic impact and conversion to passenger car equivalents. c NA =Not Applicable. tetrabay\traffic\4-4-8.doc 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 1!l SE1R BART BART currently does not directly serve the San Francisco Peninsula. The southern terminus of BART currently is located in Colma adjacent to El Camino Real. Caltrain The South San Francisco Caltrain station is located on Dubuque Avenue just north of Grand Avenue. Service is provided seven days a week and connects San Francisco and Gilroy. Forty-four trains per day currently stop at the South San Francisco station. Planned Transportation System Improvements Hickey Boulevard Extension ''' The proposed Hickey Boulevard Extension will extend from El Camino Real east to Hillside Boulevard. The segment of the extension between El Camino Real and Mission Road will be constructed by the BART District as part of the new Hickey Boulevard station improvements, and San Mateo County will construct the segment between Mission Road and Hillside Boulevard, potentially about one to two years after completion of the El Camino Real to Mission segment. The extension design includes four lanes with separate turn lanes at intersections. Signalized intersections will be provided at Hillside Boulevard, Mission Road, and El Camino Real. The City of South San Francisco portion of the Hickey Boulevard Extension was included in the City's 1992 capital improvement program and is expected to be constructed before the year 2002. The County's portion will be constructed after the City's portion is complete. u2 Oyster Point Interchange Construction The final phase of improvements at this interchange is scheduled to begin in mid-1998. A southbound off-ramp flyover will be built to bridge the interchange area and Caltrain railroad tracks and come to grade as the fifth leg of the Oyster Point Boulevard /Gateway Boulevard intersection. The flyover off-ramp will diverge from the freeway just south of the existing off-ramp which connects to Bayshore Boulevard. Completion is scheduled by mid-2000. Hillside Boulevard /Chestnut Avenue Intersection Signal's A signal was installed and began operation in May 1998 at the Hillside Boulevard /Chestnut Avenue intersection. No other roadway improvements are programmed and funded by the City of South San Francisco in the immediate vicinity of the Terrabay project site. Likewise, no improvements are planned or funded by Caltrans for the U.S. 101 freeway between the San Francisco city limits and I-380. 154 151 Crane Transportation Group conversation with Richard Harmon, City of South San Francisco Public Works Department. 152 Ibid. 153 Ibid. 177 4.4 TRAFFIC A,^JD CIRCULATION Terrabay Phase ll and 111 SEIR Chestnut Avenue Widening '~ Chestnut Avenue will be widened to west of Hillside Boulevard, starting in late 1998 or early 1999, to four full lanes with left- and right-turn lanes at select intersections. BART Extension Plans BART is planned to be extended from its current terminus at the Colma Station to the San Francisco International Airport and Millbrae by 2001 or 2002. A station will be constructed in South San Francisco as part of the BART extension (referred to as the Hickey Station) to be located between El Camino Real and Mission Road south of the new Hickey Boulevard Extension. The projected 2010 daily ridership at the Hickey Station is 8,000. Base Case (Without Project) Traffic Analysis The following discussion presents anticipated impacts on the local transportation system due to non- project "Base Case" growth in traffic expected in the site vicinity by the years 2000 and 2010. Base Case Traffic Projections Future traffic projections contained in the Draft Route 101 / Bayshore Boulevard Hook Ramps PSR / PR Traffic Operations Analysis were used as a starting point to determine year 2000 and 2010 Base Case AM and PM peak hour volumes (without project) at all of the intersections which R~ere analyzed for the project (Terrabay Phase II + II1). 156 The PSR / PR study examined full development of all properties in the East of 101 Area and in the City of Brisbane. The Brisbane projections were based on the most intense growth scenario contained in the 1994 Brisbane General Plan (Scenario K). The East of 101 projections were based upon asite-by-site evaluation of maximum development potential for remaining vacant or partially developed parcels in the area. City planning staff input was used for this evaluation. The PSR / PR study also included full buildout of the Terrabay project. However, for Base Case, Terrabay Phase II and III traffic was removed from the PSR / PR volume projections. In addition to the developments considered in the PSR / PR analysis, traffic from the folloR-ing projects was also included in the future projections analyzed in this 1998 SEIR: • Remaining Terrabay Phase l development which includes 62 single-family detached and 94 single-family attached (townhouse) units. Traffic associated with ongoing construction activity at the Phase I site was observed during counts at the Phase I entrance and was removed from the system during formulation of the final traffic projections. • E/ Camino Corridor Redevelopment Project which includes the proposed Hickey BART Station and the Hickey Boulevard Extension. 157 Although the City currently is considering some changes to this plan, land uses evaluated in the EIR on the redevelopment project produce a conservatively high level of expected traffic on the local roadway system. This study was used as 154 Crane Transportation Group conversation with Caltrans District 4 staff. 155 Crane Transportation Group conversation with Richard Harmon, op. cit. 156 Draft Route 101 / Bayshore Boulevard Hook Ramps PSR / PR Tra,~c Operations Analysis, op. cit. 157 EI Camino Corridor Redevelopment Project EIR, Wagstaff & Associates, January 1993. 178 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE/R a starting point to determine year 2000 and 2010 Base Case PM peak hour volumes at all intersections analyzed along the Hillside Boulevard comdor. • Chestnut Estates where 80 single-family uniu currently aze under construction. • Heather Heights where 34 single-family uniu currently are under construction. • Summerhiil Homes Subdivision where 160 single-family units are proposed. • Background Growth of one percent per year in ambient traffic flow along Hillside Boulevard between Daly City and the Oyster Point interchange. The City of South San Francisco Planning Department made projections about the developments in the East of 101 Area likely to be built by the years 2000 and 2010. Assumptions also were made for proposed development in Brisbane which consen~atively assumed that all development expected by 2004 (the Brisbane General Plan ten-year horizon growth estimate) would occur by the year 2000 while all remaining expected development would occur by the year 2010. In addition, the Chestnut Estates, Heather Heights, and Terrabay Phase I projects were all assumed to be completed and fully occupied by the year 2000, as was about 25 percent of the development potential in the El Camino Corridor Redevelopment Area. However, neither the BART station along El Camino Real nor the Hickey Boulevard extension was assumed to be in operation by 2000. About one-quarter of the traffic growth on Hillside Boulevazd due to development west of the Terrabay site was assumed to be related (the other end of the trip) to the East of U.S. 101 Area and Brisbane development projections. Finally, no significant diversion of commute period traffic from the U.S. 101 freeway to Bayshore Boulevard was assumed in the Terrabay analysis for this 1998 SEIR. However, the potential exists that, should peak direction commute volumes reach excessive levels, some diversion may take place. Exhibit 7.5-1 in the Appendix presents the trip generation of the remaining Terrabay Phase I units to, be built. Exhibits 7.5-2 and 7.5-3 in the Appendix present the development increments expected in the East of 101 Area and Brisbane by the years 2000 and 2010, respectively, along with the projected AM and PM peak hour trip generation from each development component. Exhibits 7.5-4 and 7.5-5 in the Appendix present Base Case AM and PM peak hour volumes, respectively, for the year 2000, while Exhibits 7.~-6 and 7.5-7 in the Appendix present Base Case AM and PM peak hour volumes, respectively, for the year 2010. Base Case Roadway System Exhibit 4.4-5 presents the intersection geometries assumed for both yeaz 2000 and 2010 Base Case analyses. The U.S. 101 southbound to east of 101 flyover off-ramp was assumed to be in operation by the yeas 2000 based upon the current construction schedule. Base Case Circulation System Operating Conditions Year 2000 Base Case Intersection Level of Service All major intersections along Hillside Boulevard, Hillside Boulevard Extension, Sister Cities Boulevard, and at the Oyster Point interchange R•ere evaluated to determine Base Case operating conditions during the AM and PM commute peak traffic hours. Existing geometries and intersection control were assumed to remain in place at each location. 1 "'9 4.4 TRAFFIC AND CIRCULATION Terrabay Phase lI and 111 SEIR All analyzed intersections would be expected to operate acceptably during the AM and PM peak traffic hours-see Exhibit 4.4-6. Base Case Signalization Requirements No unsignalized intersection would have volumes exceeding peak hour signal warrant criteria levels. Base Case Freeway Operation During the AM peak traffic hour, northbound traffic on all segments of the U.S. 101 freeway would be operating at minimum acceptable levels of service (LOS E) while in the southbound direction all but one segment would be operating unacceptably (LOS F). During the PM peak traffic hour, all southbound freeway segments would be operating acceptably (LOS D or E) while northbound traffic on all but one segment would be operating unacceptably (LOS F) -see Exhibit 4.4-7. Base Case Freeway Ramp Operation AM and PM peak hour volume levels of all five freeway ramps at the Oyster Point interchange (northbound on-, northbound off-, southbound on- from Dubuque Avenue, southbound to eastbound (flyover) off-, and the southbound off-ramp to Bayshore Boulevard) would be well under capacity in the year 2000. The reduced volumes on the southbound off-ramp connection to Bayshore Boulevard should preclude backups to the freeway mainline -see Exhibit 4.4-8. Year 2010 Base Case Intersection Leve! of Service Two intersections would be expected to experience unacceptable operations by the year 2010 during the AM peak hour, with no unacceptable operation expected during the PM peak traffic hour. The signalized Bayshore Boulevazd /Sister Cities Boulevard /Oyster Point Boulevard /Airport Boulevard Intersection would operate at LOS E during the AM peak hour in year 2010 without the project. Also The signalized Oyster Point Boulevard / Dubuque Avenue /U.S. 101 Northbound On-Ramp Intersection would operate at LOS E during the AM peak hour in yeaz 2010 without the project-see Exhibit 4.4-6. Base Case Signalization Requirements Volumes at the U.S. 101 Freeway Southbound Off-Ramp /Northbound Bayshore Boulevazd All-Way- Stop Intersection would exceed signal Warrant #11 criteria levels during PM peak hour conditions by year 2010 without the project. Base Case Freeway Operation Most U.S. 101 freeway segments would experience unacceptable LOS F operation during the AM and PM peak traffic hours including all southbound segments in the AM peak and all southbound segments except the Dubuque southbound on-ramp PM peak and all northbound segments in the PM peak hour and all northbound segments except at the Oyster Point Boulevard underpass during the AM peak hour -see Exhibit 4.4-7. Base Case Freeway Ramp Operation During the AM peak traif c hour, no freeway ramps would operate over capacity ,see Exhibit 4.4-8 iso 4.4 TRAFFIC AND CIRC~_AT10N Terrabay Phase !l and !!l SE/R During the PM peak hour, two tamps at the Oyster Point interchange (northbound on- from Oyster Point Boulevard and southbound on- from Dubuque Avenue) would have volume levels greater than each ramp's maximum theoretical capacity. This assumes both ramps maintain their single lane connections to recently constructed auxiliary lanes leading to downstream off-ramps. In addition, while the southbound off-ramp connection to Bayshore Boulevard would have volume leveL~ well within the range of acceptable capacity, the off-ramp intersection with northbound Ba~-shore Boulevard would be operating at a minimally acceptable PM peak hour LOS D with existing aeometrics and all-way-stop operation. Volumes would be above signal warrant criteria levels at this location, and it would be expected that off-ramp traffic would occasionally back up to the southbound freeway mainline (see Base Case Signali~tion Requirements, above). Recommended Mitigation for Existing and Base Case Conditions Sleasures listed below are those which could be employed by the City and / or other responsible agencies. They are needed with or without development of Terrabay Phase II or III. Existing Conditions Freeway Mainline Additional through lanes should be provided on the U.S. 101 freeway in the project area, which in the near term is impractical given funding and right-of--way limitations. Alternatively, signincant increases in area transit and local area business transportation demand management (TDM) measures should be implemented to reduce existing peak hour volumes. Also, future local area development should be reduced substantially to preclude any major increases in traffic on the local fr:~way network. While these measures would be capable of reducing existing operation to an acceptable level, it is extremely unlikely that these measures could be implemented to mitigate the impact As previously detailed, Caltrans currently has no plans or funding for widening the U.S. 101 freeway in the project area. Base Case Conditions Year 2000 Freeway Mainline Please see measures listed above for Existing Conditions, Freeway Mainline. Year 2010 Intersection Widening (see Exhibits 4.4-10 and 7.5-8) • Bayshore Boulevard /Sister Cities Boulevard /Oyster Point Boulevard /Airport Boulevard Provide an exclusive right-tum lane on the westbound (Oyster Point Boulevard) intersection approaches. This measure would require widening of the Oyster Point Boulevard freeway overpass. This measure would result in acceptable AM peak hour LOS D operation. • Oyster Point Boulevard /Dubuque Avenue / U.S. 101 N.B. On-Ramp ist 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and l/1 SEIR Provide a second exclusive right turn lane on the westbound (Oyster Point Boulevard) approach and a second left turn lane on the northbound (Dubuque Avenue) intersection approach. These measures would result in acceptable AM peak hour LOS D operation. Intersection Signalization (see Exhibit 4.4-10) • U.S. 101 Southbound Off-Ramp /Northbound Bayshore Boulevard All-Way Stop The intersection should be signalized when warranted. Also, provision of a second off-ramp approach and departure lane should be considered. These measures would result in LOS C PM peak hour operation with one off-ramp lane and LOS B with two off-ramp lanes, thus providing acceptable operation. Exhibif 4.410 Mitigated Intersection Level of Service -Year 2010 Base Case + Base Case + Base Case+Project Intersection Base Case Project Phase li Project Phase 111 Phases 11-!ll A M PM AM PM AM ~ PM AM PM Bayshore /Sister Cities D-38.5° NA D-39.2° D-31.2° NA I D-27.4` NA D-33.4° / Ai ort / O ster Point O ster Point / Dubu ue D-37.0° NA D-39.8° D-28.Sd NA ~ D-34.0° NA D-29.6° Bayshore / US 101 SB C-19.34` C-24.4` Off-Ramp NA B-8.1 ~ NA B-8.C~ NA NA NA NA D-24.1° D-29.4a I Source: Crane Transportation Group a Mitigated with exclusive right turn lane on the westbound (Oyster Point Boulevard) intersection approach. b Mitigated with exclusive right turn lanes on the eastbound (Sister Cities) and westbound (Oyster Point Boulevard) intersection approaches and restriping the southbound (Bayshore Boulevard) approach (to provide an exclusive right, a shared through / right, an exclusive through, and two left turn lanes). c Mitigated with an exclusive right tum lane on the westbound (Oyster Point Boulevard j intersection approach and restriping the southbound (Bayshore Boulevard) approach (to provide an exclusive rift, a shared through /right, an exclusive through, and two left turn lanes). d Mitigated with a second exclusive left turn lane on the northbound (Dubuque Avenu: j intersection approach. e Mitigated with Signalization and one off-ramp lane. f Mitigated with Signalization and two off-ramp lanes. g Mitigated with a second off-ramp lane -- maintain all-way stop. Freeway Mainline Please see measures listed on the previous page for Exiting Conditions, Freeway Mainline. Ramps (see Exhibit 7.5-8 in the Appendix) • Northbound On-Ramp From Oyster Point Boulevard /Dubuque Avenue Intersection Provide a second on-ramp lane connection to the U.S. 101 freeway. The second (new) lane would connect directly to the freeway mainline, adjacent to the existing on-ramp lane which would extend (as it does today) as an auxiliary lane to the next downstream off-ramp. Alternatively, future local area development should be reduced, or transit and TDM measures should be increased in order to maintain peak hour volumes below ramp capacity limits. Implementation of either measure would reduce the impact on the Oyster Point Boulevard northbound on-ramp to a level of insignificance. With an additional lane, volumes would be well under acceptable capacity. However, Caltrans approval is needed for this measure. It is not known if transit / TDM measures and / or reduced development 182 4.4 TRAFFIC AND CIRCULr1TlON Terrabay Phase ll and Ill SEIR would maintain volumes at acceptable levels. With no Caltl°ans approval for a second on-ramp and limited volume reduction through transit / TDM measures, this impact would remain significant and unmitigable. • Southbound On-Ramp From Dubuque Avenue Provide a second on-ramp lane connecting to the U.S. 101 freeway. The second (new) lane would connect directly to the freeway mainline, adjacent to the existing on-ramp lane which would extent (as it does today) as an auxiliary lane to the next downstream off-ramp. Alternatively, reduce local area development or increase transit and TDM measures to reduce peak hour volumes below existing ramp capacity. With an additional lane, volumes would be well under acceptable capacity, and the impact would be reduced to a level of insignificance. With an addition lane, volumes would be well under acceptable capacity. However, Caltrans approval would be needed for this measure. It is unknown if transit / TDM measures and / or reduced development would maintain volumes at acceptable levels. With no Caltrans approval for a second on-ramp and limited volume reduction through transit / TDM measures, this impact would remain significant and unmitigable. TERRABAY PHASE 11 + 111 PROJECT IMPACTS AND MITIGATION MEASURES Significance Criteria This 1998 SEIR used the following criteria to evaluate the significance of identified transportation impacts: • If a signalized or all-way-stop intersection with Base Case (without project) volumes is operating at LOS A, B, C, or D and deteriorated to LOS E operation (or worse) with the addition of project traffic, the impact is considered to be significant and would require mitigation. If a Base Case stop sign-controlled turn movement deteriorated to LOS F operation with the addition of project traffic, the impact is considered to be significant and would require mitigation. • If the Base Case LOS at a signalized or all-way-stop intersection is already at LOS E or F, or the Base Case LOS of a stop sign-controlled turn movement is akeady LOS F, an increase in traffic of one percent or more due to the project is considered to be significant and would require mitigation. • If traffic volume levels at a Base Case unsignalized intersection increased above Caltrans Peak Hour Warrant #11 criteria levels with the addition of project traffic, the impact is considered to be significant and would require mitigation. • If traffic volume levels at a Base Case unsignalized intersection already exceed signal warrant criteria levels, an increase in traffic of one percent or more due to the project is considered to be significant and would require mitigation. • If, in the opinion of the EIR registered traffic engineer, certain project-related traffic changes would increase safety concerns substantially or fail to comply with City code and Americans with Disabilities Act (ADA) requirements, the impact is considered to be significant and would require mitigation. Safety concerns would include maintenance of unobstructed sidewalks and travelways. (That is, no overflow parking should be allowed to occur in "no parking" zones, and vehicles parked in driveways should not intrude into sidewalks or travelways even partially.) 183 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SEJR • If freeway mainline or ramp operation with Base Case volumes is currently at LOS A, B, C, D, or E and changed to LOS F with the addition of project traffic, the impact is considered significant and would require mitigation. • If freeway mainline or ramp operation with Base Case volumes is already LOS F, an increase in peak direction traffic of one percent or more due to the project is considered significant and would require mitigation. • If proposed on-site circulation or parking is deficient based upon city code requirements or in the opinion of the registered traffic engineer conducting this study, the impact is considered to be significant and would require mitigation. • If proposed storage distance between new signalized intersections is potentially inadequate to accommodate the expected demand of traffic, the impact is considered significant and would require mitigation. Terrabay Phase ll + 111 Impacts (Year 2000 and 2010) The impacts of traffic generated by the proposed Terrabay Phase II and III project components are discussed below. For the yeaz 2000 analysis, in addition to impacts for the entire Phase II + III Terrabay development ("the project"), impacts also were determined with the addition of Terrabay Phase II traffic only and Phase III traffic only. For the 2010 horizon, the impact analysis also was conducted for the same three Terrabay development scenarios. Results of the Phase II + III analysis are presented in the main body of this 1998 SEIR while Phase II only and Phase III only analysis results aze presented in Appendix 7.5. It should be noted that off-site Terrabay impacts have been evaluated for this 1998 SEIR in the context of maximum buildout potentials for the City of Brisbane and the East of 101 Area in South San Francisco. If certain identified projects in Brisbane and South San Francisco, as well as other nearby communities, do not occur at particular ident~ed levels or particular ident~ed buildout rates, then Terrabay impacts identified in this study as significant may, in reality, be insignificant. In such cases, a lesser mitigation may be required. Alternatively, no mitigation may be required. Overall, Terrabay Phase II + III development would produce significant off-site impacts by the year 2000 along a few segments of the U.S. 101 freeway, primarily by increasing traffic levels by more than one percent on segments of the freeway network already projected to be operating at unacceptable levels. By year 2010, the proposed • development would produce significant impacts at two intersections within the Oyster Point interchange (Bayshore Boulevard /Sister Cities Boulevazd / Oyster Point Boulevazd /Airport Boulevard and Oyster Point Boulevazd /Dubuque Avenue), at one freeway ramp (the northbound on-ramp from Oyster Point Boulevazd), and along various segments of the U.S. 101 freeway (primarily by increasing traffic levels by more than one percent on segments of the freeway network already projected to be operating at unacceptable levels). On-site impacts would result due to less than desirable street widths in some azeas of the residential neighborhoods, substandard parking space dimensions in a few locations, the lack of overflow parking in the residential subareas, the lack of adequate parking on the Phase III commercial site, and the lack of trailhead parking on the Phase II and III sites. Required project off-site mitigation measures for the year 2000 would include reducing project development levels so as to preclude producing significant impacts on the U.S. 101 freeway and / or contributing funds towards regional circulation system improvements or transit expansion projects. Year 2010 off-site measures would be similar in nature to mitigate significant impacts on the U.S. 101 184 4.4 TRAFFIC AND CIRCULATION Terrabay Phase 11 and l11 SE/R freeway, but also would include added widening (additional approach lanes) at two intersections within the Oyster Point interchange and additional widening of the northbound on-ramp from Oyster Point Boulevard (or reducing project development levels to reduc: traffic increases on the on-ramp to less than significant levels). On-site mitigation measures would include select widening of some roadways in the residential neighborhoods, provision of extra parking in both the residential and commercial sites, and increasing the size of some proposed parking spaces. Terrabay Trip Generation Trip generation projections were developed for both Terrabay Phases II and III (see Exhibit 4.4-11). Base trip rates were derived from the 1997 ITE Trip Generation manual. 158 The 348 housing units proposed by the Phase II Precise Plan would be expected to generate about 90 inbound and 261 outbound trips during the morning commute traffic hour and 304 inbound and 168 outbound trips during the evening commute traffic hour. Project residential units were projected to have the potential for measurably higher than average trip generations based upon the proposed high number of bedrooms (4 to 5 per unit), the possibility of converting dens in some units to an additional bedroom, and the lack of frequent transit service within easy walking distance of the proposed units. After consultation with City public works staff, peak hour trip rates 30 percent above average were utilized for the four bedroom units in the Point & Commons subdivisions while peak hour trip rates 40 percent above average were utilized for the 4 and 5 bedroom unit mix in the Woods subdivision. All Phase II traffic is assumed to access Sister Cities Boulevard via South San Francisco Drive, although a minor amount of traffic would also be expected to use the Phase I connection to the Hillside Boulevard Extension. Likewise, a small amount of Phase I traffic may use the Phase II entrance. Exhibit 4.411 Terrabay Project Trip Generation-Phases 1/ and 111 AM Peak Hour Tri PM Peak Hour Tri s Development Size Inbound Outbound ( Inbound Outbound Rafe Volume Rafe Volume ~ Rate Volume Rafe Volume Phase ll Residential Site Woods Sin le Famil Detached ° 135 units 0.27 ° 37 0.78 ° 105 0.91 ° 123 0.50 ° I 68 Point & Commons ~ I Sin le Famil .Attached 213 units 0.25 ° 53 0.73 156 0.85 ° 181 I 0.47 ° I 100 Subtotal 90 261 ~ 304 I 168 Phase 111 Commercial Sife Retail 16,000 sf 33 21 ! 90 98 Restaurants (2 each) ~ uali 12,000 sf 0.57 7 0.24 3 . 5.02 60 2.47 ~ 30 • High Turnover, Sit Down 12,000 sf 4.82 58 4.45 54 I 6S2 78 4.34 52 Office 23,000 sf 51 7 18 I 87 Hotel 600 rooms 0.39 234 0.28 168 i 035 210 0.36 216 Subtotal 383 253 i 456 I 483 Source: Crane Transportation Group and Trip Generation - 6th Edition, Institute of Ttans3+ertation F~gineers, 1997. a Trip rates 40 percent above average to reflect potential generation from miz of four- and five-bedroom units. b Trip rates 30 percent above average to reflect potential generation from four-bedroom twits. c Ln(T) _ .596 In(X) + 2329 (61 percent in / 39 percent out). in =natural log, T =trips. and =1,000 feet'. d Ia(T) _ .660 Ln(X) + 3.403 (48 percent in / 52 percent out). e In(T) _ .797 Ln(X) + 1.558 (88 percent in / 12 percent out). f T = 1.121(X) + 79.295 (17 percent in / 83 percent out). 158 Trip Generation, 6th Edi[ion, Institute of Transportation Engineer (I'I'E). 1997. 185 4.4 TRAF,~1C AND CIRCULATION Terrabay Phase ll and l!! SE/R The Phase III development program for office, four restaurants, 600 hotel rooms, and retail use would be expected to generate about 383 inbound and 253 outbound trips during the morning commute hour and about 456 inbound and 483 outbound trips during the evening commute traffic hour. It was projected that about five percent of the total AM and PM peak hour trip generation v~~ould remain within the site (trips back and forth between the hotel /restaurant /office /retail uses). It was also projected that about five percent of the total trips generated would be attracted from traffic already on Bayshore Boulevard (pass-by capture to the site's restaurant and retail uses). Phase III traffic would access the site from the west side of Bayshore Boulevard at three locations north of the Oyster Point interchange: • .~, right-turn-in and right-turn-out driveway at the north end of the site. • .3 signalized intersection about 710 feet (between centerlines) north of the new hook ramp intersection. • .-~ second signalized intersection between the hook ramps and Oyster Point Boulevard (about 600 feet south of the hook ramps intersection). Exhibit 4.4-I2 presents the lane striping assumed for analysis purposes at these new intersections along Bayshore Boulevard. The project would generate 32 percent fewer AM peak hour and 23 percent fewer PM peak hour trips than the development concept contained in the 1996 Terrabay Specific Plan and assessed in the 1996 Terrabay SEIR. Terrabay Trip Distribution Exhibits 7.5-9 and 7.5-IO in the Appendix present the estimated AM and PM commute hour inbound and outbound distribution of Phase II residential and Phase III commercial traffic, respectively. Distribution projections are based upon input from both the hook ramps PSR / PR traffic study and distribution patterns of Terrabay Phase I traffic. Exhibit 4.4-13 presents the sum of year 2000 Base Case plus Terrabay Phase II and III traffic for AM and PM peak hour conditions, while Exhibit 4.4-14 presenu the sum of year 2010 Base Case plus Terrabay Phase II and III traffic for AM and PM peak hour conditions. Base Case Plus Project (Phases ll + Ill) Impacts and Needed Mitigation Measures Year 2000 Year 2000 Project Intersection Level of Service Impacts (see Exhibit 4.4-6) - Combined traffic from Phases II + III would not produce any significant level of service impacts at any analyzed intersection. Year 2000 Project Signalization Requirement Impacts There mould be no major unsignalized intersections in the vicinity of either Phase II or Phase III of the Terrabay development. Therefore, there would be no significant impacts. 186 z v ' ~~ a O ~ t G WJ a~ a H A C 00 y cC R t F 0 c 0 CL I • ~ _ a ~~ , ~' ~~ ~ ~ ~ ti h .p h ~ 0 ym ~ h { ~~ ~ SD ~~q ~ C m t ~ L` ~C ~ t~ W ~aD V 10~ ~V mt O ~V ~a`z_Q ~azv~Q --acnv~Q w ~ ~' a~ °a k wa Q 1 1 H H a w 3 H 0 0 N a om ~ a o L O m N _~~ m Z O N 0~ ~-~ h t19 ~ N M ~ N ~ N ~~ N O o O ~ ~ N ~ O ~ O ~ ~- r ~~ c0 U ,~aQ u7 0 0 ~~ rn o ~ ~ o ~ ~ '~ o oo ~ ~ ~o Z of ~ ~- u~ ~ 1 r ~ ~~~ ~ ~ ~ ~ N a • ~ ~O~ ~ anyanbngnp I f r- ~ ~ a° ~ ~~ a m ~ ~ "'" ~ ^v m o °v `t as Z O y m O A m '"' ~ rn 3 E O ~ t Z Z O O ~ m t ~ ~. _~~ ~° ~~ tD r~ N N _~I ® f~ ~ IOA ~ N n ~, -~• ~ H m L f0 U Q ~_ maQ ~. . ~ ~ V ~a¢ ~ O N L N n N Q1 ~ N aD fD to ~- N Q .~ 1 ~. 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CSC ~~ ~ \ i ~ v \ ~ G ~ ~ ~~z b C C ~ .~ .. ~ o w w a II II II • ~ O r an y annngn~ ~~ 3 ~ o m a ~ z ~ ZO ~>3 N C O >, ~ ~ ~i ~ ~ .^•A z _~ N ~ ~ "' U _ ~~ a ~^ ~ ~ II ~ II ~ L Z ~~ 00 a~~ ~~ a~ ~ ~ O ~> U 4 `°~" o ~ .~ •~ w 0 a o u y C 0 U h C C1 ~ +"' ~..+ ~ ~ >~ 0 3 .~ ~ ~ 3 ~o ~w ~b y ~. _ C) G~ 'd U ~ 'LJ O n c 0 m r c H m U m U 7 O 4.4 TR,4FFICAND CIRCUL.,4TION Tenabay Phase ll and 111 SEIR Year 2000 Project Freeway Impacts (see Exhibit 4.4-7) Impact 4.4-1 Year 2000 Base Case plus Phases 1I + 111 Freeway Impacts Phase ll and Ill traffic combined would increase volumes by more than one percent on segments of U. S. 101 freeway already operating unacceptably at LOS F. S • Southbound.• north of the off-ramp to Bayshore Boulevard (AM=1.25 percent / PM 2.43 percent increases), from the new Bayshore Boulevard on-ramp to the Dubuque on-ramp (PM=2.45 percent increase) and south of the Dubuque on-ramp (AM=1.66 percent increase) (Segments 1, 3 and 4 in Exhibit 4.4-2). • Northbound.• from the Grand Avenue on-ramp to the Dubuque off-ramp (AM= i.71 percent / PM=2.76 percent increases), from the Oyster Point on- ramp to the Bayshore Boulevard off-ramp (PM=1.60 percent increase) and north of the Bayshore Boulevard off-ramp (AM=1.65 percent / PM=1.75 percent increases) (Segments 5, 7 and 8 in Exhibit 4.4-2). Phase l/ and 111 traffic would change operation from LOS E to an unacceptable LOS F.• • Northbound: from the Oyster Point northbound on-ramp to the Bayshore Boulevard northbound off-ramp during the AM peak period (Segment 7 in Exhibit 4.4-2). . • Southbound: from the Oyster Point southbound cn-ramp to the Grand Avenue interchange during the PM peak period (Segment 4 in Exhibit 4.4-2). Mitigation Measure 4.41 The project sponsor shall reduce the amounts of development proposed within the Phase II and Phase III sites and / or shall assist with funding for regional circulation system improvements. Based upon the freeway segments receiving the biggest significant impact due to the project, Phase II + III trip generation would need to be reduced at least 6-~ percent to reduce project impacts to a less-than-sioatlificant level. Significance after Mitigation Reduction of Terrabay Phase II and Phase III development could accomplish the desired result of not changing freeway operation to an unacceptable level and reducing the amount of project traffic increase to less than one percent on those segments of freeway already operating at unacceptable levels. This measure would reduce the impact to ales-than-significant level. Alternatively, in conjunction with other local area and regional development, funding mechanisms could be developed to provide for expansion of the regional freeway network and / or regional and local transit. However, it is unknown whether enough funding could be provided to produce a measurable level of improvement in infrastructure. Should the development not be reduced by 64 percent, the impact would remain significant an_d unavoidable. Responsibility and Monitoring The project sponsors of Telrabay Phase II and Phase III would be responsible for implementing Mitigation Measure 4.4-1 (reduction of Terrabay development), and the City of South San Francisco would monitor implementation. Year 2000 Project Freeway Ramp Impacts (see Exhibit 4.4-8) Phase II + III combined traffic would not significantly impact any of the U.S. 101 freeway ramps providing primary access to the project site. 190 4.4 TRAr-1C AND CIRCULATION Terrabay Phase 1l and ll! SEIR Year 2000 Turn Lane Storage Impacts With construction of three new closely-spaced signalized intersections along the project's Bayshore Boulevard frontage as part of Phase III development, it is expected that storage distance between intersections would be adequate to accommodate projected peak hour traffic demand. Although not strictly required to mitigate storage impacts, signal coordination between intersections would be recommended to provide better traffic flow through this series of intersections when constructed and first put in operation. Specifics regarding potentially significant impacts as local area volumes grow are described in the Year 2020 Hook Ramps PSR / PR Environmental Analysis, presented at the end of this section. Year 2010 Year 2010 Project Level of Service Impacts (See Exhibit 4.4-6) Traffic from Phases II + III would produce significant impacts at the following intersections. Impact 4.4-2 Year 2010 Base Case plus Phases 1I + 111 Intersection Impact AM peak hour Base Case operation plus project traffic would change operation from an unacceptable LOS E to an acceptable LOS D at the Sister Cities Boulevard / Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard Intersection (a beneficial impact), but acceptable LOS D PM peak hour operation would change to an unacceptable LOS F. S Mitigation Measure 4.42 (see Exhibits 4.¢IO and 4.4-10' The project sponsor shall provide a fair share contribution towards restriping the southbound (Bayshore Boulevard) intersection approach (to provide an exclusive right, a shared through / right, a through, and two left turn lanes) and construction of exclusive right-turn lanes on the eastbound (Sister Cities Boulevard) and westbound (Oyster Point Boulevard) intersection approaches. This latter measure would require widening of the Oyster Point Boulevard freeway overpass. Although individual intersection analyses would not necessarily indicate a need to widen the Oyster Point overpass, preliminary evaluation of coordinated operation between both the Bayshore /Oyster Point and Dubuque /Oyster Point intersections indicates the need for additional storage on the overpass. Based upon total traffic growth to 2010, the project's fair share contribution would be 21 percent of the improvement costs. Significance after Mitigation Full implementation of Mitigation Measure 4.42 would result in PM peak hour LOS D operation and would reduce the impact to aless-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and Phase III and other local area development would be responsible for paying their fair share of the improvements and the City of South San Francisco Public Works Department would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. 191 4.4 TRAFFIC AND CIRCULATION Terrabay Phase I! and 1I1 SE1R Impact 4.43 Year 2010 Base Case plus Phases ll + 111 Intersection /mpact Project Phase l1 + 111 traffic would change 2010 AM peak hour operation at the Oyster Point Boulevard /Dubuque Avenue / U.S. 10i Northbound On-Ramp Intersection from an unacceptable LOS E to an acceptable LOS D (a beneficial impact) but would change acceptable PM peak hour LOS D operation to an unacceptable LOS F. S Mitigation Measure 4.43 (see Exhibits 4.4-10 and 4.4-I5~ The project sponsor shall provide a fair share contribution towazds construction of a second exclusive right-turn lane on the westbound (Oyster Point Boulevard) approach and a second exclusive left-turn lane on the northbound (Dubuque Avenue) intersection approach. Both measures would require widening existing structures. Based upon total traffic growth to 2010, the project's fair share contribution would be five percent of the improvement costs. Significance after Mitigation Full implementation of Mitigation Measure 4.4-3 would result in PM peak hour LOS D operation and would reduce the impact to ales-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and Phase III and other local azea development would be responsible for paying their fair share of the improvements and the City of South San Francisco Public Works Department would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. Year 2010 Project Signalization Requirement Impacts There would be no major unsignalized intersections in the vicinity of the combined Phases II + III development. Therefore, there would be no significant impacts. Year 201 D Project Freeway Impacts (see Exhibit 4.4-7) Project Phases II + III traffic would significantly impact peak hour operation of the U.S. 101 freeway at the following locations. Year 201 D Turn Lane Storage Impacts It is probable that- with construction of three new closely-spaced signalized intersections along the project's Bayshore Boulevard frontage as part of Phase III development, storage distance between intersections may not be adequate to accommodate projected peak hour traffic demand. Signal coordination between intersections would be required to mitigate this potentially significant impact. Specifics regarding this potentially significant impact are described in the Year 2020 Hook Ramps PSR / PR Environmental Analysis, presented at the end of this section. Year 2010 volumes at the three intersections would be virtually the same as year 2020 projections. Therefore, the results aze applicable to yeaz 2010. 193 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SEIR Impact 4.4-4 Year 2010 Base Case plus Phases ll and 111 Freeway Impact Phase ll and 111 project traffic combined would increase Base Case volumes by more than one percent on U.S. 101 freeway segments already operating unacceptably at LOS F. S Southbound: north of the off-ramp to Bayshore Boulevard (AM=1.10 percent/ PM=2.09 percent increases), from the new Bayshore Boulevard hook on- ramp to the Dubuque on-ramp (PM=2.19 percent increase) and south of the Dubuque on-ramp (AM=1.48 percent / PM = 2.00 percent increases) (Segments 1, 3 and 4 in Exhibit 4.4-2) Northbound: from the Grand Avenue on-ramp to the Dubuque off-ramp (AM=1.50 percent / PM=2.41 percent increases) from the Oyster Point on- ramp to the Bayshore Boulevard off-ramp (AM=1.34 percent/PM=1.39 percent increases) and north of the Bayshore Boulevard off-ramp (AM=1.46 percent / PM=1.51 percent increases) (Segments 5, 7 and 8 in Exhibit 4.4-2). Mitigation Measure 4.4-4 Project sponsors shall reduce the amounts of development proposed within the Phase II and Phase III sites and / or shall assist with funding for regional circulation system improvements. Based upon the freeway segment receiving the biggest significant impact due to the project, Phase II + III trip generation would need to be reduced at least.59 percent. Significance after Mitigation Reduction of Terrabay Phase II and Phase III development could accomplish the desired result of not changing freeway operation to an unacceptable level and reducing the amount of project traffic increase to less than one percent on those segments of freeway already at . unacceptable levels. This measure would reduce the impact to aless-than-significant level. Alternatively, in conjunction with other local area development, funding mechanisms could be developed to provide for expansion of the regional freeway network and / or regional and local transit. However, it is unknown whether enough funding could be provided to produce a measurable level of improvement in infrastructure. Should the development not be reduced by 59 percent, the impact would remain significant and unavoidable. Responsibility and Monitoring The project sponsors of the Terrabay Phase II and Phase III would be responsible for implementing Mitigation Measure 4.4-4 (reduction of Terrabay development), and the City of South San Francisco would monitor implementation. Year 2010 Project Freeway Ramp Impacts (see Exhibit 4.4-8) Traffic from the Phase II + III developments would produce a significant impact at the following ramp. Impact 4.4-5 Year 2010 Base Case plus Phase ll + Ill Ramp Impacts Phase ll + 111 development combined would increase PM peak hour Base Case over- capacity operation by 6.8 percent on the Northbound On-Ramp from Oyster Point Boulevard. S Mitigation Measure 4.4-5 The project sponsor shall reduce Phase II and III development trip generation. Approximately an 85 percent reduction in Terrabay trip generation would be required to reduce the project traffic impact to less than a one percent increase. Alternatively, the sponsor shall provide a fair share contribution towards construction of a second on-ramp lane connection to the U.S. 194 4.4 TRAFFIC AND CIRCULATION Terrabay Phase 11 and 111 SEIR 101 freeway. Based upon total traffic growth to 2010, the project's fair share contribution would be 12 percent of the improvement costs. Significance after Mitigation Either reduction of Terrabay Phase II + Phase III development to produce a less than one percent increase in traffic or completion of the full improvement would reduce this impact to ales-than-significant level. The latter would require Caltrans approval. Should the development not be reduced by 85 percent, the impact would remain significant and unavoidable. Responsibility and Monitoring The project sponsor would be responsible for implementing Mitigation Measure 4.4-5 (reduced Terrabay trip generation) and the City of South San Francisco Public Works and Planning Departments would monitor implementation. Alternatively, the project sponsor and other local area developers would be responsible for contributing funds towards construction of the second on-ramp lane, which would require Caltrans approval. Project On-Site Circulation and Parking Impacts Needed Mitigation 's9 Proposed roads could accommodate future traffic. However, additional width would be needed for the narrowest roads. Proposed dimensions of on-street parking spaces, gazage spaces, and driveway apron spaces would be deficient in parts of the Phase II residential site. There are no provisions for overflow pazking in residential areas or for trailhead parking on either the Phase II or Phase III sites. Parking supply is also potentially deficient on the Phase III commercial site. Access to the Phase II residential site would be via South San Francisco Drive, a public residential road proposed parallel to Hillside and Sister Cities Boulevazds. Access to the Phase III commercial site would be via three connections to Bayshore Boulevard and an unnamed private internal roadway parallel to Bayshore Boulevard. The City's approved roadway and pazking standards aze contained in the Terrabay Specific Plan and Terrabay Specific Plan District. They were developed specifically for the Terrabay site to minimize visual and grading impacts. The maximum grades allowed by the 1996 Specific Plan on the Phase II and III sites are ten percent and 12 percent for all public and private roadways; respectively, unless steeper grades on limited roadway segments are approved by the City Engineer. In no case shall the City Engineer approve grades in excess of 15 percent for any private street. The 1998 Precise Plan shows maximum grades of 12 to 15 percent. Phase l/ Residential Site South San Francisco Drive would be extended pazallel to Hillside Boulevard from the Phase I site to the Phase II site. It would connect to Hillside Boulevard at two signalized intersections. One serves the Phase I site, is already constructed, and is in full operation. The other would serve the Phase II site, is already constructed, but is not in full operation. Roadway standards proposed for the Phase II site aze presented in Exhibit 4.4-16: 159 The following analysis is based on the compilation and review of standards proposed in the Terrabay Specific Plan amendment and subsequent memoranda provided by the project sponsor's engineer (Brian Kangas Foulk). The discussion responds to questions raised during refinements to the Precise Plan. The City's adopted street and parking standards for Terrabay Phases II and III are stated initially, followed by an evaluation of the Precise Plan's consistency with these standards. 195 4.4 TRAFFIC AND CIACULATION Terrabay Phase ll and 111 SF1R Exhibit 4.4-16 Terrabay Phase l1 Residential Roadway Standards Street Type Minimum Right of Way ~ Minimum Pavement a Public Street 60 feet 36 feet Minor Private Street 38 feet 25 feet (or 22 feet as approved by City Engineer) Private Lane 38 feet 25 feet (or 22 feet as approved by Ciry Engineer) Source: Terrabay Specific Plan District a Curb-to-curb width. South San Francisco Drive, designed as a "public minor road", would be dedicated to the City as a public street. Connecting residential streets serving the Terrabay Point, Commons, and Woods neighborhoods located north of South San Francisco Drive would be privately owned and maintained by the project sponsor during development and subsequently turned over to the homeowners associations. The Point and Commons neighborhoods would have one street connection to South San Francisco Drive and are proposed to be gated communities. 160 The Woods neighborhoods would consist of two residential clusters with homes fronting on terraced hillside streets but also with a single roadway connection to South San Francisco Drive. . South San Francisco Drive would have a 36-foot curb-to-curb paved width with curbs, gutters, and a four-foot sidewalk (provided along one side only), all within a 60-foot right-of--way (ROW). The roadway would have 13-foot travel lanes, five-foot bicycle lanes, and six-foot shoulders. The shoulder area on one side would include the four-foot wide sidewalk. There would be no on-street parking or curb cuts. The private residential minor streets and lanes connecting to South San Francisco Drive would be 22 to 25 feet wide within a 38- to 43-foot ROW. All would have curbs, gutters, and afour-foot sidewalk along one side only. Private residential minor roads would be "unloaded" (no fronting housing), "single-loaded" (with fronting housing on one side only), or "double-loaded" (with fronting housing on both sides). Unloaded roadways would have no on-street parking lane -while single- or double- loaded roads would have aneight-foot on-street pazking lane along one side only. Minimum street widths would be 22 feet where aneight-foot wide on-street parking lane would be provided or 25 feet where there would be no on-street parking lane. Exhibit 7.5-11 in the Appendix illustrates these roadway dimensions. Impact 4.4-6 Roadway Width While roadways would conform to adopted standards, narrow 22-foot wide roadways raise safety concerns, not for through movements but for interference with or by curbside activities. S The project as proposed would conform to the Terrabay Specific Plan District. That is, all on-site roadways would meet the City's adopted Terrabay Specific Plan District standards. However, the discretionary 22-foot roadway width, a minimum width acceptable only if approved by the City Engineer, would raise concerns for roadway safety. The 22-foot wide streets would function 160 Letter to Nichols-Berman from James Sweenie (project sponsors representative), Sterling Pacific Management Services Company, November 6, 1997. 196 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and ill SEIR acceptably as comdors for through vehicle access. However, the narrow width would result in constrained turning movements for vehicles backing out of driveways and would leave little space for occupants exiting vehicles parked on-street to open their driver-side doors while avoiding through traffic. On such narrow streets, driver-side doors would swing open partly into the adjacent traffic lane. Other daily inconveniences could be experienced by residents and visitors on narrow roads (such as more cars doors would be dented and the potential for cars backing out of driveways to back into cars parked on-street would be increased). Any of these concerns could translate into potential injuries involving drivers, passengers, pedestrians, or bicyclists. Mitigation Measure 4.4-6 The following mitigation will be required: The Precise Plan shall be revised to provide minimum 2~-foot wide travelways on residential roadways (containing one 12.5-foot lane in each direction) in order to facilitate activities such as backing out of driveways and to improve safety and convenience for drivers exiting vehicles parked on-street. Significance after Mitigation Mitigation Measure 4.46 would eliminate the safety concerns raised by the 22-foot wide street widths shown in the Precise Plan, thus reducing the severity of impact to a less-than-significant level. However, redesigning residential roadways to increase widths would require additional land. This could be accomplished by reducing the sizes of residential lots (with an accompanying reduction in the sizes of building footprints and / or total building area) which could result in the loss of some lots and units. This also could be accomplished through more extensive grading and / or construction of more or higher retaining walls which would have significant secondary effects. Proposed roadway widths 'shown on the Precise Plan represent prior revisions made by the project sponsor in response to such secondary effects. Those revisions were to reduce the extent of development and accompanying grading, thus minimize the footprint of disturbance. If the City does not choose to amend the Terrabay Specific Plan District to require 25-foot wide streets, this would be considered a significant unavoidable impact. Responsi6iiity and Monitoring The project sponsor would be responsible for redesigning the Precise Plan to incorporate this measure, if required to do so by the City, and the City Engineer would review the Precise Plan before City approval to ensure provision of minimum 25-foot wide travelways. Impact 4.4-7 Turnarounds Angled, hammerhead, and cul-de-sac turnarounds proposed for the Phase 11 site would accommodate fire trucks. LTS The City's minimum cul-de-sac bulb dimension (curb-to-curb with no parking) is 60 feet in diameter, although the City of South San Francisco Fire Depamnent (SSFFD) prefers an 80-foot diameter culs- de-sac. An 80-foot diameter cul-de-sac is proposed in Terrabay Point to accommodate fire truck turns. Dead end streets in the Commons and Woods neighborhoods would provide angled hammerhead turnaround areas designed to conform to SSFFD criteria. These would allow three-point turns by fire trucks. The maximum length of any road extension beyond an approved fire truck turnaround area is 150 feet. The Precise Plan conforms to the Fire Department and City standards for turnarounds. Mitigation Measure 4.4-7 No mitigation would be required. 197 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SEIR Impact 4.4-8 Residential Parking Dimensions Although the Precise Plan would conform to minimum parking supply requirements, dimensions of some spaces would be substandard. S According to City standazds expressed in the 1996 Specific Plan, each residential unit is required to provide two garage spaces and two 18-foot long apron spaces. Within each residential azea there must be three on-street (visitor) pazking spaces per four units, located in close proximity to the units. the overall minimum parking requirement is 4.75 spaces per single-family detached unit and 4.25 spaces per duplex and triplex attached unit. No recreational vehicle or boat storage would be allowed. Exhibits 4.4-I7 and 4.4-I8 show the proposed parking supply and dimensions, respectively, for the Phase II residential areas. The Precise Plan conforms to the overall minimum pazking ratios required by the adopted 1996 Specific Plan. The 66 proposed Woods Floor Plan 1 and 2 units would provide two-car garages and two-car driveway aprons (a total of 132 garage spaces and 132 apron spaces). Floor Plans 3 and 4 both propose five bedrooms units with three gazage spaces and three apron spaces each. The City parking requirement for a five bedroom and /or 2,500-square foot home is a three car garage. Dimensions of all garage and apron spaces are shown in Exhibit 4.4-I8. As proposed, dimensions would be substandard for 61 percent of all parking spaces. This is considered a significant impact. Dimensions of parallel pazking spaces would be eight feet wide by 20 feet deep ,(8 x 20). The City standard is eight-and-one-half feet wide by twenty feet deep (8.5 x 20). As proposed, dimensions would be substandazd (by one-half foot). This is considered a significant impact. Driveway aprons would be required to be 18 feet long, measured from the exterior of the gazage door to either the back of the sidewalk or, if there is no sidewalk, to the back (residence side) of the curb. As shown in Exhibit 4.4-18, all driveway aprons in the Point and Commons neighborhoods would have substandard lengths. Plan A and B downslope duplexes (64 units) would provide only 15 feet of 18-foot depth within the property line, and three feet would extend into the ROW (to the front face of the curb). Driveway aprons of Plan A upslope triplexes (47 units) provide only 17 feet of the required depth within the property line, and one foot would extend into the ROW (to the back face -residence side -- of the sidewalk). This is essential to maintaining unobstructed sidewalks and travelways to comply with City and Americans with Disabilities Act (ADA) requirements. Plan B downslope units and all Plan C upslope and downslope units also would have aprons less than 18 feet long. In addition to the Point and Commons driveway apron deficiency, 21 percent of all units in the Woods neighborhood would have aprons less than 18 feet long. This is considered a significant impact. The parallel pazking, garage, and driveway apron parking spaces with deficient dimensions per Ciry standards raise significant safety concerns. As discussed in relation to Impact 4.4-7, any of these concerns could translate into potential injuries involving drivers, passengers, pedestrians, or bicyclists and would violate City and ADA standards for unobstructed sidewalks and travelways. Mitigation Measure 4.48 The parking dimensions for parallel parking, gazage, and driveway aprons shown on the Precise Plan shall be revised to comply with the Specifzc Plan, the City's Zoning Ordinance, and other applicable City standards. As shown on Exhibit 4.4-I8, this would include revisions to driveway apron lengths of Plan A and B downslope duplexes (64 units), Plan C upslope duplexes (eight units), Plan A upslope triplexes (47 units), Plan B and C downslope triplexes (94 units), and Woods Plan 1, Plan 3, and Plan 4 garage floor space dimensions (35 units, 35 units, and 34 units respectively), and the dimensions of the garage parking spaces in Woods Plan 3 (35 units). 198 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE1R Exhibit 4.41-7 Parking Supply Summary Phase ll Residential Point Commons Woods Total Number of Units 181 ~ 32 135 348 Garage S aces /Unit 2 2 2-3 ° ' Gara a Subtotal 362 ~ 64 339 765 Drivewa Aron /Unit 2 2 2-3 ° A ron Subtotal 362 64 339 765 On-Street Guest S aces 134 23 73 230 On-Street Subtotal ~ 134 23 73 230 Total Pro osed Parkin 8~8 ~ 151 751 1,760 Phase 111 Commercial Hotel Restaurant Retail Mixed-Use Units ` 380-600 rooms 12,000-18,000 sf ~ 6,000-10,000 sf 30,000-35,000 sf S ace /Unit 1 /room ~ 1 / 300 sf 1 / 200 sf 1 / 250 sf. ` S ecific Plan Re uirement 380-664 40-60 30-50 120-140 Proposed Parking Supply or each commercial use 450 159 50 ISO Total Pro osed Commercial Parkin 809 s aces s Sources: The Dahlin Group, January 15, 1998, and Crane Transportation Group a Floor Plans 1 and 2 (66 uniu) would provide two-car garages (for 133 indoor spaces) and two-car driveway aprons (for 132 outdoor spaces), and Floor Plans 3 and 4 (69 units) would provide three-car garages and aprons (for 207 and 207 spaces, respectively). Floor Plans 3 and 4 both propose five bedrooms each. The City parking requirement for afive- bedroom and/or 2,500-square foot home is a three-car garage. Dimensions of all garage and apron spaces are shown in Exhibit 2.3-12. As presently proposed, dimensions would be substandard. b Dimensions of parallel parking spaces would be eight feet wide by 20 feet deep (8x20). The City standard is eight-and- one-half feet wide by 20 feet deep (8.5x20), one-half-foot wider than proposed. c Rooms and square feet (sf). d Assumes airport-related hotels for which the Ciry requires one space rer room. The City's parking requirement for non- airport-related hotels is 1.1 spaces per room (660 spaces if the maximum 600 rooms were built in non-airport-serving hotels). e Includes office, restaurant, and retail uses not shown in the respective restaurant and retail columns. The parking rate shown assumes all offices, although a 35,000-square-foot specialty retail store could require 175 spaces (one space per 200 square feet). f The range of required parking spaces is shown, based on parking rates established for the Terrabay Specific Plan. g Maximum number of spaces proposed for all Phase III uses: hotel, restaurant, retail, and mixed use. Does not account for potential shared pazking. Terrabay\traffic\~-~i-17.doc 199 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE/R Exhibit 4.4-18 Residential Parking Dimension Summary a Attached Units Garage Spaces Apron Spaces Du lexes Number Dimensions Number Dimensions Plan A (downslo e) (3z units) 2 ~araoe s aces 20x20-22 2 a ton s aces 16x15 Plan B(downslo e) (32 units) 2 ~arase s aces 20x20-22 2 s aces 16x15 Plan C (u slo e) (8 units) 2 ~araoe s aces 22.5x20 2 a tons aces 16x17 ` Tri lexes Number Dimensions Number Dimensions Plan A (u slo e) (47 units) 2 ara e s aces 20x21.5 2 a ton s aces 16x17 Plan B (downslo e) (47 units) 2 earaoe s aces 20x23 2 a ton s aces 16x 15 ` Plan C (downslo e) (47unirs) 2 garage s aces 23x23 2 a tons aces 16x15 ` Detached Units Gara e S aces A ton S aces Woods Number Dimensions Number Dimensions Plan 1 (35 uniu) 2 ¢ara¢e s aces 19x21 2 a tons aces 16x17 ` Plan 2 (31 units) 2 oaraee s aces 20x20 2 a tons aces 16x18 Plan 3 ` (35 units) 3 garage spaces 30x18-20 ` 3 apron spaces 26x18 Plan 4`(34 units) 3 eara e s aces 29x20 ` 3 a ton s aces 26x 18 Source: Precise Plan, Part 1 Architecture, The Dahlin Group, January 15, 1998. a Parking space dimensions for new garages required by the City of South San Francisco's Zoning Ordinance (Section 20.74.110(c)) are ten feet wide by 20 feet deep (10x20) and by the Terrabay Specific Plan District for standard cars (Section 20.63.070(d)(1)) are nine feet wide by 20 feet deep (9x20). b Driveway aprons of Plan A and B downslope duplexes (64 units) provide 15 feet of the required 18-foot depth within the property line with three feet extending into the ROW to the face of the curb. Driveway aprons of Plan A upslope triplexes (47 units) provide 17 feet of the required depth on individual lots with one foot on within the ROW to the back of the sidewalk and beyond that afoot-foot sidewalk. c The proposed parking width of 19 feet, eight inched falls short of the City's 20-foot requirement. d The proposed parking width of 19 feet falls one foot short of the Ciry's 20-foot requirement e The City requires provision of a three-car garage for a five bedroom home and / or a 2,500-square foot home. The City standard for athree-car garage is 30-feet wide and 20 feet deep, free and clear of any obstructions. Both proposed garages for Floor Plans 3 and 4 fall short of the City requirement. Floor Plan 3 proposes garages measuring 30 feet wide by 18 to 20 feet deep, and Floor Plan 4 proposes garages measuring 29 feet four inches (29' 4") wide and 20 feet deep, eight inches narrower than the City's standard. f Although three spaces would be provided, one would be substandard, measuring ten feet wide by 18 feet deep (10x18). Nichols • Berman conversation with Mark Day, The Dahlin Group, January 30, 1998. 200 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE1R Significance after Mitigation Mitigation Measure 4.4-8 would eliminate safety concerns raised by non-compliance with the Specific Plan standards for parallel pazking spaces and for garage and driveway apron dimensions. Implementation of Mitigation Measure would reduce this impact to a less-than-significant level. Responsibility and Monitoring The project sponsor would be responsible for redesigning the Precise Plan to incorporate this measure, and the City Engineer would review the Precise Plan before City approval to ensure compliance with standards for parallel parking spaces and garage and driveway apron dimensions. Impact 4.4-9 Overflow Parking Although the Precise Plan would conform to minimum parking supply requirements, it does not provide for overflow parking for use by visitors attending parties or special events. S The Precise Plan does not provide for overflow parking within the residential areas. The 1996 Terrabay Specific Plan requires provision of 4.25 spaces per attached duplex and triplex unit in the Point and Commons neighborhoods and 4.75 spaces per detached unit in the Wood neighborhood. The Precise Plan would increase this supply to 4.74 spaces per attached and 5.56 spaces per detached unit. The Precise Plan parking supply is larger than the minimum requirement. This supply is considered adequate for typical weekday and weekend use and would be expected to accommodate residents and a few visitors adequately. However, no additional parking would be available within any of the residential neighborhoods to accommodate parties and larger gatherings. Due to the absence of any nearby overflow parking areas (such as along Hillside Boulevard or Sister Cities Boulevard), this lack of overflow parking area raises safety concerns as described in the Significance Criteria (page 184). Unauthorized parking likely would occur on-street, along streets with inadequate width to safely accommodate it, resulting in violations of City and ADA standards for unobstructed travelways. Mitigation Measure 4.4-9 The Precise Plan shall be revised to provide overflow parking, consisting of six to eight spaces, within each residential neighborhood. -These spaces can be provided by enlarging cul-de-sac bulbs, paving areas at the ends of hammerhead turnarounds, or eliminating one to two housing units adjacent to the street end (hammerhead or cul-de-sac). If housing units are eliminated, on-site parking should be monitored at regular intervals. ff it is found that the amount of overflow parking provided is not required, then one or both of the remaining units could be constructed. Significance after Mitigation Implementation of Mitigation Measure 4.4-9 would eliminate the impacts raised by the absence of overflow parking in the residential neighborhoods and reduce the severity of impact to ales-than-significant level. Responsibility and Monitoring The project sponsor would be responsible for incorporating overflow parking into the Precise Plan, and the City Engineer would review the Precise Plan before City approval to ensure parking adequacy. Phase 11l Commercial Site The Precise Plan proposes an unnamed "private commercial minor road" which would run parallel to Bayshore Boulevard and serve the entire Phase III commercial site. It would be connected to three tot 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and Ill SE1R entry roads intersecting Bayshore Boulevard (two signalized "T"' intersections with Bayshore Boulevard and astop-sign-controlled right-turn-only intersection at the north end of the site). - The internal roadway would be 25-feet wide curb-to-curb with one travel lane in each direction. The connections to Bayshore Boulevard would be 48 feet wide curb-to-curb, with two 12-foot lanes in each direction and asix-foot raised median. The entrance roadways would have curbs, gutters, and four-foot wide sidewalks on both sides of the road, within a 64-foot right-of--way. The Phase III on-site collector roadways would meet the City's adopted standards contained in the Terrabay Specific Plan District. Impact 4.4-10 Potential Commercial Parking Supply Shortfalls The currently proposed maximum Phase 111 development concept would not provide sufficient parking for the types and amount of development presently envisaged. S Exhibit 4.4-17 shows the total proposed parking for Phase III development. Hotel, restaurant, retail, and mixed-use development would be provided with a combined total of 809 parking spaces. As indicated by Exhibit 4.4-I7, the proposed parking supply assumes construction of airport-related hotels which requiring one space per room. However, the City's parking requirement for non-airport- serving hotels is 1.1 spaces per room (660 spaces if the maximum 600 rooms were built in non-airport- servinghotels). The mixed-use development would include office, restaurant, and retail uses in addition to separately identified restaurant and retail development. The parking rate applied to this category assumes 30,000 to 35,000 square feet of office space at a rate of one space per 250 square feet. However, if all mixed- use space were developed as specialty retail use, one space per 200 square feet would be required. This would increase the amount of parking required by another 150 to 175 spaces. Opportunities would exist for shared parking between office pazking (daytime peak parking requirement) and restaurant (evening peak parking requirement). For retail uses closing at 5:00-6:00 PM, there also would be opportunities for shared parking with restaurants having evening peak parking requirements. The actual number of spaces required would depend on the amount of development proposed by individual developers on aparcel-by-parcel basis. The actual number would also depend on the extent to which parking would be shared among commercial uses, should uses ultimately developed generate demands for parking at different times of day. The project sponsor has indicated that "cross parking easements" would be provided as a "convenience feature", although full parking would be proposed for each building. 161 However, the Plan does not identify any rates to calculate shared pazking requirements or establish a methodology to estimate overlap for the proposed hotel, retail, restaurant, and office uses. In the meantime, the potential for parking shortfalls in the commercial azea is considered a significant impact. Mitigation Measure 4.4-10 The project sponsor or individual subsequent developers shall submit parking plan(s) for each of the proposed Parcels A through G as part of an overall Phase III site Precise Plan or parcel-by-parcel Precise Plans to demonstrate compliance with minimum requirements and / or that shared parking would be adequate to accommodate uses proposed. The total amount of development proposed shall be reduced, if necessary, to an intensity which also can accommodate its required parking supply. 161 Letter to Nichols-Berman from James Sweenie, op. cit. 202 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and 111 SE1R Significance after Mitigation Implementation of Mitigation Measure 4.4-10 would bring the project into conformance with Ciry parking requirements and eliminate potential pazking shortfalls in the commercial area, thus resulting in aless-than-significant impact. City staff analyzed the Phase III parking supply as proposed. The analysis concluded that either 450 hotel rooms, 16,480 square feet of restaurant (at one space per 200 square feet for 50 percent of floor area and one space per SO square feet for 50 percent of floor area, assuming half customer and half non-customer area), 10,000 square feet of retail, and 27, 750 squaze feet of mixed use /retail /office space (assuming an average of one space per 250 square feet) or 242,700 square feet of office could be accommodated in conformance with the 809-space parking supply proposed by the Precise Plan which would conform with the City's parking ordinance. According to the Precise Plan, decked or garage parking facilities may be proposed in addition to that already anticipated on Parcel C, if a larger number of parking spaces is needed (such as if the land use ultimately proposed is primarily or entirely office). 162 Responsibility and Monitoring The project sponsor and / or individual subsequent developers would be responsible for preparing parking plans for each parcel and reflecting this in the overall or pazcel- by-parcel Precise Plan(s). The City Engineer and Chief Planner would review the Precise Plan before project approval to ensure adequate parking. Impact 4.411 Pedestrian and Bicycle Access and Trailhead Access and Parking Sidewalks, bike lanes, and a new trail would be provided with project implementation, but the project currently does not specifically provide trailhead parking. LTS The Precise Plan would provide sidewalks on one side of all roadways serving housing units. Bike lanes would be provided on South San Francisco Drive only (City policy is to provide bike lanes on new public streets t63) The Precise Plan would provide one trail connection to San Bruno Mountain State and County Park on the Phase I site (near the boundary of the Phase I and Phase II residential sites) and proposes a second trailhead at the north end of the Phase III commercial site (instead of a trail at the boundary of the Phase II and Phase III sites as previously shown by the 1996 Terrabay Specific Plan). The Precise Plan's proposed design of Terrabay Point would relocate the Phase II boundary in relation to the Phase III site. As currently proposed, the former trailhead would be confined inside the Terrabay Point neighborhood and would not be accessible to the public (due to proposed gates), resulting in violations of City and ADA standards for unobstructed travelways. This lack of trailhead pazking in Phase II would not raise significant concerns for parking adequacy. The project sponsor proposes to coordinate the location of the Phase III site trailhead with San Mateo County staff and to date has only identified a trail and trailhead conceptually. It is expected that trailhead parking in the Phase III commercial area could be accommodated in commercial parking lots. Trailhead use would be expected to be greatest on weekends and after work hours on weekdays, when the commercial parking lots would have many pazking spaces available for trail users. Mitigation Measure 4.411 No mitigation would be required. 162 Terrabay Project, South San Francisco, California, Letter to Allison Knapp, City of South San Francisco Planning Department, from Janine O'Flaherry, Brian Kangas Foulk (project sponsor's engineer), January 25, 1998. 163 Crane Transportation Group conversation with Richard Harmon, op. cit., Apri18, 1998. 203 4.4 TRAFFIC AND CIRCULATION Terrabay Phase !l and 111 SE/R YEAR 2020 HOOK RAMPS PSR / PR ENVIRONMENTAL ANALYSIS -THE SETTING This section examines the effects of providing hook ramps from U.S. 101 to Bayshore Boulevard adjacent to the Terrabay Phase III commercial site. The ramps would accommodate southbound on and southbound off movements to /from the freeway. Both the on- and off-ramp would intersect Bayshore Boulevazd at a single intersection in approximately the same azea as the existing southbound off-ramp connection to Bayshore Boulevard. However, Bayshore Boulevazd would be realigned farther west to allow provision of 90-degree curves on both ramps (see Exhibit 2.3-8b) and to increase the distance between the off-ramp diverge and Bayshore Boulevard intersection. A year 2020 evaluation was conducted to determine circulation impacts with and without the hook ramps in operation. 164 Caltrans reviewed the February 1998 version of this study and approved the findings as acceptable. 165 The March 1998 version incorporates minor revisions and additions to area developments considered as part of area buildout trip generation, as well as minor revisions /additions to freeway mainline analysis. It is not expected that these changes would alter Caltrans' overall approval of the study findings. For environmental analysis purposes, "the project" for the hook ramps Project Study Report /Project Report (PSR / PR) is provision of the new buttonhook ramps. Circulation conditions aze examined in the context of year 2020 traffic projections with and without the ramps. The same degree of future development and resulting traffic levels have been used for the "with" versus "without" project evaluation. The only major diversion of traffic due to the new ramps would be the use of the new southbound on-ramp by Terrabay Phase III commercial traffic as well as southbound traffic on Bayshore Boulevard (primarily from Brisbane) which otherwise would be required to travel through all of the intersections within the Oyster Point interchange in order to access the existing southbound on-ramp connecting to Dubuque Avenue. Thus, the "with project" condition would result in less traffic (and better operation) at the intersections within the interchange as well as less traffic (and better operation) of the existing southbound on-ramp from Dubuque Avenue. However, the "with project" condition would add a component of southbound traffic via the new on-ramp onto the freeway farther upstream than would be the case with no project. Once south of the southbound on-ramp connection from Dubuque Avenue, freeway mainline volumes would be the same with or without the project. The project would not produce any changes or impacts to traffic flow on the northbound freeway or at any northbound on- or off-ramp. The new southbound buttonhook off-ramp would be expected to have volume levels slightly higher than the existing off-ramp, primarily due to a small component of Brisbane traffic which would fmd it easier to make a right turn to travel north on Bayshore Boulevard than would be the case with the existing off-ramp alignment. Exhibit 4.¢l9 presents year 2020 AM and PM peak hour volumes for "with" and "without" project conditions. Yeaz 2020 traffic projections were developed in a manner already described above in this section's Terrabay analysis. 1 ~ Route 101 /Bayshore Boulevard Nook Ramps PSR /PR Traffic Operations Analysis, CCS Planning and Engineering, Inc., op. cit., March 23, 1998. 165 Route 101 /Bayshore Boulevard Hook Ramps PSR /PR Traffic Operations Analysis, February 2, 1998. 204 a ~ ~~ ~_ W ~ t a m s~ ~ ao r ~ i, ZOm ~~ ~~~ ~~ N m~ '1f'~ir v v iii O i N l'7 ~ m T ~ i e ~ ~ F r ~® N ~ -~ ~ 0 N ~ N ~ app ~ N ~~ ~ 0 y maQ nW - m ~_ f N h O~~ m~ ~. f N N ~ l4 ~ N < ~ ~ ^' m ~' ~~ - ~ I f M ~ ~ C Q O N h iA m ~ ' -~ ~ r v ~ 0 O O ~ ~ O ~ ~ N A N ~ m U ~ r h m H ~ ~ ID U ~ Q N m c a m ~ E a ~ ZO V Vr x ° x a a a r N m c a ~^ o $ m _ t~~ 00 2 ~t t 0 Z V 0 L a s 0 N O N L m a~ -, 0 L a _~ N O N L Ri n C1 0 0 oa y C f` F.. m C U m O 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and !Il SE/R YEAR 2020 HOOK RAMP PSR / PR ENVIRONMENTAL ANALYSIS -IMPACTS AND NEEDED MITIGATION MEASURES Significance Criteria The analysis of hook ramp impacts used the same significance criteria as employed for the Terrabay Phase II and III evaluation. In summary, LOSE is considered the poorest acceptable freeway mainline, freeway weaving, ramp and ramp merge /diverge area operation. LOS D is considered the poorest acceptable operation for intersections. Year 2020 Hook Ramp Intersection Level of Service Impacts By 2020 without the hook ramp project, one intersection in the Oyster Point interchange would be operating unacceptably during the A1~1 peak hour, and four would be operating unacceptably during the PM peak hour (see Exhibit 4.4.20). With the hook ramp project, no intersections would be operating unacceptably during the AM peak hour, and only two intersections would be operating unacceptably during the PM peak hour. Of the two locations with remaining unacceptable operation - Bayshore Boulevard /Oyster Point Boulevard /Sister Cities Boulevard /Airport Boulevard and Oyster Point Boulevard /Dubuque Avenue / U.S. 101 Northbound On-Ramp -conditions would be better with the project (LOS E at both locations) than without it, due to the removal of traffic from all major intersections within the interchange. Overall, the hook ramp project would benefit operation at most major intersections within the Oyster Point interchange. ' Exhibit 4.420 Intersection Levels of Service -- Year 2020 Hook Ramp Analysis C t l 2020f No Pro"ect 20201 Pro'ect Intersection on ro LOS Dela LOS Delay AM Peak Hour Ba shore / US 101 SB Off All-Wa Sto C 12 B 14 Ba shore / O stet Point Si al F 73 D 38 Dubu ue / O stet Point Si al D 35 D 28 Dubu ue / US 101 Rams Signal B 7 B 7 Gatewa / O stet Point Si al D 33 D 33 Ba shore / Terraba North Signal B 7 B 9 Ba shore / Terraba South SiQttal A 4 B 7 PM Peak Hour Ba shore / US 101 SB Off All-Wa Sto F 58 ` D 34 Ba shore / O stet Point Si al E 50 E 41 Dubu ue / O stet Point Si al F 72 E 5~ Dubu ue / U.S. 101 Rams Signal E 49 B 14 Gateway /Oyster Point Signal D 33 D 33 Ba shore / Terraba North Signal B 10 B 11 Ba shore / Terraba South Signal B 14 B 8 Source: CCS Planning and Engineering. Inc. a LOS =Level of service. b Delay =Average delay for all vehicles passing through intersection (in seconds). c Intersection would be signalized with project. d Future operations evaluated as five-legged intersection. 206 4.4 TRAFFIC AND CIRCULATION Terrabay Phase ll and Ill SE/R Year 2020 Hook Ramp Intersection Turn Lane Storage Impacts The ability of the proposed left-turn lanes along Bayshore Boulevard to serve the new hook ramps intersection, the two new full intersections at the Terrabay Phase III site, and the Oyster Point Boulevard intersection was evaluated to accommodate projected vehicle storage demands during peak traffic conditions. Results, presented in Exhibit 4.7-I2 in the Appendix, were reached using both "conservative" and more typical arrival pattern methodologies. The more conservative "All Stop" analysis, similar to that used by Caltrans, determines storage needs assuming all vehicles stop at an intersection (all vehicles receive a red light when arriving on an intersection). The "Partial Stop" analysis assumes that some vehicles arrive at an intersection during a green phase and do not stop or add to vehicle queuing requirements. With either methodology, the analysis indicates that storage on the proposed hook off-ramp would be adequate to prevent impacts on the mainline freeway from queues at the off-ramp intersection. However, other intersection approaches would be expected to experience significant impacts with maximum vehicle queues exceeding available proposed storage lengths during five percent or more of signal cycles (with no coordination of traffic signal operation). Impact 4.4-12 Potential Storage Distance Deficiencies Between Intersections Queues would exceed available storage capacity at three to six intersections, depending on analysis methodology. S Using the more conservative "All Stop" assumptions with the proposed hook ramp project, maximum queues would exceed available storage lengths for the following movements and time periods during five percent or more of signal cycles: • Bayshore /Terrabay North Access Northbound Left (both AM and PM peak hours) • Bayshore / U.S. 101 Ramps Northbound Through Right (PM peak hour only) • Bayshore / U.S. 101 Ramps Southbound Left (both AM and PM peak hours) • Bayshore /Terrabay South Access Southbound Through (both AM and PM peak hours) • Bayshore /Oyster Point Southbound Left (AM peak hour only) • Bayshore /Oyster Point Southbound Right (both AM and PM peak hours) Using "Partial Stop" analysis assumptions with the proposed hook ramp project, maximum queues could exceed the available storage lengths for the following movements and time periods during five percent or more of signal cycles: • Bayshore /Terrabay North Northbound Left (both AM and PM peak hours) • Bayshore / U.S. 101 Ramps Northbound Through-Right (PM peak hour only) • Bayshore /Oyster Point Southbound Left (AM peak hour only) Mitigation Measure 4.4-12 Interconnected and coordinated signal operation and flow between these four closely spaced intersections along Bayshore Boulevard shall be provided in order to preclude storage deficiencies. Due to right-of--way limitations along Bayshore Boulevazd, provision of dual left-turn lanes is not considered feasible on the northbound approaches to the Terrabay Phase III site driveways or on the southbound approach to the U.S. 101 southbound hook on-ramp. Also the northbound left-turn lane on the approach to the Terrabay North Access could not be lengthened without shortening the southbound left-turn lane on the approach to the U.S. 101 southbound on-ramp. Traffic volumes and queues shall be monitored at these intersections as development occurs on the Terrabay site to determine if the turn lane lengths and signal timing should be adjusted. zoo 4.4 TRAFFIC AND CIRCULATION Terrabay Phase Il and 1/1 SE/R Significance after Mitigation Implementation of Mitigation Measure 4.4-12 would reduce the severity of impact to ales-than-significant level. Responsibility and Monitoring The Terrabay Phase III development project sponsor, City of South San Francisco, and Caltrans would be responsible for implementing Mitigation Measure 4.4-12, and the City of South San Francisco would monitor its effectiveness. Year 2020 Nook Ramp Freeway Mainline Impacts The projected 2020 AM and PM peak hour level of service on all freeway segments without the project would be an unacceptable LOS F except for northbound flow north of Sierra Point during the AM peak hour, which would experience LOS E operation. With the proposed hook ramp project, one segment of freeway would experience a significant impact. Impact 4.4-13 Year 2020 Hook Ramps Impact on Freeway Mainline Traffic from the new on-ramp would increase AM and PM peak hour volumes by more than one percent on the U.S. 101 Freeway Southbound Mainline from the new southbound buttonhook on-ramp to the southbound on-ramp from Dubuque Avenue, a segment about 3,500 feet long that would already be experiencing unacceptable LOS F operation. SU Mitigation Measure 4.4-13 No mitigation is feasible other than not constructing the project. Significance after Mitigation This impact could be reduced to aless-than-significant level with no project construction, but otherwise would remain significant and unmitigable. It should be noted that the increase in traffic on this one segment of freeway is due to a shift in surface street volume from the Dubuque southbound on-ramp to the new buttonhook on-ramp. The net volume of southbound traffic on the freeway south of the Dubuque on-ramp would be the same with or without the proposed buttonhook ramp. The only difference would be a shift in traffic from one on-ramp to the other. Therefore, an additional 3,500 feet of freeway mainline would experience increased traffic that otherwise would remain on the surface streets. While this greater than one percent increase does meet the strict definition of a significant impact, an argument could be made that the impact is not significant in that the net effect to the downstream traffic flow is not changed. Responsibility and Monitoring The City of South San Francisco is project sponsor of the hook ramps. Year 2020 Hook Ramp Freeway Ramp Impacts Freeway ramp operation was evaluated using the "Ramps and Ramp Junctions" methodology of the 1994 Highway Capacity Manual (HCM). The merge at the new on-ramp connection to the freeway would operate acceptably during both the AM and PM peak traffic hours. The off-ramp diverge would operate at LOS E during the AM peak hour and an unacceptable LOS F during the PM peak hour, with or without the project (a southbound off-ramp is in operation with or without the project). The impact to diverge operation would be significant during one period. zoa 4.4 TRAFrIC AND CIRCULATION Terrabay Phase ll and 111 SE/R Impact 4.4-14 Year 2020 Hook Ramps Impact on Freeway Ramps Increased traffic due to the hook ramp project would increase AM peak hour off-ramp volumes by more than one percent at the diverge of the Southbound U. S. 101 Freeway Off-Ramp to Bayshore Boulevard where diverge traffic flow operation would already be an unacceptable LOS F. SU Mitigation Measure 4.4-14 No mitigation is feasible other than not to construct the project. Significance after Mitigation Impact could be reduced to aless-than-significant level with no project construction but otherwise would remain significant and unmitigable. Responsibility and Monitoring The City of South San Francisco is project sponsor of the hook ramps. 209 4.5 AlR QUALITY This section addresses air quality impacts on local and regional air quality. It describes the climate and current quality setting, ambient air quality standards and conditions, and regional air quality planning efforts. Air quality impacts are assessed using the procedures and significance thresholds recommended by the Bay Area Air Quality Management District (BAAQMD). 166 Mitigation measures to reduce significant air quality impacts are identified. AIR QUALITY -THE SETTING Meteorological conditions (such as wind speed and atmospheric stability) affect the atmosphere's ability to mix and disperse pollutants. Lonb term variations in air quality typically result from changes in air pollutant emissions while frequent short-term variations result from changes in atmospheric conditions. Climafe The climate in the Bay Area is characterized by mild dry summers and mild wet winters. The region's close proximity to the Pacific Ocean and San Francisco Bay result in a strong marine influence. Prevailing wind flow in the region tends to be from the northwest. The City of South San Francisco lies in the Bay Area's peninsula climatological subregion which extends from San Jose to the Golden Gate. Mountains exceeding 1,000 feet separate the city from the Pacific Ocean. The San Bruno gap, which is oriented from northwest to southeast, allows marine air to flow easily across South San Francisco in the direction of San Francisco Bay As a result, South San Francisco experiences relatively high winds, especially in spring and summer. These winds tend to disperse pollutants from the area. Air Pollutants and Ambient Standards Both the U.S. Environmental Protection Agency (USEP.~) and the California Air Resources Board (ARB) have established ambient air quality standards for common pollutants. These ambient air quality standards represent safe contaminant levels which avoid the specific adverse health effects associated with each pollutant. The standards cover what are called "criteria" pollutants because the health and other effects of these pollutants are described in USEPA-prepared "criteria" documents. These Federal and State ambient standazds were developed independently with different purposes and methods, although both processes attempt to avoid health-related effects. As a result, the Federal and State standards differ in some cases. In general, the California State standards are more stringent. The Federal and State standards are summarized in Exhibit 4.5-I. - In 1997, the USEPA established new ambient air quality standards for ozone and very small particulate matter (particulate matter smaller than 2.5 micro meters in diameter - PM2.5). The new ozone standard which eventually will replace the existing standard is 0.08 parts per million (ppm) for 166 BAAQMD CEQA Guidelines, Bay Area Air Quality Managemea: District, April 1996. 210 4.5 A1R QUALITY Terrabay Phase 11 and Ill SEIR Exhibit 4.5-1 Ambient Air Quality Standards Pollutant Average Time ~ California Standards a National Standards b Concentration Concentration Ozone 1 Hour 0.09 m ` 0.12 m Carbon Monoxide 8 Hour 9.0 m 9 m 1 Hour 20.0 m 35 m Nitro en Dioxide Annual Avera e 0.053 m ~ 1 Hour 0.25 m Annual Average 80 m3 Sulfur Dioxide 24 Hour 0.04 ppm 365 m3 1 Hour 0.25 m Annual Arithmetic Mean 50 m3 Suspended Particle Annual Geometric Mean 30.0 /m3 ~ Matter (l'Mto) 24 Hour 50.0 /m3 150 m3 Sulfates 24 Hour ~ 25.0 /m3 Lead Calendar Quarter 1.5 m3 30 Day Average 1.5 m3 H dro en Sulfide 1 Hour 0.03 m Vinyl Chloride (chloroethene) 24 Hour 0.010 ppm Visibility Reducing Particles d 8 Hour (10 AM to 6 PM PST) 10-mile visual range when relative humidity is less than 70 ercent Source: Illingworth & Rodkin, Inc. /Acoustics • Air Quality a California standards for ozone, carbon monoxide (except Lake Tahoe), sulfur dioxide (1-hour and 24-hour), nitrogen dioxide, suspended particulate matter (PMIO and visibility-reducing particles) are values which are not to be exceeded. The standazds for sulfates, lead, hydrogen sulfide, and vinyl chloride aze not to be equaled or exceeded. If the standard is fora 1-hour, 8-hour, or 24hour average (all standards except for lead and the PMio annual standard), then some measurements may be excluded. In particular, measurements are excluded that the ARB determines would occur less than once per year on the average. b National standards other than for ozone and those based on annual averages or annual arithmetic means are not to be exceeded more than once a year. The ozone standard is attained if, during the most recent three-year period, the average number of days per year with maximum hourly concentrations above the standard is equal to or less than one. c ppm =parts per million, and µg/m3 =micrograms per cubic meter. d This standard is intended to limit the frequency and severity of visibility impairment due to regional haze and is equivalent to a ten-mile nominal visual range when relative humidity is less than 70 percent. 211 4.5 AIR QUALITY Terrabay Phase 11 and 111 SEIR an eight-hour averaging period. The existing standard is 0.12 ppm for cone-hour averaging period. The new PM2.5 standard is 50 ug/m3 fora 24-hour averaging period. 167 These new standards will take effect during the next several years. Although these standards are stricter than the existing national standards, California's current standards are stricter. 168 Ozone is the most prevalent of a class of photochemical oxidants formed in the urban atmosphere. The creation of ozone is a result of complex chemical reactions between hydrocarbons and oxides of nitrogen in the presence of sunshine. The major sources of these reactive hydrocarbons and oxides of nitrogen, known as ozone precursors, are combustion sources (such as factories and automobiles) and evaporation of solvents and fuels. The health effects of ozone are eye irritation and damage to lung tissues. Ozone also damages some materials (such as rubber) and may damage plants and crops. Carbon monoxide is an odorless colorless gas which is highly toxic. It is formed by the incomplete combustion of fuels, and its main source in the Bay Area is automobiles. Carbon monoxide's health effects are related to its affinity for hemoglobin in the blood. At high concentrations, carbon monoxide reduces the amount of oxygen in the blood, causing heart difficulties in people with chronic diseases, reducing lung capacity, and impairing mental abilities. Nitrogen dioxide is a reddish-brown toxic gas. It is one of the oxides of nitrogen which results from combustion. It is the only oxide of nitrogen which is toxic. However, other oxides of nitrogen, particularly nitric oxide, are converted to nitrogen dioxide in the presence of sunshine. Major sources of oxides of nitrogen are automobiles and industry. Nitrogen dioxide reduces visibility and is a pulmonary irritant. Sulfur dioxide is a colorless gas with a pungent irritating odor. It is created by the combustion of sulfur-containing fuels. This substance is known to oxidize to sulfur trioxide which combines with moisture in the atmosphere to form a sulfuric acid mist. Sulfur dioxide damages and irritates lung tissue and accelerates corrosion of materials. Suspended particulate matter consists of solid and liquid particles of dust, soot, aerosols, and other elements which are small enough to remain suspended in the air for a long period of time. A portion of the suspended particulate matter in the air is due to natural sources (such aswind-blown dust and pollen). Man-made sources include combustion, automobiles, field burning, factories, and unpaved roads. A portion of the particulate matter in urban atmospheres is also a result of photochemical processes. The effects of high concentrations on humans include aggravation of chronic disease and heart /lung disease symptoms. Non-health effects include reduced visibility and soiling of surfaces. Existing Air Quality South San Francisco is within the nine-county San Francisco Bay Area Air Basin. The BAAQMD operates air quality monitoring stations throughout the region, and the station closest to the project site is located on Arkansas Street in San Francisco. Monitoring data collected during the past ten years 167 µP~~ =micrograms per cubic meter. 168 The California ambient air quality standard for PMIO(which includes PMuu) is also 50 ug/m3, and the one-hour standard is 0.09 ppm for the highest one-hour period. These are considered stricter standards. 212 4.5 AIR QUALITY Terrabay Phase 11 and 111 SEfR indicate that air quality throughout the region has been improving steadily for most pollutants. Recent monitoring data compiled for the latest five-year period are shown in Exhibit 4.5-2. Exhibit 4.5-2 San Francisco Air Pollutant Summary, 1992-1996, Arkansas Street Pollutant Monitoring Data by Year Standard 1992 1993 1994 1995 1996 Ozone 03 Hi hest 1-hour average, m a 0.09 0.08 0.08 0.06 0.09 0.07 Number of violations 0 0 0 0 0 Carbon Monoxide CO Hi hest 1-hour average, m 20 8 7 6 5 5 Number of violations 0 0 0 0 0 Highest 8-hour average, m 9.0 6.4 5.1 4.5 4.4 ~ 3.9 Number of violations ~ 0 0 0 0 0 Nitro en Dioxide N02 Hi hest 1-hour average, m 0.025 i 0.09 0.08 0.09. 0.09 0.08 Number of violations 0 0 0 0 0 Sulfur Dioxide S02 Hi hest 1-hour average, m 0.025 ~ 0.04 0.04 0.02 0.04 0.04 Number of violations 0 0 0 0 0 Particulate Matter PM,o Hi hest 24- hour average, m3 ` 50 81 69 93 50 71 Violations/Sam les 9/61 5/61 6/61 0/61 2/61 Annual Geometric Mean, g/m3 30 27.6 25.1 24.7 22.1 21.4 Lead Pb Hi hest monthl avers e, g m3 1.5 j 0.02 0.02 0.03 0.02 0.01 Number of Violations 0 0 0 0 0 Source: California Air Quality Data, 1993, 1994, 1995, 1996, and 1997, California Air Resources Board. a ppm =parts per million. b PMIO and Pb usually are measured every sixth day (rather than contir:uously as the other pollutants are). For PMio "violations /samples" indicates the number of violations of the State standard which occurred in a give year and the total number of samples which were taken that year. c µg/m3 =micrograms per cubic meter. These data indicate that, except for PMto, there have been no recorded exceedances of either State or Federal ambient air quality standards. The State ambient air quality standard for PMto has been exceeded between none and nine times each year while the Federal standard has not been exceeded. Attainment Status and Regional Air Quality Planning The Federal Clean Air Act required the State Air Resources Board, based on air quality monitoring data, to designate as "nonattainment areas" parts of the State where the Federal ambient air quality standards were not met. As of 1982, the San Francisco Ba~• Air Basin had been a nonattainment area for ozone, carbon monoxide, and particulate matter. Thz 1979 Air Quality Plan was the adopted management plan for the region when the 1982 EIR was certified. 169 It then was replaced by the 169 Draft Environmental Impact Report for the Terrabay Development Project Environmental Impact Planning Corporation, August 1982 (198? EIR). 213 4.5 AIR QUALITY Terrabay Phase ll and 111 SEIR 1982 Bay Area Air Quality Plan which set forth a regional strategy to show how the Federal standards were to be attained by 1987. Despite improvement in air quality, the Bay Area did not meet the 1987 deadline for attainment of the Federal air quality standards for ozone and cazbon monoxide. Major new Federal and State legislation enacted since 1982 required expansion of regional air quality planning and control efforts. The Federal Clean Air Act Amendments of 1990 mandated a fresh attempt at attaining the national standards and required nonattainment areas to develop plans and strategies to reduce pollutants by certain increments or face imposition of sanctions (such as withholding of highway project funding). Concentrations of Federal nonattainment pollutants have been declining gradually in the Bay Area during the past decade. A request for redesignation to "maintenance area" for carbon monoxide has been submitted to the USEPA, since the area has not exceeded air quality standazds in more than seven years, and the USEPA redesignated the Bay Area as a "maintenance area" for ozone. The unusually hot summers of 1995 and 1996 caused violations of the Federal standards for ozone which prompted the USEPA to propose changing the Bay Area's designation back to nonattainment for ozone. State and local air quality officials aze urging the USEPA not to change the area's designation. There were no measured exceedances of the Federal ozone standard during 1997. The Bay Area remains as an ozone "maintenance" azea. With enactment of the California Clean Air Act of 1988, regional air quality planning has shifted emphasis from the Federal ambient standards to meeting the State ambient air quality standards. This legislation empowers regional air quality management districts with new authority to design, adopt, implement, and enforce comprehensive plans for attaining and maintaining both the Federal and the more stringent State air quality standards by the earliest practical date. Among its provisions, the California Clean Air Act provides districts with the authority to establish new controls on mobile sources of pollution. The California Clean Air Act required preparation of an azea-wide plan showing an annual five- percent reduction in air pollutant emissions throughout the basin or implement "all feasible measures on an expeditious schedule". The BAAQMD developed and adopted a plan in October 1991. The Bay Area 1991 Clean Air Plan ('91 CAP) imposed controls on stationary sources (factories, power plants, industrial sources, etc.) and transportation control measures (TCMs) designed to reduce emissions from automobile travel. 170 Since the plan did not provide for an annual five percent reduction in air pollutant emissions, it proposed the adoption of "all feasible measures on an expeditious schedule". The `91 CAP forecasted continued improvement in regional air quality. An analysis of carbon monoxide trends shows attainment of the standards throughout the Bay Area by the mid-1990s. However, implementation of the Plan would not provide for attainment of the State ozone standard even by the year 2000. The Bay Area 1994 Clean Air Plan ('94 CAP) updated the `91 CAP. This plan included a comprehensive strategy to reduce air pollutant emissions, focusing on control measures to be implemented during the 1994 to 1997 period. It also included control measures to be implemented from 1998 and beyond. Since the carbon monoxide standazd was attained in 1993, this plan focused on the reduction of ozone precursor emissions. 170 Bay Area '91 Clean Air Plan ('91 CAP), Bay Area Air Quality Management District, 1991. 214 =.5 AlR QUALITY Terrabay Phase // and 111 SE1R The '94 CAP was recently revised (as required every three years). This new plan, the Bay Area 1997 Clean Air Plan (`97 CAP), is a continuation of the strategy established in the `91 CAP and `94 CAP-xo reduce ozone precursor emissions and eventually attain the State ozone standazd. The `97 CAP includes changes in the organization and scheduling of some `94 CAP control measures, 12 new proposed stationary and mobile source control measures, and two new transportation control measures. AlR QUALITY -IMPACTS AND MITIGATION MEASURES Significance Criteria This 1998 SEIR determined that the project would result in a significant impact if it ~~as predicted to violate any air quality standard, contribute substantially to an existing or projects air quality violation, or expose sensitive receptors to substantial pollutant concentrations. The significance of the project was evaluated at both the local and regional levels as follows: Local Air Quality Impacts A significant impact on local air quality is defined in this 1998 SEIR as a predicted violation of the carbon monoxide standard or substantial contribution to an existing or projected violation of the carbon monoxide standard. That is, if the project would result in a violation of the carbon monoxide standazd which would be greater than the no project condition. A violation of the carbon monoxide standard is a modeled concentration in excess of 20 parts per million (ppm) for cone-hour averaging period or 9.0 ppm for aneight-hour averaging period. Regional Air Quality Impact A significant impact on regional air quality is defined as an increase in emissions of an ozone precursor pollutant (reactive organic gases and nitrogen oxides) or fine particulate matter (PMIo) of 80 pounds per day or greater. Construction Air Quality Impacts Since construction is temporary and transitory, air quality impacts vary substantially from day-to-day. The potential for dust clouds to impact sensitive receptors would be considered a potential to violate the PM,o air quality standard. This would be considered a sign~cant impact. Impacts and Mitigation Measures Impact 4.5-1 Short-Term Construction Impacts Dust generated during construction periods could result in both health and nuisance effects. Although temporary, this would be a significant impact. PS Construction activities would generate dust, especially during excavation and grading of hillsides and hauling of material. The applicant proposes grading to stabilize slopes and prepare the site. Phase II, Phase III, and hook ramps construction would involve the cutting of 1.2 million cubic }-ands, filling of about 0.8 million cubic yards, and export of about 0.4 million cubic yazds of material. This type of activity has the potential to affect local air quality temporarily, as well as create a nuisance to existing and new residents. The primary pollutant of concern is PlVi,~ which is a component of dust. Dust emissions would be generated primarily from disturbance of land areas, wind erosion of disturbed areas, vehicle activity on disturbed azeas, and movement of material (both on- and off-site). z~s 4.5 AIR OUAL/TY Terrabay Phase ll and 111 SE1R It is difficult to predict the amount of particulates emitted during this activity, since daily emissions would vary substantially from day-to-day. Dust emissions would depend on site activities, soil conditions, and meteorological conditions. For example, emissions would be substantially lower after periods of wet weather and highest during active construction periods coinciding with dry windy conditions. Studies conducted by the USEPA and California ARB indicate that uncontrolled construction-related emissions of total suspended particulates are about 80 pounds per day per acre disturbed and the PMIo portion is about 51 pounds per day per acre. These are approximate values and do not represent site- specific conditions or variations in day-today conditions. Local prevailing wind conditions in the area combined with local topography would tend to transport dust emissions towards the east. Given the size of the construction area, the amount of excavation and grading activity proposed, and duration of construction activities, dust emissions from construction activities could produce dust clouds which may impact sensitive receptors. This could expose sensitive receptors to concentrations of PMIO above the State ambient air quality standard. As a result, construction activities present a potentially significant impact to local air quality. Mitigation Measure 4.5-1 The Bay Area Air Quality Management District (BAAQMD) recommends the following measures for lazge construction areas located near sensitive receptors. The BAAQMD typically determines the level of significance based on the control measures implemented. These measures constitute all feasible control measures, with the addition of a disturbance coordinator to monitor compliance with the control measures and respond to neighborhood complaints. The disturbance coordinator shall be retained by the City and paid for by the project sponsor. The following controls shall be implemented throughout the construction area: • All active construction areas shall be watered at least twice daily and more often when conditions warrant. This measure would reduce emissions by at least 50 percent. • All trucks hauling soil, sand, and other loose materials shall be covered, or all trucks shall be required to maintain at least two feet of freeboard. • All unpaved access roads and parking areas at construction sites shall be paved, watered three times daily, or treated with (non-toxic) soil stabilizers. • All paved access roads, parking areas, and staging areas at construction sites shall be swept daily (with water sweepers). • Streets shall be swept daily (with water sweepers) if visible soil material is carried onto adjacent public streets. • Inactive construction azeas (previously graded areas inactive for ten days or more) shall be hydroseeded or treated with (non-toxic) soil stabilizers. • Exposed stockpiles (dirt, sand, etc.) shall be enclosed, covered, watered twice daily, or treated with (non-toxic) soil binders. • Traffic speeds on unpaved roads shall be limited to 15 miles per hour (mph). 216 4.5 AlR QUALITY Terrabay Phase ll and 111 SEIR • Sandbags or other erosion control measures shall be installed to prevent silt runoff to public roadways. ~. • Disturbed azeas shall be replanted with vegetation as quickly as possible (within one month of the disturbance). • Wheel washers shall be installed for all exiting trucks, or the tires or tracks shall be washed off all trucks and equipment leaving the site. • Excavation and grading activity shall be suspended when winds (instantaneous gusts) exceed 25 mph and cause visible clouds to extend beyond the construction site. Activities shall be suspended until the disturbance coordinator decides that the emissions from construction activities would be controlled (such as through additional watering or installation of wind fences). This measure could reduce dust emissions by up to 80 percent. • Wind breaks shall be installed, or trees /vegetative wind breaks shall be plant on windward sides(s) of construction areas, if conditions wan-ant, to prevent visible dust clouds from extending beyond the site. • The area subject to excavation, grading, and other construction activity shall be limited at any one time. • A disturbance coordinator, retained by the City and paid for by the project sponsor, shall be designated to be responsible for monitoring compliance with dust control measures and to respond to neighborhood concerns regarding air pollutant emissions (primarily dust) during construction. The project sponsor and coordinator shall be responsible for operating a neighborhood "hotline" for neighbors to voice complaints regarding air quality during construction. Significance after Mitigation Despite the variability of construction-related emissions, the Bay Area Air Quality Management District has found that the proposed dust control measures would reduce PM,o emissions significantly. Implementation of dust control measures listed in Mitigation Measure 4.5-1 would reduce emissions by more than 50 percent and prevent visible dust clouds from impacting sensitive receptors, thus reducing the severity of the impact to aless-than-significant level. Responsibility and Monitoring The project sponsor and subsequent developers of individual parcels would be responsible for incorporating the provisions of Mitigation Measure 4.5-1 into all contractors' contracts and into the CC&Rs for the Phase III site, and individual contractors ultimately would implement the measures. (CC&Rs would govern development activities by future owners of individual Phase III pazcels, thus requiring them to impose these measure on their contractors.) The City Engineer would have ultimate responsibility monitor these measures. Impact 4.5 2 Changes in Local Long-Term Air Quality Carbon monoxide levels attributable to traffic substantially affected by the project would be below State and Federal ambient air quality standards. This would be a less-than-significant impact. LTS Carbon monoxide is the pollutant of concern at the local level. High concentrations of this pollutant aze related to high volumes of motor vehicles and traffic congestion. In the Bay Area, carbon monoxide pollution is a potential problem during the late fall and winter when winds are light, 217 4.5 AlR QUALITY Terrabay Phase ll and 111 SEIR temperatures are cold and when stagnant atmospheric conditions persist which are caused by strong temperature-based inversions. Local carbon monoxide concentrations affected by the project were modeled using the Caline4 dispersion model. 171 The analysis was limited to intersections and roadways which would be substantially affected by the project where the highest carbon monoxide levels would be likely to result. Modeled concentrations from the roadways was added to background levels to predict overall carbon monoxide concentrations. A description of the modeling methodology and model inputs is contained in Appendix 7.6. The roadway segments or intersections analyzed in this assessment included: • U.S. 101 and ramp connectors to Bayshore Boulevard • Bayshore Boulevard • Sister Cities Boulevard /Bayshore Boulevazd /Airport Boulevard /Oyster Point Boulevard intersection • Sister Cities Boulevard /South San Francisco Drive intersection (Phase II entrance) • Hillside Boulevard /Jefferson Street /South San Francisco Drive intersection (Phase I entrance) This assessment evaluated project-related carbon monoxide levels for the existing conditions (1997), project conditions in 2000, and project conditions in 2010. Concentrations were predicted for one- and eight-hour averaging periods. These predicted levels aze shown in Exhibit 4.5-3. The results reported in Exhibit 4.5-3 represent the highest modeled concentration for each intersection or roadway segment. The contribution of U.S. 101 traffic was included in the modeling. The one-hour averages are compared against the one-hour State standard of 20 ppm and the eight-hour average is compared to the State standard of 9.0 ppm. Phase ll and /11 Development Results indicate that existing carbon monoxide levels could just exceed the State eight-hour standard at the Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard intersection. In the future, carbon monoxide concentrations along roadways substantially affected by the project would remain below ambient air quality standards. Cleaner emitting vehicles and cleaner burning fuels would off-set the projected increase in traffic. Hook Ramps The project would involve the reconstruction of the existing southbound off-ramp from U.S. 101 to Bayshore Boulevard and the construction of a new southbound on-ramp from Bayshore Boulevard to southbound U.S. 101. Bayshore Boulevazd would be slightly realigned. This project component is know as the "hook ramps". Carbon monoxide concentrations were also predicted for intersections affected by both development of the Terrabay Phase II and III sites and the hook ramps. Results of this assessment also are presented in Exhibit 4.5-3. The effect of ramp metering on carbon monoxide levels was evaluated. Vehicles using the on-ramp were assumed to stop at the bottom of the ramp and then accelerate to speeds of about 55 miles per hour over a short distance. As a result, vehicles would accelerate from stop to about 45 or 55 miles per hour (depending on freeway conditions). This rate of high 171 Caline4 is a computer model developed for predicting air pollutant concentrations near roadways. It is the latest in a series of line-source dispersion models developed by Caltrans. It is approved by the BAAQMD for predicting project related carbon monoxide concentrations. its =.5 AIR QUALITY Terrabay Phase Il and Ill SEIR Exhibit 4.5-3 Predicted Carbon Monoxide Concentrations Near the Ten-abay Site a Intersection / Modeled Concentration Roadway Segment Pro "ect Scenario One-Hour Ei ht-Hour Bayshore Boulevard Existin 1997 8 5.5 north of Oyster Point Yeaz 2000 Base 7 4.0 Boulevazd Year 2000 Base + Phase II 7 4.0 Year 2000 Base + Phase II + III 10 6.4 Year 2010 Base 5 3.1 Year 2010 Base + Phase II 5 3.6 Year 2010 Base + Phase II + III 7 4.2 Year 2020 without Hook Rams 6 ~ 3.9 Year 2020 with Hook Ram s ` 10 7.0 Sister Cities Boulevard / Existing 1997 13 9.1 Bayshore Boulevazd / Year 2000 Base 12 8.0 Airport Boulevard / Year 2000 Base + Phase II 12 8.1 Oyster Point Boulevard Year 2000 Base + Phase II + III 13 8.3 Year 2010 Base 7 4.8 Year 2010 Base + Phase II 7 4.8 Year 2010 Base + Phase II + III 7 ~ 4.9 Year 2020 without Hook Rams 7 5.1 Year 2020 with Hook Ram s ` 7 4.9 Sister Cities Boulevard / Existin 1997 8 5.4 South San Francisco Year 2000 Base 8 5.1 Drive (Phase II Site Year 2000 Base + Phase II 9 5.8 Entrance) Year 2000 Base + Phase II + III 9 5.7 Yeaz 2010 Base 5 3.6 Year 2010 Base + Phase II 5 3.7 Year 2010 Base + Phase II + III 5 3.8 Hillside Boulevard / Existino 1997 10 6.6 South San Francisco Year 2000 Base 9 5.7 Drive (Phase I Site Year 2000 Base + Phase II 9 5.7 Entrance) Year 2000 Base + Phase II + III 9 5.7 Yeaz 2010 Base 6 3.6 Year 2010 Base + Phase II 6 3.7 Year 2010 Base + Phase II + III 6 3.7 State Ambient Air uali Standard 20 9.0 Source: Illingworth & Rodkin a Project analysis includes hook ramps (unless noted) with ramp metering. b In parts per million (ppm). c Includes effects of ramp metering. 219 4.5 AIR QUALITY Terrabay Phase ll and 111 SEIR acceleration would result in substantial emissions, causing localized high levels of carbon monoxide. Results of this assessment indicate that carbon monoxide ambient air quality standards would not be exceeded with or without the project components, including effects of ramp metering. The project is not predicted to cause or contribute to any exceedances of State or Federal ambient air quality standards for carbon monoxide. As a result, the project would have aless-than-significant impact on long-term, local air quality. Mitigation Measure 4.5-2 No mitigation would be required. Impact 4.5-3 Changes in Regional Long-Term Air Quality Direct and indirect emissions of air pollutants associated with full buildout of the project could inter`ere with the efforts within the region to attain ozone and PM,o air quality standards. Thus, while the incremental change between the currently and previously proposed Phase ll and Ill projects would be less-than-significant, the cumulative impact of full Terrabay project development (Phases 1, ll, and Ill) would exceed standards tightened since examination in the 1982 EIR and 1996 SEIR. SU The project would result in generation of air pollutant emissions which would affect the entire Bay Area air basin. These emissions could interfere with the region's efforts to reduce exceedances of ambient air quality standards for ozone and PMIO• To evaluate this impact, emissions of ozone precursor pollutants (reactive organic gases (ROG) and nitrogen oxides (NOS) and PMto were calculated. These emissions account for both vehicle travel generated by the project and space and water heating from the proposed land uses. Emissions from vehicle travel were calculated using the URBEMISS model. Inputs for this model included conditions recommended by the BAAQMD and project specific trip generation factors provided by the 1998 SEIR traffic engineer. As recommended by the BAAQMD, an additional PMto emission factor was included to account for reintrained roadway dust. The URBEMISS model calculates emissions of total organic gases. Therefore, a factor of 0.92 was applied to convert to ROG. The ROG portion is considered to be the portion of concern with respect to ozone formation. Emissions factors to account for water and space heating and for energy consumption were obtained from the South Coast Air Quality Management District's CEQA Guidelines. (The Bay Area Air Quality Management District CEQA Guidelines do not provide such emission factors.) Emissions from the Precise Plan evaluated in this 1998 SEIR were compared to the emissions expected from the 1996 Specific Plan assessed by the 1996 SEIR. 172 The differences in emissions for each phase are shown in Exhibit 4.5-4. Emissions for Phase I essentially would be the same due to buildout similar to that described in the 1996 SEIR, but emissions for Phases II and III would be less with the currently proposed Phase II Precise Plan and Phase III development concept. As a result, the change between the currently and previously proposed Terrabay Phase II and III projects would not represent a significant impact on regional air quality. 172 Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996. 220 4.5 AlR QUALITY Terrabay Phase 11 and 111 SE1R Exhibit 4.5-4 Difference in Regional Air Pollutant Emissions befween 1996 and 1998 Plans Project Phase Year 2000 Air Pollutant Emissions Year2010 Air Pollutant Emissions ounds er da ounds er da ROG NO, I PM~o ROG NOx PM~o Phase I 0 0 I 0 0 0 0 Phase II -14 -15 I -13 -6 -12 -13 Phase III -17 j -15 I -21 -7 -9 -20 Total (all bases) -31 -30 -34 -14 -20 -33 As shown in Exhibit 4.5-5, emissions associated with full buildout of the Ten-abay project (Phases I, II, and III) would exceed 80 pounds per day for each pollutant. Therefore, the cumulative impact would be significant. Exhibit 4.r5 Terrabay Emissions of Regional Air Pollutants Project Phase Year 2000 Air Pollutant Emission Year 200 Air Pollutant Emissions ounds er da ounds er da ROG I NOS I PMto ROG NOS PMfo Phase I 42 44 j 41 21 32 40 Phase II 63 64 I 64 31 45 61 Phase III 95 ~ 124 j 108 46 92 104 Total (all bases) 200 232 213 98 169 205 The previous 1982 EIR and 1996 SEIR concluded that full build out of Phases I, II, and III would result in emissions exceeding 150 pounds per day which would be considered significant. Since the time those findings were made, the BAAQ~II~ has adopted stricter significance thresholds of 80 pounds per day for each regional pollutant. Regional pollutant emissions for all project phases are predicted to exceed these thresholds in the year 2000. Even with reduced vehicle emission rates predicted for the year 2010, regional emissions from full buildout of the proposed Terrabay Plan would exceed 80 pounds per day for each of the pollutants. This would constitute a significant impact to regional air quality. Mitigation Measure 4.5-3 Air pollutant emissions which would be regionally significant could be reduced from motor vehicles through a reduction in vehicle trips, vehicle miles traveled, and reduced traffic congestion. The following measures either are included in the project design or shall be implemented by the project sponsor to reduce regionally significant air pollutant emissions. Coordinated traffic signals shall be installed to provide more efficient levels-of-service at intersections substantially affected by project traffic. The project includes roadway improvements to Sister Cities Boulevard which have already been constructed. Additional intersection improvements are proposed along Bayshore Boulevard as part of Phase III. This measure could reduce total year 2000 project emissions by ten (10) pounds per day of ROG, seven (7) pounds per day of NOS, and one (1) pound per day of PM,o. The U.S. 101 southbound freeway off ramp shall be reconstructed and a new U.S. 101 on ramp shall be constructed (the "hook ramps"). This measure would allow direct access on to the freeway, eliminating emissions associated with congestion at local intersections which provide 221 4.5 AlR QUALITY Terrabay Phase 11 and l1l SEIR access to southbound U.S. 101. This measure could reduce total year 2000 project emissions by five (5) pounds per day of ROG, sox (6) pounds per day of NOx, and seven (7) pounds per day-0f PM,o. Efficient transit service shall be provided to Caltrain, BART, the airport, and major employment centers. In the future, it is likely that BART and Caltrain would provide the most efficient access to downtown San Francisco, San Francisco International Airport, and other major employment centers along the Peninsula. It is difficult to assess the reduction in pollutants from this measure. However, a reduction in vehicles trips of at least three percent seems reasonable to expect. As a result, this measure could reduce total year 2000 project emissions by six (6) pounds per day of ROG, seven (7) pounds per day of NOx, and six (6) pounds per day of PM,o. Bus shelters, easy pedestrian access, and bicycle lanes shall be provided in the project design to facilitate alternative modes of transportation. This measure could reduce total year 2000 project emissions by ten (10) pounds per day of ROG, 12 pounds per day of NOx, and 11 pounds per day of PM,o. Use of public transit at Phase III commercial development shall be provided and promoted. For instance, Caltrain and bus schedules could be made available to hotel patrons. Shuttles to the airport and other major trip attractors could provide a good alternative to single occupant car use. This measure, although difficult to assess, could reduce total year 2000 project emissions by six (6) pounds per day of ROG, seven (7) pounds per day of NOx, and six (6) pounds per day of PMto. Fireplaces shall be equipped with certified wood burning fireplace inserts which meet Federal emission standards. It is difficult to assess the overall effectiveness of this measure due to the infrequent use of fireplaces. However, the measure would reduce PMto emissions from fireplaces by up to 90 percent. The applicant proposes to include outdoor electrical outlets and natural gas subs to avoid the use of gasoline-powered landscape equipment. This would provide a minor reduction in overall emissions of ozone precursor air pollutants. 173 Significance after Mitigation Implementation of these measures would reduce emissions of regional air pollutants by five to 15 percent. This reduction would not reduce emissions from full buildout of the project below BAAQMD significance thresholds. Therefore, the impact would remain significant and unavoidable. Responsibility and Monitoring Implementation of these mitigation measures would be the responsibility of the project sponsor in coordination with the San Alateo County Transit District. The project sponsor would have overall responsibility for this measure, and the City of South San Francisco would be responsible for monitoring the measure. 173 Letter to Nichols • Berman from Mark Day, The Dahlin Group (project sponsor's architect), September 11, 1997. ??~ 4.6 NOISE NOISE -THE SETTING Background Information about Noise The City of South San Francisco defines "noise" as a sound or series of sounds which are intrusive, irritating, objectionable, and / or disruptive to daily life. The objectionable nature of sound can be caused by its pitch or its loudness. Pitch is the height or depth of a tone or sound, depending on the relative rapidity (frequency) of the vibrations which produce it. Higher pitched signals sound louder to humans than sounds with a lower pitch. Loudness is intensity of sound waves combined with the reception characteristics of the ear. Intensity may be compared with the height of an ocean wave in that it is a measure of the amplitude of the sound wave. Several noise measurement scales are used to describe noise in a particular location. A decibel (dB) is a unit of measurement which indicates the relative amplitude of a sound. Zero on the decibel scale is based on the lowest sound level a healthy unimpaired human ear can detect. Sound levels in decibels are calculated on a logarithmic basis. An increase of ten decibels (10 dB) represents aten-fold increase in acoustic energy, while 20 dB is 100 times more intense, 30 dB is 1,000 times more intense, etc. The subjective noisiness or loudness of a sound are related to its intensity. Each ten-decibel increase in sound level is perceived as an approximate doubling of loudness over a fairly wide range of intensities. Technical terms are defined in Exhibit 4.6-1. There are several methods of characterizing sound. The most common in California is the A-weighted sound level or dBA. This scale gives greater weight to the frequencies of sound to which the human ear is most sensitive. Representative outdoor and indoor noise levels in units of dBA are shown in Exhibit 4.~2. Because sound levels can vary markedly over a short period of time, a method must be used to describe either the average character of the sound or the statistical behavior of the variations. Environmental sounds most commonly are described in terms of an average level which has the same acoustical energy as the sum of all the time-varying events. This energy-equivalent sound /noise descriptor is called Lam. The most common averaging period is hourly, but L~ can describe any series of noise events of arbitrary duration. The scient~c instrument used to measure noise is the sound level meter. Sound level meters can accurately measure environmental noise levels to within about one decibel (± 1 dBA). Various computer models are used to predict environmental noise levels from sources (such as roadways and airports). The accuracy of the predicted models depends on the distance the receptor is from the noise source. Close to the noise source, the models are accurate to within about one to two decibels (± 1-2 dBA). Since the sensitivity to noise increases during the evening and at night -because excessive noise interferes with the ability to sleep - 24-hour descriptors have been developed which incorporate artificial noise penalties added to quiet-time noise events. The Community Noise Equivalent Level (CNEL) is a measure of the cumulative noise exposure in a community which adds alive- decibel (5 dB) penalty to evening (7:00 PM-10:00 PM) and aten-decibel penalty (10 dB) to nocturnal (10:00 PM - 7:00 AM) noise levels. The City of South San Francisco uses the CNEL descriptor. The Day /Night Average Sound Level (L~) is essentially the same as CNEL except that the evening time period is 223 4.6 NOISE Terrabay Phase ll and 111 SE1R Exhibit 4.6-1 Definitions of Acoustical Terms Term Definitions Decibel, dB A unit describing the amplitude of sound, equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to the reference pressure, which is 20 micropascals (20 micronewtons per square meter). Frequency, Hz The number of complete pressure fluctuations per second above and below atmospheric pressure. A-Weighted Sound Level, The sound pressure level in decibels as measured on a sound level meter dBA using the A-weighting filter network. The A-weighting filter de-emphasizes the very low and very high frequency components of the sound in a manner similar to the frequency response of the human ear and correlates well with subjective reactions to noise. All sound levels in this report are A-weighted. L01~ L10~ L50> L90 The A-weighted noise levels that are exceeded one, ten, 50, and 90 percent of the time during the measurement period. Equivalent Noise Level, L~ The average A-weighted noise level during the measurement period. Community Noise Equivalent The average A-weighted noise level during a 24-hour day, obtained after Level, CNEL addition of five decibels in the evening from 7:00 AM to 10:00 PM and after addition of ten decibels to sound levels in the night between 10:00 PM and 7:00 AM. Day /Night Noise Level, Ldn The average A-weighted noise level during a 24-hour day, obtained after addition of [en decibels to levels measured in the night between 10:00 PM and 7:00 AM. Ln,~, Lin The maximum and minimum A-weighted noise level during the measurement period. Ambient Noise Level The composite of noise from all sources near and far. The normal or existing level of environmental noise at a given location. Intrusive That noise which intrudes over and above the existing ambient noise at a given location. The relative intrusiveness of a sound depends upon its amplitude, duration, frequency, and time of occurrence and tonal or informational content as well as the prevailing ambient noise level. Source: Illingworth & Rodkin, Inc., Acoustical Engineers 224 4.6 NOISE Terrabay Phase ll and 111 SE1R Exhibit 4.&-2 Typical Sound Levels Measured in the Environment and Industry At a Given Distance A-Weighted Sound Noise Subjective from Noise Source Level a Environments Impression 140 Civil Defense Siren (100') 130 Jet Takeoff (200') 120 Pain threshold 110 Rock music concert Diesel Pile Driver (100') 100 Ve loud 90 Boiler room Freight Cars (50') 85 Printing ress lant Pneumatic Drill (50') 80 Freeway (100') 75 In kitchen with garbage Vacuum Cleaner (10') 70 dis osal runnin Moderately loud 60 Data rocessin~ center Licht Traffic (100') 50 De artment store Lar e Transformer (200') 45 40 Private business office Quiet Soft Whis er (5') 30 Quiet bedroom 20 Recording studio 10 Threshold of hearine 0 Source: Illingworth & Rodkin, Inc., Acoustical Engineers a In decibels. dropped and all occurrences during this three-hour period are grouped into the daytime period. Effects of Noise Hearing Loss While physical damage to the ear from an intense noise impulse is rare, a degradation of auditory acuity can occur even within a community noise environment. Hearing loss occurs mainly due to chronic exposure to excessive noise but may be due to a single event such as an explosion. Natural hearing loss associated with aging also may be accelerated from chronic exposure to loud noise. The Occupational Safety and Health Administration (OSHA) has a noise exposure standard which is set at the noise threshold where hearing loss may occur from long-term exposures. The maximum allowable level is 90 dBA averaged over eight hours. If the noise is above 90 dBA, the allowable exposure time is correspondingly shorter. Sleep and Speech Interference The thresholds for speech interference indoors are about 45 dBA (if the noise is steady) and above 55 dBA (if the noise is fluctuating). Outdoors the thresholds are about 15 dBA higher. Steady noise of sufficient intensity (above 35 dBA) and fluctuating noise levels above about 45 dBA have been shown to affect sleep. Interior residential standards for multi-unit housing are set by the State of California at 45 dBA Ld,,. The highest steady traffic noise level during the daytime typically is about equal to the Ld,,, and nighttime levels are ten decibels (10 dBA) lower. The zzs 4.6 NOISE Terrabay Phase 11 and Ill SEIR standard is designed for sleep and speech protection, and most jurisdictions apply the same criterion for all residential uses. Typical structural attenuation is 12-17 dBA with windows open. With closed windows in good condition, the noise attenuation factor is about 20 dBA for an older structure and 25 dBA for a newer dwelling. Sleep and speech interference is possible, therefore, when exterior noise levels are about 57-62 dBA L~ with open windows and 65-70 dBA Ld with windows closed. Levels of 55-60 dBA are common along collector streets and secondary arterials while levels of 65-70 dBA are typical for aprimary /major arterial. Noise levels of 75-80 dBA are normal at the first row of development outside a freeway right-of-way. In order to achieve an acceptable interior noise environment, bedrooms facing secondary roadways need to be able to have their windows closed, and those facing major roadways and freeways typically need special glass windows. Annoyance Attitude surveys are used for measuring annoyance felt in a community about noise intruding into homes or affecting outdoor activity areas. Such surveys have determined that interference with speech, sleep, rest, radio, and television and house vibrations cause annoyance. The Ld„ as a measure of noise has been found to provide a valid correlation of noise level and the percentage of people annoyed. People have been asked to judge the annoyance caused by aircraft noise and ground transportation noise. There continues to be disagreement about the relative annoyance of these different sources. When measuring the percentage of the population highly annoyed, the threshold for ground vehicle noise is about 55 dBA Lam. At an L~ of about 60 dBA, approximately two percent of the population is highly annoyed. When the L~ increases to 70 dBA, about 12 percent of the population is highly annoyed. This results in an increase of about one percent per dBA between an L~ of 60 and 70 dBA. Between an L~ of 70 and 80 dBA, each decibel increase increases the percentage of the population highly annoyed by about two percent. People appear to respond more adversely to aircraft noise. When the L~ is 60 dBA, approximately ten percent of the population is believed to be highly annoyed. Each decibel increase to 70 dBA adds.about two percent more people who are highly annoyed. Above 70 dBA, each decibel increase results in about a three percent increase in the percent of the population highly annoyed. Existing Noise Environment The project site is affected by noise from several sources including vehicular traffic, aircraft, and trains. The eastern part of the Phase II and the Phase III site is subject to noise from U.S. Highway 101 (U.S. 101). Along the southern and western parts of the site, vehicular tralfc on Hillside Boulevard and Sister Cities Boulevard affects the adjacent project area. Aircraft from San Francisco International Airport (SETA) generate noise levels which are heard throughout the project site. A noise monitoring survey was conducted in March 1998 to update the noise monitoring data for the site. Exhibit 4.6-3 shows the site, surrounding study area, and noise levels measured. Monitoring sites designated L1 and L2 were long-term sites where noise levels were monitored fora 24-hour period. Short-term (five- to 15-minute) noise measurements were conducted at monitoring sites S 1 through S6. The CNEL levels were estimated for the short-term sites by correlating with the long-term sites. During the short-term measurements, the noise sources affecting the area were noted. Noise levels at monitoring sites S1 and S2 were dominated by vehicular tra.fnc on U.S. 101 and Bayshore Boulevard. Site S 1 was close to the roadways and at grade while Location S2 was about 600 feet from the highway but 50 feet above it. At this higher elevation, there was a better view of the roadway, and the highway noise was still substantial. At monitoring site S3, the topography shielded the highway noise resulting in substantially louder noise levels. Aircraft flying over Brisbane produced maximum noise levels of 60-62 dBA at monitoring site S3. At monitoring site S4, two 747 airplanes departing SFIA generated maximum instantaneous noise levels of 65-68 dBA. Vehicular traffic also contributed to the noise levels at this location. 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At monitoring site S6, a departing 747 generated a maximum noise level of 68 dBA. One significantly louder plane was monitored at this site as generating a maximum noise level of 82 dBA. This was likely a Stage 2 aircraft, one of the older type still operating (compared with newer "quieter" aircraft). Typical maximum noise levels resulting from observed aircraft were in the 60-70 dBA range while the loudest aircraft generated 82 dBA. Maximum noise levels generated by observed aircraft were substantially lower than the 90 dBA described in the 1982 EIR. 174 The lower aircraft noise levels are also reflected in the noise contours for the airport. The 65 CNEL noise impact boundary for the quarter ending December 31, 1996 shows the site to be located well outside the 65 dB contour. Noise levels at fixed airport noise monitoring Sites 3 and 7, which bracket the project site, were 57 and 5~ CNEL, respectively. NOISE -SIGNIFICANCE CRITERIA This analysis used the criteria listed below to determine the significance of the project's noise impacts. These criteria represent professional standards and practices routinely. used to assess noise impacts in EIRs, augmented by objectives and policies in the 1990 General Plan Noise Element. 1990 General Plan Noise Element The Noise Element of the South San Francisco General Plan sets forth the City's objectives and policies regarding environmental noise. Policy N-1 states: All new noise sensitive land uses developed within areas impacted by 65 dB CNEL or more, regardless of the noise source or source(s), shall incorporate mitigation measures to ensure that interior noise levels do not exceed 45 dB CNEL. The Noise Element states the following objective: To eliminate potential aircraft noise impacts to new land use proposals. Policy N-8 implements this objective as follows: The City shall evaluate development proposals based on the criteria contained in Table N-1 [Exhibit 4.6-4] and shall only approve proposals that are consistent with criteria contained therein. These criteria are consistent with the policies of the San Mateo Airport Land Use Commission's (ALUC) plan for the San Francisco International Airport environs. 174 Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, August 1982 (1982 E/R). 228 4.6 NOISE Tenabay Phase Il and 11l SE1R Exhibit 4.6-4 Aircraft Noise /Land Use Compatibility Guidelines Land Use CNEL Range General Land Use Criteria Less than 65 Satisfacto ;nos ecial insulation re uirements. Residential 65 to 70 Development requires analysis of noise reduction requiremenu and noise insulation as needed. More than 70 Develo went should not be undertaken. Less than 70 Satisfacto ;nos ecial insulation re uirements. Commercial 70 to 80 Development requires analysis of noise reduction requirements and noise insulation as needed. More than 80 Atrport-related development only; special noise insulation should be provided. Less than 75 Satisfactor ;nos ecial insulation re uirements. Industrial 75-85 Development requires analysis of noise reduction requirements and noise insulation as needed. Less than 85 Arport-related development only; special noise insulation should be provided. O Less than 75 Satisfacto ;nos ecial insulation re uirements. pen More than 75 Avoid uses involving concentrations of eo le or animals. Source: cienerat Ytan Noise Clement, catty oT South San Francisco, and Airport land, Use Plan, San Francisco International Airport The Noise Element states the following further objective: To mitigate and / or reduce noise impacts from vehicular traffic. Policy N-11 implements this objective as follows: Development proposals located within the 65 dB CNEL contour due to traff c noise shall include analysis by a qualified Acoustical Ena neer so as to determine appropriate measures to mitigate traffic noise impacts. City Noise Ordinance The City also has adopted a noise ordinance. 175 The ordinance limits noise from any individual piece of construction equipment to 90 dBA measured at a distance of 25 feet and provides that construction period noise levels at any point outside of the project construction area shall not exceed 90 dBA. State Building Code Title 24 of the California Code of Regulations establishes minimum noise insulation performance criteria to protect people inside new hotels, motels, apartment houses, and dwellings other than single- family detached units. 176 Interior noise with windows closed attributable to exterior sources shall not exceed an annual average level of 45 dBA CNEL (or Lam) in any habitable room. Acoustical analysis 175 South San Francisco Municipal Code, Chapter 8.32 Noise Regulations, Section 8.32-050, February 1991. 176 California Code of Regulations, Title 24, Building Standards. 229 4.6 NOISE Terrabay Phase 1l and Ill SEIR are required for projects subject to these standards located within a 60 dBA CNEL contour to show that buildings have been designed to limit intruding noise to the allowable 45 dBA CNEL interior noise level before issuance of a building permit. California Environmental Quality Act The California Environmental Quality Act (CEQA) includes qualitative guidelines for determining the significance of adverse environmental noise impacts. According to Appendix G of the State CEQA Guidelines, a "substantial" increase in noise at a sensitive location such as a residence is considered to cause a significant adverse effect. IMPACTS AND MITIGATION MEASURES Impact 4.6-1 Construction Noise Impacts During construction periods, noise levels would be elevated outside existing homes located across Hillside Boulevard and Sister Cities Boulevard from the Phase ll residential development. This would constitute a significant short-term impact. S Construction activities generate noise. The noisiest activities associated with construction on the residential development sites would be the grading activities, followed by the noise associated with the pouring of foundations, and the erection of buildings. In addition, activities associated with the construction of infrastructure, including roadways and utilities, also would generate noise. Exhibit 4.6-5 shows noise levels associated with typical construction equipment, and Exhibit 4.6-6 shows hourly average construction noise levels generated at residential construction sites. Construction activities at the Terrabay Phase II site typically would occur at a distance of at least 300 feet from the nearest non-Terrabay residences. The 300-foot buffer distance would reduce noise levels 15 decibels below those shown in Exhibits 4.6-5 and 4.6-6. During busy construction periods, construction noise levels would be audible at the neazest residences and would be elevated five to ten decibels (~-10 dB) above existing ambient levels. Based on the experience in Phase I, most site grading can be completed by conventional ripping and scrapers. However, parts of the Phase II (Point) and Phase III sites may require controlled blasting. Controlled blasting also was required during Phase I grading, using line drilling, time chazges, and blasting mats to cover the shot points. No adverse effects were noted during the blasting for Phase I. Sensitive receptors were about the same distance from the Phase I blasting sites as the Phase II sites. No complaints are known to have been received from neighbors in the area. (Phase III sites would be even farther away.) Therefore, no adverse effects aze expected for blasting required for Phases II or III provided that the same type of precautions aze taken and depending on when construction would occur on the Phase III site. If phased as proposed, Phase II and III site preparation would occur simultaneously. However, completion of Phase II housing units in the Point before Phase III site construction involving blasting could be detectable by new Terrabay residents. Similarly, completion of Phase II housing in the Commons in advance of development in the Point involving blasting could be detectable by the new Terrabay residents. The Phase III site is adjacent to U.S. 101. Apart from future Phase II (Point) site residents, no sensitive receptors currently exist in areas near the construction site which could be affected by construction noise. Furthermore, noise from U.S. 101 would mask construction activities in Phase III. No noise impacts would result from the Phase III construction activities. 230 4.6 NCISE Terrabay Phase 11 and 111 SE/R Exhibit 4.6-5 Construction Equipment Noise Level Range A-Weighted Noise Level a 60 65 70 75 80 85 90 95 100 105 Earthmovin Com actors (Rollers) ?3 87 Front loaders 71 97 Backhoes 71 93 Bulldozers 75 9~ Scra ers, graders 77 93 Pavers 83 93 Trucks 70 95 Materials' Handlin Concrete mixers 70 90 Concrete um s 75 85 Cranes (movable) 75 97 Cranes (derrick) 86- 89 Stationa Pum s 68 80 Generators 68 83 Com ressors 67 97 lm act E ui ment Pneumatic wrenches 83 89 Jackhammers and rock drill 77 99 Pile drivers ( eak) 89 105 Others Vibrators 67 83 Saws 67 94 Source: Handbook of Noise Control, Cyril Hams, 1979. a Decibels (dB) at 50 feet. Exhibit 4.6-6 Typical Ranges of Energy Equivalent Noise Levels at Construction Sites a Activity .Type -of Development Housing Ofbce Building, Hotel, Industrial, Parking Garage, Religious, Public Works, Roads Hospital, School, Amusement & & Highways, Sewers, _ Public Works Recreation, Store, Trenches Service Station b c b c b c b c Ground Clearing 83 83 84 84 84 83 8~ 84 Excavation 88 75 89 79 89 71 88 78 Foundations 81 81 78 78 77 77 88 88 Erection 81 65 87 75 84 72 79 78 Finishin 88 72 89 75 89 74 8t 84 Source: Legal Compilation on Noise, U.S. Environmental Protection Agency. a 1,~ in dBA. b All pertinent equipment at site. c Minimum required equipment present at site. 231 4.6 NOISE Terrabay Phase /l and ll1 SE1R Mitigation Measure 4.6-1 The following measures shall be required to reduce the project's short-term construction noise impacts to ales-than-significant level: • Construction Scheduling Noise-generating construction activities, including truck traffic going to and from the site for any purpose, and maintenance and servicing activities for construction equipment, shall be limited to the hours stipulated by the City's Noise Ordinance which are 8:00 AM to 8:00 PM on weekdays, 9:00 AM to 8:00 PM on Saturdays, and 10:00 AM to 8:00 PM on Sundays. I ~~ • Mufflers and Maintenance All equipment used on the project site shall be adequately muffled and maintained. All internal combustion engine-driven equipment shall be fitted with intake and exhaust mufflers which are in good condition. Use of good mufflers with quieted compressors on all non-impact tools should result in a maximum noise level of 85 dBA when measured at a distance of 50 feet. • Idling Prohibitions Powered construction equipment shall be turned off when not in use. • Equipment Location and Shielding Stationary noise-generating construction equipment shall be located as far as possible from nearby residences. • Blasting Blasting noise control measures used in Phase I, including line drilling, time delayed charges, and blasting mats, shall be used in Phase II and III where blasting is required. Blasting shall be restricted to the hours of 8:00 AM to 5:00 PM. • Noise Disturbance Coordinator A project construction supervisor shall be designated as a "noise disturbance coordinator" who would be responsible for responding to any local complaints about construction noise (as was done for Phase I site development). The disturbance coordinator shall determine the cause of the noise complaints (such as starting too eazly, bad muffler, etc.) and shall require implementation of reasonable measures warranted to correct the problem. The telephone number of the disturbance coordinator also shall be posted conspicuously at the construction site. Significance after Mitigation Mitigation Measure 4.6-1 would mitigate construction noise to a less- than-significant level. Responsibility and Monitoring Environmental and entitlement review and permit approval for each phase of development shall be conditioned on incorporation of Mitigation Measure 4.6-1 in contracts of all subsequent contractors involved in site preparation and development activities. Building permits shall be granted contingent on full compliance with the measures. t ~~ Ibid. 232 4.6 NOISE Terrabay Phase ll and 111 SEIR Impact 4.6-2 Land Use Compatibility Impact Proposed uses in Phase Il and Phase ll1 would be exposed to noise levels which .. would exceed those considered satisfactory for the intended uses. This impact would be considered significant. S Parts of the Phase II Terrabay Woods and Commons neighborhoods are located adjacent to Sister Cities Boulevard, and Terrabay Point overlooks the Sister Cities Boulevard /Bayshore Boulevard intersection and U.S. 101 corridor. The current worst case noise exposure the Woods and Commons neighborhoods is a CNEL of about 64 dB at residential lots proposed closest to and overlooking Sister, Cities Boulevard. The Point would be exposed to noise levels of up to a CNEL of 70 dB at the southeast corner overlooking the roadways. Noise and land use compatibility evaluations must be based on the existing or future noise environment whichever is higher. Roadway traffic noise would be the dominant noise source affecting the proposed residential land uses. Traffic volumes for the year 2010 were compared to existing traffic volumes to determine the future noise exposure. Noise levels along Sister Cities Boulevard are calculated to increase about three decibels (3 dB) with or without the contribution of project-generated traffic. Therefore, the worst case noise exposure of the Woods and Commons neighborhoods would increase to a level of 67 dB CNEL by the year 2010, exceeding the 65 dB CNEL significance threshold. Phase III commercial development would include hotels, restaurants, retail, and mixed-use (retail, restaurant, and office) space. Proposed building sites currently are exposed to a CNEL of about 74-75 dB along the Bayshore Boulevard / U.S. 101 corridor. Bayshore Boulevard traffic noise levels are predicted to increase about two to three decibels (2-3 dBA) as a result of increased traffic by the year 2010. U.S. 101 traffic noise is calculated to increase less than one decibel (1 dBA). The overall increase in noise levels is predicted to be about one decibel (1 dB). The City's aircraft noise and land use planning guidelines are applicable to traffic noise exposure. Proposed Phase III land uses would be considered satisfactory up to a CNEL of 70 dB. Between a CNEL of 70-80 dB (the projected noise exposure), the guidelines state that "new construction or development should be undertaken only after an analysis of noise reduction requirement is made and needed noise insulation features included in the design". The hotels and multi-unit housing also would be subject to the requirements of the State Building Code. The State Building Code would require a detailed noise assessment before building design to determine and ensure incorporation of necessary noise control treatments in the design of buildings to achieve the 45 dBA CNEL interior noise limit. In relation to aircraft noise exposure discussed above, the site currently is exposed to a CNEL noise level of less than 60 dB for aircraft noise. Therefore, all residential buildings and other noise sensitive buildings on both the Phase II and III sites would comply with City and State noise and land use compatibility guidelines. The noise monitoring survey conducted for this 1998 SEIR indicated that single-event maximum noise levels from individual aircraft overflights typically are below 70 dBA. One noisier plane (believed to be a Stage II aircraft) generated a maximum noise level of 82 dBA. Standard California construction with the windows closed would be expected to provide at least 20 dBA of noise reduction, resulting in typical aircraft overflight noise of lower than 50 dBA, thus complying with the interior L,,,a,~ level of 55 dBA suggested by the Federal Aviation Administration (FAA). However, the monitoring survey did indicate that the noisiest aircraft would generate noise levels exceeding the 55 dBA L,I,~ goal for single-event noise. Mitigation Measure 4.6-2 In order to reduce potential noise and land use compatibility impacts to a less than-significant-level, the project sponsor shall retain a qualified Acoustical Engineer to prepare a detailed acoustical analysis and mitigation plan pursuant to Title 24 of the California Code of 233 4.6 NOISE Terrabay Phase ll and lil SEIR Regulations. The report shall be submitted to the City for review and approval before issuance of building permits. The report shall include a detailed acoustical analysis of noise reduction requirements and specifications for each project phase, in accordance with land use /noise level compatibility standards established by the State and set forth in the City's Noise Element. The identified noise reduction requirements and specifications then shall be included in the siting or design of individual housing units or hotels: Noise levels in backyards of homes proposed adjacent to and overlooking the Sister Cities Boulevazd-Hillside Boulevard corridor and Sister Cities Boulevard /Oyster Point Boulevard intersection shall be mitigated with a noise barrier. The proposed upsloping geometry to a graded building pad would provide an excellent opportunity to mitigate with a property line barrier. Calculations based on the Precise Plan grading plans indicate that asix-foot high barrier measured above the rear property line elevation would be appropriate at locations shown on Exhibit 4.6-7. To be effective, the barrier must be constructed airtight over its face and at the base and have a minimum surface weight of three pounds per square foot. Suitable materials include wood, masonry block, precast masonry, or precast concrete panels. If the barrier is constructed of wood, a post and panel or board and batten construction method should be used to eliminate sound leaks. Forced air mechanical ventilation shall be provided pursuant to residential building sound insulation requirements so windows may be kept closed at the discretion of building occupants to control noise. Additional building sound insulation treatments (such as sound rated windows and doors) would likely be required in parts of the Point neighborhood and for the hotels overlooking U.S. 101. The interior CNEL shall be reduced to a level of 45 dB or less to conform with City General Plan and State Building Code requirements. The noise analysis also shall include adequate consideration of aircraft noise to achieve the FAA's recommended maximum single-event noise level of 55 dBA in bedrooms of housing units and also shall be applied to proposed hotel rooms. Significance After Mitigation Implementation of Mitigation Measure 4.6-2 would reduce the noise and land use compatibility impacts to less-than-significant levels. Implementation of Mitigation An acoustical report including noise reduction measures shall be required before approval of a building permit. The report shall be submitted pursuant to City (Noise Element) and State (State Building Code) requirements. Acoustical mitigatiori measures which aze likely to be identified in the report include sound rated windows and doors, forced air mechanical ventilation, sound ratings for through-the-wall air conditioning units, special wall construction details, etc. Impact 4.6-3 Traffic Noise Impacts Traffic-generated noise would not increase ambient noise levels measurably on existing neighborhood streets or roadways which would provide access to the project site. This impact would be less-than-significant. LTS The 4.4 Traffic and Circulation section describes existing traffic conditions, baseline conditions, and cumulative conditions. Project-generated trips were added to baseline and cumulative conditions. Traffic increases were modeled to evaluate the potential increase in noise levels along the streets in the vicinity of the project site. Traffic noise levels are predicted to increase by three decibels (3 dBA) at most along Sister Cities Boulevard. The three-decibel increase would occur with or without the 234 4.6 NOISE Terrabay Phase Il and 111 SEIR contribution of Terrabay Phase II or III traffic. This increase would not be substantial and would not constitute a significant impact. The incremental increase due to the project would not be measurable when compared with baseline traffic anticipated without the project in either the short- or long-term. Mitigation Measure 4.6-3 No mitigation would be required. Impact 4.6-4 Traffic Noise Impacts from the Hook Ramps Traffic-generated noise from the proposed hook ramps would not change noise levels noticeably at any noise-sensitive land uses. This impact would be less than significant. LTS Noise generated by traffic using the hook ramps would change noise levels by less than three decibels (3 dBA). This would not constitute a significant change in noise levels. Noise impacts from construction and operation of the hook ramps would be subject to Federal Highway Administration (FHWA) noise abatement criteria (23 CFR Part 772). Under these criteria, reasonable and feasible noise abatement measures should be incorporated into highway projects where noise levels at active land uses approach or exceed noise abatement criteria. However, there currently are no active land uses adjacent to the hook ramps site. Implementation of the proposed Terrabay project would result in development of mixed-use commercial and office land uses on the Phase III site near the hook ramps and realigned Bayshore Boulevard. Those land uses envisaged by the Precise Plan near the proposed hook ramps would constitute active land uses. However, as discussed in Impact 4.6-2 and Mitigation Measure 4.6-2 (above), proposed future development would need to be evaluated by a qualified acoustical engineer who would prepare and submit a detailed acoustical analysis of the appropriate noise reduction requirements to meet Federal, State, and local noise standards and policies on a project-by-project basis. As a result, noise impacts from operation of the hook ramps would be reduced to less-than-significant levels. Mitigation Measure 4.6-4 No additional mitigation would be required. 235 i ~. i ,~1II iI \ ~ ~ I1 ' m ~~ 1 ~~ ~ ~ ' ; ~ ~ - , 'n o ~l I I I~ r,,,~ , ~ \~ 1 11 1,1i~-.~ ~!, T / ' ~ C Z III ~ r_ ; ~ -~-~~ ~ ~ I~~ ~ F i. ! i ~ ; '' I ~ a it I ~' ~,~+ ' 1 I, I, ~ • , 1 ~ ; 1{ I, ,I ~ I ~V , ~ / , 1 YI/ - I ~I' -- _ I - I:'~ r; c ~~ j. (~ ~' ~ ~ ~ ~ . I t `r .. _rC ~ ~ ~ I ~ " r, ~ ~ 1 4a nn` ~, I .. ~ j 7 ~ ~'i' I ;..~ liil .. I I t r!i r ~ ~~ ,, t ~t. I~ ~/ I ti I r r ~ ~ /•~ ;' i, ;~ ~ i ~ ~ ~ ~ ~ ~i" ~ I ~ ; ; / ,% ~ ~ ~ ~~ ~ -~fF ~F 1 ~ ~ I t 1 ~ I~ . , I II 71~ 1~ t ~, 11ij. ,;j. 1, .. C ~i, , 5 "" ~' ;; i tl .. ~ mini. ~I. , ' i I \, 1 ~ ~' I ~ `' i II . \ ' i i ' ~ ~ \ ~~ ~ ;, ~, ; _ 1 t; 1 . / I / I 1 / `, ~.l c .r~ '~ r ~ ~ - j ~~ ~_,,~. ~/~/ ~~~/ , ' Ili i //, , 14 l/ ~'/I /'1 ,l /~'I I l 1/j i 1 iiil i ~ 111 ` .'`~ 111 I '~I11 ~I 11 \ __ \11 :~'.I I' III II II 111 l d ~ , ~~~~~ \\1,1111 , ~ ~11 I~ ,,1',,11. II ~~ \ .. Y~ ~ ~ •t. ~Il 1~ 1 V\ t 1~1~ 'lf 1 ,~ ~'1 Y t~ 1 1 1I 111 ~ , 'll I ;.I'I I" ~ -~ ,~ \ ili' "~ ~~/~ ,; // -%, ,/Iii ,~ 11.1 ,1~, I '`1 1 4'.` .. _ - 1 ~ I I ~,/ ~ ~, i' <.~'. ~ -~ / ~•J ~L~ .I ..? f l.i I`II1 ~~~~, I ~~11`\ 1' - _ ., i ~:. .. _ .. /Ji " ~ 1 ~ ~ -.~ ,~~ A ~ ~ ~ ~~~Il,' ~~~~; 1~ ~1 ~ 111 ~ I i I .. ~.1-'~I~ G 1,1` ~. `; .1' - y 1~1' I II II~1' ,. ~ , ~ // :'•/~/?jti;~l~t ,' 1` I\ I. ~j \ ~' •~ ,i I I III \ ! 1 I' i' I ~~ `t ~~*', fir' \ . ~ ~I I -`~. ` ~ I ~;~ ~1 ~~'~ i i :1 11. t r: r ,nom 1/ 1vv J / i~~~j ~~~jl~~l ~ ~'1 ` ,~ ~ r ,. ,, - \ ~1 ~ 11 ~', I 1 C ,/!~ .\ ~ 11,111}) ~ \ /\,1\, :•,~/~~I~lltlil/~ 1 / _~ ~_= ` _ ~ `, 1 I, ~r III ~'~ ~ _ .. '~ ~I ~ ~ /._ .... .. .. .., r. I+ I ~, ~ I'I j ~ l -- ' ` , _ ,, -: V ti ;. y ~ O ~ ~ -ern ~ Q ~2 ~ o. ~~v~ 4.7 PUBLIC SERVICES This section focuses on two issues related primarily to the proposed intensity of development on the site, police protection and schools, as described below. It updates the 1996 SEIR for the issues addressed but otherwise incorporates the 1996 SEIR by reference for other aspects of these and other public services. 178 POLICE SERVICES -THE SETTING 179 The City of South San Francisco Police Department (SSFPD) employs 110 people, including 75 sworn officers of whom 68 are involved in street patrol activities. This staffing represents an increase since 1996 when the Department employed 105 people full time and four people part time, including 73 sworn officers of whom 51 were involved in street patrol activities. 180 The SSFPD has quantified its level of effort to serve residential and commercial development. The result has been to identify per capita ratios of Department personnel in relation to the City's population and numbers of calls for service by the type and size of commercial development. Current SSFPD staffing results in a ratio of 1.32 officers per 1,000 residents - 1.19 per 1,000 involved in street services and 0.09 per 1,000 involved in traffic control. 181 This ratio is an improvement from 1996 when the SSFPD employed 1.26 officers per 1,000 residents. According to the Department, its objective is to maintain a ratio of 1.3 officers per 1,000 residents in the future with new residential development -- 1.18 per 1,000 involved in street services and 0.09 per 1,000 involved in traffic control. The SSFPD also has calculated the number of calls for service from commercial development and has translated increased police service demands in terms of additional personnel needs. These are shown in Exhibit 4.7-I for the land uses proposed on the Terrabay Phase III site. According to the SSFPD, it generally takes one year to hire and train an officer to be capable of functioning alone on a patrol beat. In addition, every 2.7 officers require a police vehicle. 178 Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996 (1996 SEIR). 179 This section is based on memorandum to Nichols • Berman from Sargent Mike Massoni, Crime Prevention /Planning / Traffic, City of South San Francisco Police Department, October 23, 1997, and Nichols • Berman conversations with Sargent Massoni. 180 Draft Supplemental Environmental Impact Report for the Terrabay Speci, f:c Plan and Development Agreement Extension, op. cit. 181 Memorandum to Nichols • Berman from Sargent Massoni, op. cit., using a 1997 City population of 57,000 residents. The 1.32, 1.19, and 0.09 figures are in the original, although the sum of 1.19 and 0.09 is 1.28, rounded to 1.3. Because it is the City's objective to maintain a rate of 1.3 officers per 1,000 residents, it is the number used to estimate the police personnel requirements of the project (see Impacts and Mitigation, below). 237 4.7 ?UBLIC ScRVICES Terrabay Phase ll and 111 SEJR Exhibit 4.7-1 Call fnr SArvir_A Ratinc fnr !'_nmmn~nJ~l I ~.,rl l l~n a Land Use Calls for Service b Sworn Officer ` Street Patrol d Hotel 032 /room 1 / 1,356 hotel rooms 1 / 1,950 hotel rooms Mixed Use ` 4.0 / 1.000 s uare feet 1 / 1,759,286 s uare feet 1 / 2,592.631 s uare feet Restaurants 1.1 / 1.000 s uare feet 1 / 396,360 s uare feet 1 / 582,727 s uare feet Retail 1.5 / 1.000 s uare feet 1 / 290,852 s ware feet 1 / 436,623 s uare feet u ~~~u .,,, , »~ ~~., .~, ~~, ~:~~ ua~. ,v,cu,u,a„uum ,o ,~,cnois • net~nan trom urgent Mace hlassom, C:rme Prevention / Planning /Traffic, City of South San Francisco Police Department, October 23, 1997. b Annual calls for service (CFS). c Need to employ one additional sworn officer. d Need to assign one additional sworn officer to street patrol activity. e Flex-space and mixed-use commercial. Besides increased personnel requirements resulting from new development in the City. the SSFPD is concerned about potential communications problems in parts of South San Francisco which are located out of the line-of-sight of the police and fire radio transmitter. 182 The SSFPD loses radio contact in the vicinity of the Terrabay Phase III commercial site and developing area east of U.S. 101 due to interference by San Bruno Mountain which blocks communications between the transmitter and emergency service vehicles. POLICE SERVICES -SIGNIFICANCE CRITERIA According to the State CEQA Guidelines (Guidelines) and professional practices, the project would have a significant effect on the environment if it: • Required the addition of an officer position or acquisition of a patrol vehicle. • Lengthened emergency services response times beyond three minutes for Priority 1 calls and 15 minutes for other calls. POLICE SERVICES -IMPACTS AND MITIGATION MEASURES This 1998 SEIR analysis focuses on the following SSFPD concerns related to additional responsibilities attributable to: 183 • An increased residential population due to substantially more bedrooms proposed by the 1998 Precise Plan than b}~ the 1996 Specific Plan. • The intensity of commercial area uses. • Phasing of the Oyster Point interchange modifications (flyover and hook ramps). 182 Terrabay Precise Plan Re:-iex• -- Phase II and III Specific Plan, Memorandum to Allison Knapp, City o; South San Francisco Planning Division from Sargent Mike Massoni, op. cit., October 15, 1997, and Nichols • Berman conversation with Sargent Massoni, Octo'oer 24, 1997. 183 Terrabay Fiscal Analysis, \lemorandum to Allison Knapp, op. cit., from Sargent Mike Massoni, op. ci:., October 15, 1997. 238 4.7 PUBLIC SERVICES Terrabay Phase I! and ll! SEIR The loss of communication contacts between the City's police and fire transmitter and emergency services vehicles in the shadow of San Bruno Mountain. Impact 4.7-1 Impact of Residential Development on Police Services The 1998 Precise Plan proposes 84 fewer housing units than the 1996 Specific Plan. However, larger three-, four-, and five-bedroom units currently are proposed compared with smaller two-, three-, and four-bedroom units previously proposed. The South San Francisco Police Department is concerned that this difference would result in a larger residential population on the Phase ll site with a proportionate increase in demands for police services. The future Phase ll site population would not be expected to change staffing requirements by one full officer position. The 0.2- to 0.3- officerdifference would be considered aless-than-significant impact. LTS The impact of residential development on provision of police services is related to population, and a number of sources were examined for this 1998 SEIR to estimate the future residential population of the project as now proposed. These numbers are compared in Exhibit 4.7-2. Exhibit 4.7-2 Comaarison of Household Density Rates Source Persons Per Household Residential Population a Pro'ect s onsor 2.09 726 ABAG (Projections '94 for 2000) • 1996 S ecl c Plan (432 Phase II units) 2.99 1,292 ° • 1998 Precise Plan (348 Phase II units) ` 2.99 1,041 California De artment of Finance (19971 3.023 1,052 - ABAG (Projections '98 for 2005) 3.18 1,107 a Estimated population of the 348 housing units the Precise Plan proposes for the Yhase ll stte except Tor the 4lS units shown for the 1996 Specific Plan. b Factor used for analysis in the 1996 SEIR. c Applies 1996 SEIR household population factor to the proposed 1998 Precise Plan. As shown in Exhibit 4.7-2, the project sponsor estimates that the Phase II site would have a residential population of 726 people at full buildout and occupancy of the Point, Commons, and Woods neighborhoods. 184 This number would represent an average density of 2.09 people per household (pph). The 1996 SEIR assumed an average household density of 2.99 pph for the year 2000 in analyzing the 1996 project. Applied to the 1998 Precise Plan, this density would result in a residential population of 1,041 people on the Phase II site. 185 According to the California Department of Finance's Demographic Research Unit, the number of persons per household in South San Francisco increased since publication of the 1996 SEIR to 3.023 pph by 1997. 186 In addition, the Association of Bay Area Governments (ABAG) estimates that household density will continue to increase to 3.18 184 Letter to Nichols • BetTnan from James Sweenie, Sterling Pacific Management Services, Inc. (project sponsor's representative), November 6, 1997. 185 projections '94, Association of Bay Area Governments (ABAG), as reported in the Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, op. cit. 186 Ciry /County Population and Housing Estimates, January 1, 1997, San Mateo County, Official State Estimates, Califomia Department of Finance's Demo~aphic Research Unit. 239 4.7 PUBLIC SERVICES Terrabay Phase ll and 111 SE/R pph by the year 200. 187 It is standard practice in EIRs to use ABAG projections to assess population-based impacts unless more relevant data are available. SSFPD staff review of the project to date has concluded that these Phase II site residential population rates appear lower than expected by the Department and, therefore, would under-estimate impacts. The SSFPD reached this conclusion in view of the three-, four-, and five-bedroom housing units currently proposed by the 1998 Precise Plan for the Point, Commons, and Woods neighborhoods. This number would intensify development compared with the two-, three-, and four-bedroom units being built on the Phase I site and previously anticipated for the Phase II site by the 1996 SEIR. 188 Implementation of the 1998 Precise Plan as proposed would result in construction of 348 housing units containing a total of 1,446 bedrooms (see Exhibits 2.3-3 and 4.7-2). Use of all bedrooms by one person each -- not allowing for home offices, guest rooms, or more than one person per bedroom - could result in a Phase II residential population of 1,446 people. This number would represent a household density of 4.16 pph, 31 percent more residents than estimated using ABAG's projection for year 2005 (1,107 residents at 3.18 pph). This number also represents 12 percent more residents than estimated by the 1996 SEIR using ABAG's projection for year 2000 (1,292 residents also at 2.99 pph but for 432 housing units then proposed). These estimates suggest that 84 fewer but larger housing units proposed by the 1998 Precise Plan (348 units with three, four, and five bedrooms) would demand more police services than more but smaller units proposed do the Phase II site by the 1996 Specific Plan (432 units with two, three, and four bedrooms). Based on the objective of employing 1.3 officers per 1,000 South San Francisco residents, a 1998 Precise Plan Phase II site population of 1,446 residents would result in the need for 1.9 new officers. This would represent 0.2 officer more than required to serve the 1996 Specific Plan Phase II site population of 1,292 residents. Alternatively, a 1998 Precise Plan Phase II site population of 1,107 residents (assuming ABAG's intensity of 3.18 pph) would result in the need for 1.4 new officers. This would represent 0.3 officer less than the 1996 Specific Plan Phase II site population of 1,292 residents. In either case, the difference would be less than one full officer position. Moreover, this difference would not have a physical impact on the SSFPD indicating significance under the California Environmental Quality Act (CEQA). Mitigation Measure 4.7-1 No mitigation would be required 187 Projections '98> Association of Bay Area Governments (ABAG), and Nichols • Berman conversation with Hing Wong, ABAG, October 17, 1997. 188 The 1996 SEIR analyzed the entire three-phased Terrabay project. This discussion focuses on the Phase II residential site, Impact 4.7-2 focuses on Phase III commercial development, and Impact 4.7-3 looks at Phases II and III combined. 240 4.7 PUE~/C SERVICES Terrabay Phase ll and 111 SEIR Impact 4.7-2 Impact of Commercial Development on Police Services Proposed commercial development would generate 367 additional calls for service . per year and require the combined effort of 0.91 officer. Prior environmental review did not address the impact of commercial development separately from the entire three-phased project which was determined to require 3.0 additional officers. The 1982 EIR and 1996 SEIR assumed heavy reliance on use of private security on the Phase 111 site to minimize impacts on fhe South San Francisco Police Department. Although prior EIRs did not separate the demands for commercial development, in view of the estimated need for less than one new officer position for the Phase Ill site alone, the impact would be considered aless-than-significant. This is because it still would not result in a physical impact, such as the requirement for a new patrol vehicle. LTS The development concept proposed for the Phase III site would result in estimated 367 calls for service and would require the addition of 0.54 sworn officer and 0.37 sworn officer devoted to street service, less than one full officer position (0.91 officer combined) (see Exhibit 4.7-3). Exhibit 4.7-3 Estimated Phase 111 Police Service Needs a Land Use Calls for Service Sworn Officer Street Patrol Hotel 192 0.44 0.31 Mixed Use 140 0.02 0.01 Restaurants 20 0.05 0.03 Retail 15 0.03 0.02 Total 367 0.54 0.37 a Based on rates shown in Exhibit 4.7-1. Memorandum to Nichols • Berman from Sazgent Mike Massoni, Crime Prevention /Planning /Traffic, City of South San Francisco Police Departrnent, October 23, 1997. The 1996 SEIR estimated the need for three additional police officers to serve the entire three-phase Terrabay project, based on residential population alone and not accounting for responses to calls for service from commercial development. The 1996 SEIR confirmed the conclusion of the 198? EIR and reiterated the mitigation measure required in 1982. That measure required the creation of a fully- staffed new beat and provision of a new police vehicle, the latter to be funded by the project sponsor. The 1996 SEIR also reported that the SSFPD expected to "rely heavily on specific-plan-required on- site security to report activity of concern". While the need for an additional 0.54 sworn officer and 0.37 sworn officer providing street services was omitted by prior analyses, the combined need would be less than one full officer position. According to the SSFPD, the addition of 2.7 sworn officers would require a new patrol vehicle. As noted above (Impact 4.7-1), this demand would not have a physical impact on the SSFPD indicating significance under CEQA. Mitigation Measure 4.7-2 No additional mitigation would be required beyond project sponsor provision of a new police vehicle as previously required. eat 4.7 PUBLIC SE,4VICES Terrabay Phase Il and Ill SEIR Impact 4.7-3 Combined Project Impact on Police Services The combined effect of Terrabay Phase ll and Ill development according to the 1998. Precise Plan could be interpreted to require one additional police position (0.91 position) which still would represent aless-than-significant impact. LTS Omission of Phase III site commercial development from prior analyses of impacu on police services, combined with a conservative assessment of potential residential intensification on the Phase II site, could be interpreted as requiring one (1.11) full officer position in addition to the three positions previously identified by prior environmental documents. One additional officer mould represent a 25 percent increase in police personnel needed for all three phases of the Terrabay project but also would represent 1.3 percent of the SSFPD's current staff of 75 sworn officers (and less than one percent of the full 110-person staff). One officer position would neither cause a physical impact (such as by requiring a new patrol vehicle) nor constitute a "considerable" impact. According to the Guidelines, an individual project's impacts must be "considerable" before cumulati~~e impacu can be viewed as significant. "Considerable" is defined to mean that two or more incremental effecu which would be minor individually would compound or increase other environmental impacu when considered together. "Considerable" also relates to the context of aproject-specific impact when viewed in comparison with other such projects and when taking the condition (or degradation) of the. environment into account. Mitigation Measure 4.7-3 No mitigation would be required. Impact 4.7-4 Impact on Police Communications . The Phase Ill site is located in a communications shadow formed by San Bruno Mountain which would inhibit police and fire radio transmissions to and from emergency service vehicles on patrol on the site or farther east of U.S. 101. The South San Francisco Police Department will require the first project developed within the shadow, whether on the Phase 111 site or elsewhere, to install required relay equipment. S Commercial development on the Phase III site would be constructed in two- to four-story buildings with maximum heights ranging from 70 feet (non-hotel uses) to 250 feet (hotels). 189 The finished grade elevation of proposed Parcel G, located at the southern end of the Phase III site, would be about 60 feet. Restricting building heights on that parcel to avoid interfering with views of Point residents would mean that both the graded landform and proposed structures would block the line-of-sight from the Phase III site to the police and fue department transmitter located southwest of the southeast ridge of San Bruno Mountain. Other commercial pazcels proposed on the Phase III site would be located farther north of Parcel G. Although some proposed finished pads would have elevations as high as 9~ feet (Parcel C), San Bruno Mountain elevations also increase adjacent to these parcels. Buildings up to 250 feet in height, together with internal access roadways and surface parking lots, would be located within a communications shadow formed by San Bruno Mountain. 189 A hotel of up to 250 feet in height could be built on the northern part of the Phase III site (propos~i Parcel B), but the maximum height of a hotel on the southern part of the site (proposed Parcel G) would be lower than 250 feet. The lower height at the southern end of the site would be to ensure that [he hotel structure would not interfere with views of Point residents. Nichols • Berman conversation with Allison Knapp, City of South San Francis:. l~Say 4, 1998. 242 4.7 PUBL/C SERVICES Terrabay Phase /l and ll1 SE/R According to the SSFPD, the Department has identified three potential projects where relay equipment could be installed to facilitate communications in this shadow area. 190 These include the Terrabay Phase III site and sites located east of U.S. 101 (the Ameribay Suites Hotel at Sierra Point and a building within the Bay West Cove project). 191 The SSFPD will require, as a condition of approval, the first of these projects to be built to install relay equipment. The Terrabay project sponsor proposes to begin grading the Phase II and III sites immediately upon City approval. However, as of February and March 1998, when this 1998 SEIR was being prepared, the project sponsor had not identified any developer(s) of proposed Phase III site commercial parcels. Therefore, it is not lmown whether development on the Phase III site would precede or follow development on one of the two other sites identified for installation of relay equipment. Mitigation Measure 4.7-4 The developer of the first building constructed on the Terrabay Phase III site shall install relay equipment suitable to facilitate police and fire communications between the transmitter and land located behind San Bruno Mountain, if required to do so by the South San Francisco Police Department as a condition of approval. Equipment installed shall meet South San Francisco Police Department specifications. If such equipment is installed on another project constructed before development proceeds on the Terrabay Phase III site, no additional mitigation would be required. Significance after Mitigation Implementation of Mitigation Measure 4.7-4 in compliance with the City of South San Francisco Police Department would reduce the severity of impact to a less-than- significant level. Responsibility and Monitoring The project sponsor shall notify prospective purchasers of commercial parcels on the Phase III site of this measure, and the parcel owner /developer shall be responsible for implementing the measure to the satisfaction of the South San Francisco Police Department. The Department shall be responsible for monitoring this measure. Impact 4.7-5 Traffic Impact on Police Response Times Congestion causing delays in future traffic_conditions with the project would be expected at two intersections at the Oyster Point interchange but not before the year 2010. Unconstrained conditions elsewhere would off-set potential future delays, thus not affecting police response times significantly. LTS Police response times reflect the severity of activities being reported and travel time for officers on patrol to reach sites where calls for service originate. 192 The average response time to serious felonies and Priority 1 calls for the entire city does not exceed three minutes, and response time to other calls does not exceed 15 minutes. 193 190 Nichols -Berman conversations with Mike Massoni, op. cit., October 1997 and May 1998. 191 The Phase III site and area east of 101 are shown on Exhibit 2.1-2. 192 This differs from fire or ambulance response times which involve [ravel time from a fined location (fire station). 193 Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, op. cit. 2d3 4.7 PUBLIC SERVICES Terrabay Phase ll and I/I SEIR Future traffic conditions on study area streets with the contribution of project-generated traffic would begin to deteriorate in about year 2010, primarily at two intersections within the Oyster Point interchange -- the Oyster Point /Dubuque intersection and the Bayshore Boulevard /Airport Boulevard /Sister Cities Boulevard /Oyster Point Boulevard intersection (see 4.4 Traffic and Circulation). 19a By that time, delays would be expected to occur in operations at those intersections. From a traffic perspective, projected delays at those two locations would be off-set by unconstrained travel elsewhere in the study area. Conditions west of those intersections along Sister Cities Boulevard-Hillside Boulevard adjacent to the Phase II site would be unconstrained. The segment of Bayshore Boulevard adjacent to the Phase III site similarly would be improved and provide capacity to accommodate traffic and emergency response within SSFPD average response times (three minutes to Priority 1 and 15 minutes to other calls). Mitigation Measure 4.7-5 No mitigation would be required. Impact 4.7-6 Police Impact from Cumulative Development Substantial cumulative development by the year 2010 would greatly increase the number of calls for service to the South San Francisco Police Department and could require an estimated 5.4 to 6.2 additional police positions plus two additional police vehicles. While these cumulative impacts would be significant, the incremental contribution of Terrabay Phase ll and 111 development would not be "considerable'; thus less-than-significant for the purposes of CEQA. LTS Substantial cumulative development is expected to occur within the City of South San Francisco by the year 2010 -- the study period assumed by this 1998 SEIR for Terrabay Phase II and III. Exhibits 2.4-Za and 2.4-Ib in Section 2.4 show development of 2,039,160 square feet of research and development, office, and other employment-generating land uses, 2,282 additional hotel rooms, another 845 employees, and 274 housing units. This level of development is summarized in Exhibit 4.7--4195 Cumulative non-residential development in South San Francisco is assumed to be concentrated east of U.S. 101, and cumulative residential development in the City is assumed to occur west of U.S. 101. 196 This level of development is expected to generate substantial increases in calls for service in the future. Without Terrabay Phase II, cumulative residential development could expand the City's population by about 870-1,140 people who would generate a need for one to two additional police officers. 197 Without Terrabay Phase III, cumulative development of 2,039,160 square feet of non- 194 Nichols • Berman conversation with Mark Crane, Crane Transportation Group (1998 SEIR traffic consultant), Apri18, 1998. 195 The difference between Exhibits 2.4-Ia-2.4-1b and 4.7-4 is inclusion and exclusion, respectively, of development outside South San Francisco (in Brisbane) which would not be served by the SSFPD. 196 Cumulative development east of U.S. 101 reflects expected intensification of development compared with land uses assumed by the East of 101 Area Specific Plan. Therefore, the anticipated impacts on the SSFPD of implementing that Plan are under-estimated because intensification would result in more development than previously planned. 197 Bo[h the residential population and police officer ranges reflect use of 3.18 and 4.16 pph for the 274 cumulative development housing units _ 1,000 x 1.3 officers = 1.13-1.48 officers, rounded. 244 4.7 PUBLIC SERVICES Terrabay Phase ll and 111 SEIR Exhibit 4.7--4 Cumulative Development Requiring Police Protection Non-Residentia/ Use Hotel Use Other Non-Residential Residential Use Year 200D 806,500 s uare feet 1,107 rooms 165 em to ees ° 114 units 20 acres auto Year 2010 1,232,660 s uare feet 1,175 rooms 650 em to ees ° 160 units Total Cumulative Pro'ects 2,039,160 s uare eet 2,282 rooms 845 em to ees 274 units 20 acres auto Terraba Phase ll and 111 Pro'ect 343,000 s uare feet 600 rooms 780 em to ees ` 348 units a Total employment of cumulative non-residential projects is not shown, only employees expected to be added by Genentech. b Includes 280,000 square feet of hotel development also shown as 600 rooms in the next column. c Estitnated employment is for all Phase III development. Exhibit 4.7-5 Summary of Cumulative Police Impacts Land Use Terrabay Development ,Other Development Total Cumulative Residential Develo ment Number of Units 348 274 622 Po ulation • 3.18 h 1,107- 871- 1,978- • 4.16 h 1,446 ° 1,140 2,588 Officers • 3.18 h 1.44- 1.13- 2.57- • 4.16 h 1.88 1.48 3.36 Non-Residential Develo ment Amount of Develo ment 343,000 ` 1,039,160 2,382,160 ` Officers • Sworn officers 0.54 ` 1.16 1.70 • Street services 0.37 ` 0.79 a 1.16 Total 0.91 1.95 2.86 Cumulative Residential and Non-Residential Residential 1.44-1.88 1.13-1.48 2.57-3.36 Non-Residential 0.91 1.95 2.86 Cumulative Total 2.35-2.79 3.08-3.43 5.43-6.22 a 1,446 bedrooms _ 348 units = 4.155 pph, rounded to 4.16 pph. b 1.3 officers per 1,000 residents. c Square feet including hotels (600 rooms). d Square feet excluding hotels (2,292 rooms). e Derived from Exhibit 4.7-3. f Assumes one per 1,759,286 square feet of flex space. g Assumes one per 2,592,631 square feet of flex space. 245 4.7 PUBL; C SERVICES Terrabay Phase /l and 111 SE1R residential uses could generate a need for about two more police officers. 198 The future demand of Terrabay Phase II and III development combined with other cumulative development would be approximately 5.4 to 6.2 additional police positions (Exhibit 4.7-5). 199 Based on the need for one additional vehicle per 2.7 officers, cumulative development also would require purchase of two new police cars. This would be a significant cumulative impact. About half the additional police positions estimated above would result from increased residential population (2.6 to 3.4 positions or 48 to 54 percent) and half from non-residential development (2.9 positions or 46 to 52 percent). These amounts account for all Phase II units (not just the intensity increase in fewer units compared with the 1996 Specific Plan). They also double-count Phase III hotels compared with other cumulative development which separates hotel from other non-residential development. In that context, of the residential contribution, an increased Phase II 1998 Precise Plan population could be interpreted as accounting for 0.2 officer more than estimated for the 1996 Specific Plan (Impact 4.7-1). This increment is not "considerable", as defined by the Guidelines, when compared with the total cumulative demand for 2.6 to 3.4 officer positions. Of the commercial contribution, the Phase III development concept as proposed would account for 0.91 officer more than believed to be estimated for the 1996 Specific Plan. This translates into 32 percent of the increased commercial development personnel demand. However, 63,000 square feet of commercial development on the Phase III site, excluding 600 proposed rooms, would represent three percent of cumulative non- residential development (2,039,160 square feet) which also excludes 2,282 additional hotel rooms. This increment similarly is not "considerable". 200 Therefore, while cumulative impacts would be expected to be significant, the' contribution of Phase II and III development would not meet the standard of significance. Mitigation Measure 4.7-6 No additional mitigation would be required of the Terrabay Phase II or III project than identified by Mitigation Measure 4.7-4 and the 1982 EIR / 1996 SEIR. The prior EIRs required funding provision of a separate new fully-staffed beat (1982 EIR) to consist of three off cer positions and one new patrol vehicle (1996 SEIR). 198 One additional sworn officer (1.16 officer) and a second sworn officer (0.79 officer) devoted to street service activity (1.95 officers combined), assuming 2,039,160 square feet of flex-space. This estimate does not include hotels for which cumulative development assumptions have not identified sizes (only the number of rooms, 1,107). Therefore, the estimated SSFPD personnel requirement for cumulative non-residential development (without Terrabay Phase III) is low. 199 This total covers 2.57 officers for all cumulative residential development plus 2.86 officers for all cumulative non- residential development (1.70 sworn officers and 1.16 sworn officers assigned to street service activity). 200 As discussed in Impact 4.7-3, "considerable" means that two or more minor effects would compound or increase other impacts when combined, when compazed with other such projects, or when accounting for prevailing environmental conditions. 246 4.7 PUBLIC SERV/CcS Terra6ay Phase ll and Ill SE1R PUBLIC SCHOOLS -THE SETTING Different parts of the Terrabay project site are located in different school districts. The Point and Commons neighborhoods (and the entire Phase III site) are located in the Brisbane School District (BSD) and Jefferson Union High School District (JUHSD). The Woods neighborhood is located in the South San Francisco Unified School District (SSFUSD) (as are the Village and Park neighborhoods of the Terrabay Phase I site). Site subareas are shown in Exhibit 2.3-1 in the Project Description . Brisbane School District 201 The Brisbane School District provides elementary and middle school education for students who live in the District and attend local schools plus students who live outside the District but attend BSD schools as capacity permits. The current proportion of non-District to District residents makes the BSD a "recipient" district. 202 The BSD operates two schools, both for ten months per year, Brisbane Elementary School and Lipman Intermediate School. Capacity of Brisbane Elementary School is the District's main concern and the focus of this 1998 SEIR, due to local adoption of the State's class size reduction initiative. This initiative originally was enacted by the State in June 1996 for local districts to adopt locally. The BSD adopted the initiative in the fall of 1996 for Grades 1-3, expanded it in the fall of 1997 to add two kindergarten classes, and plans to revise it again in the fall of 1998 to include all kindergarten classes. The initiative reduces the maximum number of students per classroom from 30 to 20 which translates into smaller future capacity of Brisbane Elementary School. Brisbane Elementary School is located on San Bruno Avenue, north of the project site in the City of Brisbane. The BSD currently uses 12 classrooms for school instruction and leases two additional classrooms to a day care provider on a year-to-year basis. The BSD plans to take back one classroom for the 1998-1999 school year and the second classroom the following school year. The 1997-1998 capacity is 285 students, and enrollment is 213 students. This capacity will decrease to 257 students in 1998-1999 due to continued implementation of class size reductions without the classroom taken back for the 1998-1999 school year or second room to be returned the following year. The District does not have a lonb term facilities plan and does not intend to build new schools. It would like to build two additional classrooms and amulti-purpose room at Brisbane Elementary School but does not have funds to do so. Other than returning the two leased classrooms at Brisbane Elementary School to instructional use, the District has not identified other ways to expand capacity. Although Lipman Intermediate School has three portable classrooms and may have sufficient space for more portables, installation of new or additional portable classrooms is not planned at either school. 201 This section is based on Nichols • Berman conversations with Stephen Waterman, Esq., Superintendent, Brisbane School District, October 1997 and March 1998, and letter to Nichols • Berman, from Stephen Waterman, March 10, 1998. 202 In the past, enrollments of non-District students enabled the BSD to operate more efficiently than would have been possible with fewer BSD resident students. Ibid. 247 4. ,PUBLIC SERVICES Terrabay Phase Il and 111 SE/R The 1996 SEIR estimated that construction of 228 townhouse and condominium units then proposed in the Terrabay Point and Commons neighborhoods would increase BSD enrollments by 90 students. 203 The 1996 SEIR also reported that residential development now underway on the Northeast Ridge of San Bruno Mountain in Brisbane was expected to increase BSD enrollments by 120 students at Brisbane Elementary School and 60 students at Lipman Intermediate School. As of the 1997-1998 school year, only one student from Northeast Ridge development is enrolled at Brisbane Elementary School. The BSD does not expect to experience an influx of additional students from new development in the District for approximately five years after construction but anticipates increased enrollments from such projects thereafter. 204 The BSD estimates that each square foot of residential development generates 0.000178 student and 130-240 jobs generate 1.0 student. 205 Jefferson Union High School Disfrict 206 The Jefferson Union High School District (JUHSD) is a "district of choice" with open enrollment. This means that students, including those living in the Terrabay Point and Commons neighborhoods, can select which of the four JUHSD schools to attend. These include Jefferson and Westmoor High Schools in Daly City and Oceana and Terra Nova High Schools in .Pacifica. The 1996 SEIR indicated that most Terrabay JUHSD students were expected to attend Jefferson High School. As of March 1998, the JL'HSD had a total enrollment of 5,321 students, including 5,121 students assigned to the four high schools and 200 in continuing education, independent study, and additional programs based at the District headquarters or other facilities. Jefferson High School has a capacity of 1,665 studenu (and enrollment of 1,471 students in the 1997-1998 school year), Oceana High School has a capacity of 1,330 students (and enrollment of 765 students), Terra Nova High School has a capacity of 1,700 students (and enrollment of 1,215 students), and Westmoor High School has a capacity of 1,625 students (and enrollment of 1,676 students). These school capacities represent 80 percent of actual space and assume use of classrooms for five periods per day but do not include additional special use rooms. 203 The 1996 SEIR estimated school generation of the Point and Commons neighborhoods as then proposed but did no[ indicate a student generation rate or estimate the proportion of elementary and proportion of intermediate school students. An estimated 90 students from 228 housing units represents a rate of approximately 0.4 student per unit. Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996. 204 Nichols • Berman conversations with Stephen Waterman, op. cit., based on a study performed for the South San Francisco unified School District (SSFUSD). 205 Letter to Nichols • Berman from Stephen Waterman, op. cit., March 10, 1998. According to Mr. Waterman, the San Bruno Park School District (SBPSD) conducted a development impact study in the early 1990s. The SBPSD is an elementary school district and has neighborhood characteristics the BSD expects to be similar to those proposed in the Terrabay Phase II neighborhoods within the BSD. The SBPSD study indicated that each new housing unit with an average size of 2,500 square feet generates 0.446 grade K-8 student. 206 This subsection is based on tiichols • Berman conversations with Dr. Albert Pucci, Deputy Superintendent, Jefferson Union High School District, October 1997, and district staff April 1998. 248 4.7 PUBLIC SERVICES Terrabay Phase 11 and Ill SElR The JUHSD estimates student generation based on housing density. Its factors range from 0.08 student per unit for very low density housing to 0.20 student per unit for very high density housing. The rate currently considered appropriate for the Terrabay Point and Commons neighborhoods is 0.10 student per unit for low-medium density housing. The 1996 SEIR estimated that 228 Terrabay Point and Commons townhouse and condominium units would increase enrollments by approximately 20 students at JUHSD schools which the 1996 SEIR reported were expected to exceed capacity without Terrabay students. 207 In addition to planned growth within the District, the JUHSD has identified other factors expected to affect enrollments. One is an increased number of persons per household in the District, due to extended families living together. The JUHSD expects that more persons per household of all ages would increase the District's student population, at least incrementally. Another factor affecting future enrollments is that some existing housing, previously thought to consist of single-family units, actually contains second units. This housing supply, being documented through legalization of second units in Daly City, also is increasing the number of District residents, including those of high school age. In anticipation of future development within the JUSHD and resulting expanded high school enrollments, the District is modernizing and expanding its facilities to increase capacity. 208 The Terrabay project is one development contributing to the need for these improvements. Improvements include making maximum use of available space and upgrading computer and laboratory facilities. Jefferson High School improvements will be completed in the summer of 1998 at which time improvements will begin at Terra Nova High School. South San Francisco Unified School District 209 The South San Francisco Unified School District (SSFUSD) provides elementary, middle, and high school education for students who live in the District which includes the Cities of Daly City, San Bruno, and South San Francisco. In addition to enrollments by residents, 150-200 students who live outside the District usually attend SSFUSD schools. Terrabay Woods is located in the attendance areas of Hillside Elementary School, Parkway Heights Middle School, and EI Camino High School. Hillside Elementary School is one of three SSFUSD elementary schools where enrollments of attendance area residents have been increasing since 1992, although elementary school enrollments have stabilized within the District overall. District-wide approximately 20 percent of elementary school students do not attend their neighborhood schools. This attendance area shift reflects the SSFUSD's open enrollment policy, parents' preferences, and District assignments to avoid over-capacity. In addition to stabilizing elementary school enrollments, 207 Based on the rates of 0.1 student per unit for Terrabay Point and 0.08 student per unit for Terrabay Commons. These rates result in 22 students, derived as follows: (0.1 student per unit x 181 Point units =18 students) + (0.08 student per unit x 47 Commons units = 4 students) = 22 students. 208 Nichols • Berman conversation with Dr. Albert Pucci, op. cit., October 1997. 209 This subsection is based on the following materials provided by the South San Francisco Unified School District: District-wide Enrollment Trends and Forecasts, South San Francisco Unified School District, Lapkoff & Gobalet Demographic Research, Inc, December 1997, New Noosing and Its Impact on SSFUSD Elementary Enrollments, Lapkoff & Gobalet Demographic Research, Inc, November 1997, and Elementary Four Year Forecasts by Attendance Area, Lapkoff & Gobalet Demographic Research, Inc, December 1997. 249 4.7 PUBLIC ScRVlCES Terrabay Phase ll and !lI SE1R middle and high school enrollments currently are growing as age group "cohorts" progress through the system. In most years, more elementary school studenu leave the SSFUSD than enter Grades K-4, enrollment grows for middle school grades, and enrollment shrinks for each high school grade. These trends reflect demographic changes in the District, including natural increase (births), migration into and out of the District (families with children are the nation's most mobile group), and transfers between public and private schools at different grade levels. In higher grades, these trends also reflect early graduation and dropping out. - The SSFUSD estimates a student yield of 0.4~ student per single-family detached housing unit. This factor is the sum of 0.20 Grade K-5 student, 0.11 Grade 6-8 student, and 0.14 Grade 9-12 student per household. The effect of new development on SSFUSD school enrollments changes as housing ayes. The SSFIJSD has found that recently built housing yields fewer studenu than older units. New housing yields an average of 0.08 elementary school student per unit, and older housing yields 0.20 student per unit (the rate shown above). This change is estimated to occur during a 20- to 30-year period. In the next ten years, the SSFUSD expecu that planned development of approximately 1,000 new housing units will increase elementary school enrollments by about 100 students, but in 20 to 30 years, the same 1,000 units could yield 300 studenu. The 1996 SEIR reported that 260 students of all grade levels were expected to attend SSFLJSD schools from Terrabay Phase I and II units located in the District without identifying the student generation rate used. The 517 units then proposed for the Terrabay Village, Park, and Woods neighborhoods combined represent an approximate generation rate of 0.50 student per unit. 210 Based on that rate, 204 units previously expected in the Phase II Woods neighborhood could have accounted for about 103 Grade K-12 students out of the 260-student total for all 517 units. 211 The SSFiJSD's 1997 housing forecasts account for both Terrabay Phase I and II development. The District assumes completion of 290 Phase I uniu by 1999 and construction of 137 Phase II units in Terrabay Woods between 2000 and 2002. 212 The SSFUSD expects Phase I units to account for 15 new elementary school students in 1998 and 1999 and expects the Phase II units to yield 11 new elementary school students in between 2000 and 2002. 210 The 1996 SEIR estimated the number of studenu expected by grade level, thus permitting the following breakdown: 0.23 student /unit (K-5), 0.12 student /unit (6-8), and 0.1 ~ student /unit (9-12). This assumes a uniform rate for all housing types, including detached and attached units. 211 Based on the SSFIJSD's current rates, implementation of the 1996 Specific Plan would generate 92 (not 103) studenu, as shown in Exhibit 4.7-8 (below), indicating that [he numtxr of housing units proposed [o be built would be the main factor in determining student generation of the project 212 The 137-unit forecast represents a previous development concept for the Terrabay Woods neighborhood, subsequently revised to 135 units. o 4.7 PUBLIC ScRVICES Terrabay Phase ll and 111 SE1R PUBLIC SCHOOLS - S1GNlFlCANCE CRITERIA Judicial Context Z" The 1995 court decision in Goleta Union School District v. Regent of California established the significance criterion currently used to analyze projects' impacts on public schools in EIRs. 214 This case addressed impacts attributable to classroom capacity. The decision held that increased classroom enrollment resulting in school overcrowding "is not, in itself, a significant environmental impact requiring mitigation under CEQA. Instead, increased enrollment will only lead to such an impact if the increased enrollment will ultimately require physical changes in the environment, such as construction of new school facilities or new bus schedules" (emphasis in the original). 215 Thus, according to Goleta, 216 The addition of students to a school district is not a significant impact requiring mitigation under CEQA unless the increase in students necessitates a physically impacting activity such as the construction of new classrooms, temporary classrooms, or addition of bus lines. Consequently, a local agency that wants to ensure that it can require mitigation for impacts to schools under CEQA must demonstrate a connection between a project's generation of students and the need to undertake a physical activity, such as the construction of new school facilities. SE/R Significance Criteria Based on CEQA Guidelines and recent court decisions 217, the following criterion was use to assess whether the proposed project would result in a significant environmental impact on schools. A project impact is considered significant if it: Required any of the three Districts to expand facilities beyond what is already expected in current plans and the resulting development caused a significant adverse physical change in the environment. PUBLIC SCHOOLS -IMPACTS AND MITIGATION MEASURES The pending Precise Plan proposes construction of 213 attached duplex and triplex units in the Point and Commons neighborhoods, compared with 228 attached townhouse and condominium units analyzed by the 1996 SEIR, a difference of 15 fewer housing units than in 1996. The Precise Plan also proposes construction of 135 detached housing units in the Woods East and West neighborhoods, compared with 204 detached units proposed in 1996, a difference of 69 fewer units than in 1996. Altogether 84 fewer units of all types are proposed by the 1998 Precise Plan than 1996 Specific Plan. 213 This subsection is based on the discussions presented in the Guide to the California Environmental Quality Act (CEQA),Michael Remy, Tina Thomas, James Moose, and Whitman Manley, 1996. 214 Goleta Union School District v. Regent of California (1995) 37 Ca1.App.4[h 1025. 215 /bid., Guide to the California Emzronmental Quality Act (CEQA), page 250. 216 Ibid., page 251. 217 Goleta Union School District v. Regent of California, op. cit. 251 4.7 PUBLIC SERVICES Terrabay Phase ll and 111 SE1R Housing unit sizes proposed by the 1998 Precise Plan would differ substantially from those approved in the 1996 Specific Plan. Exhibit 4.7-6 shows that the largest attached units proposed in 1998 (2,390 square feet) would be about nine to ~9 percent larger than the largest units proposed in 1996 (1,500- 2,200 square feet). The smallest attached units (2,027 square feet) currently proposed by the Precise Plan would be about 103 to 268 percent larger than the smallest previously proposed attached units (550-1,000 square feet).''-18 Sizes of detached units proposed by the Precise Plan would be 68 to 9'8 percent larger than previously envisaged b~~ the 1996 Specific Plan. Exhibit 4.7-6 Comparison of Unit Sizes 1996 Specific Plan 1998 Precise Plan Units Size Range Units Size Range Brisbane Elements /Jefferson Union Hi h School Districts Point 181 1.000-2,200 181 2.027-2,390 Commons 47 »0-1,500 32 2,027-2,390 Total 228 213 South San Francisco Unified School District Woods 204 1.200-1,800 135 2,378-3,024 The larger size of units suggested potentiallv~ larger household populations, including the possibility of more school age residents per unit. This prospect prompted the City to include in the scope of this 1998 SEIR a task to estimate student generation of 1998 Precise Plan housing compared with 1996 Specific Plan housing. While larger housing unit sizes may result in a higher number of persons per household (pph), the three school districts do not quantify student generation rates uniformly and do not all establish a direct correlation between larger units and / or a larger residential population per se and more school age residents of those households. lmpacf 4.7-7 Impact on Brisbane School District Development of 213 duplex and triplex units in the Terrabay Phase ll Point and Commons neighborhoods and creation of an estimated 720-780 jobs on the Phase 11l . site would add about 85-88 new students to Brisbane School District (BSD) schools. This number would be fewer than the 90 students previously estimated to be generated by the Terrabay project. Approximately 85-88 new students would contribute incrementally to capacity constraints, but class size reductions are affecting school capacity more profoundly than increased enrollments attributable to new development. LTS The BSD estimates elementary school student generation rates of 0.000178 student per square foot of residential development and 1.0 student per 130-240 jobs. 219 Based 'on those rates, 460,329 square feet of residential development in the Phase II Point and Commons neighborhoods could add an estimated 82 elementary school students to BSD schools, and 720-780 people employed at Phase III commercial development could account for another three to six elementary school students to district 218 Precise Plan duplex units would range from 2,11 ~ to 2,390 square feet in size and would have four bedrooms, and triplex units would range from 2,02.7 to 2,255 square feet in size and would have three and four bedrooms. Neither [he 1996 Specific Plan nor 1996 SEIR identifies nutrbers of bedrooms. 219 Letter to Nichols • Berman from Stephen Waterman, op. cit., March 10, 1998. 252 4.7 PUELIC SERVICES Terrabay Phase ll and 111 SE1R schools. This increased enrollment of approximately 85-88 total new students, while fewer than the 90 estimated in 1996, would account for 4.4 classrooms meeting the 20-student maximum classroom size requirement. This number is greater than the expanded capacity the BSD plans to achieve by the 1999-2000 school year through renewed use of two classrooms currently leased for day care use. However, this calculation assigns all 85-88 Phase II and III students to Grades K-3, although an unlmown portion of that number would attend higher grades. The BSD is gradually reducing class size from 30 to 20 students per classroom, beginning with Grades 1-3 in 1996. Subsequently implemented and planned reductions will continue to decrease capacity without the addition of new students, such as from Terrabay Phase II and III development. The addition of Terrabay site students would exacerbate capacity constraints. After returning two leased classrooms to instructional use, the BSD does not have capital improvement or facilities plans for expanding Brisbane Elementary School. Despite the present absence of improvement or facilities plans, the BSD ultimately would need to expand facilities in the future to accommodate existing and new students, including from the Terrabay Phase II and III site and other development (such as by building the two additional classrooms desired but not funded or by placing portable classrooms at the Brisbane Elementary School site). Alternatively, the BSD would need to increase class size, contrary to its class size reduction initiative. Although the physical impacts of providing adequate classroom space cannot be specified until the BSD identified how it would build or renovate space, secondary impacts likely would include short-term traffic, air quality, and noise impacts. Another secondary effect of expanded enrollments of District residents would be to reduce enrollments of students who live outside the District. That displacement could have a cascading effect on other local school districts. Mitigation Measure 4.7-7 Implementation of Brisbane School District efforts to carry out its class size reduction policy -- when facility improvements (and funding sources to make them) have been identified -- will mitigate the impact of decreasing elementary school capacity. Such efforts would accommodate students originating from development of the Terrabay Phase II or III site at Brisbane Elementary School, and no additional mitigation would be required. Impact 4.7-8 Impact on Jefferson Union High Schoo! District Fewer but larger Point and Commons units proposed by the Precise Plan would generate virtually the same number of students to Jefferson Union High School District schools (21 students) as estimated from more but smaller units previously proposed by the Specific Plan (22 students). LTS Based on the rate of 0.1 high school student per unit currently assumed by the JUHSD for Terrabay Phase II development within the District, 181 Point and 32 Commons units would add about 21 high school students to its high school enrollments. This increased student population attributable to the 213-unit 1998 Precise Plan would be virtually identical to the 22-student increase estimated for the 1996 Specific Plan's 228 units in those neighborhoods (rounded in the 1996 SEIR to 20 students). Terrabay development constitutes part of the planned growth the JUSHD is already working to accommodate through its program of expanding and modernizing facilities. Jefferson High School currently has an excess capacity to accommodate 194 additional students, if all approximately 21 Terrabay Point and Commons students were to attend that school. These Terrabay Phase II students could attend Terra Nova or Westmoor High Schools without creating capacity problems. Therefore, the project would not result in a significant impact. ~ 53 4.7 PUBLIC SERVICES Terrabay Phase 11 and 111 SE1R Mitigation Measure 4.7-8 No mitigation would be required. Impact 4.7-9 Impact on South San Francisco Unified School District Development of 135 housing units in the Terrabay Phase ll Woods neighborhood would add about 45-6i students to South San Francisco Unified School District (SSFUSD) schools, including about 11-27 students in Grades K-5, 15 students in Grades 6-8, and 19 students in Grades 9-12. This number would be fewer than the 103 students previously estimated from the former 204-unit Terrabay Woods part of the Phase l/ project. This also is the same elementary school enrollment increase as estimated by the SSFUSD (1 i students). LTS The SSFUSD uses a student generation rate of 0.45 student per single-family detached unit. This rate is composed of 0.20 elementary school student (Grades K-5) per unit, 0.11 middle school student (Grades 6-8) per unit, and 0.14 high school student (Grades 9-12) per unit. Based on these rates, development of 135 units in the Phase II Woods neighborhood would increase SSFUSD enrollments by about 61 students, including 27 elementary, 15 middle, and 19 high school students. Because the SSFUSD has determined that new housing units generate only about 0.08 elementary school student within the first approximately ten years after development, 135 Phase II units could yield as few as 11 new elementary school students in the short term, although that population would be expected to rise to the 27 elementary school students estimated above in about 20 to 30 years. The total of 45-61 SSFUSD students expected from implementation of the proposed Precise Plan would be fewer than could have been generated by the prior 204-unit Phase II Woods project envisaged by the 1996 Specific Plan. These estimates are compared below. Exhibit 4.7-7 SSFUSD Student GPnaratinn Grades K-5 ..Grades 6-8 .Grades 9-72 Grades K-12 1996 SE/R Students (517 units) 120 60 80 260 Student /Unit 0.23 0.12 0.15 0.50 1996 S ecific Plan Student /Unit 0.23 0.12 0.15 0.50 Students (204 units) 47 25 31 103 1998 Precise Plan Student /Unit 0.20 0.11 0.14 0.45 Students (135 units) 27 15 19 61 Difference 1996-7 -20 -10 -12 -42 a Based on the 1996 SEIR which estimated the number of students by grade level (shown immediately above) for all 517 units [hen proposed. b The rate of 0.20 student per unit is the conservative long-term average of older housing units. The rate of 0.08 elementary school student per newer housing unit would yield 11 K-5 pupils. The SSFUSD anticipates that new development within the Hi'ilside Attendance Area would increase enrollments at Hillside Elementary School by 28 students between 1998 and 2003, of which Terrabay Woods would account for 11 students (39 percent). The SSFUSD estimate assumed 137 housing units (compared with 135 now proposed) at the rate of 0.08 student per new unit. Implementation of the Precise Plan would conform with SSFUSD estimates. This would be aless-than-significant impact. 254 4.7 PUBLIC SERVICES Terrabay Phase I! and 111 SE1R Mitigation Measure 4.7-9 No mitigation would be required. Impact 4.7-10 Cumulative Impacts Schools Substantial residential and non-residential development could increase Brisbane School District and Jefferson Union High School District enrollments by an unknown number of students by year 2010, although the Terrabay Phase Il and Ill share of students would not be defined as "considerable". Planned development within the South San Francisco Unified School District has been taken into account by district plans for elementary school enrollments. LTS By year 2010, cumulative development within the Brisbane School District (BSD) and Jefferson Union High School District (JL-HSD) could result in the addition of about 934 housing units of all types, including 569 units on the Northeast Ridge of San Bruno Mountain but excluding Terrabay development (see Exhibits 2.4-Ia and 2.4-Ib in 2.4 Cumulative Development). Substantial new non- residential development also could occur in Brisbane by year 2010, including a potential 4,200,000 square feet of new building area in the Baylands alone. The sizes of housing units and number of potential jobs are not known. However, 213 Terrabay Phase II units would represent 19 percent of the combined total of 1,147 cumulative development housing units, and 343,000 square feet of Terrabay Phase III commercial development would represent eight percent of potential Baylands development without consideration of all other cumulative projects. This substantial amount of cumulative development could increase BSD and JUHSD enrollments proportionately during the next decade until 2010. It is not presently known how the BSD would handle such enrollments and implement class size reduction requirements in the absence of a capital improvement or facilities plan. Although the student generation of cumulative development other than Terrabay Phases II and III cannot be estimated, based on the relative amounts of development per se, the contribution of Terrabay students would not be defined as "considerable". The student generation of Phase II Woods units, taken into account in SSFLISD elementary school enrollment projections, is part of district-wide estimates for the cumulative effect of development until year 2003. Approximately 1,118 housing units are expected to built during that time with implementation of 14 different de~~elopment projects in the City of South San Francisco part of the SSFUSD, including full buildout of the Terrabay Phase I and II sites (counted as three of the 14 development projects). 220 This level of development could generate 100-300 additional elementary school students in the short- (ten-) to loner term (30-year). The SSFUSD indicates that enrollments at Buri Buri and Skyline Elementary Schools can be expected to increase by 50 students each in the short-term (during the next four years). The contribution of Terrabay Woods students (11-27 elementary school students) to these numbers would not constitute a significant impact. Exhibits 2.4-Ia and 2.4-Ib indicate that 274 additional housing units could be built in South San Francisco west of U.S. 101 by year 2010. The SSFiJSD's analysis of the impact of new housing 220 SSFUSD documents round these 1,118 units to 1,000 for planning purposes, as discussed above in relation to the 100- to 300-student increase expected in elementary school enrollments from new development in South San Francisco in the short- and long term. The full (1,118) number is used here for comparison with the cumulative development assumptions shown in Exhibits 2.4-1a and 2.4-16. Note also [hat the SSFUSD projection is for year 2003 and Exhibits 2.4-1a and 2.4-Ib are for 200 and 2010, respectively. 255 4.7 PUBLIC SERVICES Terrabay Phase ll and 111 SEIR development on elementary school enrollments by year 2003 fully accounts for these projects, as follows: Exhibit 4.7-8 Cumulative Develeement in Snuth San Francic~-n Ilnifiorl C.,F,nnl n:~fri..• Project Elementary School Attendance Area Cumulative Development a SE1R Estimate SSFUSD Estimate Chestnut Estates Sunshine Gardens 80 80 Heather Hei hts Hillside 34 34 Summerhill Los Cerritos 160 158 Total 274 272 a ivumoer of um~s. The two-unit difference would not represent a significant cumulative impact. Mitigation Measure 4,7-10 No mitigation would be required. 256 4.8 HAZARDS This section focuses on two potential hazards to public health from different aspects of the project examined in this 1998 SEIR. One is exposure of construction workers to concentrations of lead deposited in soils on the site of the hook ramps part of the project. The second is exposure of future residents of Terrabay Commons to magnetic fields generated by the PG&E transmission lines. The first topic is evaluated in response to Caltrans environmental review requirements, and the second addresses potential impacts and required mitigation as directed by the 1996 SEIR. AERIAL LEAD -THE SETTING ~~ This section addresses lead contamination within the part of the site defined as the hook ramps project area, specifically where material would be disturbed during excavation. It focuses on two issues. One relates to the classification of material containing lead as hazardous or designated waste under Federal and State laws. The. other relates to risks to human health and safety, primarily of construction and subsequent maintenance workers who contact materials containing lead. The reason for examining these issues is to determine the suitability of contaminated soils for reuse on-site as fill material or, alternatively, to identify whether lead concentrations would require export and disposal of soil off-site. Soil naturally contains about 50 parts per million (ppm) of lead and in urban areas typically contains 200 to 500 ppm. Soil along road corridors contains higher concentrations of lead deposited when emissions of vehicles burning leaded fuel settled onto the ground. Lead was a common fuel additive until the 1980s. Caltrans has found that aerially deposited lead ("aerial lead") primarily is concentrated within 30 feet of the roadway pavement and within the top 0.5 foot of soil, although the agency has encountered lead as deep as 2.0 to 3.0 feet below the surface. Lead is not a highly mobile substance in the environment. However, when groundwater is near the surface or when surface water flows across contaminated areas, aerial lead can enter groundwater or surface receiving water where people (and wildlife) can contact and be harmed by it. The primary risk to humans from lead is exposure as a result of ingestion or inhalation. The Federal Environmental Protection Agency (USEPA) and California Environmental Protection Agency's (CaIEPA's) Department of Toxic Substances Control (DTSC), formerly the California 221 This section is based on the following materials and Nichols • Berman conversations with Leslie Dumas, CH2IvI HILL (SEIR hazardous waste consultant): • Caltrans Variance for Reuse of Lead Contaminated Soil, California Environmental Protection Agency (CaIEPA) and Department of Toxic Substances Control (DTSC), November 1995. • Evaluation of Groundwater Impact From Lead-Affected Soils Beneath Caltrans Inbound /Outbound Ramps, San Francisco International Airport, SOMA Environmental Engineering, Inc., August 1996. • San Francisco International Airport and Caltrans Right-of--Way, Inbound /Outbound Ramps / Caltrans Project, Draft Report for Environmental Investigation Volume 1, CH2MHill /AGS and Rust /AGS, April 1996. • Soil Sampling at Oyster Point, January 13, 1998 Technical Memorandum and January 21, 1998 Technical Memorandum, CH2M HILL . • Stanford Sand Hill Road Corridor Projects DEIR, EIP Associates, June 1996. • Status of the Phase 11 Site Investigation for BART's SFO Extension, Technical Memorandum, Camp Dresser & McKee, Inc., and CH2M HILL / DMJM, August 1997. 257 4.8 HAZARDS Terrabay Phase !! and 111 SE/R Department of Health Services, have established maximum permissible levels of contaminants above which materials are classified as hazardous waste when disturbed by excavation. USEPA and DTSC regulatory levels for lead determine whether the material is defined as hazardous under the Federal Resource Conservation and Recovery Act (RCRA) or by California as a hazardous waste, a designated waste, or non-classified material. In California, material constitutes "hazardous waste" if it contains lead with a "total threshold limit concentration" (TTLC) level of 1,000 milligrams per kilogram (mg / kg) or a "total soluble lead concentration" (STLC) of five milligrams per liter (5.0 mg / L), as determined by a citric acid "waste extraction test" (WET). California hazardous waste must be disposed of in a Class 1 landfill. California also classifies as "designated waste" material with lead levels less than 5.0 mg / L but which constitute a threat to the environment and human health because the level present can leach to groundwater and, thus, impact the waters of the State. Designated waste must be disposed of in a Class 2 landfill. The Regional Water Quality Control Board (RWQCB) shares regulatory responsibility for designated waste with the DTSC. According to RCRA, material constitutes a "hazardous waste" if it contains soluble lead with a "toxicity concentration leaching potential" (TCLP) level of 5.0 mg / L, as determined by deionized water (rather than WET) testing. Soil excavated within the project area which contains lead at or above these levels would require special handling during construction and / or disposal in landfills designed to accept the type of waste involved (hazardous or designated)(see Exhibit 4.8-I). Soil within the project area not disturbed by construction and which would remain in place potentially could be hazardous, depending on concentrations, but would not be classified as "waste" material. Only soil disturbed by the project would constitute a "waste". - Exhibit 4.&7 Federal and State Reaulaterv Levelc fnr t Aarl Total Lead '''Soluble Lead Federal Hazardous Waste (RCRA) 1,000 m / k 5 m / L ` California Hazardous Waste 1,000 m / k 5 m / L ` California Desi nated Waste NA less than 5 m / L Non-Classified Material NA less than 5 m~ / L a Total Threshold Limit Concentration (TTLC). b mg / kg =milligrams per kilogram. c Toxicity Concentration Leaching Potential (TCLP) as determined by deionized water testing d mg / L .milligrams per liter. (5 mg / L approximately corresponds to 125 mg / kg). e Soluble Lead Concentration (STLC) as determined by citric acid waste extraction testing. In 1995 Caltrans obtained a variance from the DTSC for the restricted reuse of soil containing aerial lead and meeting specific lead concentration criteria, as long as the contaminated soil is handled properly, reused along the same segment of highway (within the freeway corridor), and covered with non-hazardous soil or roadway. 222 The variance reduces Caltrans' costs to improve existing transportation facilities in urban areas by minimizing transport and disposal expenses to remove soils 222 New Variance for Manifest Transportation, Storage, and Disposal, Issued to State of California Department of Transportation (Caltrans) District 4, June 7, 1995, Department of Toxic Substances Control (DTSC), cited by San Francisco International Airport and Caltrans Right-of--Way, Inbound /Outbound Ramps / Caltrans Project, Draft Report for Environmental Investigation Volume I, op. cit. 258 4.8 HAZARDS Terrabay Phase ll and 111 SE1R containing specified levels of lead. The variance is effective for five years, until June 2007. Lead concentrations allowed by the variance are shown in Exhibit 4.8-2. As with DTSC and USEPA criteria, hazardous materials which exceed the threshold levels of Caltrans' five-year variance are classified as hazardous (or designated) wastes and must be removed and disposed of in a Class 1 (or 2) landfill. The Regional Water Quality Control Board (RWQCB) approves use of the variance on a case-by-case basis. 223 The variance only applies to the Caltrans' right-of-way (ROW). Material excavated outside the ROW containing aerial lead levels shown in Exhibit 4.8-I would require disposal in the appropriate landfill (Class 1 or 2). Alternatively, the City would need to obtain a separate variance to reuse material on-site, but a separate variance would require further environmental review (in addition to this 1998 SEIR). Exhibit 4.&2 DTSC Aerially Deposited Lead Variance Extractable Lead a Total Lead ° Caltrans May Take the Following Steps Soil may be reused as long as it is placed at least two feet Less than 0.5 ppm Less than 1,575 ppm above the water table and covered with one foot of clean soil. More than 0.5 ppm More than 1,575 ppm Soil may be used as fill as long as it is placed two feet above but less than 4,150 ppm the water table and covered with pavement or similar cap. Source: Caltrans Variance for Reuse of Lead Contaminated Soils, California Environmental ProtectOn Agency and Department of Toxic Substances Control November 1995. a These numbers relate to tests which determine if the lead is likely to move in water through the environment. The numbers are in parts per million (ppm) and are approximate conversions from micrograms per liter (µg / L). b Total lead is the total amount of lead in the soil. The numbers shown are in parts per million (ppm) and are approximate conversions from milligrams per kilogram (mg / kg). In addition to these criteria to classify waste, concentrations of 400 mg / kg of lead in soil represent a risk to human health. 224 This risk primarily relates to exposure to contaminated soils by workers who come in contact with aerial lead during project construction and future maintenance. AERIAL LEAD -SIGNIFICANCE CRITERIA According to Appendix G of the State CEQA Guidelines, a project would have a significant effect on the environment if it created a potential public health hazard or involved the use, production, or disposal of materials which pose a hazard to people or animal or plant populations in the area affected. Based on this criterion, the project would have a significant effect if implementation: Involved excavation within Caltrans' ROW of soil contaminated with concentrations of aerially deposited lead in excess of specific criteria established in Caltrans' variance, thus requiring off- site disposal. The concentrations are defined in Exhibit 4.8-2. 223 Ibid. 224 Region IX Preliminary Remediation Goals (PRGs), Second Nalf 1995, U.S. Environmental Protection Agency Repon IX, September 1995. 400 mg / kg is the soil exposure threshold for residential land use, and 1,000 mg / kg is the exposure for industrial use. 259 4.8 HAZARDS Terrabay Phase ll and 111 SEIR Involved excavation outside Caltrans' ROW of soils contaminated with concentrations of aerially deposited lead in excess of the USEPA and DTSC threshold criteria shown in Exhibit 4.8-1, thus requiring off-site disposal. Exposed construction workers to an unacceptable health risk from contact with aerial lead. An unacceptable risk is defined as soil with an areawide concentration of lead in excess of 400 mg / kg. AERIAL LEAD -IMPACTS AND MITIGATION MEASURES The City of South San Francisco authorized CH2M HILL, an engineering consulting firm, to conduct soil sampling of the proposed hook ramps and Bayshore Boulevard realignment in order to quantify lead levels in the project area. When this 1998 SEIR was being prepared, CH2M HILL had received an encroachment permit from Caltrans to perform the work but had not yet sampled the soil. The results of this testing program and final conclusions about the project's impacts discussed below will be reported in the Final 1998 SEIR. The following discussion presents the scope of work to be undertaken within the hook ramps project area for this EIR and also summarizes the outcome of equivalent testing programs completed in the vicinity or at locations with similarities to the hook ramps project area. The purpose of this discussion is to provide a basis for estimating the potential severity of impact and making preliminary conclusions about the feasibility of mitigating potential impacts successfully. Hook Ramps Project Area When performed, the aerial lead testing program for the hook ramps and Bayshore Boulevard will involve making 20 borings to a maximum depth of 2.5 feet below the existing ground surface (or pavement) and collecting soil samples. 225 Installation of borings will use dtrect push drilling through asphalt and will space borings evenly across the project area. The program will result in collection of two samples per boring (one at the ground surface and one at 1.5 to 2.0 feet below the ground surface) and analysis for total lead concentration (T'TLC) using USEPA Method 200.7 / 6010. Oyster Point Interchange Improvements In December 1997, CH2M HILL conducted aerial lead analyses at two locations at the terminus of the Oyster Point Interchange flyover east of U.S. 101. 226 One aerial lead testing site was located on the Railroad property north of Oyster Point Boulevard (west of Gull Drive), and the second was located south of Oyster Point Boulevard near Gateway Boulevard. Three borings were drilled and analyzed at the first site north of Oyster Point Boulevard, and five were installed and analyzed at the site second south of Oyster Point Boulevard. North of Oyster Point Boulevard Work consisted of placing three borings with a hand auger to depths of 1.0 to 1.5 feet below the ground surface, collecting composite samples manually, and analyzing samples for total extractable petroleum hydrocarbons (TEPH), semi-volatile organic compounds (SVOCs), and priority pollutant metals (including lead). Total lead concentrations of 73 to 240 mg / 225 Proposal to Conduct Soil Sampling at Proposed Hook Ramps and Bayshore Boulevard Realignment Locations, letter to Nichols • Berman from Leslie Dumas and Starr Dehn, CH2M HILL, January 14, 1998. 226 Soil Sampling at Oyster Point, January 13, 1998 Technical Memorandum, op. cit., and .lanuary 21, 1998 Technical Memorandum, op. cit. 260 4.8 HAZARDS Terrabay Phase ll and 111 SE/R kg were found in all three samples. Additional soluble lead (STLC) analysis confirmed that concentrations of 6.0 mg / L to 8.9 mg / L exceeded the State standard (5 mg / L). If excavated, material containing these aerial lead concentrations would be defined as a California hazardous waste. South of Oyster Point Boulevard Work here involved installing five borings with a hand auger to depths of 1.0 to 2.7 feet below the ground surface, collecting samples at the bore surface and bore termination, and analyzing samples for both total and soluble lead concentrations ('ITLC and STLC). Both samples in four of the five borings were found to contain lead concentrations in excess of Federal and State standards. Levels ranged from total lead concentrations of 97 to 580 milligrams per kilogram (mg / kg) compared with a standard of 1,000 mg / kg and soluble lead concentrations of 1.3 to 27 mg / L compared with a standard of 5 mg / L. Testing at both locations indicated the need for additional chemical analysis to determine if the soils should be classified as hazardous wastes under the Federal RCRA. San Francisco International Airport Another preliminary environmental investigation conducted in 1996 examined proposed inbound and outbound U.S. 101 ramps at the San Francisco International Airport.'27 This site, located south of the U.S. 101-Bayshore Boulevard hook ramp project area, is also a very heavily traveled freeway segment. The study determined that lead levels ranged from 5.0 mg / kg at two feet below the surface to 540 mg / kg at the ground surface in parts of the airport project area where construction would occur at grade. Analysis of six samples with total lead levels between 50 mg / kg and 100 mg / kg by citric acid WET tests resulted in lead solubility levels less than 5 mg / L. The report concluded that the mass of soil to be excavated for the project was not hazardous as defined by DTSC criteria and that excavated soils could be reused without regulation by the DTSC or without invoking the Caltrans' variance. Impact 4.&1 Soil Contamination by Aerially Deposited Lead Construction of the hook ramps and realignment of Bayshore Boulevard would occur in a project area where levels of aerially deposited lead potentially could exceed thresholds established by Federal and / or State regulations defining hazardous wastes. Lead levels within the Caltrans right-of--way could exceed criteria of a five- year variance for Caltrans projects which allow reuse and containment of contaminated soils on-site in specific circumstances. Such levels of contamination would require special handling by construction workers to remove and dispose of excavated soils at a Class 1 landfill. S The hook ramps would be located adjacent to the U.S. 101 freeway mainline and would occupy the same site as the existing U.S. 101 southbound off-ramp and Bayshore Boulevard. The project area includes land in the present Caltrans right-of-way (ROW) and land in the Cities of Brisbane and South San Francisco. The existing facilities typically carry large volumes of traffic daily. The freeway mainline carries approximately 188,000 vehicles past the site per day 228, and approximately 6,650 227 San Francisco International Airport and Caltrans Right-of--Way, Inbound /Outbound Ramps /Caltrans Project, Draft Report for Environmental Investigation Volume 1, op. cit. 228 Average daily traffic both northbound and southbound between the Oyster Point Interchange and northbound Bayshore Boulevard off-ramp (to Brisbane) based on the average for all months in the year 1996 as calculated by Caltrans. Nichols • Berman conversation with Mark Crane, Crane Transportation Group (1998 SEIR traffic consultant). 261 4.8 HAZARDS Terrabay Phase 11 and 111 SEIR vehicles per day use the "scissors" off-ramp. 229 Substantial concentrations of lead are expected to have been deposited along these roadways between the 1950s when U.S. 101 was rerouted from Bayshore Boulevard east of Visitation Point to its present alignment and the 1980s when lead additives were phased out of gasoline. Concentrations of aerial lead aze expected to be highest within 0.5 foot of the ground surface in a band extending 30 feet west of the freeway ramp pavement. (Concentrations would be expected to decrease with distance farther west of that point.) The eastern edge of the existing alignment of Bayshore Boulevazd is located approximately 30 feet west of the present scissors ramp diverge from U.S. 101, and the roadway centerline is located about 30 feet from the existing ramp terminus. Both the proposed hook ramps terminus and realigned Bayshore Boulevard would be located west of the existing western edge of roadway pavement. The depth to groundwater nearest the freeway mainline is estimated to be approximately five feet below the ground surface. Farther west of the 30-foot band (and existing roadway pavement), wetlands contain surface water on a seasonal basis. These wetlands are located on the proposed site of the hook ramps terminus and would be eliminated by placement of fill material with project implementation. Presence of lead in the top 0.5 foot of soil, an estimated five feet above the groundwater table could constitute a hazard subject to Federal or State regulation. 230 The RWQCB reviews and approves projects on a case-by-case basis because potential impacts are site-specific. Project implementation would disturb soil located in the project azea due to earth moving activities. Once soil is out of the ground, it would constitute "waste" and be subject to governmental regulatory thresholds which define hazardous, designated, or non-classified waste. Exhibit 2.3-IS shows that grading of the combined hook ramps /Bayshore Boulevard realignment project is expected to involve cutting of 10,000 cubic yards (including 9,000 cubic yards for the hook ramps alone) and filling of 58,000 cubic yards (including 8,000 cubic yazds for the hook ramps). Therefore, up to 10,000 cubic yards of soil containing aerially deposited lead potentially could need to be removed from the project area if found to be contaminated by levels in excess of DTSC criteria. The relative proportions of material inside and outside the Caltrans right-of--way (ROW) have not been estimated. When calculated, this amount would indicate how much material potentially could be subject to the Caltrans variance and reused on-site and how much material could need to be disposed of in a Class 1 or 2 landfill. The aerial lead testing program for the project summarized above will quantify concentrations and document the vertical and horizontal extent of this substance within the project area. Based on the foregoing discussion, it is expected that lead levels between 0.0 and 2.5 feet below the ground surface within the 30-foot band nearest to the freeway would meet or exceed levels found on both sides of Oyster Point Boulevard east of U.S. 101 discussed above. Until testing determines lead concentrations, it is not possible to estimate without speculating whether levels in project azea soils would constitute a hazardous or designated waste and require special handling and disposal. However, 229 See 4.4 Traffic and Circulation. AI~1 peak hour traffic (795 trips) and PM peak hour traffic (535 trips) represent a total of approximately 20 percent of average daily traffic. 230 Borings drilled in 1990 for the Oyster Point Interchange improvements, located in the general vicinity of [he hook ramps and Bayshore Boulevard realignment project, encountered groundwater at elevations of seven to 14 feet. Groundwater elevations were found to be higher proceeding west (towards the locations of seeps and springs on San Bruno Mountain). Nichols • Berman conversation with Anna Demorest, CH2M HILL, May 1998. CH2M HILL is drilling new borings for the flyover and hook ramps in June 1998, the results of which will be available for inclusion in the Final SEIR. 262 4.8 HAZARDS Terrabay Phase 11 and Ill SEIR the methods to mitigate such impacts are well known, and the City would be required to implement those measures in compliance with State and Federal regulations. -- Mitigation Measure 4.8-1(a) The City shall complete the lead testing program for total lead concentrations authorized for the project area in order to characterize site soils. If levels do not exceed State criteria defining a hazardous or designated waste, no additional mitigation would be required. If levels exceed State thresholds listed in Exhibit 4.8-I, Mitigation Measure 4.8-1(b) shall be required. tifitigation Measure 4.8-1(b) If the preliminary environmental investigation is inconclusive or identifies total lead concentrations in excess of State criteria, the City shall perform, at a minimum, supplemental citric acid waste extraction (WET) tests to identify soluble lead levels and determine whether soils within Caltrans' right-of-way could be reused without further regulation in project fills in compliance with Caltrans' variance. If found appropriate to be used on-site, Mitigation Measure 4.8-1(d) shall be required. If not capable of reuse on-site or if located outside Caltrans' right-of-way, Mitigation Measure 4.8-1(c) shall be required. Mitigation Measure 4.8-1(c) If the supplemental analysis program identifies levels in excess of State criteria, the-City shall remove, transport, and dispose the contaminated soil at a Class 1 (or 2) landfill which is licensed and operated to accept hazardous (or designated) waste. Mitigation Measure 4.8-1(d) If project area soils containing permissible levels of lead are to be reused on-site, the City shall comply fully with all the conditions, limitations, and other requirements specified by the DTSC variance for Caltrans projects. The following measures include some but all of the variance's requirements: • • The lead-contaminated soil shall be placed a m;n;mum of two feet above the maximum water table elevation and covered with at least one foot of clean soil. • Lead-contaminated soil shall not be moved outside the specified corridor boundaries. Any lead- contaminated soil which cannot be buried and covered within the Caltrans right-of--way shall be managed as a hazardous waste (see Mitigation Measure 4.8-1(c)). • Lead-contaminated soil shall not be buried in areas where it will be in contact with groundwater, surface water, or plants. Lead-contaminated soil shall only be buried and covered in locations protected from erosion and stormwater run-on and run-off and shall not be buried within ten feet of culverts or locations subject to frequent worker exposure. • Lead-contaminated soil shall be buried and covered in a manner which will prevent accidental or deliberate breach of the asphalt, concrete, and / or cover soil. - • Excavated contaminated soil shall be stockpiled and managed on a daily basis according to the variance, including no stockpiling in environmentally sensitive areas. • All field work to drill test borings and perform subsequent excavations on the site during project implementation shall be conducted in compliance with a site safety plan which meets requirements contained in the Occupational Saferv and Health Guidance Manual to protect field crew and construction workers' health. These measure shall include monitoring and exposure standards as provided by the variance. They also shall include required worker training in advance of implementation. 263 4.8 NAZ.1 RDS Terrabay Phase ll and 111 SE1R Significance after Mitigation Implementation of relevant Mitigation Measures 4.8-1(a) through 4.8- 1(d) which apply to the project would reduce the severity of potential aerial lead impacts to a less- than-significant level. In the event that export and disposal would be necessary due to the concentrations of lead found within the project area, secondary impacts would occur as a result of truck trips to haul material to a Class 1 or 2 landfill, together with associated noise and air quality effects along the haul route. The landfills which would accept hazardous or designated wastes for disposal is not known at this time. Class 1 landfills which can accept hazardous wastes include Kettleman Hills Landfill, the only Class 1 landfill in California. Class 2 landfills which can accept designated wastes include Ox Mountain Landfill in Half Moon Bay and Vasco Road Landfill in Livermore. Responsibility and Monitoring The City of South San Francisco would be responsible for implementing the relevant aspects of Mitigation Measures 4.8-1(a) through 4.8-1(d) which apply to the project, depending on the conclusions of each element of the measure. The City would be responsible for monitoring the handling, storage, transport, and / or storage of materials according to the site safety plan and variance and / or in compliance with Department of Toxic Substances Control (DTSC) and Regional Water Quality Control Board (RWQCB) requirements and procedures. The landfill operator ultimately would be responsible for monitoring compliance if soils require disposal. MAGNETIC FIELDS -THE SETT/NG23~ Introduction This section presents an evaluation of magnetic fields at the Commons West subarea of the Phase II residential site which was conducted specifically for this 1998 SEIR by Enertech Consultants. The evaluation included measuring magnetic fields on-site and independently reviewing a report prepared by Pacific Gas and Electric Company (PG&E) on the magnetic fields attributable to double circuit 115 kilovolt (kV) and 60 kV transmission lines which traverse the site. 232 The purpose of this evaluation is to describe existing magnetic field levels at the site and assess the potential impact of the ma~etic fields on the proposed residential development. The evaluation was conducted in response to the 1996 SEIR measure to mitigate Supplemental Impact LU-2-Compatibility between Project Residential Units and Existing Electrical Transmission Lines which directs as follows: 233 As part of the future review process for project Phase II, request from the applicant an independent study of this PG&E transmission line and its potential project Phase II impacts and mitigation needs. Also require that the project-specific environmental documentation for project Phase II includes 231 This section is based on the report, Terrabay Commons West Supplemental EIR Evaluation of Magnetic Fields of PG&E Electric Transmission Lines, prepared by Enertech Consultants (SEIR study team member), October 1997. A copy of the complete report is on file with the Planning Division, City of South San Francisco Economic and Community Development Department, City Hall, 400 Grand Avenue and is available for public review during normal business hours. 232 Letter to Janine O'Flaherty, Brian Kangas Foulk (project sponsor's engineer), from Dave Gregory, Pacific Gas and Electric Company, August 20, 1997. This letter (the PG&E "report") also is part of the City's project file and can be examined as noted above. 233 Draft Supplemental Environmental Impact Repon for the Terrabay Specific Plan and Development Agreement Extension, «'agstaff and Associates, January 1996. 764 4.8 HAZARDS Terrabay Phase 11 and Ill SElR adequate examination of this transmission line, its potential EMF [electromagnetic field] impacts on Phase II residential units, and warranted mitigation needs. ... The evaluation is focused on the part of the Phase II residential site exposed to magnetic fields from the transmission lines, the Commons West subarea. Description of Magnetic Fields Any object with an electric charge on it has a voltage (potential) at its surface and can create an electric field. When electrical charges move together (lmown as "current"), they create forces on other electric currents. These forces are represented by magnetic fields. Magnetic fields occur throughout nature and are one of the basic forces of nature. All electric currents create magnetic fields. The strength of the magnetic field depends on the current (higher currents create higher magnetic fields), the configuration / size of the source, and distance (magnetic fields grow weaker as the distance from the source increases). The most commonly used magnetic field unit is the Gauss (G). Usually for convenience, the smaller unit of milliGauss (mG) is used which is one thousandth of a Gauss. Magnetic fields can be static /unchanging in direction (caused by direct current (DC)) or changing / alternating in direction (alternating current (AC)). For example, static magnetic fields occur in nature. The earth has a natural static magnetic field of about 510 mG (0.51 Gauss) near the project site. 234 Magnetic fields from other sources (such as transmission lines and appliances) differ from DC fields (like the earth) because these fields are due to alternating currents and change direction at a rate of 60 cycles per second or 60 Hertz. The magnetic field under most transmission and distribution lines usually is smaller than values neaz many common household appliances. The main reason for this is the height above ground at which electric power lines aze supported. Since the field decreases with distance from the source, the line height above ground effectively reduces the magnetic field to levels which are less than many appliances. Transmission line magnetic fields attenuate at a rate of about one over the distance squared, while magnetic fields from appliances attenuate at a rate of about one over the distance cubed. The magnetic field of a number of typical household appliances has been measured, and typical values aze given in Exhibit 4.8-3. 235 Site Description The Commons West subarea is located in hilly terrain which extends uphill from South San Francisco Drive on the south side of San Brtuto Mountain (Exhibit 4.8-~. An existing PG&E right-of--way (ROW) traverses the site in a north-south direction. The site otherwise is vacant but is proposed for construction of attached duplex and triplex housing units, parking, and associated development. Housing units would be located adjacent to the ROW. 234 The Earth's Magnetic Field, R.T. Merrill and M.W. McElhinney, International Geophysics Series No. 32, Academic Press, 1983. 235 Household Appliance Magnetic Field Survey, U.S. Naval Electronic Systetns Technical Report No. E06549-3, Illinois Institute of Technology Research Institute, March 1984. 265 4.8 HAZARDS Terrabay Phase Il and Ill SE/R Transmission Line Description The PG&E ROW is 150 feet wide and developed with double circuit transmission lines, the San Mateo- Martin Circuits. 236 Exhibit 4.8-5 illustrates the transmission line ROW and placement of the different electric circuits in the ROW, as reported by PG&E. The basic electric design is for nominal 115,000 volt (115 kV) electric circuits, except for one circuit operated at 60 kV. The PG&E ROW contains six transmission line circuits supported on three towers. Each circuit is supported in a vertical configuration with one circuit on opposite sides of a steel lattice tower (a double circuit arrangement). Exhibit 4.8-5 shows the present phasing arrangement. The transmission line crosses the site in approximately one complete span. One set of three towers is located on San Bruno Mountain uphill from the site, and a second set is developed on the hilltop south of the site (and both South San Francisco Drive and Sister Cities Boulevard) which together form the span. Exhibit 4.8-6 presents photographs of the towers. Because the support towers are located on rather high hills, the Exhibit 4.8-3 Magnetic Fields Due to Typical Household Appliances a Magnetic. Field b Appliance 121nches Away Maximum Electric ran e 3-30 mG 100-1,200 mG Electric oven 2-5 mG 10-50 mG Garba a dis osal 10-20 mG 850-1,250 mG Refri erator 0.3-3 mG 4-15 mG Clothes washer 2-30 mG 10-400 mG Clothes d er 1-3 mG 3-80 mG Coffee maker 0.8-1 mG 15-250 mG Toaster 0.6-8 mG 70-150 mG Crock of 0.3-1 mG 15-80 mG Iron 1-3 mG 90-300 mG Can o ever 35-?50 mG 10,000-20,000 mG Mixer 6-100 mG 500-7,000 mG Blender, o er, rocessor 6-20 mG 250-1,050 mG Vacuum cleaner 20-200 mG 2,000-8,000 mG Portable heater 1-40 mG 10-1,100 mG Fans /blowers 0.40 mG 20-300 mG Hair d er 1-70 mG 60-20,000 mG Electric shaver 1-100 mG 150-15,000 mG Color TV 9-20 mG 150-500 mG Fluorescent li ht 2-40 mG 140-2,000 mG Fluorescent desk lam 6-20 mG 400-3,500 mG Circular saw 10-250 mG 2,000-10,000 mG Electric drill 25-35 mG 4,000-8,000 mG a ttousenota ftppt:ance Magnetzc rie[d Jutvey, op. cit. b MilliGauss (mG). 236 A 30-foot wide gas line easement is also located within the ROW but is unrelated to this analysis of magnetic fields. ,~ Exhibit 4.8-4 Location of Commons Neighborhood Project Site Boundary S/Star cues eon/e ''tea Source: Enertech Consultants Exhibit 4.8-5 Sketch of PG&E Transmission Lines at Site #4 #3 #2 #1 #6 #5 v Sl nl ng Source: Enertech Consultants 'n ,fl w w o (View North) o x x Exhibit 4.&6 Photographs of PG&E Transmission Lines ~r ~~~ f. . Source: Enertech Consultants '~ xG K Top-View of Northern Towers on San Bruno Mountain Bottom-View of Towers South of Site 4.8 HAZARDS Terrabay Phase ll and 111 SE1R much lower elevation of the development site (near mid-span) means that the conductors are much farther from the ground than would be the case for most typical transmission lines. PG&E Report PG&E performed magnetic field measurements on August 14, 1997 to determine field values adjacent to proposed site development. Lateral profiles (magnetic field versus distance) were taken across and extending beyond the PG&E ROW at two locations -along South San Francisco Drive (on-site) and along Airport Boulevard (off-site). 237 Project site terrain is very hilly, and the measurements were taken at different locations to evaluate the effect of transmission line height. Measured magnetic field values reported by PG&E range from about 2.4 mG on the ROW (dtrectly under the lines on South San Francisco Drive) to about 1.5 mG at the ROW edge. PG&E reports the various circuits to be loaded as follows: Exhibit 4.8-7 Transmission Line Loading Values at Time of PG&E Measurements Circuit 'Loading Numbers 5 / 6 300 am s ~ Numbers 1 / 2 450 am s Numbers 3 / 4 250 am s PG&E reported that these are normal operating conditions for the time of year when the measurements were taken. Based on the PG&E report, it can be estimated that magnetic fields of less than about 1mG could be expected in the center of residential units proposed contiguous to the transmission line ROW. SE/R Measurements In addition to PG&E's August 1997 measurements, Enertech Consultants made measurements on September 24, 1997. The purpose of Enertech's measurements was to collect independent on-site data near the centers of building pads proposed next to the east side of the PG&E ROW. Exhibit 4.8-8 shows measurement locations. In addition to magnetic field measurements, a distance measurement instrument was used to determine the approximate height of the transmission line conductors where they cross South San Francisco Drive, as follows: 237 Letter to Janine O'Flaherty from Dave Gresory, op. cit. 270 Exhibif 4.8-8 Building Pad Measurement Locations •• ~~ . M Y, ` ~ ---- '~~•-- ----- • • ~ X x X ,' ~. ---- • ` ` ', ~ ~ ------- -_ `` •• .• ~ ~ ` ~ •• ` Source: Enertech Consultants 4.8 HAZARDS Terrabay Phase ll and 111 SEIR Exhibit 4.8:•9 Approximate Height of PG&E Transmission Line Conductors Circuits Approximate Height Above Street West Side Number 4 94 feet Number 3 86 feet Number 2 98 feet Number 1 100 feet Number 6 96 feet Number 5 97 feet East Side The magnetic field measurements were made using an EMDEX-SNAP survey meter manufactured by Enertech. The meter was calibrated at Enertech's laboratory in accordance with the 1994 American National Standards Institute standards. 238 Measurements were made at one meter and five meter heights to evaluate the change in readings for multi-story residential units. Although the existing terrain is hilly, grading plans indicate that the measurements were taken at elevations within about ten to 15 feet of proposed finished elevations. This means the measurements are representative of final conditions for practical purposes. Measured values are all taken at the approximate centers of building pads close to the PG&E ROW with the following results: Exhibit 4.8-70 Magnetic Field Levels Measured at Building Pads Magnetic Field a Building Pad b One-Meter Height Five-Meter Height 1 D 0.9 mG 1.1 mG 2D 0.3 mG 0.3 mG 3D 0.1 mG 0.2 mG ST 0.5 mG 0.5 mG 9T 0.2 mG 0.1 mG a MilliGauss (mG). b See Exhibit 4.8-8 for the location of building pads. Numbers refer to pad location and letter to building type (D = duplex; T =triplex). MAGNETIC FIELDS -IMPACTS AND MITIGATION MEASURES Magnetic field levels within parts of the Commons West site primarily result from the presence of the existing PG&E transmission lines which traverse the site. Magnetic fields measured at the centers of proposed building pads closest to the transmission lines generally are less than 1.0 mG. Values measured directly underneath the transmission lines are about 1.0-2.0 mG. Field levels attenuate with distance from the line. Stationary measurements at building pad 1D indicated that the magnetic field remained relatively constant during the measurement period. The magnetic field values measured by PG&E and Enertech are far below any existing standards. 238 "IEEE Standard Procedures for Measurement of Power Frequency Electric and Magnetic Fields From AC Power Lines", IEEE Standard 644-1994, March 1995. ?7? 4.8 HAZARDS Terrabay Phase 11 and 111 SE1R Significance Criteria The State of California has established no EMF standards. The State has considered this subject but did not fmd a basis for setting numerical standards or guidelines. After a careful review of research on E1VIF, the California Public Utility Commission (CPUC) stated in its conclusion of law: 239 It is not appropriate to adopt any specific numerical standard in association with EMFs until we have a firm scientific basis for adopting any particular value. Although there are no Federal health standards specifically for 60 Hertz magnetic fields, two organizations have developed guidelines -the International Radiation Protection Association of the International Commission on Non-Ionizing Radiation Protection (IR.PA / Lti'IRC) 240 and the American Conference of Governmental Industrial Hygienists (ACGII-~. 241 Both of these guidelines are much higher than levels found within the project site. Exhibits 4.8-II and I2 summarize the electric and magnetic field levels of these guidelines, respectively. Since it has not vet been determined whether magnetic field exposure constitutes a health hazard, it cannot be determined what levels of exposure are "safe" or "unsafe". Exhibit 4.&11 Summary of IRPA /INIRC Exposure Guidelines a Exposure (50/60 Hz) Electric Field b Magnetic Field Occu ational Whole Workin Da 10 kV/m (10,000 V/m) 5 G (5,000 mG) General Public U to 24 Hours er Da 5 kV/m (5,000 V/m) 1 G (1,000 mG) Few Hours er Da 10 kV/m (10,000 V/m) 10 G (10,000 mG) a International Commission on Non-Ionizing Radiation Protection Guidelines, op. cit. b KiloVolu per meter (kV/m) and volts per meter V/m). c Gauss (G) and Mi1liGauss (mG). Exhibit 4.&12 Summary of ACGIH Exposure Guidelines a Electric Field Magnetic Field Occupational exposures should not exceed Occupational exposures should not exceed: 25 kV/m 10 G (from 0 Hz to 100 Hz) (10.000 mG) For workers with cardiac pacemakers For workers with cardiac pacemakers maintain exposure the field should not exceed at or below 1 kV/m 1 G (1,000 mG) a ACGIH Occunational Threshold Limit Values for (>n-Hz FMF nn cir 239 Califonva Public Utility Commission Decision 93-11-013. 240 •`Interim Guidelines on Limits of Exposure to 50 / 60-Hz Electric and Magnetic Fields°, International Non-Ionizino Radiation Committee of the International Radiation Protection Association (IItPA/Lti-IlZC), Health Physics, 58: 113-122, 1990. 241 "1994-1995 Threshold Limit Values for Chemical Substances and Physical Agenu and Biological Exposure Indices", American Conference of Governmental Industrial Hygienists (ACGIH), ISB'r 1-88241--06-2, 1994. 273 4.8 HAZARDS Terrabay Phase /l and 111 SE/R .. There are no State of California or Federal magnetic field standards for parks or public use facilities. At least six states other than California have adopted engineering-based guidelines or standards for transmission line electric fields, and two of these states also have standards for magnetic fields. The purpose of most of these standards is to make the field levels from new power lines similar to the field levels from existing lines or to avoid nuisance effects due to spark discharge from large vehicles in the electric fields of 345 to 765 kV transmission lines. Exhibit 4.8-13 summarizes these standards. 242 Exhibit 4.&13 State Regulations Limiting Field Strengths on Transmission Line ROWs State Electric Field Limit Magnetic Field Limit Montana 1 kV/m at edge of ROW in residential areas None Minnesota 8 kV/m maximum in ROW None New Jerse 3 kV/m at edge of ROW None New York 1.6 kV/m at ed e of ROW 200 mG at ed a of ROW (Max Load) North Dakota 9 kV/m maximum in ROW None Ore on 9 kV/m maximum in ROW None Florida 10 kV/m maximum for 500 kV lines in ROW 200 mG for 500 kV lines at edge of ROW (Max Load) 2 kV/m maximum for 500 kV lines at edge of ROW 250 mG for double circuit 500 kV lines at edge of ROW (Max Load) 8 kV/m maximum for 230 kV and smaller lines in ROW 150 mG for 230 kV and smaller lines at edge of ROW (Max Load) 3 kV/m maximum for 230 kV and smaller lines at edge of ROW EMF Health Effects Concerns about exposure to electric and magnetic fields (EMl~~ primarily relate to health effects. EMF exposure in residential and occupational situations has been studied for a wide variety of sources, including transmission lines, distribution lines, household wiring, electric appliances, electrically operated equipment or machinery, etc. A number of studies during the last approximately 20 years generally have found no conclusive evidence of harmful effects from typical power line and substation electric and magnetic fields. Some studies during this period did report the potential for harmful effects, and others did not. The most recent and largest study of childhood cancer by The National Cancer Institute did not report an association between cancer and proximity to power lines. 243 The overall evidence for such an association is inconclusive, and the most recent independent comprehensive review of the scientific literature by the National Academy of Sciences reached the following conclusion: 244 242 "Fields From Electric Power", Carnegie Mellon University, Department of Engineering and Public Policy, 1995. 243 possible Health Effects of Exposure to Residential Electric and Magnetic Fields, National Academy of Sciences, National Research Council, 1996. 244 "Residential Exposure to Magnetic Fields and Acute Lymphoblastic Leukemia in Children", M.S. Linet et. al., The New England Journal of Medicine, Volume 337, Number 1, July 3, 1997. 274 4.8 HAZARDS Terrabay Phase ll and 111 SE1R Based on a comprehensive evaluation of published studies relating to the effects of power-frequency electric and magnetic fields on cells, tissues, and organisms (including humans), the conclusion of the committee is that the current body of evidence does not show that exposure to these fields presents a human-health hazard. Specifically, no conclusive and consistent evidence shows that exposures to residential electric and magnetic fields produce cancer, adverse neurobehavioral effects, or reproductive and developmental effects. The committee reviewed residential exposure levels to electric and magnetic fields, evaluated the available epidemiologic studies, and examined laboratory investigations that used cells, isolated tissues, and animals. At exposure levels well above those normally encountered in residences, electric and magnetic fields can produce biologic effects (promotion of bone healing is an example), but these effects do not provide a consistent picture of a relationship between the biologic effects of these fields and health hazards. An association between residential wiring co~gurations (called wire codes) and childhood leukemia persists in multiple studies, although the causative factor responsible for that statistical association has not been identified. No evidence links contemporary measurements of magnetic-field levels to childhood leukemia. Impact 4.8-2 Effect of EMF on Future Residents Residential development of fhe Commons West site would not expose residents to unusual magnetic field levels or, in the absence of California State or Federal standards, levels which government entitles outside California regulate. LTS ' Thirty-two (32) housing units are proposed to be built on the Commons West site. Of those, the duplex proposed on pad 1D and triplex located on pad ST would be immediately contiguous to the PG&E ROW, and the 27 other units would be built farther away from the ROW (Exhibit 4.8-8). The magnetic field measurements taken for this SEIR on the five building pads shown in Exhibit 4.8-8 were made during power line loading conditions representative of typical loads. The measured magnetic field levels at the site's representative housing unit locations range from about 0.1 to 1.0 mG. These levels are encountered routinely in everyday life at many common locations. The magnetic field levels measured for the proposed residential building sites aze faz lower than existing standards in other states and occupational or general public exposure guidelines. The study of magnetic field levels at the project site found nothing unusual at the site, and measured fields are at levels commonly encountered in many typical situations. No State or Federal regulations are known which would restrict residential development of the site as proposed. Mitigation Measure 4.8-2 Although the proximity of electric power lines to proposed housing units would not be expected to result in significant impacts requiring mitigation, the August 1997 PG&E report reviewed by this SEIR makes two recommendations. The first corresponds with 1996 SEIR mitigation. These are to: An advisory disclosure statement shall be included on all deeds of properties within the Commons West subazea of the site that the subject property is located neaz power lines and purchasers should be awaze that there is ongoing reseazch on the potential health effects associated with magnetic fields which exist wherever there is electric current. Potential buyers shall be reminded that PG&E can and will, upon request, provide information on EMF and the current state of ongoing reseazch on the potential health effects of EMF. z~s 4.9 ARCHAEOLOGY ARCHAEOLOGY -THE SETTING The 1998 SEIR focuses solely on the Terrabay Phase III site and its immediate vicinity, the location of known cultural resources identified by the 1982 EIR and 1996 SEIR. Review Methods This section was prepared by the EIR archaeologist, David Chavez, I.A., who has 20 years of experience in Cultural Resources Management (CRM) and applying requirements of the California Environmental Quality Act (CEQA). He was assisted in report revieR-, critical analysis, and field inspection by Nina Ilic, M.A., an archaeologist with more than ten years of experience in CRM work. Independent peer review by David Chavez & Associates included critical analysis of all recent Holman & Associates (the project sponsor's archaeologist) Terrabay project technical archaeological reports for content, conclusions, and recommendations. All other reports, maps, site records and correspondence relevant to the Terrabay project, CA-SMa-40, and CA-SMa-92 also were reviewed. Sources for these materials included the Historical Resources Information System, Northwest Information Center (KWIC) at Sonoma State University, the City of South San Francisco Planning Division, Caltrans District 4, and Holman & Associates. The materials most relevant to the project area and archaeological resources are referenced in the text. The Phase III site and the speck locations of CA-SMa-40 and CA-SMa-92 were inspected in December 1997 and February 1998. Weather conditions and saturated soils somewhat hampered the effectiveness of those field observations. Additional field review was accomplished in early April 1998, and site inspection conditions were greatly improved. This independent peer review also involved contacting and soliciting input from members of the Native American community. David Chavez & Associates requested a list of Coastanoan / Ohlone Most-Likely-Descendants from the Native American Heritage Commission in Sacramento. Individuals and organizations were contacted by letter, and preliminary response to the project and the potential impacts to CA-SMa-40 was elicited. Letters and telephone calls were received from some of the Native Americans contacted. However, it is expected that more specific response will follow public review of the Draft SEIR. 245 Ethnohistory The late prehistoric period inhabitants of the San Francisco Peninsula belonged to a Native American group identified by anthropologists as the Costanoans (from the Spanish "Costanos" or coast people). Costanoan refers not to a politically unified group occupying a distinct geographic area but, rather, to different groups of people who shared similar cultural traits and belonged to the same language family. Linguistic evidence suggests that the Costanoans (a Utian population) moved into the San Francisco Bay Area circa A.D. 500 and replaced an earlier Hokan population. This theory of prehistoric 245 Additional discussions rejarding Native American concerns are presented in the subse`tion on Significance Criteria (see CA-SMa-40). 276 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SE1R population movement and displacement is supported by the appearance of distinct artifact assemblages in archaeological deposits that coincide with the A.D. 400 period. 246 Many, but not all, present-day descendants prefer to be identified as Ohlone rather than Costanoan. The Terrabay Phase III site is located within the one-time Ramaytush subdivision of the Costanoan / Ohlone domain which included present-day San Mateo and San Francisco Counties. Based on Spanish mission records and archaeological information, it has been estimated that the Ramaytush had a population of 1,400 in 1770. 247 Within the Ramaytush ethno-linguistic unit, the Costanoan / Ohlone population was further divided into tribelets. In 1770, these tribelets were (believed to be) autonomous groups with from 50 to X00 individuals and an average population of 200. Tribelet territories were defined by physiographic features and usually had one or more permanent villages surrounded by a number of temporary camps. The camps were likely positioned to exploit seasonally available subsistence resources. 248 The Urebure tribal settlement of Siplichouin was located somewhere in the San Bruno azea. 249 With the Spanish entry into the San Francisco Bay Area in 1769, the traditional Costanoan / Ohlone lifeway rapidly deteriorated as Native populations and cultures were decimated by introduced diseases, a declining birth rate, the awesome impacts of the mission system and, beginning in 1833, the secularization of mission lands by the Mexican government. The Costanoan / Ohlone were transformed from hunters and gatherers into agricultural laborers who lived at the missions and worked with former neighboring groups such as the Yokuts, Miwok and Patwin. With secularization, most of these Native populations gradually moved to ranchos to work as laborers. Consequently, multi-ethnic Indian communities formed in and around former Costanoan / Ohlone territory by the onset of the American Period in the late 1840s. An estimated 200-plus Native Americans of Costanoan / Ohlone ancestry currently reside in the greater San Francisco Bay Area. Several organizations and individuals, acting asofficially-designated Most-Likely-Descendants, are active in efforts to preserve and otherwise manage prehistoric and ethnohistoric cultural resources on the San Francisco Peninsula. Prehistory The eastern slopes of San Bruno Mountain formed an attractive setting for prehistoric cultural activity and settlement. The San Francisco Bay waters and extensive marshlands would have provided Native American populations with an abundance of important dietary resources, as would the upland terrain which fronted the Bay. Potable water was available from creeks and perennial springs (such as those located on the Terrabay Phase III site). Numerous bayside prehistoric azchaeological sites have been 246 People of the West, the Ohlone Story", P. Michael Galvan, Indian Historian, 1967-1968; "Costanoan", Richard Levy, Handbook of North American Indians, 1978; and California Archaeology, Michael J. Moratto, 1984. 247 Ibid., "Costanoan", Richard Levy. 248 Ibid., and A Cultural Resources Assessment for San Francisco Resource Supply Study (San Mateo Substation to Martin Substation), Daly City to Ciry of San Mateo, San Mateo County, California, Rebecca Loveland Anastasio and Donna Garaventa et. al., 1988. 249 A Time of Little Choice, the Disintegration of Tribal Culture in the San Francisco Bay Area, 1769-1810, Randall Milliken, 1995. 277 4.9 ARChAEOLOGY Terrabay Phase 11 and 111 SE/R recorded up and down the San Francisco Peninsula. Some are extensive shellmounds which have yielded artifact assemblages and exhibited cultural features indicating long-term permanent village habitation. Other sites exhibit characteristics of temporary and seasonal encampments. Yet others are variations of the more permanent and / or the more temporary of sites in function and duration of use. Archaeological History The Terrabay Phase III site has been the subject of several azchaeological investigations of varying intensity which have resulted in the documentation of two prehistoric archaeological sites - CA-SMa- 40 (located within the Phase III site development area) and CA-SMa-92 (situated adjacent to the western boundary of the Phase III site). In 1950, CA-SMa-40 was recorded and described as a large shellmound 250 and was re-recorded in 1968. 251 In 1982, Archaeological Resource Management conducted a field reconnaissance and a subsurface testing program at CA-SMa-40 for the 1982 EIR. 252 Those investigations resulted in preliminary definitions of cultural deposits at the site. In 1984, Caltrans archaeologists updated the site record. 253 In 1988, an archaeological field reconnaissance was conducted by the Bay Area Mountain Watch, and the condition of the site was once again summarized. 254 Beginning in 1988, Holman & Associates conducted comprehensive surface and subsurface. azchaeological investigations of CA-SMa-40. Those investigations have resulted in: A preliminary report which presents in detail azchaeological excavation methods and findings, explores the cultural history of the site and evaluates the significance of the resource. 255 An interim archaeological report which summarizes the previous reseazch history, cultural nature, and potential significance and presents preliminary impact and mitigation discussions in response to the current Terrabay project. 256 A final report which details the archaeological investigative efforts and findings for CA-SMa1l0 and presents impact and mitigation discussions in response to the pending Terrabay Phase III development concept. 257 250 Archaeological Site Record for CA-SMa-40 and Field Notes, A. Pilling, 1950. 251 Supplemental Archaeological Site Record for CA-SMa-40, R. Schenk, 1968. 252 Cultural Resources Evaluation of the South Slope Project on San Bruno Mountain in the County of San Mateo, Robert Cartier, 1982, and Limited Subsurface Testing for the Archaeological Site Boundary Delineations for the Proposed South Slope Project in the County of San Mateo, Robert Cartier, 1982. 253 Supplemental Archaeological Site Record for CA-SMa-40, L. Weigel and Robert Gross, 1984. 254 The Archaeology of San Bruno Mountain, San Mateo County, California (Preliminary Report), Joseph Majer, 1988. 255 Preliminary Report of Archaeological Investigation at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clark, 1989. 256 Interim Report of Archaeological Evaluation of the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clark, 1997. 278 4.9 ARCHAEOLOGY Terrabay Phase ll and 111 SE/R The second archaeological site associated with the Terrabay site is CA-SMa-92 which originally was recorded in 1954 and described as a small shell midden. 258 The original site location placed CA- SMa-92 within the boundary of the Phase III site. Subsequent surface reconnaissance efforts to relocate the cultural deposit, as originally identified, were unsuccessful. 259 The 1982 Archaeological Resource Management subsurface investigations included efforts to locate and define CA-SMa-92.260 The findings were inconclusive despite the excavation of 13 backhoe trenches. However, survey efforts did result in the discovery of what was believed to be an additional prehistoric cultural site, CA-SMa-234, upslope from CA-SMa-92.261 The site description for CA-SMa-234 was essentially identical to that of CA-SMa-92. Intensive archival research and field inspections led Holman & Associates to conclude that CA-SMa- 92 and CA-SMa-234 are the same prehistoric cultural resource - a single shell midden situated at the officially-recorded location of CA-SMa-234. 262 Holman & Associates determined that: • The location of CA-SMa-92 must have been mapped inconrectly when originally recorded at the University of California, Berkeley Archaeological Survey and / or incorrectly transferred to the Northwest Information Center (KWIC) files at Sonoma State University • Because of the incorrect mapped location, subsequent field inspections failed to relocate the site. • The 1982 recording of CA-SMa-234 263 was not a new discovery but, rather, a revisit to the actual CA-SMa-92 site location. Holman & Associates documented these findings and conclusions and presented revised site record and mapping materials to the NWIC. The NWIC concurred in those conclusions and deleted the site designation CA-SMa-234. The trinomial CA-SMa-92 now identifies the small prehistoric site immediately west of the Terrabay Phase III site boundary, and the former location of CA-SMa-92, at 257 Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clark, 1998. 258 Archaeological Site Record for CA-SMa-92, Plus Field Notes, D. F. McGeein, 1954. 259 pn Archaeological Reconnaissance of San Bruno Mountain, Phase Two, David Chavez and Miley Holman, 1974; Preliminary Cultural Resources Identification: San Francisco Bay Study for Flood Control, U.S. Army Corps of Engineers, David Chavez, 1979; and The Archaeology of San Bruno Mountain, San Mateo County, California (Preliminary Report), Joseph Majer, op. cit. 260 Limited Subsurface Testing for the Archaeological Site Boundary Delineations for the Proposed South Slope Project in the County of San Mateo, Robert Cartier, op. cit. 261 Cultural Resources Evaluation of the South Slope Project on San Bruno Mountain in the County of San Mateo, Robert Cartier, op. cit. 262 Identijcation of Site CA-SMa-92 / CA-SMa-234 and the Potential Construction Impacts for Phase III of the Terrabay Development in the City of South San Francisco, Matthew Clark, 1997. 263 Limited Subsurface Testing for the Archaeological Site Boundary Delineations for the Proposed South Slope Project in the County of San Mateo, Robert Cartier, op. cit. 279 4.y Nf-lt,nr+CVLVV ~ Terrabay Phase l! and ll! SE/R one time believed to be within the project area boundaries, is no longer a recognized cultural resource site. 264 Discussions of these two prehistoric archaeological resources are based primarily on the information presented in Holman & Associates investigative reports and other materials and a critical review of the reports and field verification by David Chavez & Associates. 265 CA-SMa-40 The stated purpose of the Holman & Associates subsurface archaeological testing program was to assess the boundaries, condition, depositional integrity, and research significance of the site. These avenues of archaeological inquiry were couched within a research design which identified nine specific research questions: • Does enough of the original deposit remain intact to allow scientifically valid samples to be extracted and analyzed for comparison with other archaeological assemblages? • What time span is included in the cultural deposition at the site? • What kind of site is CA-SMa-40? All researchers have assumed it to be an occupation site, - probably a village. Is this demonstrable? • How old is the most recent prehistoric occupation of CA-SMa-40? How old is the earliest occupation? Does the deposit exhibit continuous use through time or are there definable breaks in the sequence? • What data relative to subsistence strategies and regional economy does CA-SMa-40 contain? • Are there changes in subsistence strategies reflected in economic data from the site? How do such changes relate to the chronology of the site? • What data does CA-SMa-40 contain relative to area, regional, and wider trade networks? Is change evident in these networks through time? • Does CA-SMa-40 contain intact human burials? • Changes in cultural styles and practices through time are already documented in the Bay Area. What data does CA-SMa-40 contain to further document and help explain these changes? The investigations were initiated with the excavation of mechanical and hand-auger borings followed by test unit excavations which were completed in the summer of 1989. Twenty-seven (27) six- to 264 "Site Record Forms for CA-SMa-92 / 234", letter from Maria Ribeiro, Site Record Coordinator, Historical Resources Information System, Northwest Infortation Center, to Matthew Clark, Holman & Associates, November 18, 1997. 265 preliminary Report of Archaeological Investigations at the San Bruno Mountain Mound, Site CA-SMa-40, South San Francisco, California, op. cit.; Interim Report of Archaeological Evaluation of the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, op. cit.; Identificarion of Site CA-SMa-92 / CA-SMa-234 and the Potential Construction Impacts for Phase III of the Terrabay Development in the Ciry of South San Francisco, op. cit.; Archaeological Site Record for CA-SMa-92, op. cit.; Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa~10, South San Francisco, California, op. cit.; and "Limits of Archaeoloa cal Site CA- SMa-92 in relation to Terrabay Project Impacts", letter to Nichols • Berman, February 16, 1998. 280 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SE/R eight-inch diameter mechanical borings, 18 three-inch diameter hand-auger borings, and six one- by two-meter test units were excavated. Test unit soils were removed in ten- to 20-centimeter (four- to eight-inch) arbitrary levels, and 21.4 cubic meters of soil were removed from the six units. Except for column samples, which were removed for site soil constituent analysis, all excavated materials were passed through one-quarter- and one-eighth-inch mesh wire shaker screens. Excavation, record keeping, mapping, and cultural material processing methods and techniques appear to have been well within the bounds of current professional standards. Holman & Associates determined that the site is roughly circular in plan view. It extends over an estimated 9,000 square meters (approximately 2.2 acres), is more than three meters (ten feet) deep in at least one location, and contains only 70 centimeters of cultural deposits in the most shallow unit. Precise boundaries have been marked on project plan maps on file with the City of South San Francisco. 266 The cultural strata displayed structural and locational integrity beneath a relatively shallow surface layer of disturbed soil. Charcoal samples were extracted from undisturbed cultural strata, and 18 radiocarbon dates ranging from 5,155 to 460 years before the present (B.P.) were obtained, suggesting that the site is one of the oldest documented bayside shellmounds in the Bay Area. Some moderately time-sensitive artifacts were recovered, including shell beads, projectile points, and ground stone items which tend to be compatible with the radiocarbon dates in assessing the antiquity and cultural history of CA-SMa-40. Obsidian samples were subjected to sourcing analysis which led to preliminary conclusions about prehistoric economic systems and trade networks. Obsidian hydration (time depth) analysis gave additional but tentative support to time depth theories. Column sampling analysis led to faunal and dietary information regarding prehistoric environmental setting and subsistence practices of the CA- SMa-40 inhabitants. Fragmentary remains of approximately 15 individuals were recovered from five of the six test units, a certain indication that additional Native American burials are present. Holman & Associates conclude that CA-SMa-40 is a prehistoric shellmound created by Native American occupants of the San Francisco Peninsula beginning approximately 5,150 years B.P. (3200 B.C.). The most abundant constituent of the shellmound is, as the tenor implies, remains of marine shellfish. The mound was both a resource extraction and utilization site and along-term habitation site for the several different groups who held the Peninsula during different periods up to approximately 460 B.P. (1490 A.D.). Beyond the shellfish remains, the mound contains lesser quantities of materials reflecting the range of activities carried out at the site including all the phases and types of cultural activities which typically took place at a permanent settlement. Intact cultural features (such as hearths, faunal remains other than shell, artifactual materials imported into the region, and chronologically diagnostic artifacts and materials) are present. The mound also contains the remains of the people who created it. While the number of human burials is unknown, the results of test excavations strongly suggest that numerous prehistoric Native American burials are present and may be encountered in any portion of the deposit. Under a relatively shallow disturbed surface, intact strata corresponding to the depositional history of the mound are present. Archaeological materials are arrayed throughout the strata in the general chronological order of deposition. No one part of the mound can be said to be more or less complex or significant than any other. 266 As noted in 1.3 Information Used to Prepare the EIR, unrestricted access to site-specific information about cultural resources is limited in order to protect the integrity of the resources. 281 4.9 AHGHAEULUCGY Terrabay Phase 11 and 111 SE/R It is apparent that the archaeological research questions posed by Holman & Associates can be addressed through the analysis of CA-SMa-40 cultural deposits. It is concluded, therefore, that the site is an important cultural resource under criteria defined by CEQA Section 21083.2, including in Appendix G, and Appendix K. It is further believed that the site meets the criteria for nomination to the National Register of Historic Places. As an important resource, any significant impacts to CA- SMa-40 would require mitigation under the provisions of CEQA (see Impacts and Mitigation Measures, below). CA-SMa-92 The most recent documentation of this site is by Holman & Associates. 267 It is described as a relatively small prehistoric cultural deposit with fire-fractured rock, a scant amount of Franciscan chert flakes, and some historic period glass present. The dimensions of the site, which is located on a rocky bench, are 28 meters (north-south) by approximately 35 meters (east-west). The site parameters are physically limited by the topographic setting -steep rocky upslope (north), upslope (northeast), steep downslope (southeast), and a ravine and seasonal drainage (southwest). The site boundaries have been estimated by ground-surface inspection only. However, the reliability of this determination is good, given the physiographic constraints which surround the rocky bench where CA-SMa-92 is located. CA-SMa-92 is located relatively close (upslope at a higher elevation) to the large site CA-SMa-40 and may have been closely associated with the larger village site. Holman & Associates speculate that CA-SMa-92 may have been used by the inhabitants of CA-SMa-40 on occasions of high tidal waters. Based on its close proximity and possible connection to the larger and apparently significant site (CA- SMa-40), CA-SMa-92 may have a potential for meeting CEQA criteria as an important cultural resource. In the event that further research establishes such a connection, it is possible that the two sites could be part of an important archaeological district. 268 The most recent site record places CA-SMa-92 on San Bruno Mountain State and County Park property. 269 A recent Holman & Associates communication indicates that the site location is on property still owned by the Terrabay project sponsor and not yet dedicated to the County. 270 Nichols • Berman (the 1998 SEIR preparer) has determined that the latter is true, and it is concluded that CA- SMa-92 is located on the Terrabay project HCP land and is not within the proposed commercial development area. Potential project impacts are discussed under Impact to CA-SMA-92. 267 Identification of Site CA-SMa-92 / CA-SMa-234 and the Potential Construction Impacts for Phase III of the Terrabay Development in the Ciry of South San Francisco, Matthew Clark, op. cit., and Archaeological Site Record for CA-SMa- 92, Matthew Clark, op. cit. 268 The mitigation program identified for CA-SMa-4U, discussed in Mitigation Measure 4.9-1(a) (below), does not address CA-SMa-92 or the relationship between the two sites. '269 Ibid, Archaeological Site Record for CA-SMa-92. 270 Identification of Site CA-SMa-92 / CA-SMa-234 and the Potential Construction Impacts for Phase III of the Terrabay Development in the City of South San Francisco, Matthew Clark, op. cit. 282 4.9 ARCHAEOLOGY Terrabay Phase ll and !ll SE/R ARCHAEOLOGY- SIGNIFICANCE CR/TER/A Under CEQA, potential damage to or disturbance of important (unique) archaeological or historical resources resulting from a proposed project would be considered a significant impact. An important cultural resource is a location which meets one of the following Appendix K criteria: • Is associated with an event or person of Recognized significance in California or American history, or Recognized scientific importance in prehistory. • Can provide infotTnation which is both of demonstrable public interest and useful in addressing scientifically consequential and reasonable or archaeological research questions. • Has a special or particular quality such as oldest, best example, largest, or last surviving example of its kind. • Is at least 100 years old and possesses substantial_stratigraphic integrity • Involves important research questions which historical research has shown can be answered only with archaeological methods. Holman & Associates apply the more specific criteria elements presented in CEQA Section 21083.2(g) in evaluating the Terrabay site resources. 271 Section 21083.2(g) states that a unique (important) archaeological resources is (emphasis added): an archaeological artifact, object, or site, about which it can be clearly demonstrated that, without merely adding to the current body of knowledge, there is a high probability that it meets any of the following criteria: 1. Contains information needed to answer important scientific reseach questions and there is a demonstrable public interest in that information. 2. Has a special and particular quality such as being the oldest of its type or the best available example of its type. 3. Is directly associated with a scientifically recognized important prehistoric or historic event or person. CA-SMa-40 By realizing reseazch design elements applied to subsurface azchaeological investigations, Holman & Associates demonstrate that the site meets the criteria as aunique / important prehistoric cultural resource as discussed below. 272 There is a high probability that CA-SMa-40 "contains information needed to answer important scientific research questions" (such as when the Bay Area was initiaIly occupied). Information from 271 Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clark, op. cit. 272 Ibid. 283 4.9 ARCHAEOLOGY Terrabay Phase 11 and ll! SEIR the site also might allow archaeologists to better understand the circumstances under which the Hol:an peoples were replaced by later Utian populations. There also is a "demonstrable public interest" in the cultural content and preservation of the site, as evidenced by public response to date on the proposed Terrabay project. The Native American community has a particularly strong interest in the fate of CA- SMa-40, including concerns voiced at the October 1997 public scoping meeting held by the City of South San Francisco Planning Commission and at the January 1998 joint working sessions held by the City's Planning Commission and Historic Preservation Commission. In addition, public interest has been expressed in local newspaper and television reports. The documented antiquity of CA-SMa-40, based on the radiocarbon date of 5,155 years B.P., suggests that the site may be the "oldest of its type" on the Peninsula and perhaps within the San Francisco Bay region. Because of its long prehistoric occupation (5155 B.P. to 460 B.P.) and the fact that few such relatively-undisturbed shellmounds still exist in the Bay Area, it certainl~~ is one of the "best available examples" of the shellmound-type site. Neazly all of the approximately 425 lazge shellmound sites recorded around the Bay Area early in the 20`" century have been destroyed or greatly impacted by natural forces and modern cultural activity. By 1973, urban expansion had damaged or destroyed more than 50 percent of the estimated number of archaeological sites (approximately 9,675) in the nine Bay Area counties. Lazge Bay-fronting shellmounds have been impacted disproportionately aseasily-filled shallow Bay flats have been most attractive for development. 273 Avery few well known large shellmounds survived long enough to be part of the modern archaeological record. The Emeryville, West Berkeley, Ellis Landing, and Coyote Point Sites in Alameda and Contra Costa Counties, the DeSilva Island Site in Marin County, the University Village Site in Santa Claza County, and the San Bruno Mountain shellmound are among these unique cultural resources. In addition to the effects of development, Holocene siltation has covered an unlrnown number of older (more than approximately 4,000 years B.P.) sites with several meters of alluvial deposits, probably rendering them inaccessible to archaeological documentation and investigation. 274 Archaeological sites approaching the antiquity of CA-SMa-40 are examples of the oldest settlement and economic patterns yet found around the Bay. The site is one of the oldest shellmounds on the Bay margin lazgely due to its unique location, on the toe of a steep slope at the edge of the Bay, which made it less subject to burying under colluvial, alluvial, or subaqueous sedimentation. CA-SMa-40 is "directly associated with a scientifically recognized important prehistoric event" because it is the oldest site yet recorded on the San Francisco Peninsula (the initial arrival of people in the Bay region being an "important prehistoric event"), because it contains evidence of changes in subsistence strategy as well as stylistic changes over time (probably related to the hypothesized replacement of the older Hokans by the more recent Utians, another important prehistoric event), and because it possesses a very long cultural sequence compared to other regional sites. shellmounds contain impressive amounts of data related to the environment and changes in the environment. Therefore, CA-SMa-40 contains a record of environmental change as well as how human inhabitants in the region adapted to changing conditions. C:~-SMa-40 is the oldest site 273 Ibid. 274 The Holocene era of geologic time extends from 10,000 years ago to the present time. 284 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SEIR reported on the Peninsula, contains a record of San Francisco Bay Region prehistory, and ties the site to the period just prior to the contact of European and Native cultures. CEQA Appendix G addresses issues of site importance based on cultural significance to Native Americans. A significant impact may occur if a project disrupts or adversely affects a prehistoric archaeological site or property of historic or cultural significance to a community or ethnic group or social group, except as part of a scientific study. The documented presence of Native American burials at CA-SMa-40 and the potential for additional human remains establish the site as an important cultural as well as religious resource to the Costanoan / Ohlone community. Preliminary responses to the Phase III development plans by Native Americans -- who have attended meetings and have responded to this 1998 SEIR archaeologist's written inquiries -- have varied in intensity and emphasis. However, most have expressed concern over disturbance and destruction of ancestral cultural materials and, particularly, burials. Many but not all Native Americans view archaeological excavation at prehistoric sites as the destruction of important places of ancestral cultural and, where burials are known (or suspected) to be present, places of sacred and religious importance. More specific Native American concerns aze expected to be expressed after review of the Draft 1998 SEIR. Such comments likely will contain supplemental information regazding significant impacts under CEQA Appendix G. 275 However, it is likely that Coastanoan / Ohlone organizations and individuals generally would agree that to preserve CA-SMa-40, without conducting extensive mitigation excavations and without placing destructive amounts of fill on the site, would be a more acceptable mitigation plan. Holman & Associates' test excavations at CA-SMa-40 in 1989 were monitored by Ms. Ella Rodriquez who is listed with the Native American Heritage Commission and is well-known throughout the Bay Area as a diligent guazdian of Costanoan / Ohlone sensibilities regarding prehistoric cultural deposits and burials. However, an official MLD has not been designated for the proposed Terrabay project mitigation plan, and impact issues regarding prehistoric burials and ancestral cultural deposits would require negotiation with ayet-to-be-designated MLD. 276 CA-SMa-92 This relatively small prehistoric cultural resource has not been subjected to the rigorous azchaeological evaluations applied to CA-SMa-40. Holman & Associates state that "the approximate limits of site SMA-92, the lower limits of which come to within about 20-25 meters of the HCP line / City of South San Francisco limits, but are ... quite a bit farther from the limits of grading ... work for 275 This 1998 SEIR's archaeologist initiated contacts with members of the Native American community as part of the early consultation process recommended by the State CEQA Guidelines. The purpose of this process is to obtain input and provide information in Draft EIRs in response to concerns expressed in order to adequately disclose a project's impacts to the public. Individuals contacted for this 1998 SEIR had not yet had opportunities to review the documents this 1998 SEIR's archaeologist independently reviewed Thus, they were not able to respond fully without the ability to read these materials for themselves. Subsequent information involving additional significant impacts not identified in this 1998 SEIR would require recirculation of the Draft EIR. 276 Ibid. 285 4.9 ARCHAEOLOGY Terrabay Phase ll and 111 SE1R Terrabay will not impact the site, particularly if all work and traffic is restricted to within the HCP line in the site vicinity". 277 It would appear that, because the site is located outside the direct impact area of the proposed Terrabay Phase III project, additional CEQA (important resource) consideration was not pursued. However, the site is located relatively close to CA-SMa-40, and Holman & Associates speculate that CA-SMa-92 may have been used by inhabitants of CA-SMa-40 during periods of high tidal waters. Based on its close proximity and possible connection to the larger and presumed-to-be important site, CA-SMa-92 also may have a potential for meeting CEQA criteria as an important cultural resource. In the event that further research establishes such a connection, it is possible that the two sites could be perceived as an important azchaeological district. ARCHAEOLOGY- IMPACTS AND MITIGATION MEASURES The proposed Terrabay project has brought attention to both archaeological sites (CA-SMa-40 and CA-SMa-92) and increased public awareness of their locations. It is recommended that protective measures should be implemented in order to deter .possible damage to the sites. Temporary but substantial fencing of the resources can be considered until permanent project management plans are decided and implemented. However, fence building activities and the fences themselves may only attract further attention to the site locations. Increased local law enforcement patrol and public awareness may serve just as well in protecting the resources. Vigilant San Bruno Mountain enthusiasts have proved to be most effective in local environmental protection. Impacts to CA-SMa-40 The pending application proposes grading and filling of the Terrabay Phase III site in order to provide building pads, site access and internal circulation, parking lots, and utility and storm drain connections to prepare for future commercial development. East of the Phase III site and immediately adjacent to the archaeological site, Bayshore Boulevazd would be raised, widened, and realigned in conjunction with the hook ramps project. While the Bayshore Boulevard work would be separate from the Terrabay project, impacts from the two undertakings would commingle, and the two are being planned to function together when both aze completed. 278 The project proposes the placement of engineered earth fill (placed and compacted in layers) over the CA-SMa-40 cultural deposits. No surface grading or terracing is proposed prior to filling. Generally, fill would be deeper on the eastern than on the western side of the site and deeper on the north and south sides than in the middle which would be contoured into a swale converging into a drainage basin. Pads for parking lots would be located on top of the northern and southern sides of the site, the central part would be landscaped as a small pazk (described further below), the western edge would support the proposed internal roadway (built on five to six feet of fill), and the eastern side would be the location of a drainage basin built within fill with about five feet of fill covering the archaeological deposit at the bottom of the basin. The new contours would be higher at the northeast and southwest 277 Identification of Site CA-SMa-92 / CA-SMa-234 and the Potential Construction Impacts for Phase 11/ of the Terrabay Development in the City of South San Francisco, Matthew Clark, op. cit. 278 Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clark, op. cit. 286 4.9 ARCHAEOLOGY Terrabay Phase 11 and ill SE1R with a Swale built in to run from near the site center to the southeast. Depth of fill over the site would range from approximately eight feet at the western edge -where the north-south internal roadway would be built (and where the archaeological deposit appears extensively disturbed) and in the bottom of the drainage basin -- to more than 20 feet at the eastern and southeast quadrants. Fill over the northern parking lot pad would range from 21 feet at the east to about ten feet from the middle to the west. Fill over the southern parking pad would range from approximately 23 feet to about eight feet. All utilities, drainage, landscaping, paving, curbs, etc. would be placed in the fill covering the site, and no penetration of the prehistoric cultural deposit is proposed. Holman & Associates summarize that adverse (and sign cant) impacts to CA-SMa-40 resulting from the proposed Terrabay Phase III development would be as follows: 279 [Engineering fill] placed over the site will compress and deform the archaeological deposit, compressing it up to an estimated 30 percent in the deepest areas. This will distort intact strata below the disturbed surface and near surface shell midden, displacing archaeological data, cultural features, and inhumations ... [and] placement of engineering fill and the proposed features and facilities in and on the fill will preclude research opportunities at the site for the foreseeable future. Minor effects are also likely, as the site surface is cleared of vegetation and cultural features and fill is placed on the site, and as realigned Bayshore Boulevard and the supporting keyway are constructed close to the eastern site margin. Bayshore Boulevard in the vicinity of CA-SMa-40 would be realigned on a new raised roadbed approximately 13 to 14 feet higher in elevation than the current road. The new roadway would curve west from the current alignment, and the new western curb would be approximately 125 feet from the existing edge of the pavement -near the archaeological site (but not reaching the mapped boundary of the prehistoric cultural deposit). The proposed realigned right-of--way would be located within about six feet of the mapped eastern boundary of'the azchaeological site. However, the proposed new edge of curb would be 12 feet farther east, about 18 feet from the site boundary. Holman & Associates conclude that the actual road realignment would not directly impact the archaeological deposit. 280 According to the SEIR geologist see 4.1 Geology, Soils, and Seismicity), realignment of Bayshore Boulevard and construction of a "keyway" could result in disturbance within the boundaries of CA- SMa-40. Further evaluation is presented in Impact 4.9-1 and Mitigation Measure 4.9-1(b). Holman & Associates state that 281 virtually the entire archaeological deposit will be preserved in-situ under a cap of engineered fill, and other than parking lots, [a roadway,) and landscaping, no large-scale construction is planned on the site. While filling over the site certainly constitutes a significant impact, there will be no direct construction excavations into the site, and (excepting possible mitigative data recovery excavations) the entire archaeological deposit will remain in place. In short, current construction plans call for filling over the entire site, greatly reducing impacts formerly proposed, and lessening though not obviating the need for mitigative actions. 279 Ibid. 280 Ibid. 281 Ibid. 287 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SE/R Separate from the Holman & Associates report (and the mitigation program discussed below), the project sponsor proposes to create a 2.02-acre subdivision parcel at the location of CA-SMa-40, establish private parking and utility easements on the parcel, develop part of the parcel as a park, and deed it to a university or other non-profit institution.''-82 Development of a park with lawns, landscaping, pedestrian paths, and interpretive elements is an accepted practice and provides an appropriate educational and aesthetic way of preserving such resources. Development and use as a park would not cause or contribute to the direct and indirect physical environmental impacts evaluated in Impacts 4.9-1 and 4.9-2 and is not assessed separately in this 1998 SEIR. However, differences in application materials' descriptions of proposals for this site should be identified to enable the project sponsor to clarify precisely what is proposed and when to enable public officials to make decisions about the project. Impact 4.9-1 Damage to CA-SMa-40 Placement and compaction of eight to 23 feet of fill would irreparably damage and probably would destroy the integrity of cultural materials and features present on a site acknowledged to be an extremely important resource under CEQA and believed to be eligible for listing on the National Register of Historic Places. This would be a significant impact. S A theme repeated throughout the 1998 Holman & Associates report, and rightly so, is that the site is an extremely important prehistoric cultural resource given its stratigraphic integrity, early occupation date, and unique potential for scientific inquiry regarding the prehistory of the San Francisco Peninsula. The proposed placement of fill over the CA-SMa-40 shellmound site would result in significant impacts to the site. The weight of the fill would result in the compression of the cultural deposits, the stratigraphic integrity of the site would likely be destroyed, and cultural materials and features, including Native American burials, would be crushed. Capping or covering an archaeological site with a layer of soil before building on the site is an acceptable method of preserving a resource in place and well within CEQA Section 21083.2. Holman & Associates' recommendations (see Mitigation Measure 4.9-1(a), below) would leave the site intact but, unfortunately, would also result in significant impacts to CA-SMa-40 -impacts which otherwise might be avoided, if other methods of preserving the resource in place, equally acceptable under CEQA, were to be considered. (Mitigation Measure 4.9-1(b), also below, presents alternative recommendations.) Mitigation Measure 4.9-1(a) A data recovery program for CA-SMa-40 should be carried out before any fill is placed on the site or commercial development activities occur there with the goal of completely recording the current condition of CA-SMa-40. This mitigation program, recommended by Holman & Associates (hence interpreted to be proposed as part of the applications pending City approval), should be accompanied by long-term post-construction monitoring of site compression after placement of fill, as well as monitoring of subsequent development at any location within 30 meters (100 feet) of the mapped boundary of CA-SMa-40. 282 As noted in 2.3 Project Description, the Vesting Tentative Map and Preliminary Grading Plan shows a 2.02-acre parcel at CA-SMa-40, Holman & Associates identify the size of CA-SMa-40 as 2.2 acres, and Park at the San Bruno Mountain Indian Midden, Terrabay, South San Francisco, California states, first, [hat "the area of the midden is approximately 2.5 acres, as delineated by the archaeoloo st [Holman & Associates]" and, second, that "earth fill under the 1.7-acre park site will vary from five to 30 feet [emphasis added]". 288 4.9 ARCHAEOLOGY Terrabay Phase lI and 111 SE1R The data recovery program should include: • Mitigative data recovery excavations. • Data analysis. • Curation of recovered materials. • Report(s) preparation. • Post-fill compression study. The proposed data recovery program is intended to "allow CA-SMa-40 to be understood in the regional archaeological context and to contribute to anthropological understanding of the development and history of human habitation in the Bay Area, specifically, and Central California and Western North America". 283 The program proposes to address the following reseazch topics: • Geo-archaeological landscape reconstruction. • Environmental change and human adaptation (and related environmental questions). • Prehistoric chronology. • Culture history. • Coastal settlement patterns and economic models. • Local, regional, and wider cultural /social relationships • Population increase, resource utilization intensification, and changes in cultural patterns. Holman & Associates recommended that the site investigation include the excavation of a total of approximately 35.5 to 40.5 cubic meters (an average of 38 cubic meters) of cultural deposit and involve excavation of one large three- by three-meter unit at one of the deeper locations in the site and four one- by two-meter units from other parts of the site. Standazd professional procedures should be employed to record artifacts, features (including burials), and other cultural phenomenon which would contribute to the desired archaeological data base. Artifacts should be collected, processed, and analyzed, and obsidian should be collected and processed for sourcing and dating. Carbon samples also should be collected for dating. Column sampling, geotechnical, soils, biological, and faunal analyses should be conducted. Following backfilling of excavation units but before placement of geotextile fabric and fill over the site, a series of compression monitoring stations should be placed on the site surface. According to Holman & Associates, data obtained from the stations would represent "a first contribution to development of a data base describing the effects of filling over archaeological sites...". 284 Holman & Associates also recommended that all construction work on or within 30 meters (100 feet) of the boundaries of CA-SMa-40 should be monitored during project implementation. Work on the remainder of the Phase III development site from "the rocky prominence south of the southerly 283 Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa-40, South San Francisco, California, Matthew Clazk, op. cit. 284 Ibid. 289 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SEIR billboard now standing above Bayshore Boulevard south of CA-SMa-40" should also require periodic (but not constant) monitoring. 285 Lona term post-construction mitigation measures should include: Completion of a comprehensive archaeological report. Monitoring of the compressive effects of the engineered fill on the site. Appropriate disposition of recovered cultural materials including Native American burials. Significance after Mitigation The activities described by Mitigation Measure 4.9-1(a) would constitute a highly professional and aggressive scientific archaeological program at CA-SMa-40. However, while implementation of this measure could reduce Impact 4.9-1 to ales-than-significant level under CEQA, it would not avoid or eliminate the impact and does not explore other feasible measures to do so (as presented in Mitigation Measure 4.9-1(b)). In addition, Mitigation Measure 4.9- 1(a) neither addresses CA-SMa-92 nor the hook ramps and Bayshore Boulevard realignment sites. Thus, the relationship of CA-SMa-92 to CA-SMa-40 and their combined significance would not be investigated through further reseazch. Moreover, the Holman & Associates' program described in Mitigation Measure 4.9-1(a) does not indicate how long it would take to implement and when it would occur in relation to the project sponsor's planned schedule to initiate Phase III site grading. Impact 4.9-2 addresses additional impacts related to Impact and Mitigation Measure 4.9-1(a). For these reasons, although Mitigation Measure 4.9-1(a) would conform with the basic requirements of CEQA Appendix K, this SEIR does not recommend its implementation as the preferred measure to mitigate project impacts and only recommends requiring Mitigation Measure 4.9-1(a) if no more environmentally suitable mitigation is available. Responsibi/ity and Monitoring The project sponsor would be responsible for formally incorporating Mitigation Measure 4.9-1(a) in the project, and the sponsor's archaeologist would implement and carry out short- and long-term archaeological monitoring to be overseen, in turn, by the Most Likely Descendant (MI,D) designated for the project. Completion of the data recovery program described in Mitigation Measure 4.9-1(a) to the satisfaction of the sponsor's archaeologist and MLD should be a condition of receiving a grading permit for any development activity within 30 meters (100 feet) of the boundaries of CA-SMa-40. Mitigation Measure 4.9-1(b) As an alternative to Mitigation Measure 4.9-1(a), the project should be revised to prevent sign~cant impacts on CA-SMa-40 and to preserve the azchaeological site through a combination of site planning to avoid damage to this resource and permanent protection by establishing a conservation easement. CEQA Appendix K states that: public agencies should seek to avoid damaging effects on an archaeological resource. ... In-situ preservation of a site is the preferred manner of avoiding damage to archaeological resources.... Preservation may also avoid conflict with religious or cultural values of groups associated with the site. Avoiding damage may be accomplished by various means including: • Planning construction to miss archaeological sites • Planning parks, green space, or other open space to incorporate archaeological sites • "Capping" or covering archaeological sites with a layer of soil before building tennis courts, pazking lots, or similar facilities. Capping may be used where: 285 Ibid. 290 4.9 ARCHAEOLOGY Terrabay Phase 11 and 111 SE1R The soils to be covered would not suffer serious compaction The covering materials are not chemically active The site is one where natural processes of deterioration have been effectively arrested, and The site has been recorded • Deeding archaeological sites into permanent conservation easements Attention is drawn to the CEQA discussion about "capping" archaeological sites, particularly the statement that "capping may be used where the soils to be covered will not suffer serious compaction". The Terrabay project proposes to cover CA-SMa-40 with a substantial volume of fill as a result of which compaction, compression, and serious damage to the cultural deposit would be expected to occur. Holman & Associates state that the "scale and design of the Terrabay project have been duly considered during a long planning and public hearing process. The proposed scale would appear to be locked in, though the exact nature of the Phase III commercial development around CA-SMa-4O is not yet determined." However, "relocating the commercial zone and hook ramps is not viable due to the topographic location and shape of the Terrabay development. The Route 101 Freeway and Bayshore Boulevazd run along the narrow terrace between San Bruno Mountain's steep slope and the Bay. This location has inviolable State and County Park property on the mountain side, and the freeway and then Bay on the other. There is just nowhere else to locate the Terrabay access roads, which must hug the foot of the mountain to wrap around to the southwest and meet the major residential development areas". 286 Further "the most viable alternative to mitigate adverse impacts is data recovery and monitoring ... , given that the project is going forward, traffic access is necessary, and attendant adverse impacts not avoidable. Mitigation of adverse impacts by data recovery should recover a significant and representative portion of the scient~c value from the site prior to impacts, recover a portion of the site itself as midden samples and acontrolled-recovery assemblage, recover and study as many human remains as necessary, analyze the data, assess the impacts, and result in a report on SMa-4O for addition to the regional archaeological data base. Although azchaeologists, planners, developers, permitting authorities, and effected parties and groups -especially Native American Indians -for widely varying reasons, theoretically all regard excavation of archaeological sites the last resort to mitigate inevitable adverse impacts, in this case data recovery seems the likely viable alternative". 287 It can be argued that the proposed project approach (Mitigation Measure 4.9-1(a)) to managing the potential for significant impacts to CA-SMa-4O is not justified. As Holman & Associates state above, the exact nature of Phase III commercial development around CA-SMa-4O has not yet been defined. It will not be known until individual projects are proposed on aparcel-by-parcel basis. The absence of detailed projects raises questions about the wisdom of implementing.a management plan of placing extensive fill on perhaps the most important extant archaeological shellmound in the Bay Area and 286 Ibid. Reference to the `"Terrabay access roads" appears to mean the Phase III site internal roadway along the west side of the development azea (except for proposed Pazcel C which would be located west of the road). No road connection is proposed between the Phase II residential and Phase III commercial sites. The scale of commercial development noted by Holman & Associates currently is the subject of a pending Terrabay Specific Plan amendment request to change the previously approved development concept for the Phase III site to the presently proposed one. See also ~.0 Alternatives where a Phase IIII site plan alternative to the project as presently proposed is assessed. 287 Ibid. 291 4.9 ARCHAEOLOGY Terrabay Phase 11 and Ill SEIR destroying, through compression, a unique scientific and Native American cultural /religious resource. This is especially so when other means of site preservation, less destructive to CA-SMa-40, are available which also would accommodate development. In considering alternative means of protecting CA-SMa-40, it is appropriate to remember that the resource management plan contained in Mitigation Measure 4.9-1(a) would result in severe damage, if not total destruction, of CA-SMa-40. Archaeological data retrieval will satisfy the letter of CEQA requirements, but an important cultural resource would be lost. The following is a less destructive alternative which is more in keeping with CEQA's emphasis on resource preservation. The Mitigation Measure 4.9-1(b) protection plan should combine planning construction to avoid the archaeological site and creating a permanent conservation easement on the archaeological site. The conceptual development plan should be revised to remove parking lots on the north and south parts, the access road on the west side, and utility comdors across the archaeological site. These revisions would eliminate the need to place substantial fill on CA-SMa-40 and should be incorporated in the Terrabay Specific Plan with requirements for subsequent Precise Plans to provide sufficient detail to demonstrate that proposed development would avoid the site. The project sponsor's proposal to create a park at the site location would be compatible with Mitigation Measure 4.9-1(b) and actually would help protect the resource. A shallow layer of fill, no more than two to three feet deep, could be placed on CA-SMa-40. Appropriate landscaping, a shallow irrigation system, foot trails, and information displays could be installed within and above the fill layer with no disturbance to or compression of the underlying archaeological site. The site "cap" should include a geotextile cover along with earth and rock fill as well as an adequate drainage system. Significant impacts as defined by CEQA are a direct result of damage or destruction of an important archaeological site. Mitigation Measure 4.9-1(a) would result in damage and destruction of site deposits due to soil compaction created by the weight of the fill. Significant impacts created by the placement of fill (Mitigation Measure 4.9-1(a)) would be eliminated with implementation of Mitigation Measure 4.9-1(b) because little to no soil compression would occur as a result of placing a shallow cover of fill on CA-SMa-40. According to the SEIR geologist, a maximum depth of two to three feet of fill could be placed on the site with no subsequent soil compression and, consequently, no damage to the subsurface prehistoric cultural deposits. The CA-SMa-40 site should also be protected by a permanent conservation easement or dedicated to San Bruno Mountain County Park. These measures would preclude the need to place substantial fill on CA-SMa-40 and eliminate Impact 4.9-1 attributable to the project approach. In considering Mitigation Measure 4.9-1(b), the City may determine that the project sponsor's proposed access road on the west side of CA-SMa-40 cannot be eliminated because internal connections between all commercial parcels would be necessary to avert a significant public health or safety hazard which would be caused by resulting inaccessibility by emergency service vehicles or because of significant off-site traffic impacts due to turning movements at Phase III site entrances on Bayshore Boulevard. In those circumstances, Mitigation Measure 4.9-1(b) could still work by allowing the road construction and conducting apre-construction data recovery through excavation mitigation program only for the part of CA-SMa-40 directly affected by significant impacts as a result of roadway construction. The data recovery program could be a scaled-down version of that proposed in Mitigation Measure 4.9-1(a). That is, data recovery would be limited to the western periphery of the site, Realignment of Bayshore Boulevard and construction of a "keyway" are proposed on the east side of the archaeological site. In the event that Mitigation Measure 4.9-1(b) is implemented, the threat of site ?g~ 4.9 ARCHAEOLOGY Terrabay Phase !I and I!l SE/R compression would be eliminated for most of CA-SMa-40. However, the eastern edges of the site still may be subject to significant impact. According to the SEIR geologist, construction of the roadway and keyway would extend far enough west of the existing Bayshore Boulevazd alignment to include the periphery of the site. The construction of a retaining wall would be required which could impact the site. In the event that a wall is necessary, data recovery through excavation of the potentially impacted site area is recommended, along with monitoring. If such mitigation measures are required, the excavation and monitoring programs should be similaz to those proposed for Mitigation Measure 4.9-1(a) but smaller in scale and limited to the direct impact location. An alternative would be to construction a pier supported bridge or flyover and avoid the archaeological site altogether. Some site disturbance would occur as a result of building footings, but it would be limited to the eastern periphery of CA-SMa-40 where soils disturbance has already taken place as a result of past water pipeline construction by the City and County of San Francisco and, possibly, for construction of Bayshore Boulevazd. Some archaeological data recovery and monitoring would be recommended, details of which the project archaeologist should develop in consultation with project engineers. Data recovery through archaeological excavation would be necessary with both alternatives. More excavation over a larger area would be required with Mitigation Measure 4.9-1(a) because the entire site would be damaged by soil compression. The fill proposed by Mitigation Measure 4.9-1(a) would result in up to 30 percent compression of the archaeological site soils. ,Mitigation Measure 4.9-1(b) would result in no compression (zero percent) of site soils. Less excavation, limited to the east and west edges of the site, would be required with Mitigation Measure 4.9-1(b). According to Holman & Associates, the estimated total volume of CA-SMa-40 is 13,118 cubic meters. By implementing Mitigation Measure 4.9-1(a), approximately 38 cubic meters of cultural soils (0.29 percent of total site volume) would be excavated. Combined with that removed during the 1989 test excavations, the total volume of removed site soil would be approximately 59.4 cubic meters or about 0.453 percent of the site volume. A rough estimate of the volume of soils to be excavated at the east and west edges of CA-SMa-40, if Mitigation Measure 4.9-1(b) were implemented, would be no more than eight (8) cubic meters or 0.061 percent of the total volume of the azchaeological site. Combined with that removed during the 1989 test excavations, a total of 29.4 cubic meters would be removed (0.224 percent of the site volume). The comparison reveals that a considerably smaller portion of CA- SMa-40 would be removed by Mitigation Measure 4.9-1(b) azchaeological excavations than by Mitigation Measure 4.9-1(a) excavations. In comparing the two mitigation measures, a critical issue is that all but 0.224 percent of the site (approximately 99.776 percent), including the deeper portions of the cultural deposit, would be preserved with Mitigation Measure 4.9-1(b). Mitigation Measure 4.9-1(a) would place excavation units in the deeper portions of the site and then "cap" it, but the cap itself would destroy the remaining 99.547 percent of CA-SMa-40 as a result of soil compression throughout the site. These quantitative comparisons support the conclusion that, by CEQA criteria for significant impacts, implementation of Mitigation Measure 4.9-1(b) would result in the least amount of damage to and destruction of CA- SMa-40. Exhibit 4.9-I compares schematic cross-sections of the two mitigation measures. Variations of Mitigation Measure 4.9-1(b) aze possible as long as the basic premise of site preservation is maintained and the need for site destroying fill compaction and compression is eliminated. One suggested variation comes from the Native American community which recommends that the site location be controlled and managed by the Costanoan / Ohlone themselves. Environmental documents and archaeological reports of this nature often defer to Native American sensibilities but seldom consider a full partnership in the actual control of the cultural resource. 293 p~ana~nog a~cus,Seg Q~ a .... W m C C i0 d Q m m N m LL O N ~ I Q c .~ c 0 O C 7 m C l0 LL C O R Of L A O Q N N m U U Q m c `m c LL C :~ ,. O :: _~.. m U O ~O m L U Q N m Q U O y N Q N m ~_ U e c U O 4.9 ARCHAEOLOGY Terrabay Phase /l and 111 SE1R Significance after Mitigation Mitigation Measure 4.9-1(b) would protect CA-SMa-40 and reduce both Impacts 4.9-1 and 4.9-2 (below) to aless-than-significant level. CEQA Appendix K defines significant impacts to archaeological sites as damage or disturbance of important resources. Mitigation measures which eliminate or reduce that damage or disturbance would reduce the potential impacts to the desired "less-than-significant" level. That is, the potential significant impact (damage to and destruction of archaeological deposits by means of soil compression as a result of the placement of extensive fill on the site) would be eliminated. Consequently, the threat of a significant impact would no longer be present. Mitigation l~ieasure 4.9-1(b) would address CEQA issues related to both Impacts 4.9-1 and 4.9-2 (below) by preserving CA-SMa-40 as an intact archaeological /scientific resource and, for the most part, would eliminate conflict with Native American concerns for ancestral cultural deposits and burials. It constitutes the environmentally superior mitigation (other than the No Development Alternative) because it not only meets the basis requirements of CEQA Appendix K for mitigating significant impacts but also it fulfills CEQA Appendix K emphasis on the preservation of archaeological sites. Whereas Mitigation Measure 4.9-1(a) fulfills CEQA requirements for mitigation, it would not preserve CA-SMa-40. Rather, because of site soil compression, it would result in the eventual destruction of a unique highly important archaeological resource. This 1998 SEIR recommends that the City adopt Mitigation Measure 4.9-1(b) as the measure required to mitigate Impact 4.9-1. Responsibility and Monitoring The short-term construction monitoring program identified for Mitigation Measure 4.9-1(a) would be required for Mitigation Measure 4.9-1(b). The project sponsor's archaeologist and MLD designated for the project would be responsible for monitoring all construction work within 30 meters (100 feet) of the boundaries of CA-SMa-40 and for periodic (not constant) monitoring of development elsewhere on the Phase III site. Mitigation Measure 4.9-1(c) In the event that the City elects to adopt Mitigation Measure 4.9-1(a) instead of requiring Mitigation Measure 4.9-1(b), Mitigation Measure 4.9-1(a) should be revised to incorporate the following additional provisions: • CA-SMa-92 should be investigated to determine its relationship to CA-SMa-40 and thus provide adequate documentation for the two sites and determine their cultural and temporal relationship. The sanitary sewer proposed to cross CA-SMa-40 should be relocated to the west side of the internal access road right-of--way and, if required for operation, pumping facilities should be installed. Significance after Mitigation Implementation of Mitigation Measure 4.9-1(c), together with Mitigation Measure 4.9-1(a), would conform with the basic requirements of CEQA Appendix K, as noted above. This combination of measures would still be less preferable to preservation of the site as described by Mitigation Measure 4.9-1(b).the environmentally superior mitigation. No secondary environmental impacts are anticipated in the event that Mitigation Measure 4.9-1(b) is implemented. Responsibility and Monitoring Same as for Mitigation Measure 4.9-1(a). The project sponsor would be responsible for formally incorporating Mitigation Measure 4.9-1(c) in the project, and the sponsor's archaeologist and MLD would iinplement and carry out short- and long-term archaeological monitoring. 295 4.9 ARCHAEOLOGY Terrabay Phase ll and 111 SE/R Impacts to CA-SMa-92 This site is located outside the development area and proposed limits of grading. However, a hiking trail traverses the small site, and increased human presence, resulting from both Phase II and Phase III development, would put the site at greater indirect long-term peril. Because CA-SMa-92 would not be subject to direct significant impacts, neither the proposed Specific Plan amendment nor mitigation measures recommended by the project sponsor's archaeologist address this resource. Impact 4.9-2 Indirect Impacts on CA-SMa-92 Increased recreational frail use on the archaeological site could result in impacts to the resource. The magnitude of impact is not known at this time but would depend on property ownership and associated issues of preservation methods and resource management. Until the project addresses such issues, the impact is considered potentially significant PS Development of the Terrabay Phase II and III sites would increase the recreational use of public pazklands and open space on San Bruno Mountain, including foot traffic on existing and improved trails, one of which traverses this small site. While no direct, construction-related impacts would result from the project, long-term, indirect impacts aze a possibility. Even the most benign of curious visitors can be expected to trample, pick-up and poke around on a known archaeological site. Project plans submitted to the City as of January 1998 do not identify a trailhead location on the Phase III site, although the project sponsor would coordinate the locarion with San Mateo County staff. 288 This site is located on HCP land to be dedicated to the San Mateo County for ultimate inclusion in San Bruno Mountain County Pazk. Mitigation Measure 4.9-2 CA-SMa-92 should be protected from damage resulting from increased use in and around the archaeological site azea. The following measures would mitigate potentially significant impacts on this archaeological site: The project sponsor and County should agree on a trailhead location, and the County should connect the trailhead to other trails in the park via a route which would avoid CA-SMa-92. This measure may include relocating any existing trails or routes which impinge on the archaeological site. The project sponsor should "cap" CA-SMa-92 with a shallow layer of fill to retard the erosive nature of human visitation and help maintain the integrity of the site as a potentially important and unique archaeological resource. This should be completed before County accepts dedication of the parcel which CA-SMa-92 is located. Significance after Mitigation Implementation of Mitigation Measure 4.9-2 would reduce the severity of direct impacts on CA-SMa-92 to aless-than-significant level. CEQA Appendix K defines significant impacts to archaeological sites as damage or disturbance of important resources. Mitigation measures which eliminate or reduce that damage or disturbance would reduce the potential impacts to the desired "less-than-significant" level. That is, the potential significant impacts which could result from trail use by the public would be greatly diminished, if not totally eliminated, by 288 Terrabay Project, South Sax Francisco, California, Letter to Allison Knapp from Janine O'Flaherty, Brian Kangas Foulk (project sponsor's engineer), January 25, 1998. 296 4.9 ARCHAEOLOGY Terrabay Phase 11 and /ll SEIR capping the site and curtailing access to the cultural deposit. Unless Mitigation Measures 4.9-1(b) or 4.9-1(c) are implemented, the full significance of CA-SMa-92 would not be investigated and documented at this time. However, protection as described in Mitigation Measure 4.9-2 would preserve this archaeological resource undisturbed. Responsibility and Monitoring The project sponsor and San Mateo County would be responsible for implementing this measure, in selecting an appropriate trailhead location, trail route, and preserving the site before transfer of the parcel to public ownership. Once the County accepts dedication of the parcel and incorporates it in San Bruno Mountain County Park, the County would have long-term responsibility through its park management practices of monitoring to ensure that CA-SMa-92 is not damaged by people who create new trails by leaving the designated trail. 297 5.0 ALTERNAT/VES 5.0 ALTERNATIVES TO THE PROPOSED PROJECT This 1998 SEIR assesses five alternatives. Two are required by the State CEQA Guidelines (two variations of the "no project" alternative) and cover both the Phase II residential and Phase III commercial sites. Other alternatives focus on elements of the Phase II and III sites and assess different development concepts for them individually (without considering the other site(s)). Of the five alternatives examined altogether, two are constraints alternatives -the Phase II Reduced Residential Development Alternative and the Phase III Reduced Commercial Development Alternative. They were formulated in response to an analysis of existing environmental conditions whereas the remaining alternatives are conceptual only. The alternatives evaluated in this 1998 SEIR include: No Project Alternatives No Development Alternative (one "no project" alternative variation)(Phase IIand III sites) Existing Specific Plan Alternative (the other "no project" alternative variation)(Phase IIand III sites) Project Alternatives Phase II Reduced Residential Development Alternative (Phase~II site only) Phase III Reduced Commercial Development Alternative (Phase III site only) Phase III Permanent Open Space Alternative (Phase III site only) The reasons for selecting these alternatives and the steps undertaken to formulate them are summarized below, followed by an analysis of each alternative and identification of the environmentally superior alternative at the end of the chapter. PURPOSE OF THE ALTERNATIVES' EVALUATION EIRs are required to assess a range of alternatives which feasibly could attain the project's objectives and avoid or substantially reduce the severity of the project's significant impacts. The project sponsor's goals and objectives, listed in 2.3 Project Description, are to develop the Phase II residential and III commercial sites to expand housing supply and employment opportunities, respectively, while also reducing environmental impacts (by blending development into the topography and by protecting cultural and biological resources) and preserving open space (on ridges between development areas and between development and Habitat Conservation Plan (HCP) areas farther uphill). Although the previous EIRs for Temabay site development considered alternatives, this 1998 SEIR focuses on testing the extent to which significant impacts of the project, as currently proposed, could 298 5.0 ALTERNATIVES Terrabay Phase ll and 111 SEIR be reduced by examining alternatives to the project. 289 This 1998 SEIR cannot dismiss an evaluation of alternatives on the basis of prior environmental review. This is because the 1998 SEIR must evaluate prevailing circumstances, thus any substantial changes from those which existed when the former EIRs were prepared. However, it is not appropriate for this 1998 SEIR to assess altogether different land uses or substantially different development concepts and, therefore, does not revisit the series of decisions made and reiterated by the City during more than 15 years. Instead, the chief reason for assessing alternatives in this 1998 SEIR is to determine the extent to which additional revisions or further refinements of previously approved land use and development concepts could better address existing circumstances in a more environmentally compatible manner. EIRs are expected to address a range of reasonable alternatives, not all potential alternatives. The governing objective in formulating potential altematives and choosing which ones to analyze is to ensure that the selection and discussion of alternatives fosters informed decision-making and informed public participation. Analyses of a project and alternatives can cover subaltematives or variations of alternatives without assessing each individually by providing sufficient information to enable readers to reach conclusions about such alternatives. This approach avoids assessing an unmanageable number of alternatives or analyzing alternatives which differ too little to provide additional meaningful. insights about their environmental effects. The alternatives analyzed in this 1998 SEIR ultimately were identified because their evaluation and that of the project would provide readers with adequate information to judge the relative effectiveness of the project and alternative ways to mitigate or avoid significant adverse impacts and to enable them to make decisions about the project. ALTERNATIVES ASSESSED The alternatives analyzed and the reasons for selecting them aze summari~pd below. Their characteristics aze compared in Exhibit 5.0-I. No Project Alternatives The California Environmental Quality Act (CEQA). requires every EIR to evaluate a "no project" alternative to provide a baseline for comparing environmental impacts. This 1998 SEIR assesses two variations of the "no project" alternative, as specifically required by CEQA, the State CEQA Guidelines (Guidelines), and case law resulting from judicial decisions. One variation is the "no development" alternative. The other variation is the "existing General Plan" alternative which, for this 1998 SEIR, is the Terrabay Specific Plan as amended in 1996. 289 The 1982 EIR on the entire three-phase project assessed a Concept Plan Alternative (745 housing units, a 200-room hotel, three restaurants with a total of 600 seats, and 210,000 square feet of offices), a Sphere of Influence Study Alternarive (1,036 attached and detached housing units, shopping center, and then-proposed commercial uses, including high technology, offices, health club, restaurant, and hotel), General Plmt Amendment Alternative (985 housing units and "more intense" commercial land uses than then proposed, including warehouse development). The 1996 SEIR, also on the entire three-phase project, concluded that, due to prior project approvals and initial implementation, the No Project Alternative meant "no further development activity beyond the current entitlement termination date of February 14, 1997" and that analysis of other alternatives was not warranted. Draft Environmental Impact Report for the Terrabay Development Project, Environmental Impact Planning Corporation, august 1982 (1982 EIR) and Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, Wagstaff and Associates, January 1996 (1996 SEIR). 299 5.0 ALTERNATIVES Terrabay Phase //and 111 SE/R No Development Alternative The No Development variation of the "no project" alternative assesses continuation of existing environmental conditions with no development at this time at any location on either the Terrabay Phase II or III sites or the hook ramps and Bayshore Boulevard realignment sites. This means that the Specific Plan would not be amended, the Precise Plan would not be approved and implemented, and existing uses (scissors ramp and Bayshore Boulevard) would remain unchanged. This alternative acknowledges that development could occur at a future time, consistent with existing City land use designations and zoning (as assessed in the Existing Specific Plan Alternarive, discussed below). Therefore, it is not an open space alternative (as assessed in the Phase III Site Permanent Open Space Alternative). Instead, it illustrates the effects of maintaining the status quo (should existing conditions persist unmitigated). Thus, it provides a basis for understanding the effects of buildout according to the proposed Precise Plan and Specific Plan amendment (as assessed in the preceding chapter) and for comparing those effects with impacts expected from the other alternatives. With the No Development Alternative, other growth in the region would continue to occur, but the Terrabay Phase II and III sites would not contribute to this cumulative development. Existing Specific Plan Alternative The Existing Specific Plan Alternative assumes buildout according to the Terrabay Specific Plan as amended in 1996, including the land uses and densities ' Exhibit 5.0-i Comparison of Alternatives' Assumptions Alterna#ive - No .Development Existing Specific Plan Reduced Residential Develo meat Reduced Commercial Develo merit Permanent Open Space Phase 11 Residential Site (housin ~tsJ Point 0 181 181 ` Commons 0 47 0 ` Woods 0 204 135 ` Total 0 432 316 ` Phase 111 Commercial Site (s uare eet, exce t hole(s) Hotel (rooms) 0 400 380 0 Mixed-Use - 0 0 30,000 0 Office 0 57,500 0 Retail 0 0 6,000 0 Restaurant 0 5,000 12,000 0 Other 0 268,000 ° 0 0 0 18,000 0 0 0 0 0 1,624,788 s Total 0 348,500`- 669,300 d _ 48,000`- 293,000 d 1,624,788 - s High technology center. f Offices could be one component of mixed-use development. The Red,.ced !~. Health club. Commercial Developrttent Alternative assumes second- and third-story offices c Without hotel. above restaurant and retail uses. ~ With estimated hotel area. g Permanent open space within "development area". The project and all r No assumptions for this part of site. alternatives would preserve open space outside the development area. anticipated under the adopted Plan. Under the Existing Specific Plan Alternative, 432 housing units could be built on the Phase II site (181 units in the Point, 47 in the Commons, and 204 in the Roods neighborhoods), and an estimated 669,300 square feet of commercial .development could be built on the Phase III site (268,000 square feet of high technology, 57,500 square feet of office, 18,000 square feet of health club, and 5,000 square feet of restaurant space and a 400-room hotel). The 1996 SEIR 300 5.0 ALTERNATIVES Terrabay Phase 1! and Ill SElR analyzed this development concept, together with Phase I residential development now underway, and identified significant unavoidable regional air quality and cumulative (yeaz 2010) traffic impacts. The 1996 SEIR also identified significant (but mitigable) land use,~geology, vegetation and wildlife, public service, noise, and cultural resource impacts. As described in l.2 EIR Detail and Objectivity, the 1996 SEIR provided the basis for determining the potential environmental impacts requiring analysis in this 1998 SEIR and for identifying the focus of this document. Project Alternatives Phase Il Reduced Residential Development Alternative The Reduced Residential Development Alternative assesses construction of 316 housing units on the Phase II residential site, assuming development as proposed by the Precise Plan except in the Commons neighborhood where no development would occur. This alternative assumes development of 181 single-family attached duplexes and triplexes in the Point and 135 single-family detached units in the Woods neighborhood (32 fewer units than the project as proposed). Previously graded parts of the Commons "development area" aze assumed to be landscaped and developed with neighborhood park facilities. The Reduced Residential Development Alternative was identified for analysis in this 1998 SEIR to avoid exposing residential development to slope stability hazards or causing significant secondary effects from mitigating those impacts. The Reduced Residential Development Alternative only addresses reduced residential development on the Phase II site and does not make any •assumptions about what would occur on the Phase III site. Phase 111 Commercial Development Site Plan Alternative The Reduced Commercial Development Alternative assesses construction of 293,000 squaze feet of hotel, mixed-use (including office), restaurant, and retail uses and required parking on an approximately 14acre development azea of the Phase III site. It also assumes no development (including either parking or utilities) within ten meters (30 feet) of the archaeological site (CA-SMa-40) except for construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevard in the vicinity of the Phase III site. This alternative was formulated expressly to assess an "environmentally superior" development concept to the proposed project in this 1998 SEIR. The effort undertaken to identify the assumptions and development parameters focused on determining potential constraints to development and on avoiding those constraints through site planning. That process is outlined below (see Process Used to Formulate Alternatives). Similaz to the Reduced Residential Development Alternative, the Reduced Commercial Development Alternative only addresses reduced commercial development on the Phase III site and does not make assumptions about what would occur on the Phase II site. Phase 111 Permanent Open Space Alternative The Permanent Open Space Alternative assesses purchase and permanent preservation of the entire Phase III commercial site. Preservation could be guaranteed either by public purchase and addition to San Bruno Mountain County Park or by acquisition by an azchaeological resource trust, university, or other public /quasi-public institution for protection and management as an archaeological preserve. The reason for identifying this as an entirely separate alternative in this 1998 SEIR is to distinguish it from the No Development Alternative. The Permanent Open Space Alternative assumes no development in the future, apart from protection of archaeological resources and, possibly, low-impact trail use elsewhere on the Phase III site. (The No Development Alternative assumes no development in the short-term only but acknowledges that development eventually would occur at some time in the future.) The Permanent Open Space Alternative would be contrary to the development assumptions adopted by the Ciry and County with approval of the 1982 Terrabay Specific Plan and San Bruno Mountain Habitat Conservation Plan which identified the Phase III site as one area of planned development in exchange for permanent preservation of the remainder of the mountain. As discussed above, the Permanent 301 5.0 ALTERNATIVES Terrabay Phase 11 and ltl SEIR Open Space Alternative only addresses the Phase III site and does not make assumptions about what would occur on the Phase II site. For the purposes of this 1998 SEIR's analyses, both the Reduced Residential Development and Reduced Commercial Development "development alternatives" are assumed to incorporate relevant mitigation measures ident~ed in the preceding chapter. All alternatives are analyzed in terms of differences in outcome, compared with the proposed project, not at the same level of detail afforded environmental topics in the preceding chapter. PROCESS USED TO FORMULATE ALTERNAT/VES The environmental analyses conducted for the preceding chapter were used to identify alternatives for evaluation in this 1998 SEIR (other than the CEQA-mandated alternatives). City staff and environmental consultants reviewed existing conditions and anticipated impacts which posed potential constraints to development or for which mitigation would not be fully successful. The Reduced Residential_ Development Alternative responds primarily to geologic hazards in the Commons neighborhood of the Phase II residential site, the Reduced Commercial Development Alternative primarily addresses archaeologic, geologic, and biologic conditions on the Phase III commercial site, and the Permanent Open Space Alternative focuses on the archaeologic resources of the Phase III commercial site. Reduced Residential Development Alternative The Reduced Residential Development Alternative was identified primarily in Fesponse to the proximity of debris slides to housing units proposed by the Precise Plan. This 1998 SEIR's slope stability analysis concluded that landslide repair would be required before housing development could proceed as proposed in the Commons neighborhood and estimated that repairs would extend the area subject to mass grading uphill beyond previously disturbed slopes. The analysis identified geotechnical and site planning alternatives to encroaching farther onto HCP land. Geotechnical alternatives include constructing retaining walls (where not proposed), building higher retaining walls (than proposed), and increasing the grades of filled slopes. Site planning alternatives include limiting residential construction to lower elevations of the Commons neighborhood. This would eliminate a minimum of the top four triplex lots (12 units). Thus, variations of this alternative could include some limited residential development on lower elevations of the Commons neighborhood (such as 24 or fewer units) and private open space without recreational uses on upper elevations. However, for the purposes of this 1998 SEIR's evaluation, the Reduced Residential Development Alternative assumes no residential development in the Commons area. Reduced Commercial Development Alternative Formulation of the Reduced Commercial Development Alternative involved several tasks to define an alternative development concept. The initial task involved preliminary identification of environmental conditions on the Phase III site affecting site development (summarized below) and making site planning and development assumptions about them. Archaeology Due to the presence of CA-SMa-40, this task focused on identifying a setback from the archaeological site to buffer it from development on adjacent parcels. The 1998 SEIR archaeologist estimated the distance to be 30 feet (ten meters) around the perimeter of the site, as mapped by Holman & Associates. Although Mitigation Measure 4.9-1(b) indicates that impacts from 302 5.0 ALTERNATIVES Terrabay Phase 11 and 111 SEIR construction of the internal site roadway proposed for the Phase III are capable of being mitigated, elimination of a roadway on any part of CA-SMa-40 would be preferable environmentally. Geology The presence of landslides, debris slides, rockslides, rockfall source areas, and the placement of artificial would require mass grading of previously disturbed and undisturbed parts of the site to mitigate the potential impacts of those geologic hazards. In addition, proposed development farther west on the Phase III site than previously anticipated would involve more extensive alterations to the natural landform. Confining development to flatter, lower elevations would reduce mass grading otherwise necessary to mitigate geologic conditions. The limit of the development area identified for this alternative is defined by the 70-80-foot contour north of the archaeological site and the 60-foot contour the south of the site which generally corresponds to the previously disturbed parts of the Phase III site. Biology Important biological resources of the Phase III site include the undisturbed hillsides above the previously graded area, the wetlands adjacent to Bayshore Boulevard, and callippee silverspot butterfly hostplants (Viola pedunculata), sometimes called "golden violas". Although no special- status species or other biological constraints had been identified on the site at the time this alternative was being formulated, elimination of steeper undisturbed slopes from the potential development-area for geologic reasons would protect habitat regardless of conclusions of special-status species surveys there. However, this alternative acknowledged the loss of wetlands for construction of the hook ramps and realignment of Bayshore Boulevard. Land Use The primary land use consideration taken into account in identifying Phase III site development area was the assumed construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevard. These roadway projects would affect site size (by about two acres) and access considerations, in order to conform with minimum distances from the ne~vv hook ramps /Bayshore Boulevard intersection. Other Constraints No other considerations were identified as potential constraints governing the location of the potential development area or assumptions required as integral components of the alternative. Inclusion and elimination of areas identified above result in a total unconstrained site development area of about 14 acres (13.89 acres), consisting of a northern development area covering 9.58 acres and a southern development area covering 4.31 acres, separated by CA-SMa-40. This total area is 45 percent of the proposed commercial lot area (30.88 acres) and 37 percent of the entire Phase III site area (37.28 acres) examined in the previous chapter. This alternative's development program assumed the same land uses currently proposed for the Phase III commercial site (hotel, mixed-use, restaurant, and retail development), accounted for associated parking requirements, and identified intensity assumptions (number of stories). The objective was to accommodate as much of the development anticipated under the project as possible within the ±14-acre unconstrained site development area. These areas are compared below (square feet of building area): Land Use Proposed Project a Alternative a Hotel 235,000-280,000 245,000 Restaurant 12,000-18,000 12,000 Retail 6,000-10,000 6,000 Mixed Use 30,000-35,000 30,000 Total Commercial 283,000-343,000 293,000 a Square feet. 303 5.0 ALTERNATIVES Terrabay Phase ll and 1/1 SE/R A variation of the Reduced Commercial Development Alternative could be no development on the 9.58-acre area north of CA-SMa-40, thus confining any Phase III site development to the 4.31-acre area south of the archaeological site. This variation would reduce the development program proportionately. It also would avoid creation of an isolated island of development on Bayshore~ Boulevard, neither associated with other commercial uses elsewhere in South San Francisco nor with Brisbane. Phase Ill Permanent Open Space A/ternative This alternative was formulated to completely restrict development on the Phase III site and permanently protect archaeological resources there. ALTERNATIVES CONSIDERED BUT REJECTED In addition to potential variations of the alternatives identified above, off-site alternatives and alternatives for the hook ramps and Bayshore Boulevard realignment are not analyzed in this 1998 SEIR. Those potential alternatives and the reasons they were dismissed from further consideration are discussed below. Otf--Site Alternatives The California Supreme Court has recognized two general classes of alternatives for analysis in EIRs. These include alternative uses or plans on the same site where the project is proposed and off-site locations for the proposed uses. The reason for assessing off-site alternatives is to evaluate the extent to which significant impacts attributable to the project as proposed could be alleviated at a different location. Off-site locations selected for analysis should feasibly attain the basic objectives of the project - in this case, the Specific Plan and proposed Precise Plan. No off-site alternatives were analyzed in this EIR. This primarily is because City (and County) policy is to allow limited development on the lower elevations of San Bruno Mountain, including within the Terrabay site, in exchange for preservation of the significant amount of open space habitat protected within San Bruno Mountain County Park. Transferring Terrabay Phase II and III site development to other locations would alter that long-established policy about the location and pattern of development in South San Francisco. Nevertheless, it theoretically would be possible to develop the types and amounts of residential and commercial land uses proposed for the Terrabay Phase II and III sites at other locations in South San Francisco or other nearby communities. In South San Francisco, for instance, mixed-use commercial development potentially could occur in the vicinity of the planned new BART station, within the El Camino Real /Highway 82 corridor, or in the area east of U.S. 101 where new development, redevelopment, and intensification of existing uses are expected in both the short- and long-term. Capacity also exists elsewhere (such as the Southern Pacific "Baylands" in Brisbane) to accommodate the level of development anticipated from the proposed Terrabay Phase II and III project. While Terrabay Phase II and III development theoretically could be accommodated at other locations - and the environmental effects could be analyzed and compared with those expected at the Terrabay site -the pending application is a refinement and provides more detailed defmition of the Specific Plan already adopted for the site. One explicit objective of the currently proposed project is to reduce the impacts attributed to the prior development concepts approved for the site, including as recently as in the 1996 Specific Plan. 304 5.0 ALTERNATIVES Terrabay Phase 11 and 111 SE/R Of the impacts identified in the preceding chapter, all are capable of being mitigated on-site, although, in order to do so, aspects of the project would need to be redesigned or revised to reduce the severity of impact to less-than-significant levels or to avert significant secondary impacts. The site-specific impact of greatest sign~cance in view of alternative site analyses relates to the azchaeological site, CA-SMa-40. Relocation of commercial development to completely avoid CA-SMa-40 would not be required by Appendix G of the Guidelines. Hook Ramps and Bayshore Boulevard Realignment Alternatives The current hook ramps and Bayshore Boulevard realignment design represents a redesign of this combined project in specific response to identified environmental and freeway engineering constraints. Analyses of prior designs determined significant unmitigable archaeological impacts on CA-SMa-40, the location of the hook ramps terminus. The hook ramps subsequently were redesigned to avoid the archaeological site. This 1998 SEIR was prepared to serve as the environmental document for Caltrans' Project Study Report /Project Report (PSR / PR), as described in 4.4 Traffic and Circulation. PSRs are prepared after various project design alternatives have:been.identified and studied preliminarily, on the basis of which the proposed project has been selected. Factors examined in studying alternatives and ultimately selecting the proposed hook ramps and Bayshore Boulevard realignment design involved Caltrans' engineering requirements, involved obtaining Caltrans' agreement to specific exceptions to criteria, and involved coordination of designs for the hook ramps with the flyover. 305 5.0 ALTERNr'.TIVES Terrabay Phase 11 and /!! SE/R A variation of the Reduced Commercial Development Alternative could be no development on the 9.58-acre area north of CA-SMa-40, thus confming any Phase III site development to the 4.31-acre area south of the archaeological site. This variation would reduce the development program proportionately. It also would avoid creation of an isolated island of development on Ba~~shore Boulevard, neither associated with other commercial uses elsewhere in South San Francisco nor with Brisbane. Phase /ll Permanent Open Space Altemative This alternative was formulated to completely restrict development on the Phase III site and permanently protect archaeological resources there. ALTERNAT/VES CONSIDERED BUT REJECTED In addition to potential variations of the alternatives ident~ed above, off-site alternatives and alternatives for the hook ramps and Bayshore Boulevard realignment are not analyzed in this 1998 SEIR. Those potential alternatives and the reasons they were dismissed from further consideration are discussed below. Off-Site Alternatives The California Supreme Court has recognized two general classes of alternatives for analysis in EIRs. These include alternative uses or plans on the same site where the project is proposed and off-site locations for the proposed uses. The reason for assessing off-site alternatives is to evaluate the extent to which significant impacts attributable to the project as proposed could be alleviated at a different location. Off-site locations selected for analysis should feasibly attain the basic objectives of the project -- in this case, the Specific Plan and proposed Precise Plan. No off-site alternatives were analyzed in this EIR. This primarily is because City (and County) policy is to allow limited development on the lower elevations of San Bruno Mountain, including within the Terrabay site, in exchange for preservation of the significant amount of open space habitat protected within San Bruno Mountain County Park. Transferring Terrabay Phase II and III site development to other locations would alter that long-established policy about the location and pattern of development in South San Francisco. Nevertheless, it theoretically would be possible to develop the types and amounts of residential and commercial land uses proposed for the Terrabay Phase II and III sites at other locations in South San Francisco or other nearby communities. In South San Francisco, for instance, mixed-use commercial development potentially could occur in the vicinity of the planned new BART station, within the El Camino Real /Highway 82 corridor, or in the area east of U.S. 101 where new development, redevelopment, and intensification of existing uses are expected in both the short- and long-term. Capacity also exists elsewhere (such as the Southern Pacific "Baylands" in Brisbane) to accommodate the level of development anticipated from the proposed Terrabay Phase II and III project. While Terrabay Phase II and III development theoretically could be accommodated at other locations - and the environmental effects could be analyzed and compared with those expected at the Terrabay site -the pending application is a refinement and provides more detailed definition of the Specific Plan already adopted for the site. One explicit objective of the currently proposed project is to reduce the impacts attributed to the prior development concepts approved for the site, including as recently as in the 1996 Specific Plan. 304 5.0 ALTERNATIVES Terrabay Phase ll and 111 SE/R Of the impacts identified in the preceding chapter, all are capable of being mitigated on-site, although, in order to do so, aspects of the project would need to be redesigned or revised to reduce the severity of impact to less-than-significant levels or to avert significant secondary impacts. The site-specific impact of greatest significance in view of alternative site analyses relates to the archaeological site, CA-SMa-40. Relocation of commercial development to completely avoid CA-SMa-40 would not be required by Appendix G of the Guidelines. Hook Ramps and Bayshore Boulevard Realignment Alternatives The current hook ramps and Bayshore Boulevard realignment design represents a redesign of this combined project in specific response to ident~ed environmental and freeway engineering constraints. Analyses of prior designs determined significant unmitigable azchaeological impacts on CA-SMa-40, the location of the hook ramps terminus. The hook ramps subsequently were redesigned to avoid the azchaeological site. This 1998 SEIR was prepazed to serve as the environmental document for Caltrans' Project Study Report /Project Report (PSR / PR), as described in 4.4 Traffic and Circulation. PSRs aze prepared after various. project design alternatives have:been.identified and studied preliminarily, on the basis of which the proposed project has been selected. Factors examined in studying alternatives and ultimately selecting the proposed hook ramps and Bayshore Boulevard realignment design involved Caltrans' engineering requirements, involved obtaining Caltrans' agreement to specific exceptions to criteria, and involved coordination of designs for the hook ramps with the flyover. 305 5.1 NO DEVELOPMENT ALTERNATIVE The No Development Alternative assumes no development as presently proposed on the Terrabay Phase II, Phase III, or hook ramps /Bayshore Boulevard realignment sites and maintenance of the status quo, although regional growth would occur off-site. The Phase II and III sites would remain vacant and continue to be privately owned, and the public roadway facilities would operate as at present. Existing environmental conditions would continue for the foreseeable future, and none of the mitigation measures ident~ed in the preceding chapter would be assumed to be implemented. The No Development Alternative would not meet the project sponsor's objectives to develop the Phase II and III sites with residential and commercial uses, respectively. GEOLOGY, SOILS, AND SEISMICITY The No Development Alternative would not involve any additional.-grading for development or landslide repair (or generate off-site disposal needs) and, thus, would not alter existing slopes in ways which would produce unstable gradients. However, this alternative would not result in landslide repair or landslide mitigation. While development would not be exposed to impacts from deep seated landslides, shallow debris flows, rockslides, or rockfalls, those materials would continue to move downslope naturally or as secondary effects of seismic shaking and would accumulate in the temporary sediment basins previously installed during Phase I. Such materials potentially could fill and / or clog those facilities unless maintained in anticipation of eventual development of the Phase II and III sites at some time in the future. No new fill material would. be placed on the sites but non- engineered fills or stockpiles would remain. Natural erosive processes would not be expected to accelerate and adversely affect the archaeological site, although erosion and gullying would continue unabated at specific on-site locations. No grading, placement of fill, and potential settlement impacts would occur for construction of the hook ramps and realignment of Bayshore Boulevard. None of these effects would be significant. HYDROLOGYAND DRAINAGE None of the proposed permanent drainage facilities would be installed on the site with the No Development Alternative, although existing temporary (and permanent) facilities would remain. Without repair and maintenance, prevailing conditions at temporary facilities would persist or deteriorate, particularly those in the Woods West neighborhood. In order to prevent worsening conditions, an outlet sump and downstream apron would need to be excavated at the existing culvert under the unpaved roadway leading into Woods West, and rock for energy dissipation would need to be placed below the outlet. In addition, the temporary sediment basin would need to be maintained. None of the significant or potentially significant impacts ident~ed in this 1998 SEIR as specifically attributable to aspects of the project's plans would occur with the No Development Alternative. BIOLOGY This alternative would avoid adverse impacts on sensitive biological resources and disturbance to existing habitat on the site. Grassland habitat and the larval hostplants for the callippe silverspot butterfly would remain undisturbed, thus contributing to the overall habitat value of San Bruno 306 5.0 ALTERNATIVES Terrabay Phase l/and 111 SE1R Mountain. Freshwater marsh and riparian habitat would not be eliminated, including the important perennial spring on the Phase III site. This No Development Alternative would not address the existing problem of invasive weedy plant species on the site which would continue to spread and replace grassland habitat. Provisions in the development approval process include control of invasi~ir exotics and other weedy species as part of the Restoration Plan which would be of benefit to the habitat value of the site and adjacent open space. TRAFFIC AND CIRCULATION The No Development Alternative would result in the "base case" impacts ident~ed for existing, year 2000, and year 2010 conditions, including significant adverse freeway and freeway ramp operations (which only Caltrans could mitigate) and some intersection impacts. This alternative assumes thaz none would be mitigated. The result would be degraded service levels on U.S. 101 segments leading to longer peak periods, jammed conditions, and / or diversions to surface streets where conditions would also decline commensurately. The No Development Alternative would not result in any on-site circulation or pazking impacts but also would not provide for any trailhead access. No construction of the hook ramps would result in .AM and PM peak hour LOS C and F operations, respectively, at the existing southbound US 101 off-ramp at Bayshore Boulevard, AM and PM peak hour LOS F and E operation, respectively, at the Bayshore Boulevard /Oyster Point Boulevard intersection, AM and P_L1 peak hour LOS D and F operation, respectively, at the Dubuque Avenue /Oyster Point Boulevard intersection, AM and PM peak hour LOS B and E operation, respectively, at the Dubuque Avenue / U.S. 101 Ramps, and LOS D operation in both the AM and PM peak hour at the Gateway /Oyster Point Boulevard intersection. AIR QUALITY This alternative would not result in any air pollutant emissions in addition to those currently produced from the site. None of the significant (or potentially significant) air quality impacts would result from this alternative. NOISE None of the potentially sianificant noise and land use compatibility issues or short-term construction noise impacts would result from the No Development Alternative. There would be no noise related issues. PUBLIC SERVICES The No Development Alternative would result in n Francisco Police Department (SSFPD) and would District, Jefferson Union High School District, or schools. o additional calls for service to the South San not increase enrollments in Brisbane School South San Francisco Unified School District HAZARDS With no reconstruction of the existing southbound U.S. 101 off-ramp (scissors ramp), no construction of a new southbound U.S. 101 on-ramp, and no realignment of Bayshore Boulevard, no soils would be 307 5.0 ALTERNATIVES Terrabay Phase 11 and 1!/ SEIR disturbed which potentially are contaminated by aerial deposits of lead contained in vehicle emissions. With no site development, no future residents would be exposed to electromagnetic fields (EbiF~. Because EMF effects would not be significant with the project or any of the alternatives, this topic is not repeated below for the other alternatives. (However, as with the No Development Altemative, the Phase II Residential Development Alternative would result in no development at all in the Commons neighborhood.) ARCHAEOLOGY With the No Development Alternative, none of the activities anticipated with the project would occur at the archaeological site CA-SMa-40. Fill would not be placed to accommodate parking or to develop a park and utilities. Moreover, no additional investigation of the site would be required to be conducted to mitigate the effects of placing fill on this cultural resource. Unless protected, even with temporary measures (such as fences), collection of materials from the site would continue, and increased public awareness of the site could accelerate these activities and aggravate their concomitant impacts from loss of or damage to archaeologically significant materials. Without protection, damage to CA-SMa-92 also would be expected for the same reasons and with similar consequences as to CA- SMa-40, resulting in impacts on both resources. 308 5.2 EXISTING SPECIFIC PLAN ALTERNATIVE The Existing Specific Plan Alternative assumes construction of 432 housing units on the Phase II site, approximately 669,300 square feet of commercial development on the Phase III site, and the U.S. 101 southbound hook ramps east of the Phase III site, consistent with the 1996 Specific Plan and as previously analyzed in the 1996 SEIR (see Exhibit 5.0-1). 290 The Existing Specific Plan Alternative would result in development of 84 more housing units, 326,300 to 386,300 more square feet of commercial space, a somewhat different mix of commercial land uses than currently proposed by the Precise Plan, and the hook ramps terminus on the archaeological site. While the 1996 SEIR contained measures to mitigate significant land use, geology, vegetation and wildlife, public service, noise, and cultural resource impacts to less-than-significant levels, examination of some of these impacts under present conditions and in view of Precise Plan definition of the project indicated that some of the corresponding mitigation measures would not be adequate to reduce their severity. 291 The Existing Specific Plan Alternative would not meet the project sponsor's objectives, as expressed in the proposed Precise Plan and Speck Plan amendment, both initiated by the sponsor. According to the project sponsor, "the underlying purpose of the changes is to improve the housing product and commercial mix over that proposed by the original 1982 Specific Plan". 292 GEOLOGY, SOILS, AND SEISMICITY The Existing Specific Plan Alternative assumes more residential development (432 units) than the 1998 Precise Plan (348 units) or any other alternative. In view of the amount and location of grading proposed to accommodate the 1998 Precise Plan, at least the same or potentially more severe impacts would be expected from implementing this alternative as anticipated from the project. On the Phase III site, the land use programs of this alternative and the project are substantially different and would be expected to result in different footprints of development, although conceptual in both cases. The -Existing Specific Plan Alternative would result in more development per se, although 400 hotel rooms would be built in one 18-story building with this alternative compared with 600 hotel rooms in three hotels of varying heights proposed by the pending project. Compared with the 1998 Precise Plan, this alternative would not appear to result in development as far west on the Phase III site as currently anticipated due to the different terminus and realignment locations of the southbound U.S. 101 hook ramps and Bayshore Boulevard. In view of the amount and location of grading proposed to accommodate the 1998 Precise Plan, at least the same or possibly somewhat less severe impacts would be expected from implementing this alternative as anticipated from the project. 290 Ibid. 291 The 1996 SEIR also identified significant unavoidable regional air quality and cumulative (year 2010) traffic impacts. 292 TerraBay Modified Specific Plan, Letter to Allison Knapp, City of South San Francisco, from James Sweenie, Sterling Pacific Management Services, Inc., December 1, 1997. 309 5.0 ALTERNATIVES Terrabay Phase ll and UI SE1R HYDROLOGYAND DRAINAGE Permanent drainage facilities installed with implementation of the Phase I project were designed to accommodate the intensity of development assumed by the Existing Specific Plan Alternative, thus adequate to handle surface flows from this alternative and the project equally well. This alternative would result in replacement of existing temporary sediment basins with permanent collection and conveyance facilities and permanent debris basins, probably quite similar to the drainage concept currently proposed. Therefore, it is expected that the significant and potentially significant impacts associated with this alternative either would be avoided through detailed design or would not differ measurably from those attributable to the project. B/OLOGY 1996 SIER measures to mitigate the Existing Specific Plan Alternative did not address potential impacts of development on wetland resources, protection and replacement of larval hostplant populations for the callippe silverspot, or all of the problems associated with the proposed approach to habitat restoration on graded slopes. While the limits of grading for this alternative would be similar to the currently proposed project, the density of development under the Existing Specific Plan Alternative would be greater than with the project and would result in more land area devoted to structures and parking rather than landscaped slopes and other habitat useable by wildlife. While development under this alternative still would require appropriate permits from jurisdictional agencies for potential impacts on wetland and endangered species, additional provisions have been included in the review of the currently proposed project to provide adequate mitigation under CEQA. TRAFFIC AND CIRCULATION The Existing Specific Plan Alternative would increase traffic generation and related impacts compared with the project as proposed. This alternative would account for an estimated 326 residential and 1,124 commercial site trips in the AM peak hour (a total of 1,450 AM peak hour trips or approximately 147 percent of the traffic generated by the project). During the PM peak period, this development concept would generate 438 residential and 1,400 commercial trips (for a total of 1,838 trips or approximately 130 percent of the traffic generated by the project). Exhibit 5.2-I shows trip generation of the Existing Specific Plan Alternative, and Exhibit 5.2-2 compares the project and development alternatives. The resulting traffic volumes would exacerbate the significant impacu attributable to the project, including at intersections of surface streets and on freeway ramps and mainline segments. As with the project, some significant impacts could be mitigated (such as through widening of intersection approaches or ramps funded by contributions of area-wide developers), although freeway impacts are unlikely to be mitigated due to Caltrans' right-of--way and funding constraints. The result would be to aggravate congested service levels throughout the local and regional transportation network. The on-site circulation and parking impacts of the Existing Specific Plan Alternative could be less severe than those expected with project implementation due to smaller units, although higher trip generation could increase conflicts and hazards on narrow streets. AIR QUALITY Potentially significant construction impacts would occur under this alternative, similar to those expected as a result of the proposed project. Impacts on regional air quality also would be significant and would be more severe with this alternative than the project. No significant impacts on long-term local air quality would be anticipated under the Existing Specific Plan Alternative. 310 .;.0 ALTERNATIVES Terrabay Phase Il and Ill SEIR Exhibit 5.2-1 Existing Specific Plan Alternative Trip Generation AM Peak Hour Tri s PM Peak Hour Tri l t D Size Inbound Outbound Inbound Outbound eve opmen Rate Volume Rate Volume Rate Volume Rate Volume Phase l1 Residential Site Woods Sin le Famil 204 units 0.19 39 0.56 115 0.65 133 0.36 74 Point & Commons Single Fami] 228 units 0.19 44 0.56 128 0.65 149 0.36 82 Subtotal 83 243 282 156 Phase 111 Commercial Site Technolo Center Office 27,800 sf 60 a 8 19 92 Showroom 240,900 sf 1.15 277 0.10 25 0.10 25 1.15 277 Quality Restaurants 650 seats 0.028 19 0.002 2 0.17 110 0.09 59 Health Club 600 members 0.015 10 0.005 5 6.52 15 0.016 10 Office 57,500 sf 106 14 24 120 Seminar Center 600 seats 0.50 300 0.05 30 0.11 65 0.~0 300 Hotel 400 rooms 0.39 156 0.28 112 0.35 140 0.36 144 Subtotal 928 196 398 1,002 Source: Crane Transportation Group, Trip Generation - 6th Edition, Institute of Transportation Engineers, 1997. a Ln('T) _ .797 Ln(X) + 1.558 (88 percent in / 12 percent out). Ln =natural log, T= trips, and X = 1,000 square feet. b T = 1.121(X) + 79.295 (17 percent in / 83 percent out). Exhibit 5.2.2 Gross Trip Generation Comparison of Pro%ect and Alternatives . - . - AM Peak Hour .: PM Peak Hour _. Condition. Two-Way Trips Two-Way Trips Tri s % of Project a Tri s % of Pro'ecta Proposed Project 987 100 percent 1,411 100 percent Existing Specific Plan Alternative 1,450 147 percent 1,838 130 percent Residential Development Alternative 321 33 percent 430 30 percent Commercial Development Alternative ` 415 42 percent 680 -l8 percent - Source: Crane Transportation Group a Percent traffic in relation to proposed project. b Phase II site only. c Phase III site only. 311 5.0 ALTERNATIVES Terrabay Phase ll and 111 SE/R NOISE More residential units would be exposed to noise levels exceeding levels considered satisfactory by the City's General Plan under the Existing Specific Plan Alternative than the project. Construction periods would be extended, increasing the period when construction noise levels would affect the noise environment of existing residents living in the area. The additional residential units and commercial development would cause greater increases in traffic noise levels on the local street network than with implementation of the project. PUBLIC SERVICES The Existing Specific Plan Alternative could have similar effects on the South San Francisco Police Department as reported in the 1996 SEIR and as expected from the currently proposed project. Since completion of the 1996 SEIR, the State Department of Finance and Association of Bay Area Governments (ABAG) have monitored and projected increased numbers of persons per household (pph) in South San Francisco (from 2.99 pph in 1996 to 3.18 pph projected in 2005). This difference would increase police protection requirements but not equivalent to,one full officer's position. 293 However, the 1982 EIR and 1996 SEIR do not appear to have separated residential demand and increased calls for service from the commercial development concept reflected by the Existing Specific Plan Alternative. Because this alternative assumes 95 percent more commercial development (about 669,300 square feet) than the proposed project 343,000 square feet, the net impact of this alternative on police services would be greater than from the project. Radio transmission relay equipment could be installed at the Existing Specifcc Plan Alternative's 18-story hotel. Since completion of the 1996 SEIR and independent of the Terrabay project, the Brisbane School District and South San Francisco Unified School District have adopted class size reduction measures, instituting maximum class sizes of 20 students. This action has reduced existing school capacity by one-third of that reported in the 1996 SEIR, with or without additional students generated by Terrabay development. Accommodating additional Terrabay students would exacerbate these districts' capacity constraints_ Therefore, applying current student generation rates to more housing units under the Existing Specific Plan Alternative and accounting for student generation of commercial development in view of these prevailing constraints this alternative would result in more severe impacts than the proposed project. HAZARDS Levels of lead accumulations at the original hook ramps site assumed by the Existing Specific Plan Alternative would be similar to those found at the proposed site and would not represent a difference in outcome from the project as proposed. Residents of the Commons (West) neighborhood would not be exposed to EMF levels which would constitute an impact, the same effect as with the project. 293 Based on the Department's current provision of 1.32 officers per 1,000 population and the 82-person difference between 432 housing units with a 1996 household density of 2.99 pph (1,292 residents) and 432 units with a 2005 densiry of 3.18 pph (1,374 residents) which would require 0.11 officer. (82 residents - 1,000 = 0.082 x 1.32 = 0.10824 officer.) 312 5.0 ALTERNATIVES Terrabay Phase !l and 1Il SEiR ARCHAEOLOGY The Existing Specific Plan Alternative would result in substantially more severe impacts on CA-SMa- 40 than with implementation of the project as proposed. Design of the hook ramps originally conceived for the adopted Specific Plan located the terminus on the archaeological site. The significant impacts previously determined to result from construction of the hook ramps as then designed was one reason the hook ramps were redesigned. Impacts on CA-SMa-92 would be similar (potentially significant) for both the Existing Specifzc Plan Alternative and project. 313 5.3 PHASE l/ REDUCED RESIDENT/AL DEVELOPMENT ALTERNATIVE The Reduced Residential Development Alternative assumes construction of 316 housing units on the Phase II site but makes no land use or development assumptions about the Phase III commercial site or hook ramps / Bayshore Boulevard site covered by this 1998 SEIR (see Exhibit S.0-I). The Reduced Residential Development Alternative would result in 32 fewer units than proposed by the Precise Plan (a nine percent difference), due to no residential development in the Commons neighborhood. Development of the Point and Woods neighborhoods are assumed to be the same as proposed by the Precise Plan (64 attached duplex, 117 attached triplex, and 135 detached units). The entire 7.5-acre Commons "development area" would be redesignated either as a public park or as common area to be owned and maintained by the Phase II Master Association. The previously graded area is assumed to be landscaped and developed with park facilities. The Reduced Residential Development Alternative assumes incorporation of mitigation measures identified in the preceding chapter with development of the Point and Woods neighborhoods as currently proposed. The Reduced Residential Development Alternative would not achieve all of the project sponsor's objectives in terms of the total amount of residential assumed compared with the total proposed. Based on experience on the Phase I site, substantial landslide repair efforts (and associated costs) required to reduce hazards to development proposed in the Commons neighborhood potentially could balance the loss of 121ots (32 units). GEOLOGY, SOILS, AND SEISMICITY The Reduced Residential Development Alternative would avert the most significant landsliding impacts on the Commons, expected with implementation of the project as proposed, by assuming no development in that neighborhood. As a result, no people and property in the Commons would be exposed to injury or damage from potential landslides. Alternatively, potentially significant secondary impacts world not occur upslope of the Commons' development area which otherwise would be required to stabilize slopes and repair landslides in close proximity to housing (as with the project). The other geologic impacts associated with development and discussed for the proposed project would not occur in the Commons neighborhood. Those geologic impacts still would be expected to occur in the other residential development areas assumed by the Reduced Residential Development Alternative -- the Point, Woods East, and Woods West subareas -but could be mitigated as discussed in the previous chapter for the project. The area and volume of grading involved for the remaining development areas under the Reduced Residential Development Alternative would be proportionately smaller and less, respectively, than the project. Grading still would occur elsewhere on the Phase II site and require mitigation recommended for the project, including for landslide repair in the Woods West neighborhood where the development concept assumed by this alternative would be identical to that proposed by the project. Rockslide and rock fall impacts would be similar in the Point and Woods East neighborhoods, artificial fill impacts would be similar in the Point neighborhood, and seismic impacts would be similar in the Point and Woods neighborhoods for both the Reduced Residential Development Alternative and project. 314 5.0 ALTERNATIVES Terrabay Phase ll and 111 SEIR HYDROLOGYAND DRAINAGE As discussed for the Existing Specific Plan Alternative, permanent drainage facilities installed with implementation of the Phase I project were designed to accommodate anticipated buildout of the Phase II site. Thus, those facilities would be expected to be more than adequate to handle surface flows from the Reduced Residential Development Alternative, the least intense residential development concept assessed by this 1998 SEIR. Implementation of this alternative also would result in installation of permanent collection and conveyance facilities and debris basins in place of existing temporary sediment basins in the Point and Woods neighborhoods. Use of the Commons subarea as a park, assumed by this alternative, would require maintenance and / or drainage improvements and removal, regrading, and restoration of the two existing dirt roads in the Commons neighborhood in order to prevent downstream sedimentation and resulting clogging of facilities serving the developed Terrabay neighborhoods. No residential development in the Commons would avoid specifically identified drainage plan deficiencies of the project as proposed. Overall, this alternative either would avoid the significant and potentially significant impacts expected from the project through detailed design or would not differ measurably from the project. BIOLOGY This alternative would focus development on parts of the Phase II site which generally have been disturbed by previous grading performed as part of the Phase I project. Eliminating residential development in the Commons neighborhood could allow for preservation of the two populations of callippe silverspot hostplant through careful design as part of open space improvements in this drainage. The Reduced Residential Development Alternative alone, without consideration of a Phase III site development concept, would not involve the most sensitive resources examined in this 1998 SEIR. Those resources are located on the Phase III site and include wetlands, the largest population of callippe silverspot hostplants, and the perennial spring. TRAFFIC AND CIRCULATION The Reduced. Residential Development Alternative would generate an estimated 321 trips in the AM peak hour (67 percent fewer than the project) and 430 trips in the PM peak hour (70 percent fewer than the project), as shown in Exhibit 5.3-I and compared with the project in Exhibit 5.2-2. These Exhibit 5.3-1 Phase ll Reduced Residential Alternative Trip Generation AM Peak Hour Trips PM Peak Hour Trips Development Size Inbound. Outbound Inbound Outbound Rafe Volume Rate 'Volume Rafe Volume Rate Volume Woods Detached ° 135 units 0.27 37 0.78 105 0.91 123 0.50 68 Point Attached ° 181 units 0.25 ` 46 0,73 ` 133 0.85 ` 154 0.47 ` 85 Total 83 238 277 ISj Source: Crane Transportation Group. and Trip Generation - 6th Edition, Institute of Transportation Engineers, 1997. a Single-family units. Detached in the Woods and attached in the Point and Commons neighborhoods. b Trip rates 40 percent above average to reflect potential generation from mix of four- and five-bedroom units. c Trip rates 30 percent above average to reflect potential generation from four-bedroom units. 315 5.0 ALTERNATIVES Terrabay Phase Il and Ill SE1R volumes would reduce the project site's contribution to off-site traffic conditions proportionately at the Oyster Point interchange intersections and ramps. The net effect of the Residential Development Alternative ultimately would depend on the development or no development concept with which this alternative was paired on the Phase III site.''-94 AIR QUALITY Potentially significant construction impacu would occur under this altemative, but these impacts would be less than those attributable to the proposed project. No significant impacts on long-term air quality (regional or local) would occur under this alternative. NOISE Elimination of residential development in the Commons neighborhood would reduce the number of Phase II site residents exposed to unsatisfactory noise levels. This would not make a substantial difference in noise impacts, compared with the project described in the Precise Plan. Existing residents who live directly across Sister Cities Boulevard from the Commons neighborhood would experience less construction noise. Overall this alternative would not' differ significantly from the project as proposed with respect to environmental noise. PUBLIC SERVICES Implementation of the Reduced Residential Development Alternative would generate fewer calls for service to the South San Francisco Police Department and require fewer additional police officers to provide service than the project. Development of 316 rather than 348 housing units would result in an estimated population of about 945-1,005 residenu compared with approximately 1,040-1,105 residents under this alternative and the project, respectively, although this difference would be equivalent to less than one full police position. 295 Development of fewer housing units within the Brisbane School District would reduce the number of new students attending Brisbane Elementary School. The Reduced Residential Development Alternative would generate an estimated 70 studenu to Brisbane Elementary School compared with 82 294 If commercial development also were reduced in intensity on the Phase III site, ensuing impacts on local surface streeu and the freeway mainline might also be partly mitigated through similar reductions in the amount of development (such as in the East of 101 Area and Brisbane) but just as easily could be offset on the freeway mainline by development elsewhere along the U.S. 101 corridor. 295 g~~ on the Department's current provision of 1.32 officers per 1,000 population. The 316-unit Residential Development Alternative would have a population of ± 945-1,005 residents based on 2.99-3.18 pph and would require 1.25-1.32 officers (945 residenu + 1,000 = 0.945 z 1.32 = 1.25 officers and 1,005 residents _ 1,000 = 1.005 x 1.32 = 1.32 officers) compared with the project's population of ± 1,040-1,107 who would generate a need for 1.37-1.46 officers (1,040 residents _ 1,000 = 1.040 x 1.32 = 1.37 officers and 1,107 residents _ 1,000 = 1.1075 x 1.32 = 1.46 officer). The difference would be 0.12-0.14 police position. 316 5.0 ALTERNATIVES Terrabay Phase 11 and ll! SE1R students with implementation of the project. 296 These students would contribute incrementally to ,the District's capacity constraints which have resulted from class size reductions. However, this impact would be proportionately less severe than the addition of 82 students generated by the project. Because the Reduced Residential Development Alternative and project assume the same number of housing units in the Woods East and West neighborhoods as the project (135 units), impacts on the South San Francisco Unified School District would be identical. HAZARDS As noted above, no development would occur in the Commons neighborhood with the Reduced Residential Development Alternative. No residents would be exposed to any electromagnetic fields, although, as with the project, measurements indicate that impacts on prospective residents of the proposed Commons neighborhood would be less-than-significant. The Reduced Residential Development Alternative only addresses the Phase II site and makes no assumptions about the Phase III or hook ramps / Bayshore Boulevard sites. Therefore, implementation of the Reduced Residenrial Development Alternative would not have any impacts from exposure of construction workers to soils contaminated with lead and would not require any measures to retain soils on-site or export soils to a Class lA landfill. ~ ` ARCHAEOLOGY The Reduced Residential Development Alternative only addresses the Phase II site and makes no assumptions about the Phase III site. The Phase III site could be used, or developed as assumed by the project or No Development, Existing Specific Plan, Commercial Development, or Permanent Open Space Alternatives. 296 Based on the rate of 0.000178 student per square foot of new residential development, 391,705 square feet assumed by the Point neighborhood would generate 70 new students. ('The 68,624 square feet of residential development proposed by the project for the Commons neighborhood but not by the Residential Development Alternative would generate an estimated 12 students.) Because this alternative makes no assumptions for the Phase III site, the number of potential students generated from that site to Brisbane School District schools cannot be estimated but would be in addition to the 70 students estimated above. 317 5.4 PHASE 11/ REDUCED COMMERCIAL DEVELOPMENT ALTERNATIVE The Reduced Commercial Development Alternative assumes construction of 293,000 square feet of commercial development on the Phase III site, construction of the hook ramps, and realignment of Bayshore Boulevard but makes no land use or development assumptions about the Phase II site. This alternative would accommodate the low end of the development range proposed for the Phase III site but would confine that development within a 14-acre development area (45 percent of the 30.9 acres of commercial lots proposed for development with 283,000-343,000 square feet of building area). Assumed uses include 245,000 square feet in three hotels providing 380 rooms (compared with 235,000-280,000 square feet in three hotels with 380-600 rooms), 30,000 square feet of mixed-use including offices (compared with 30,000-35,000 square feet), 12,000 square feet of restaurant (compared with 12,000-18,000 square feet), and 6,000 square feet of retail uses (compared with 6,000- 10,000 square feet). Restaurant and retail space are assumed to be built on ground floors with two stories of offices above, effectively combining all restaurant, retail, and mixed-used into a mixed use development. Building footprints are assumed to be minimized to accommodate required parking (684 spaces on 273,600 square feet) and would result in three-story buildings. The parking supply would satisfy City zoning without requiring shared parking, although the latter could reduce the number of spaces and paved area as could taller buildings and smaller footprints. One entrance each would provide site access to the northern and southern development areas which would not be connected internally by a north-south access road west of Bayshore Boulevard. No development would occur within ten meters (30 feet) of the archaeological site (CA-SMa-40) except for construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevard in the vicinity of the Phase III site. The alternative assumes permanent preservation of the archaeological site according to Mitigation Measure 4.9-1(b) by an appropriate public or quasi-public entity. The Reduced Commercial Development Alternative assumes incorporation of relevant mitigation measures ident~ed in the preceding chapter for the Phase III site development concept as can ently proposed. As noted above, it only assesses commercial development of the Phase III site and makes no assumptions about use or development on the Phase II site. (Similarly, the Reduced Residential Development Alternative does not make assumptions about the Phase III site.) The Reduced Commercial Development Alternative is illustrated conceptually in Exhibit S.¢I and is summarized in Exhibit 5.4-2. The Reduced Commercial Development Alternative would fulfill the project sponsor's conceptual development program for the Phase III site in terms of total amount of development and land use composition, including preservation of CA-SMa-40. GEOLOGY, SOILS, AND SEISMICITY The Reduced Commercial Development Alternative would substantially reduce the location and volume of grading on the Phase III site compared with the project by confining these activities to lower elevations. Because lower site elevations are located along the eastern boundary of the Phase III site, implementation of this alternative would not extend development as far west as with the project and, consequently, would not result inasmuch disturbance through cutting and filling. Fill still would 318 5.0 ALTERNATIVES Terrabay Phase Il and 111 SE1R Exhibit 5.4-2 Phase ll/ Reduced Commercial Development Alternative Development Summary .~ a, v, as a~ as ~' a tyiJ y :. +.. Y O V '_ ~ C ~.. L L O L y .N O O` is R[ O. ~4 i O eC O O a COQ ZQ ~ ~ ~ ~ 4 a~ N 4Q Ira 1~~L 6 143,748 107,811 Hote11130) 85,000 3 28,333 1/room 130 52,000 52,000 80,333 Restaurant 7,200 1 1/50+1/200 90 36,000 5 142,877 107,158 Retail 3,600 1 10'800 1/200 18 7,200 72,000 82,800 Ivlixed-Use 18,000 2 - 1/250 72 28,800 4 130,680 98,010 Hotel (130) 85,000 ` 3 28,333 1/room 130 52,000 52,000 80,333 Restaurant 2,640 1 1/50+1/200 34 13,600 3 50,965 38,224 Retail 1,320 1 3,960 1/200 7 2,800 27,200 31,160 Mixed-Use 6,600 2 -- 1/250 27 10,800 Restaurant` 2,160 1 1/50+1/200 28 11,200 2 43,560 32,670 Retail 1,080 1 3,240 1/200 6 2,400 22,400 25,640 Mixed-Use 5,400 2 -- 1/250 22 8,800 1 93,128 69,846 Hotel (120) 75,000 3 25,000 1/room 120 48,000 48,000 73,000 605,048 453,719 293,000 99,666 684 273,600 273,600 373,266 a See Exhibit 5.4-1. Parcels are listed north to south in [his exhibit. b The entire amount of restaurant, retail, and mixed use development was combined and distributed among Parcels 2, 3, and 5 according to the size of each parcel (its proportion of the combined three-parcel area of 237,402 square fee[). Restaurant and retail uses are assumed to be located on ground floors (resulting in a footprint of the combined area) with two levels of mixed-use (offce) above. Sixty (60) percent of restaurant, retail, and "mixed-use" development is assumed on Parcel 5. c Hotel area was increased b}• 10,000 square feet compared with the project. Parcel 4 has extra capacity, and Parcel 1 would be tight. A 7,000-square foot hotel could fit on the gross area of Parcel 1 but would exceed the net parcel area. The 75,000-square foot hotel on Parcel 1 is considered feasible because parking and circulation needs are accounted for twice -- in 400-square foot per parking space (which allows for parking and aisle area) and through the calculation of net area (75 percent of gross area). d Assumes 22 percent of total restaurant, retail, and mixed-use (office) on Parcel 3, as discussed in footnote b (above). e Assumes 18 percent of total restaurant, retail, and mixed-use (office) on Parcel 2, as discussed in footnote b (above). 319 5.0 ALTERNATIVES Terrabay Phase ll and Ill SE/R be required to build the hook ramps and realign Bayshore Boulevard, assumed to occur with the Reduced Commercial Development Alternative. The combination of maintaining (rather than cutting into) natural slopes and setting development back from hillslopes similarly would reduce exposure to and impacts from slope instability and erosion, landslides, rockslides and rockfalls, and seismic impacts compared with the project. This alternative would eliminate altogether adverse impacts on the archaeological site from placement of fill as proposed by the project. HYDROLOGYAND DRAINAGE The Reduced Commercial Development Alternative does not assume specific drainage plan features for the Phase III site. However, any development of the Phase III site would require mitigation for debris basin design or alignment and downstream conveyance facilities to reduce or avoid impacts ident~ed for the project in the previous chapter. Thus, this alternative would mitigate impacts associated with the project's proposed design (or omission) of debris basins. This approach to the Reduced Commercial Development Alternative would also apply to reducing the impact of Phase III development in conjunction with construction of the hook ramps and realignment of Bayshore Boulevard at the existing 48-inch culvert. BIOLOGY The Reduced Commercial Development Alternative would reduce impacts on biological resources compared with the project as currently proposed, although some loss of sensitive resources still would occur. These would include part of the large, callippe silverspot hostplant population, the approximately one- acre willow thicket along the Bayshore Boulevard frontage, and some of the freshwater seep areas. While this alternative would preserve the perennial spring, approximately 1.5 acres of jurisdictional wetlands and other waters still would be affected. The loss of wetland habitat would require preparation of a detailed wetland mitigation plan, but the additional area preserved on the lower elevations of the Phase III site by the Reduced Commercial Development Alternative would allow for adequate replacement and enhancement. The wetland mitigation effort preferably would be concentrated in the vicinity of the perennial spring and seep (on the project's proposed Parcel C) and incorporated into the open space lands of the City or County above the development area. TRAFFIC AND CIRCULATION The Reduced Commercial Development Alternative would generate an estimated 415 trips in the AM peak hour (58 percent fewer than the project) and 680 trips in the PM peak hour (52 percent fewer than the project), as shown in Exhibit 5.4-3 and compared with the project in Exhibit 5.2-2. These volumes would reduce the impacts of site development on future AM and PM peak hour conditions at all locations. The Reduced Commercial Development Alternative was formulated to fulfill the entire parking requirement of the land uses identified and would do so in surface parking lots. However, the footprint of development could be concentrated further with development of commercial buildings over one or more level(s) of parking. Internal circulation would be accommodated via entrances from Bayshore Boulevard to the northern and southern parts of the Phase III site, but no internal roadway linlang those parts of the site would be provided. The Reduced Commercial Development Alternative assumes construction of the U.S. 101 southbound hook ramps. The reduced traffic generation of this alternative would reduce delay (and improve LOS) somewhat compared with the project. As with the Reduced Residential Development Alternative, the net effect of the Reduced Commercial Development 321 5.0 ALTERNATIVES Terrabay Phase l! and UI SE1R Alternative would depend on the development or no development concept with which it was paired on the Phase II site. Exhibit 5.4-3 Phase 111 Reduced Commercial Development Alternative Trip Generation AM Peak Hour Tri s PM Peak Hour Tri s Development Size Inbound Outbound Inbound Outbound Rate Volume Rate Volume Rate Volume Rate Volume Retail 12,000 sf a 27 a 18 b 75 b 80 Restaurants . Qualit (2) 12,000 sf 0.57 7 0.24 3 5.02 60 2.47 30 .High Turnover, Sit Down (1) 6,000 sf 4.82 29 4.45 27 6.52 39 4.34 26 Office 18,000 sf c 42 c 6 d 17 d 83 Hotel 380 rooms 0.39 149 0.28 107 0.35 133 0.36 137 Total 254 161 324 356 Source: Crane Transportation Group and Trip Generation - 6th Edition, Institute of Transportation Engineers, 1997. a Ln('T) _ .596 Ln(X) + 2.329 (61 percent in / 39 percent out). Ln =natural log, T =trips, and X = 1,000 square feet. b Ln('T) _ .660 Ln(X) + 3.403 (48 percent in / 52 percent out). c Ln('1~ _ .797 Ln(X) + 1.558 (88 percent in / 12 percent out). d T = 1.121(X) + 79.295 (17 percent in / 83 percent out). A1R QUALITY Potentially significant construction impacts would occur with this alternative but would be less than from implementation of the proposed project. Significant long-term impacts on regional air quality would occur but would be less severe than with the project. Similar to the proposed project, no significant impacts on local long-term air quality are anticipated with the Reduced Commercial Development Alternative. NOISE Commercial development under this alternative would be concentrated on six development parcels adjacent to the U.S. 101 / Bayshore Boulevard corridor. Noise related issues would be no different for the Reduced Commercial Development Alternative than for the project. Because this alternative makes no land use or development assumptions about the Phase II site, there would be no land use compatibility issues associated with residential components of the project. PUBLIC SERVICES The somewhat smaller development concept on the Phase III site with this alternative, compared with the project, would reduce calls for service proportionately but not substantially. Three-story buildings assumed by the Reduced Commercial Development Alternative would be located in the shadow of San Bruno Mountain. The South San Francisco Police Department will require installation of communications relay equipment in the first project built within this shadow, whether at development east of U.S. 101 or with this alternative, as also would occur with the project as proposed. The Reduced Commercial Development Alternative would create approximately 525 jobs on the Phase III site, including 240 mixed-use, restaurant, and retail and 285 hotel jobs, compared with an estimated 322 5.0 ALTERNATIVES Terrabay Phase ll and !ll SE/R 720-780 people employed at Phase III site project development. These employees could add two to four students to Brisbane Elementary School enrollments, compared with three to six students from the project. Thus, the Reduced Commercial Development Alternative would reduce impacts on the Brisbane School District proportionately. HAZARDS This alternative makes no assumptions about the Phase II site, although the PG&E electric transmission lines across the Commons site would result in the same less-than-significant electromagnetic field impacts with the project or any Phase II site alternative. Because the Reduced Commercial Development Alternative assumes construction of the hook ramps and realignment of Bayshore Boulevard as currently proposed, aerial lead impacts would be identical for this alternative and the project. ARCHAEOLOGY The Reduced Commercial Development Alternative would eliminate the project's direct impacts on CA-SMa-40. Because no development would occur within 30 feet (ten meters) of the archaeological site, no fill would be placed on this resource other than to preserve the site. In addition, no parking areas or utilities would be developed on or near the site. By eliminating these impacts, this alternative would obviate the need to investigate the site further in order to record the resource before the type of filling envisaged by the project. This would avoid any further disturbance of the site including activities which would reveal additional scientific and educational information about the cultural materials at the site. While it would be preserved intact, commercial uses would be built north and south of the site, and it is not known whether the Native American community would consider this to be a potentially significant impact. The Reduced Commercial Development Alternative also assumes that CA-SMa-92 would be preserved. 323 5.5 PHASE 111 PERMANENT OPEN SPACE ALTERNATIVE The Permanent Open Space Alternative assesses permanent presen•ation of the entire Phase III commercial site as undeveloped open space through purchase by a public agency (such as for addition to San Bruno Mountain County Park) or by a public / quasi-public institution (such as an archaeological resource trust or university) for protection and management as an archaeological preserve. This alternative assumes no future development anywhere on the Phase III site except for measures necessary to protect archaeological resources and except possible trail(s) and trailhead(s) but would not exclude limited commemorative or educational features, if desired by the Native American community. The Permanent Open Space Alternative assumes construction of the U.S. 101 southbound hook ramps and realignment of Bayshore Boulevard adjacent to the Phase III site but makes no assumptions about the Phase II site. The Permanent Open Space Alternative would not satisfy the project sponsor's objectives to develop the Phase III site. The alternative assumes a willing seller and identification of a buyer and / or the availability of funds (if a public agency were to acquire the land). GEOLOGY, SOILS, AND SEISMICITY The geology, soils, and seismicity impacts of the Permanent Open Space Alternative would be the same as those identified for the No Development Alternarive, none of which would be significant. HYDROLOGYAND DRAINAGE The hydrology and drainage impacts of the Permanent Open Space Alternative would not change existing conditions on the Phase III site, thus the same as for the No Deti•elopment Alternative. BIOLOGY This alternative would avoid most of the sensitive resources of the Phase III site, including the more sensitive freshwater seep wetlands, the large population of callippe silverspot hostplants, and the perennial spring. Approximately one acre of wetlands associated with the large willow thicket along the Bayshore Boulevard frontage would be eliminated to accommodate the hook ramps. However, this habitat type would be easily relocated within the remaining undeveloped lands of the site, perhaps as part of restoring the existing level paved areas in the southern part of the Phase III site. TRAFFIC AND CIRCULATION Because the Permanent Open Space Alternative assumes construction of the U.S. 101 southbound hook ramps, conditions at the Oyster Point interchange intersections and ramps would be improved compared with existing and future base case conditions without the hook ramps. This primarily would benefit traffic originating in Brisbane. Traffic generation of the Permanent Open Space Alternative was not estimated because it would be negligible. Because trips would be expected to be limited to open space users, including hikers parking at a trailhead, few if any would occur during the AM or PM peak period. As a result, such trips would not contribute measurably to congested conditions at the freeway interchange intersections, ramps, or mainline. No on-site parking or circulation assumptions 324 5.0 ALTERNATIVES Terrabay Phase Il and !!I SE1R were made for this alternative, but access to trailhead parking could be provided north of the archaeological site directly from Bayshore Boulevard. Six to ten spaces could accommodate expected parking demand. A/R QUALITY This alternative would have similar impacu to those of the No Development Alternative. Rather than no new emissions, some negligible emissions would result from trips by visitors to the Phase III site permanent open space. Those trips could include hikers traveling to a trailhead. These would constitute aless-than-significant effect. NOISE The Phase III site is exposed to high noise levels generated on U.S. 101 and Bayshore Boulevard. The Permanent Open Space Alternative would generate substantially less traffic than the Reduced Commercial Development Alternative or project and would reduce traffic noise levels on the nearby street network. While noise levels would be compatible with open space designation, traffic noise would make the Phase III site less desirable for park use. PUBLIC SERVICES Implementation of the Permanent Open Space Alternative would not result in increased police protection demands on the South San Francisco Police Department, although occasional calls for service could originate from the Phase III site. However, if purchased and added to the San Bruno County Park, it is possible that San Mateo County would deannex the site from the City of South San Francisco. If so, the County Sheriff would be responsible for providing police protection. Development projects east of U.S. 101 also in the shadow of San Bruno Mountain would be responsible for installing communications equipment needed by the South San Francisco Police Department. With no development of the Phase III site, the Permanent Open Space Alternative would not increase enrollments at Brisbane Elementary School. HAZARDS Construction of the southbound U.S. 101 hook ramps and realignment of Bayshore Boulevard, assumed by the Permanent Open Space Alternative, would have the same impacts as the project and Reduced Commercial Development Alternative. ARCHAEOLOGY The Permanent Open Space Alternative would be the environmentally superior alternative from an archaeological perspective. This is because all the site's cultural resources, both CA-SMa-40 and CA- SMa-92, would be permanently preserved intact in an open undeveloped landscape. Purchase by an archaeological resource trust or a public /quasi-public institution specializing in protecting cultural resources would guarantee long-term maintenance and monitoring of the site. Acquisition and dedication to the County might not insure the same level of protection if funding constraints limited land and resource management activities. It is believed that the Permanent Open Space Alternative also would be preferable to the Native American community. 325 5.6 ENVIRONMENTALLY SUPERIOR ALTERNAT/VE Of all the alternatives to the proposed project analyzed, a combination of the No Development Alternative on the Phase II site and the Phase 111 Permanent Open Space Alternative on the Phase III site would be the environmentally "superior alternative". Of the development alternatives assessed, implementation of the Phase II Reduced Residential Development and Phase Ili Reduced Commercial Development Alternatives would be environmentally superior. The discussion presented immediately below compares the outcome of all alternatives with each other to provide a basis for understanding the selection of the environmentally superior alternative. The following subsection then discusses the ways in which the combined Phase li Reduced Residential Development /Phase III Reduced Commercial Development Alternative would result in less severe environmental impacts and, thus, be the preferred "development alternative". The environmental effects of the project and alternatives are compared in Exhibit 5.~1, presented at the end of this section. COMPARISON OF ALL ALTERNATIVES The "no project" alternatives ("no development" and Existing Specific Plan alternatives) make assumptions about the entire project site, but the "project alternatives" consider the Phase II and Phase III sites individually without making assumptions about the rest of the site. As a result, this 1998 SEIR concluded that, for some topics analyzed, a combination of alternatives would have effects environmentally superior to the project as proposed. Geology, Soils, and Seismicity From a geologic perspective, a Phase II No Development and Phase III Permanent Open Space Alternative would be environmentally superior, but the Phase li Residential and Phase III Commercial Development Alternatives would be the environmentally superior development alternative. This is because continuation of the status quo would result in no significant geologic impacts. A combination of the Phase II Residential and Phase III Commercial Development Alternatives would reduce geologic impacts through avoidance of some conditions (such as by setting development back from or eliminating development in relation to geologic hazard areas) and by minimizing other aspects of development (such as by reducing the area and quantity of new disturbance by grading). Hydrology and Drainage The No Development and Permanent Open Space Alternative would be the environmentally superior alternatives (or the Residential Development Alternarive combined with any "no development" alternative on the Phase III site) because the Phase III site is the least altered from natural conditions by previous grading. Drainage patterns on the Phase III site are closer to their natural alignments and character than on the Phase II site, although the Permanent Open Space Alternative would result in significant disturbance due to construction of the hook ramps and realignment of Bayshore Boulevard. Of the "development alternatives", a combination of the Residential Development and Commercial Development Alternatives on the Phase II and III sites would be environmentally superior. This primarily is because less overall development would occur and because that development would be more concentrated on the sites than assumed by the Precise Plan. 326 5.0 ALTERNATIVES Terrabay Phase 11 and !ll SEIR Biology A combination of the No Development Alternative on the Phase II site and Permanent Open Space Alternative on the Phase III site would be environmentally superior, although weedy exotic species would continue to invade the Phase II site in the absence of the type of eradication program there which a public or quasi-public agency could implement on the Phase III site. Of the "development alternatives", a combination of the Residential Development Alternative on the Phase II site and Commercial Development Alternative on the Phase III site would be superior. Traffic and Circulation The No Development Alternative would not generate any new traffic but also would not result in completion of the hook ramps. Therefore, additional traffic would not contribute to congested conditions, but, at the same time, roadway improvements serving areawide traffic would not be made. Therefore, the Permanent Open Space Alternative would be the environmentally superior "no development" alternative. Of the "development alternatives", a combination of the Residential Development and Commercial Development Alternatives for the Phase II and III sites, respectively, would be superior. The Existing Specific Plan Alternative would intensify impacts expected from implementing the project as proposed. Air Quality The No Development Alternative is the only alternative which would not result in any si~ificant (or potentially significant) air quality impacts and, therefore, would be the environmentally superior alternative, followed by the Permanent Open Space Alternative. While other alternatives would result in long-term emissions of air pollutants above existing conditions, neither the Residential Development nor Commercial Development Alternatives would increase existing emissions. Noise The No Development Alternative would be the environmentally superior alternative, followed by the Permanent Open Space Alternative. The noise impacts associated with the Residential Development and Commercial Development Alternatives would not differ significantly from the proposed project but would be superior to the Existing Specific Plan Alternative. Public Services From the perspective of both police protection and school capacity, a Phase II No Development and Phase III Permanent Open Space Alternative would be environmentally superior because there would be no change from existing conditions. It also is possible that the County Sheriff would be responsible for providing police services to the Phase III site. Of the "development alternatives", the Phase 11 Residential and Phase III Commercial Development Alternatives would be environmentally superior because less overall development would result in less overall demand for these services compared with the level of service attributed to the project. Hazards On the Phase II site, the project and all alternatives would be equal insofar as impacts from exposure to EMR is concerned because this would be ales-than-significant impact in all respects. The No Development Alternative on the Phase III site would result in no disturbance of potentially contaminated soil and, thus, would be the environmentally superior "no development" alternative. The project and all other Phase III site alternatives assume implementation of essentially identical 327 5.0 ALTERNATIVES Terrabay Phase ll and 111 SE1R hook ramps construction / Bayshore Boulevard realignment and also would be equal in terms of potential impact. Archaeology The Permanent Open Space Alternative would be the environmentally superior of all alternatives from an archaeological perspective, including the No Development Alternative and Commercial Development Alternatives, because the site's cultural resources would be preserved and managed intact in an undeveloped landscape. ENVIRONMENTALLY PREFERRED DEVELOPMENT ALTERNATIVE Based on the foregoing discussion, the preferred "development alternative" for the entire site would be a combination of (and a variation on) the Phase 11 Reduced Residential Development Alternative and the Phase III Reduced Commercial Development Alternative. This Reduced Residential /Reduced Commercial Development Alternative would assume: • Residential development of the Point, Woods East, and Woods West neighborhoods (316 total units) on the Phase II site and no residential development in the Commons neighborhood with the latter retained as a public neighborhood park or private common area. • Commercial development of alternative parcels 1, 2, and 3 on the Phase III located south of CA- SMa-40 (a total of 94,200 square feet, including one 120-room hotel, 4,800 square feet of restaurant, 2,400 square feet of retail, and 12,000 square feet of mixed-use / office development) (see Exhibit 5.6-2). ' • Hook ramps development and Bayshore Boulevard realignment along the east side of the Phase III site. • No development on or within 30 feet of CA-SMa-40, no development north or west of CA-SMa- 40, and permanent preservation of the remainder of the Phase III site. This composite "environmentally superior" alternative would incorporate the relevant mitigation measures identified for the project in the previous chapter of this 1998 SEIR. Geology, Soils, and Seismicity From a geologic perspective, the Reduced Residential /Reduced Commercial Development Alternative would be the environmentally superior development alternative. This is for two main reasons. First, implementation of this alternative would reduce geologic impacts through avoidance of some conditions. As noted above, it would set development back from and 1 or eliminate development in relation to geologic hazard areas, specifically in the Commons where landslide mitigation would avoid one impact but result in significant secondary impacts from grading uphill of the development area. Second, this alternative would minimizing other aspects of development, such as by reducing the area and quantity of new disturbance by grading. This would occur throughout the site but most notably on the Phase III site where development would be confined to previously altered areas and not extend as far west as proposed by the project. 328 5.0 ALTERNATIVES Terrabay Phase !l and I!! SElR Hydrology and Drainage The Reduced Residential /Reduced Commercial Development Alternative would be environmentally superior to the project as proposed, even with incorporation of the mitigation measures ident~ed in this 1998 SEIR in the project, because less overall development would occur and because that development would be more concentrated on the sites than assumed by the Precise Plan. Biology The Reduced Residential /Reduced Commercial Development Alternative would preserve the natural spring and seep areas on the Phase III site which aze located west and uphill of both the development and non-development areas assumed by the alternative. The loss of these biologic resources would be difficult to mitigate successfully (unlike the ability to mitigate loss of wetlands effectively). It also would preserve all callippe silverspot hostplants in the Commons neighborhood on the Phase II site and throughout the Phase III site. This is because this alternative "variation" assumes no development in the Commons and no development on and north of CA-SMa-40, thus resulting in no loss of this plant. For these reasons, this alternative would be environmentally superior even though it would result in filling of the Phase III wetlands due to hook ramps construction. Traffic and Circulation The Reduced Residential / Reduced Commercial Development Alternative would be the environmentally superior "development altemative" by decreasing impacts expected from implementing the project as proposed. The trip generation of this alternative would be equivalent to 49 percent of trips generated by the project as proposed in the AM peak hour and 55 percent of project trips in the PM peak hour. In the year 2000, this alternative would reduce impacts on six of nine U.S. 101 freeway segments identified in Impact 4.4-1 as sign~cant with the project. In the year 2010, the Reduced Residential /Reduced Commercial Development Alternative would result in significant impacts at the Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard and the Oyster Point Boulevard /Dubuque Avenue intersections (Impacts 4.4-2 and 4.4-3) where existing conditions aze neazly at the threshold of significance. Also in year 2010, traffic generated by this alternative would reduce impacts on four of 11 U.S. 101 freeway segments identified in Impact 4.4-1 as significant with the project (Impact 4.4-4) but still would result in significant impacts at the northbound on-ramp from Oyster Point Boulevard. In the year 2020, the Reduced Residential /Reduced Commercial Development Alternative would reduce storage deficiency impacts predicted on Bayshore Boulevard (Impact 4.4-12) because Phase III site development assumes only one signalized intersection (compared with two proposed by the project). However, the sign~cant unavoidable impacts on the freeway mainline (Impact 4.4-13) and southbound off-ramp diverge (Impact 4.4-14) with the hook ramps would remain significant unavoidable. This is because reduced Phase III site development would decrease volumes on the southbound on-ramp, but most traffic contributing to conditions projected there, originating from Brisbane, would not decrease, thus exceeding the one percent significance threshold (Impact 4.4-13). Similarly, Reduced Residential / Reduced Commercial Development Alternative traffic would not decrease volumes using the southbound replacement off-ramp substantially enough to eliminate the sign~cant unavoidable impact projected for year 2020. Air Quality The Reduced Residential /Reduced Commercial Development Alternative would increase long-term emissions of air pollutants above existing conditions. However, this increase would be less than the project as currently (1998 Precise Plan) or previously proposed (1996 Specific Plan). Therefore, this 329 5.0 ALTERNATIVES Terrabay Phase ll and Ill SE/R would be the environmentally superior development alternative. Although the reduced trip generation of this alternative would contribute fewer regional emissions to cumulative conditions, those cumulative conditions would be such that the impact of incremental emissions attributable to Terrabay development would remain significant and unmitigable. Noise Noise impacts associated with the Reduced Residential /Reduced Commercial Development Alternative would not differ significantly from the proposed project. Public Services Of the "development alternatives", the Reduced Residential /Reduced Commercial Development Alternative would be environmentally superior because less overall development would result in less overall demand for police service compared with the level of service attributed to the project and would generate fewer students to the Brisbane, Jefferson Union, and South San Francisco School Districts. Hazards The project, the "no development" alternatives, and the "development" alternatives would be equal in terms of less-than-significant EMF exposure impacts. Therefore, no residential development in the Commons neighborhood under the Reduced Residential /Reduced Commercial Development Alternative would not differ from the other concepts analyzed. On the Phase III site, the Reduced Residential /Reduced Commercial Development Alternative would result in identical hook ramps construction / Bayshore Boulevard realignment as the project and other ".development" alternatives, thus also equal in terms of potential impact. Archaeology The Reduced Residential /Reduced Commercial Development Alternative would preserve and manage the archaeological site's cultural resources intact. While the Phase III site would be partly developed under this alternative, development would be set back from CA-SMa-40, and the landscape in the immediately vicinity of and both north and west of CA-SMa-40 would remain undeveloped. 330 5.0 ALTERNATIVES Terrabay Phase lI and UI SE1R Exhibit 5.6-1 Comparison of Project and Alternatives a Alternatives No Pro "ect Alternatives Pro eGt Alternatives ` Impact Project NO Existing Reduced Reduced Permanent Environmentalty d Preferred Development Specific Residential Commercial Open Deve%pmerrt Plan Develo menf Develo ment S ace A/temative Geo% ,Soils, and Seismici 4.1-1 LTS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS 4.1-2 S/I.,TS LTS/LTS S/LTS S/LTS S/LTS LTS/LTS LTS/LTS 4.1-3 S/I..TS LTS/LTS S/LTS S/LTS S/LTS LTS/LTS LTS/I TS 4.1-4 S/LTS LTS/LTS S/LTS S/LTS S/LTS LTS/LTS ., LTS/LTS 4.1-5 S/I,TS LTS/LTS S/LTS S/LTS LTS/LTS LTS/LTS LTS/LTS 4.1-6 S/LTS LTS/LTS S/LTS S/LTS S/LTS LTS/I.TS LTS/LTS 4.1-7 S/LTS LTS/LTS S/LTS S/LTS LTS/LTS T TR/t TC I h drolo and Draina e 4.2-1 PS/I..TS LTS/LTS PS/LTS PS/LTS f j LTS/LTS 4.2-2 PS/LTS LTS/LTS PS/LTS PS/LTS f f LTS/LTS 4.2-3 S/L.TS LTS/LTS S/LTS S/LTS f f LTS/LTS 4.2-4 PS/LTS LTS/LTS PS/I.TS PS/LTS LTS/LTS LTS/LTS LTS/LTS 4.2-5 PS/I..TS LTS/LTS PS/LTS PS/LTS LTS/LTS ' LTS/LTS LTS/LTS 4.2-6 S/LTS LTS/LTS S/LTS S/LTS f f LTS/LTS 4.2-7 S/LTS LTS/LTS S/LTS S/LTS J f LTS/LTS 4.2-8 S/I,TS LTS/LTS S/LTS S/LTS f f 4.2-9 S/LTS LTS/LTS S/LTS S/LTS f f LTS/LTS 4.2-10 S/LTS LTS/LTS S/LTS S/LTS J f LTS/LTS 4.2-11 ~:-~---- PS/LTS LTS/LTS PS/LTS PS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS 4.3-1 S/I..TS LTS/LTS S/LTS LTS/I.TS S/LTS LTS/LTS LTS/LTS 4.3-2 s S/LTS LTS/LTS S/LTS S/LTS f S/LTS S/LTS S/LTS 4.3-3 S/I.,TS LTS/LTS T S/LTS LTS/LTS S/LTS LTS/LTS LTS/LTS raffrc and Clrculat~on 4.41 S/LTS'' LTS/LTS S/LTS S/LTS S/LTS LTS/LTS S/LTS 4.42 S/LTS LTS/LTS S/LTS S/LTS S/LTS LTS/LTS S/LTS 4.43 S/LTS LTS/LTS S/LTS S/LTS S/LTS LTS/LTS S/LTS 4.4~ S/LTS '' LTS/LTS S/LTS LTS/LTS S/LTS LTS/LTS S/LTS 4.45 S/LTS ~ LTS/LTS S/LTS S/LTS S/LTS LTS/LTS S/LTS 4.46 S/LTS LTS/LTS f S/LTS f LTS/LTS LTS/LTS 4.47 LTS/LTS LTS/LTS f S/LTS f LTS/LTS LTS/LTS 4.48 S/LTS LTS/LTS f S/LTS f LTS/LTS LTS/LTS a Before /after mitigati on. using the folln wino ahh~nvi~r;n„c• rTC_,e.....~..._ .. - ______ „ • ------..-. --. ~ - ..N~-u,a..-„s.,.~,~aa,~, ~~ = po~enuatty stgmncant mtttgable, J = significant mitigable, SU =significant unmitigable. b Both Phase II and III sites assumed by alternative. c Only Phase II or Phase III site assumed by alternative. d Alternative incorporates applicable mitigation measures identified for the project and also reduces the amount of and area covered by development. e Landslides are present throughout the site and could be mitigated at all locations. However, mitigation in the Commons would result in significant adverse secondary impacts. Thus, this alternative would mitigate landslide impacts in the Commons by avoidance. f No assumptions made for this alternative. g Impact relates to construction of the hook ramps and realignment of Bayshore Boulevard, separate from the Terrabay Phase II and III project. h Without mitigation, these impacts would remain significant and unmitigable. The mitigation measures would require reduction of the proposed development, in some cases up to 85 percent. However, without mitigation, the impacts would remain significant and unavoidable. terrabay\alts\ex5-6- l .doc 331 5.0 ALTERNATIVES Terrabay Phase II and 111 SE/R Exhibit 5.6-1 -- Continued Comparison of Project and Alternatives a Alternatives No Pro-eci Alternatives Pro 'ect Alternatives ° Environmentally ° No Existing Reduced Reduced Permanent Preferred Impact Project Development Specific Residential Commercial Open Development Plan Deve/o ment Develo ment S ace Alternative Traffic and Circulation -- Continued 4.49 S/LTS LTS/LTS f S/LTS ~ ~ LTS/LTS LTS/LTS 4.410 S/LTS LTS/LTS ~ t ~ S/LTS LTS/LTS LTS/LTS 4.411 LTS/LTS LTS/I.TS f LTS/I.TS I S/LTS LTS/I.TS LTS/LTS 4.412 S/LTS LTS/LTS S/LTS ~ I S/LTS LTS/LTS LTS/LTS 4.413 a SU/SU LTS/LTS SU/SU f SU/SU SU/SU SU/SU 4.414 a SU/SU LTS/LTS SU/SU J ~ SU/SU SU/SU SU/SU Air Qual' 4.5-1 PS/LTS LTS/LTS S/LTS S/LTS ~ S/LTS S/LTS LTS/LTS 4.5-2 a LTS/I,TS LTS/LTS LTS/LTS LTS/I.TS ~ LTS/LTS LTS/LTS LTS/LTS 4.5-3 SU/SU SU/SU SU/SU SU/SU ~ SU/SU SU/SU SU/SU Noise 4.6-1 S/I,TS LTS/LTS S/LTS S/LTS I LTS/LTS LTS/LTS LTS/LTS ~ LTS/LTS LTS/LTS 4.6-2 S/LTS LTS/LTS S/LTS S/LTS I LTS/I.TS 4.6-3 LTS/LTS LTS/LTS PS/LTS LTS/LTS ~ LTS/LTS LTS/LTS LTS/LTS 4.6-4 a LTS/LTS LTS/LTS LTS/LTS LTS/LTS i LTS/I..TS LTS/LTS LTS/LTS Services 7-1 LTS/I..TS LTS/LTS LTS/LTS LTS/LTS f LTS/LTS LTS/LTS 4 . 4.7-2 LTS/L,TS LTS/LTS S/LTS f LTS/LTS LTS/LTS LTS/LTS 4.7-3 LTS/I..TS LTS/LTS S/LTS LTS/LTS ~ LTS/LTS LTS/LTS LTS/LTS 4.7-4 S/LTS LTS/LTS LTS/LTS f ~ LTS/LTS LTS/LTS LTS/LTS 4.7-5 LTS/LTS LTS/LTS S/LTS LTS/LTS ~ LTS/LTS LTS/LTS LTS/LTS 4 7-6 LTS/LTS LTS/LTS LTS/I.TS LTS/LTS t LTS/LTS LTS/LTS LTS/LTS . 7-7 4 LTS/LTS LTS/LTS LTS/LTS LTS/LTS I LTS/LTS LTS/I.TS LTS/LTS . 4.7-8 LTS/I.,TS LTS/LTS LTS/LTS LTS/LTS ~ LTS/LTS LTS/LTS LTS/LTS 4.7-9 LTS/I,TS LTS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS LTS/LTS 4.7-10 LTS/I.,TS LTS/LTS LTS/LTS LTS/LTS I LTS/LTS LTS/LTS LTS/LTS Hazards 8-1 s S/I.TS LTS/LTS S/LTS f ~ S/LTS S/LTS LTS/LTS 4 . 4.8-2 LTS/LTS LTS/LTS LTS/LTS LTS/LTS ~ f f LTS/LTS Archaeolo 4.9-1 S/I.,TS S/LTS SU/SU ~ LTS/LTS LTS/LTS LTS/LTS 9-2 PS/LTS PS/L.TS PS/LTS J LTS/LTS LTS/LTS LTS/LTS 4 . 'fi " abl S - a Before /after mitigation, using the following abbrevtattons: LTS =less-than-stgmficant, PS =potentially stgm cant mthg e, - significant tttitigable, SU =significant unmitigable. b Both Phase II and III sites assumed by alternative. c Only Phase II or Phase III site assumed by alternative. d Alternative incorporates applicable mitigation measures identified for the project and also reduces the amount of and area covered by development. e Landslides are present throughout the site and could be mitigated at all locations. However, mitigation in the Commons would result in significant adverse secondary impacts. Thus, this alternative would mitigate landslide impacts in the Commons by avoidance. f No assumptions made for this alternative. g Impact relates to construction of the hook ramps and realignment of Bayshore Boulevard, separate from the Terrabay Phase II and ID project. terrabay\alts\ex5-6-1.doc 332 ~~ .•;". ~ 1 I ; ~ 1 ~ • •' I I t~Y• ~'-• t~ $ ~ Apr~p , ,' %k / 1 , I I I' ,V 1''V 1''•~' +\ .~tt"~,h„1~. ~ ~~ ~ t '+` ~ ~'~; ~ fit' 0 t Y ~•'~ y \ '~, t ~ f0 a~ !' I O ! I `I i /; -''~ +.t , i ~~~-{i ~~ 1`'-k ' 114- ~-~ l `, o ~.. w I 1 1,1 I', f I ~ / r~ •101++ j f.~.fr~... '' r ~ ,:..1 ~_ ~' fD `~ i '~ ~ .z ~. i ~! I I' ; I ' I ~ 4 r ~ ~-f l ~' G i I I. 1' I yl I v `) ~'' ~ ~ - mil,, _ . ;. . , , I ~ I yl~ J ~ /, lei,/'' ' ! ~ /• . _. , , . • ~ i II I~ .I ~ I ,, ' it 1 ~ /~ / / / ,,1 ,~:\+.~ ~'' '.+ '.1 I y '~ I f I i I ' ~~,~' l ~,! .. ~,_ ''. / ~., 1~ '1 ~ 1 I I' I I f ' I IJ it ~ h 1 ~ , ~ ~ ! I I .' ,~ .*r 'r '1 i / ! I : /' ~ / ~ l I~ /' i /i l it ,/ / ~ ~ % • ~ . rl i I ''I ~ t ! 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I ~..J ~ ~ i ~ 1 1 I , ' i, 1' i I ' 1 i I 1 ', I'4 ' I I 'I ,: t.. ~ • •+.r* .•~ys.:.+•,~• r. ...~'*' ',, ,,; ~ r ~_ZI I y ' { ,I ', I I I ,,, f , . I I. I `. I ,{!~ •,~~.~ S ~G'" r -•I_'~,~_?" ... ~1. ~ I I ~•r r !,l Jl , ~ ~ I I I ( I , , , , i I'' ~ "e , ! I it , / , ,. ,, 1 i 1 '" 11,11 ' ice,' / I' ! '~ ,!~ ~.{jl;,~;,~'jll~( `•; 1, ~, ' I 4'1 '.1 II r .... r ti i1' I ~ I.tr .... li ', j''I~j, ,t .I 4 ~J,' ,, .'/~'r r ~ .. .Ililll~l~4 ~f/lJ'; , / ' , ,~ , l l'' t,ly ,l;l ! , 'r," ,1,41 ~,;,, i ~ _. , / ,, ,, ,. I I ~V11 '1' 1 I' ', ~ I',i'~ r / j !l ,''tV, 1, " .r -- I ' l J j ~ I ~I~ l' ' ~ _. n~ cp ~, C1 ~ ~~ 4~i `C~ k ~ b Otr ~~ y~~ ~D N ... 6.0 IMPACT OVERVIEW 6.0 IMPACT OVERVIEW 6.7 CUMULATIVE IMPACTS This 1998 SEIR assesses the effects of implementing the proposed project under existing environmental conditions and under anticipated future "cumulative" conditions. As discussed in 2.4 Cumulative Development, this SEIR used the following assumptions to conduct cumulative analyses for year 2000, 2010, and 2020 conditions (the last for the hook ramps only): • Completion and occupancy of Terrabay Phase I residential development in South San Francisco • Development east of U.S. 101 in South San Francisco (updating the East of 101 Area Plan) • Development west of U.S. 101 in South San Francisco • Development in Brisbane according to the City's most intense General Plan land uses The analyses identified cumulative traffic, air quality, and public service impacts. TRAFFIC AND CIRCULATION The traffic analysis concluded that implementation of the Phase II and III project would result in: Significant cumulative impacts on freeway segments which would be operating at or would decline to unacceptable service levels (LOS F) in both years 2000 and 2010 (Impacts 4.4-1 and 4.4-4). Significant cumulative impacts on the Sister Cities Boulevard / Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard and the Oyster Point Boulevard /Dubuque Avenue / U.S. 101 Northbound On-Ramp intersections where PM peak hour operations would decline to unacceptable service levels in the year 2010, despite improvements in AM service levels (Impacts 4.4-2 and 4-.4-3). Significant cumulative PM peak hour impacts on the Oyster Point interchange U.S. 101 Northbound On-Ramp in year 2010 (Impact 4.4-5). These impacts are described in 4.4 Traffic and Circulation, and cumulative impacts with implementation of Phase II only and with Phase III only aze described in 7.5 Appendix. Additional year 2020 cumulative impacts were identified in the hook ramp analysis at intersections, the freeway mainline, and freeway ramps (Impacts 4.4-12 through 4.4-14). A/R QUALITY The air quality analysis determined that, while the difference in emissions of regional pollutants (ozone and PMIO) between the current 1998 and previous 1996 Phase II and III projects would not constitute a significant impact on air quality, the combined effect of Terrabay Phases I, II, and III would represent a sign~cant cumulative impact (Impact 4.5-3). Regional emissions would exceed 334 6.O IMPACT OVEAVIEW Terrabay Phase ll and 111 SEIR Bay Area Air Quality Management District thresholds, even with full implementation of available mitigation measures. PUBLIC SERVICES The Phase II and III project would contribute to increased cumulative demands for police services, but the impact attributable to the Terrabay project would not be "considerable" (Impact 4.7-6). The project also would be responsible for increased student enrollments at schools within the Brisbane, Jefferson Union, and South San Francisco Unified School Districts, although the cumulative impacts would not be "considerable" (Impact 4.7-10). (In order to be defined as "considerable", two or more. incremental effects which would be minor individually would compound or increase other impacts when combined.) None of the other topics evaluated in this 1998 SEIR was found to result in cumulative impacts. However, the value of biological and archaeological resources assessed in the EIR reflects the cumulative effect of impacts to other such resources to date. In addition to these topical analyses of on- and off-site effects of implementing the project, this 1998 SEIR and previous environmental documents which examined the .Terrabay and related projects address cumulative impacts on San Bruno Mountain. Among those are the impacts on biological resources. For instance, the significance of losing water sources on the Terrabay project site directly reflects the importance of Phase III site seeps and springs for wildlife using the entire mountain and similarly results from incremental losses of water sources attributable to past development and expected from future development (in Brisbane). Other cumulative impacts on San Bruno Mountain covered by the prior documents are incorporated in this 1998 SEIR by reference (see 1.3 Information Used to Prepare the EIR), and include the Environmental Impact Report /Environmental Assessment for Adoption and Implementation of the San Bruno Mountain Habitat Conservation Plan and Endangered Species Act Section 10(a) Permit. The HCP provides the basis for allowing limited development on the mountain in exchange for landowner participation in a mountain-wide mitigation program which is overseen by the HCP monitor. 6.2 GROWTH INDUCING IMPACTS The 1998 Precise Plan for the Phase II site and the Specific Plan development concept for the Phase III site would not be expected to stimulate additional, premature, or unplanned growth, either directly or indirectly. While the current project would decrease the number of Phase II housing units and reduce Phase III commercial development compared with the prior project, no aspects of either the 1996 or 1998 projects were determined to induce growth. This conclusion reflects the considerations discussed below. The 1998 project would reduce development by 84 units and approximately 326,300 square feet of commercial development compared with the 1996 project. This difference represents a hypothetical "residual capacity" which could be implemented elsewhere. However, in relation to commercial development at least, less development was proposed specifically to reduce off-site impacts attributable to the prior development concept. Therefore, reduced development at the Terrabay site would not produce an "opportunity" to add an equivalent (or greater) complement of development elsewhere in the region. 335 6.0 IMPACT OVERVIEW Terrabay Phase ll and 111 SEIR The Terrabay Phase II and III project site has been planned for development for more than 20 years, first by San Mateo County and, since adoption of the 1982 Terrabay Specific Plan, by the City ~f South San Francisco. The project site was identified for development as part of a comprehensive agreement to allow limited development on specific parts of San Bruno Mountain (including the project site) in exchange for permanent preservation of the rest of the mountain. Therefore, project implementation would not open on- or off-site land to development which adopted public plans designate for another land use. In addition, project implementation would not hasten development of the project site -- such as development previously planned but not foreseen until some time in the future. Specific Plans typically provide for development in the immediate short-term and are intended to be prepared and implemented when planned development is imminent. Project implementation would not introduce new urban infrastructure with the capacity to accommodate more or more intense development than previously identified on the Terrabay site and /~ or accommodate unplanned development elsewhere. Implementation of the Phase I project resulted in construction of many facilities required for buildout of the entire three-phase site. These included Sister Cities Boulevard and the Hillside Boulevard Extension (off-site) and water distribution, wastewater collection, and stormwater conveyance facilities (on-site), mainly on the Phase II site. Their capacities were determined on the basis of then-anticipated densities of development which subsequently were reduced by the pending project. However, on-site facilities were designed to stub- out permanently and not provide for extension elsewhere on- or off-site. 6.3 SIGNIFICANT UNAVOIDABLE IMPACTS This section lists the impacts which could not be eliminated or reduced to an insignificant level by mitigation, whether measures are included by the project or identified by this 1998 SEIR. These significant unavoidable impacts relate to anticipated cumulative conditions discussed above, including the contribution of the project. A significant effect on the environment is defined as a substantial or potentially substantial adverse change in the physical conditions which exist in the area affected by the proposed project. In 20 years (by year 2020), traffic conditions on the U.S. 101 freeway mainline and southbound Bayshore Boulevard off-ramp are expected to be LOS F without the addition of traffic from construction of the hook ramps (Impacts 4.4-13 and 4.4-14). Then, the proposed new on-ramp would increase volumes by more than one percent in both the AM and PM peak hours on the southbound mainline segment between the new Bayshore Boulevard and existing Dubuque Avenue on-ramps. In the AM peak hour, volumes would increase by more than one percent at the new southbound off-ramp diverge. No measures would be available mitigate these effects of building the hook ramps, short of not building them, thus resulting in unavoidable impacts of the project. Vehicle emissions of regional pollutants from the combined Terrabay Phase I, II, and III project would exceed Bay Area Air Quality Management District (BAAQMD) thresholds for reactive organic gases (ROG), nitrogen oxides (NOx), and PM,o of 80 pounds per pollutant per day (Impact 4.5-3). These emissions would result in cumulative impacts, despite the fact that the 1998 Precise Plan project would reduce emissions compared those estimated for the 1996 Specific Plan project. Since publication of the 1996 SEIR, the BAAQMD has tightened its threshold from 150 to 80 pounds per pollutant per day. 336 6.0 IMPACT OVERVIEW Terrabay Phase ll and 111 SEIR 6.4 EFFECTS OF NO SIGN/FICANCE As discussed in I.I EIR Requirement, the scope of this 1998 SEIR was determined through a process which included preparation of an Initial Study /Environmental Checklist in August 1997. The Initial Study concluded that a focused Supplemental EIR (1998 SEIR) would be required for the project and identified a number of topics for analysis in the 1998 SEIR. Responses to the Notice of Preparation - sent to governmental agencies and other parties with an interest in or jurisdiction over the project - and comments made at the public scoping session further refined the scope of the 1998 SEIR. Based on the scoping process and the analyses conducted as part of this 1998 SEIR, it was determined that a number of potential project impacts would not be significant, among them the issues listed below. This determination does not rule out any change per se as a result of the project's implementation but makes the distinction between substantial effects which would exceed the significance criteria identified in the Chapter 4 analyses and effects which would not exceed those thresholds. In addition to the following issues, others selected for analysis in this 1998 SEIR were found, upon closer examination, to represent less-than-significant project effects. They are listed in 3.3 Less-than- Significant Impacts and are described in detail in Chapter 4. EARTH 297 lb. The project would not disrupt, displace, compact, or cover the soil. 298 lc. The project would not change topography or ground surface relief. 298 ld. The project would not destroy, cover, or modify any unique geologic or physical features. le. The project would not increase wind or water erosion of soils, either on or off the site. lf. The project would not change deposition or erosion of beach sands or change siltation, deposition, or erosion which many modify the channel of a river or stream or the bed of the ocean or any bay, inlet, or lake. A/R Zb. The project would not create objectionable odors. 2c. The project would not alter air movement, moisture, or temperature or any change in climate, either locally or regionally. 297 Numbers and letters refer to items on the Ciry's Initial Study /Environmental Checklist of August 1997. 298 The Initial Study /Environmental Checklist originally dismissed an analysis of project disruption, displacement, or covering of soil and project changes in topography or ground surface relief. These issues are addressed in Impacts 4.1-5 and 4.1-1, respectively. 337 6.0 IMPACT OVERVIEW Terrabay Phase ll and 111 SE/R WATER 299 3a. The project would not change currents or the course or direction of water movements, in either marine or fresh waters. 3c. The project would not alter the course or flow of flood waters. 3d. The project would not change the amount of surface water in any water body. 3e. The project would not dischazge into surface waters or result in any alteration of surface water quality, including but not limited to temperature, dissolved oxygen, or turbidity. 3f. The project would not alter the direction or rate of flow of ground waters. 3g. The project would not change the quantity of ground waters, either through direct additions or withdrawals or through interception of an aquifer by cuts or excavations. 3h. The project would not substantially reduce the amount of water otherwise available for public water supplies. 3i. The project would not expose people or property to water related hazards, such as flooding or tidal waves. PLANT LIFE 300 4c. The project would not introduce new species of plants into an•azea or result in a barrier to the normal replenishment of existing species. 4d. The project would not reduce the acreage of any agricultural crop. ANIMAL LIFE Sb The project would not reduce the numbers of an}• unique, rare, or endangered species of animals. 301 Sc. The project would not introduce new species of animals into an area or result in a barrier to the migration or movement of animals. Sd. The project would not result in deterioration of existing fish or wildlife habitat. NOISE 6a. The project would not increase existing noise levels. 299 The Initial Study /Environmental Checklist originally dismissed an analysis of the project's changes to currents or the course or direction of water movements, in either marine or fresh waters (3(a)) and alterations to the direction or rate of flow of ground waters (3(f)). These issues are addressed in impacts 4.2-1 through 4.2-11 for the respective aspects of the project. 300 The Initial Study /Environmental Checklist originally dismissed an analysis of project changes on the diversity of species or number of any species of plants (including trees, shrubs, grass, crops, and aquatic plants) and reductions in the numbers of any unique, rare, or endangered species of planes (Items 4a and 4b). The 1998 SEIR scope then was expanded as discussed in Impacts 4.3-1 and 4.3-2. 301 This topic also was dismissed from study initially, then investieated. and ultimately found to result in no significant impact. - 338 6.0 IMPACT OVERVIEW Terrabay Phase ll and 111 SE/R LIGHT AND GLARE 7a. The project would not produce new light or glare. LAND USE 8a. The project would not result in a substantial alteration of the present or planned land use of an area. NATURAL RESOURCES 9a. The project would not increase the rate of use of any natural resources. 9b. The project would not substantially deplete an}~ nonrenewable natural resource. RISK OF UPSET 10a. The project would not involve a risk of an explosion or the release of hazardous substances (including but not limited to oil, pesticides, chemicals, or radiation) in the event of an accident or upset conditions. lOb. The project would not result in possible interference with an emergency response plan or an emergency evacuation plan. POPULAT/ON l la. The project would not alter the distribution, density, or growth rate of the human population of an area. HOUSING 12a. The project would not affect existing housing or create a demand for additional housing. TRANSPORTATION /CIRCULATION 13c. The project would not have a substantial impact upon existing transportation systems. 302 13e. The project would not alter waterborne, rail, or air traffic. PUBLIC SERVICES 14a. The project would not have an effect upon or result in a need for new or altered governmental services in any of the following areas: fire protection ... schools, parks or other recreational facilities, maintenance of public facilities, including roads, or other governmental services. 303 302 The Initial Study /Environmental Checklist originally dismissed but 1998 SEIR ultimately addressed existing transportation systems. 339 6.0 IMPACT OVERVIEW Terrabay Phase I! and 111 SEIR ENERGY 15a. The project would not use substantial amounts of fuel or energy. 15b. The project would not substantially increase demands upon existing sources of energy or require the development of new sources of energy. UTlLIT1ES 16a. The project would not result in a need for new systems or substantial alterations to the following utilities: power or natural gas, communications systems, water, sewer or septic tanks, storm water drainage, or solid waste and disposal. HUMAN HEALTH 17a. The project would not create any health hazard or potential health hazard (excluding mental health). 304 AESTHETICS 18a. The project would not result in the obstruction of any scenic vista or view open to the public or create an aesthetically offensive site open to public view. RECREATION 19a. The project would not result in an impact upon the quality or quantity of existing recreational opportunities. 6.5 AREAS OF CONTROVERSY AND ISSUES TO BE RESOLVED This 1998 SEIR identifies a number of issues which require City decisions and, based on public input to date, are expected to represent areas of controversy. The latter may include issues related to the environmental effects of the project (analyzed in this 1998 SEIR) or related to the merits of aspects of the project (which this 1998 SEIR will be used to address). 303 The Initial Study /Environmental Checklist originally focused out project impacts on police services and public schools. These topics were investigated in response to the scoping process for the EIR and ultimately were found to result in no significant impacts. 304 This topic was added to the 1998 SEIR analysis of the hook ramps and Bayshore Boulevard part of the project when the EIR was expanded to cover those transportation facilities. It remains aless-than-significant impact for the Terrabay Phase II and III part of the project. 310 6.0 IMPACT OVEr?VIEW Terra6ay Phase I1 and 111 SE1R ARCHAEOLOGICAL RESOURCES The importance of CA-SMa-40 is undisputed, due to its antiquity, size, location, and contents, including human remains, such that it qualifies for inclusion on the National Register of Historic Places. The project sponsor proposes to place fill on the site to accommodate development of a park, roadways, parking lots, and public utilities. Archaeologists agree that the proposed amount of fill, including thicknesses of up to 23 feet in places, would consolidate and crush the cultural materials within the site, thus irrevocably destroying its integrity. The California Environmental Quality Act provides a range of mitigation approaches from most preferable (avoiding the resource) to increasingly less preferable measures (capping the resource). The project sponsor proposes a data recovery program before placing fill on the site. This represents one mitigation approach. This 1998 SEIR recommends another approach -placing two to three feet of fill but nothing else on the site to protect it intact. The 1998 SEIR also assesses alternative land use and development concepts for the surrounding area. These include Phase III site development (but set back beyond the boundary of CA- SMa-40), development south of CA-SMa-40 (but not north or west of the site), and permanent preservation of the entire Phase III site with no development whatsoever. The mitigation approaches and land development concepts are the focus of intense controversy. BIOLOGICAL RESOURCES The Habitat Conservation Plan (HCP) was formulated to permanently protect and manage the resources of San Bruno Mountain while permitting limited development in specific locations, even if that development would eliminate some species or their habitat. The site contains biologic resources which would be affected to different degrees by project implementation. These include populations of Viola pedunculata, the sole larval foodplant of the callippe silverspot butterfly listed as endangered by the Federal government in December 1997, and azeas of sensitive freshwater seeps, riparian habitat, and a perennial spring. The most important and numerous of these resources are located within the proposed development azea of the Phase III site. While measures are available to mitigate impacts on these resources and implementation of these measures would comply with the HCP, avoiding the resources and averting the impacts still would be preferable to disturbance and mitigation. This is because it would be difficult for instance, to recreate the Phase III site's perennial spring and its associated habitat, thus influencing the effectiveness of mitigating this loss. In addition, effects on callippe silverspot foodplants may be controversial despite the HCP. In both cases, grading to create building pads for Phase III projects not yet defined by Precise Plans would result in premature resource losses which subsequent Precise Plans potentially could avert entirely or minimize more successfully than currently could occur: GEOLOGIC HAZARDS The site is subject to geologic conditions which must be mitigated in order to protect public health and safety within the proposed development areas of the site. Mitigation measures pose choices involving mass grading for landslide repair and site preparation. Choices include grading farther uphill, affecting previously undisturbed land, and potentially encroaching on HCP land or limiting grading. Limiting grading would require cutting of steep slopes in unstable materials, building high retaining walls, or setting development away from hillslopes, thus reducing the total amount of development. In order to accommodate site development the HCP provides flexibility to allow grading of up to ten acres (on the Terrabay Phase I, II, and III sites combined) of HCP land no more than 50 feet inside the HCP area. Project implementation in compliance with these HCP provisions still would affect previously undisturbed land and have secondary impacts, primarily on biological resources. 34] 6.0 IMPACT OVERVIEW Terrabay Phase ll and 111 SEIR Altogether, these issues represent concerns and choices about: The location and amount of development on the Phase II site. Timing of Phase III grading in the absence of a Precise Plan and specific projects. The location and amount of development on the Phase III site. 342 7.0 APPEND/CES 7.0 APPENDICES 7.1 REPORT PREPARERS This 1998 SEIR was prepared by an environmental study team led by Nichols • Berman under contract to the City of South San Francisco. The analyses were coordinated primarily with Jim Harnish, the City's Chief Planner, and Allison Knapp, the City's Consulting Planner for the Terrabay project and EIR. Nichols • Berman, Environmental Planning Bob Berman, Environmental Planner Debbie Kropf, Site Planner Louise Nichols, Environmental Planner Phyllis Yamada, Graphics CH2M HILL, Aerial Lead Leslie Dumas David Chavez & Associates, Archaeology David Chavez, Archaeologist Nina Ilic, Archaeologist Clearwater Hydrology, Hydrology Bill Vandivere, PE, Hydrologist Crane Transportation Group, Traffic Carolyn Cole, AICP, Transportation Planner Mark Crane, PE, Registered Traffic Engineer Enertech Consultants, Electromagnetic Fields Mike Silva, PE Environmental Collaborative, Biology Bang Anderson, Biologist Richard Arnold, PhD, Entomological Consulting Services, Ltd. Dianne Lake, Biologist Jim Martin, Biologist Sam McGinnis, PbD, Biological Consultant Illingworth & Rodkin, Inc., Air Quality and Noise James Reyff, Air Quality Analyst Rich Rodkin, PE, Acoustical Consultant McHuron Geosciences, Geology Eric McHuron, PhD, Geologist 7.0 APPENDICES Terrabay Phase 11 and Ill SEIR 7.2 PEOPLE AND ORGANIZATIONS CONTACTED Mike Aronson, CCS Planning and Engineering (City of South San Francisco's traffic consultant) Dennis Chuck, Department of Public Works, City of South San Francisco Mark Day, The Dahlin Group (project sponsor's architect) David Freyer, Freyer & Laureta, Department of Public Works, City of South San Francisco Richard Harmon, Department of Public Works, City of South San Francisco Jim Harnish, Planning Division, City of South San Francisco Victoria Harris, Thomas Reid Associates (HCP Monitor) David Kaplow, Pacific Open Space (project sponsor's HCP consultant) Allison Knapp, Planning Division, City of South San Francisco Frank Lozano, Brian Kangas Foulk (project sponsor's engineer) Sargent Mike Massoni, City of South San Francisco Police Department Carol Nelson, Planning Department, City of Brisbane Jan O'Flaherty, Brian Kangas Foulk (project sponsor's engineer) Gary Parikh, Parikh Consultants (project sponsor's geotechnical consultant) Joe Peterson, Hydraulics Section, Caltrans District 04 Albert Pucci, PhD, Deputy Superintendent, Jefferson Union High School District James Sweenie, Sterling Pacific Management, Inc., (project sponsor's representative) Stephen Waterman, Esq., Superintendent, Brisbane School District Hing Wong, Association of Bay Area Governments 7.3 BIBLIOGRAPHY American Conference of Governmental Industrial Hygienists (ACGII~, "19941995 Threshold .Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices", ISBN 1- 882417-06-2, 1994. Anastasio, Rebecca Loveland and Donna Garaventa with Stuart Guedon, Robert Harmon, and John Schoenfelder, A Cultural Resources Assessment for San Francisco Resource Supply Study (San Mateo Substation to Martin Substation), Daly City to City of San Mateo, San Mateo County, California, report on File at the Historical Resources Information System, Northwest Information Center, Sonoma State University, 1988. Association of Bay Area Governments, Projections '98, 1998. Bonilla, M.G., Preliminary Geologic Map of the San Francisco South Quadrangle and Pan of the Hunters Point Quadrangle, California, U.S. Geological Survey Miscellaneous Field Studies. 7. o APPENDICES Terrabay Phase ll and 111 SE/R Brian Kangas Foullc, Area Calculations for Terrabay (Development Areas), September 26, 1997 (revised February 20, 1998). Storm Drainage Report-Collection System and Debris Basins, December 13, 1997. Terrabay Phase 11 Residential Land Use Summary, January 23, 1998. Terrabay Phase 11 & 111 Vesting Tentative Map and Preliminary Grading Plan, January 15, 1998. Terrabay Precise Plan, Part 11 Engineering, January 15, 1998. Janine O'Flaherty, Terrabay Project, South San Francisco, California, Letter to Allison Knapp, City of South San Francisco, January 25, 1998. Brisbane, City, Brisbane 1993 General Plan, Traffic & Circulation Technical Memorandum, "Trip Generation, 10-Year Development Scenario, PM Peak Hour". California, State, Uniform Building Code, 1994. California Environmental Protection Agency, Department of Toxic Substances Control, Caltrans Variance for Reuse of Lead Contaminated Soil, November 1995. ,New Variance for Manifest Transportation, Storage, and Disposal, Issued to State of California Department of Transportation (Caltrans) District 4, June 7, 1995. Department of Fish and Game, California Endangered Species Act of 1984 (CESA). California Fish and Wildlife Coordination Act of 1958. Guidelines for Assessing Effects of Proposed Development on Rare and Endangered Plants and Plant Communities, 1994. Department of Transportation, Caltrans Traffic Manual. California Native Plant Society, Inventory of Rare and Endangered Vascular Plants of California, 1994. Camp Dresser & McKee, Inc., and CH2M HILL / DMJM, Status of the Phase II Site Investigation for BART's SFO Extension, Technical Memorandum, August 1997. - - Carnegie Mellon University, Depamnent of Engineering and Public Policy, "Fields From Electric Power", 1995. Carroll /Resources Engineering & Management, Compilation of Documents Pertaining to Terrabay Development-Debris Basin Facilities, September 1988. Stage 1 Grading, Unit 3 Terrabay Woods West, Rough Grading and South San Francisco Drive- Hillside Boulevard Extension Rough Grading, Terrabay Development, South San Francisco, April 1989. 7. D APPENDICES Terrabay Phase ll and !ll SE/R Terrabay Resubdivision of Parcels 1 do 2 Recorded in Volume 53 of Parcel Maps at Pages 82- 83, Records of San Mateo County, May 1990. Cartier, Robert, Cultural Resources Evaluation of the South Slope Project on San Bruno Mountain in the County of San Mateo, 1982 (1982a). _, Limited Subsurface Testing for the Archaeological Site Boundary Delineations for the Proposed South Slope Project in the County of San Mateo, 1982 (1982b). CCS Planning and Engineering, Route 101 / Bayshore Boulevard Hook Ramps PSR / PR Traffzc Operations Analysis, March 1998 and Draft Route 101 / Bayshore Boulevard Hook Ramps PSR / PR Traffic Operations Analysis, February 1998. Chavez, David, Preliminary Cultural Resources Identification: San Francisco Bay Study for Flood Control, US Army Corps of Engineers, 1979. Chavez, David and Miley P. Holman, An Archaeological Reconnaissance of San Bruno Mountain, Phase Two, 1974. CH2MHill, Borings Logs B-1 and B-4 Oyster Point Interchange and Grade Separation, 1998. Foundation Report for Southbound Flyover at Oyster Point Boulevard, 1997. Soil Sampling at Dyster Point, January 13, 1998 Technical Memorandum, and January 21, 1998 Technical Memorandum, 1998. CH2MHill /AGS and Rust /AGS, San Francisco International Airport and Caltrans Right-of--Way, Inbound /Outbound Ramps / Caltrans Project, Draft Report for Environmental Investigation Volume 1, April 1996. Clark, Matthew, Preliminary Report of Archaeological Investigations at the San Bruno Mountain Mound, Site CA-SMa-40, South San Francisco, California, 1989. Interim Report of Archaeological Evaluation of the San Bruno Mountain Mound Site, CA- SMa-40, South San Francisco, California, 1997 (1997a). Identifzcation of Site CA-SMa-92/CA-SMa-234 and the Potential Construction Impacts for Phase III of the Terrabay Development in the City of South San Francisco, 1997 (1997b). Archaeological Site Record for CA-SMa-92, 1997 (1997c). - Evaluative Archaeological Investigations at the San Bruno Mountain Mound Site, CA-SMa- 40, South San Francisco, California, 1998 (1998a). "Limits of Archaeological Site CA-SMa-92 in relation to Terrabay Project Impacts" letter to Nichols • Berman, February 16, 1998 (1998b). Environmental Impact Planning Corporation, Draft Environmental Impact Report for Terrabay Development Project, August 1982 (1982 EIR). Fong, Calvin„ "Subject File No. 18052S91A", Regulatory Branch, Department of the Army, Corps of Engineers Apri120, 1990. 7.0 APPENDICES Terrabay Phase ll and 111 SE/R Galvan, Andrew, "People of the West, the Ohlone Story", Indian Historian, 1(2):9-13, 1967-1968. IEEE, IEEE Standard Procedures for Measurement of Power frequency Electric and Magnetic Fields From AC Power Lines, IEEE Standard 644-1994, March 1995. Institute of Transportation Engineers, Trip Generation, 6`~ Edition,1996. International Non-Ionizing Radiation Committee of the International Radiation Protection Association (IltPA/INIRC) "Interim Guidelines on Limits of Exposure to 50/60-Hz Electric and Magnetic Fields", Health Physics, 58: 113-122, 1990. Kaplow, Dave, Viola Pedunculata Survey, Pacific Openspace, Inc., February 5, 1998. Lapkoff & Gobalet Demographic Research, Inc., District-wide Enrollment Trends and Forecasts, South San Francisco Unified School District, December 1997. New Housing and Its Impact on SSFUSD Elementary Enrollments, November 1997. Elementary Four Year Forecasts by Attendance Area, December 1997. Levy, Richard, "Costanoan", Handbook of North American Indians, Volume 8:485-495, 1978. Linet, M.S., et al, "Residential Exposure to Magnetic Fields and Acute Lymphoblastic Leukemia in Children", The New England Journal of Medicine, Volume 337, Number 1, July 3, 1997. Majer, Joseph, The Archaeology of San Bruno Mountain, San Mateo County, California (Preliminary Report) 1988. McGeein, D. F., Archaeological Site Record for CA-SMa-92, plus field notes, 1954. McGinnis, Samuel, The Status of the California Red-Legged Frog on the Lavine Property, Brisbane, California, 1997. Merrill, R.T. and M.W. McElhinney, The Earth's Magnetic Field International Geophysics Series No. 32, Academic Press, 1983. Milliken, Randall, A Time of Little Choice, the Disintegration of Tribal Culture in the San Francisco Bay Area, 1769-1810, 1995. Moratto, Michael J., California Archaeology, 1984. Parikh Consultants, Inc., Geologic Map and Geologic Summary Report, Terrabay Development Phase 11 & III, South Slope San Bruno Mountain, San Mateo County, California, September 1997. Geologic and Geotechnical Impact and Mitigation Summary Report, Terrabay Development Phase 11 & III, South Slope San Bruno Mountain, San Mateo County, California, February 1998. Supplemental Subsurface Exploration (Test Pits), Terrabay Project, South San Francisco, January 1998. Pilling, A., Archaeological Site Record for CA-SMa-40 and Field Notes, 1950. 7.0 APPENDICES Terrabay Phase ll and 111 SEIR PSC Associates, Geotechnical Feasibility Study, Phase 1, South Slope San Bruno Mountain, South San Francisco Area, San Mateo County, April 1982. Geotechnical Feasibility Study, Phase II, South Slope San Bruno Mountain, South San Francisco Area, San Mateo County, May 1982. Reynolds, Vicki, Preliminary Jurisdictional Determination Pursuant to Section 404 of the Clean Water Act, Terrabay Development Site, South San Francisco, California, April 1998. Ribeiro, Maria, "Site Record Forms for CA-SMa-92/234", letter from Maria Ribeiro, Site Record Coordinator, Historical Resources Information System, Northwest Information Center, to Matthew R. Clark, Holman & Associates, November 18, 1997. San Francisco, City and County, Office of Environmental Review, Crystal Springs Pipeline No. 1 Replacement at Locations Described, in Brisbane and Daly City, June 1997. Schenk, Robert, Supplemental Archaeological Site Record for CA-SMa-40, 1968. SOMA Environmental Engineering, Inc., Evaluation of Groundwater Impact from Lead Affected Soils Beneath Caltrans Inbound /Outbound Ramps, San Francisco International Airport, August 1996. South San Francisco, City, Terrabay Specific Plan, 1996. SunChase G.A. California I, Inc., Park at San Bruno Mountain Indian Midden, Terrabay, South San Francisco, California, July 1977. Terrabay Modified Specific Plan, January 22, 1998. The Dahlin Group, Terrabay Precise Plan, Part I Architectural, Landscape, HCP Restoration, January 15, 1998. Thornton, Robert D., Nossaman, Gunther, Knox & Elliott, LLP, San Bruno Mountain HCP: Section 10(a) Permit Amendment Regarding Callippe Silverspot Butterfly, March 11, 1998. Transportation Research Board, Highway Capacity Manual, 1994. Special Report 209. United States, Department of Agriculture, Soil Conservation Service (Resource Conservation Service), Soils Survey of San Francisco and San Mateo Counties, 1996. Department of the Interior, Clean Water Act, Section 404. Endangered Species Act of 1973 (FESA). U.S. Geological Survey Working Group, Probabilities of Large Earthquakes in the San Francisco Bay Region, California, U.S. Geological Survey Circular 10532, 1990. Environmental Protection Agency, Region IX Preliminary Remediation Goals (PRGs), Second Half 1995, September 1995. 7.0 APPENDICES Terrabay Phase lI and ll! SEIR National Academy of Sciences, National Research Council, Possible Health Effects of Exposure to Residential Electric and Magnetic Fields, 1996. _, Naval Electronic Systems, Household Appliance Magnetic Field Survey, Technical Report No: E06549-3, Illinois Institute of Technology Research Institute, March 1984. Wagstaff and Associates, Draft Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, January 1996, Final Supplemental Environmental Impact Report for the Terrabay Specific Plan and Development Agreement Extension, "Revised Transportation Impact and Mitigation Findings [and] Responses to Comments on Revised Findings", and "Responses to Comments on the Draft SEIR", October 1996 (1996 SEIR). El Camino Corridor Redevelopment Project EIR, January 1993. Weigel, L. E. and Robert Gross, Supplemental Archaeological Site Record for CA-SMa-40, 1984. APPENDIX 7.4 BIOLOGY Plant List for: Terrabay Ferns and Allies Polypodiaceae Polypodium calirhiza Polypodium scouleri Pteridaceae Adiantum jordanii Pentagramma triangularis friangularis Polypody Leather-leaf fem California maidenhair fern Goldback fern Angiosperms - Dicots Anacardiaceae Toxicodendron diversilobum Apiaceae Daucus pusillus *Foeniculum vulgare Lomatium dasycarpum dasycarpum Lomatium utriculatum ' Sanicula bipinnata Sanicula bipinnatifida Asteraceae Achilles mi/lefolium Achyrachaena mollis Agoseris grandiflora Artemisia californica Aster chilensis Baccharis pilularis *Carduus pycnocepha/us *Centaurea melitensis *Centaurea solstitialis Cirsium quercetorum *Cirsium vulgare *Conyza bonariensis Conyza canadensis *Filago gallica Gnaphalium californicum *Gnaphalium luteo-album Western poison-oak Rattlesnake weed Anise Lace parsnip Bladder parsnip Poison sanicle Purple sanicle Yarrow Blow-wives False dandelion California sagebrush Common California aster Chaparral broom Italian thistle Napa thistle Yellow star-thistle Brownie thistle Bull thistle Hairy fleabane Horseweed Narrow-leaved filago California everlasting Weedy cudweed * Indicates non-native species Page 1 of 7 Gnaphalium ramosissimum Pink everlasting Grindelia hirsutula hirsutula Gumplant Heterotheca sessiliflora bolanderi Bolander's goldenaster *Hypochaeris glabra Smooth cat's-ear *Hypochaeris radicata Rough cat's-ear *Lactuca virosa Wild lettuce Lasthenia glabrata glabrata Yellow-ray goldfields Madia sativa Coast tarweed Madia sp. Madia *Picris echioides Bristly ox-tongue *Senecio vu/garis Common groundsel *Silybum marianum Milk thistle *Solvia sessilis Solvia *Sonchus asper asper Prickly sow-thistle *Sonchus oleraceus Common sow-thistle *Urospermum picroides Urospermum Wyethia angustifolia Narrowleaf mules ears Boraginaceae Amsinckia menziesii intermedia Common fiddleneck Brassicaceae Barbarea orthoceras American winter cress Cardamine oligosperma Few-seed bitter cress Erysimum franciscanum San Francisco wallflower *Hirschfeldia incana Hoary mustard *Raphanus raphanistrum Jointed wild radish "Raphanus sativus Wld radish Rorippa nasturtium-aquaticum Water cress Caryophyllaceae *Cerastium glomeratum Mouse-ear chickweed *Silene gallica Catchfly *Spergula arvensis arvensis Stickwort *Spergularia rubra Ruby sand-spurrey *Stellaria media Common chickweed Chenopodiaceae *Atriplex semibaccata Australian saltbush *Chenopodium sp. Goosefoot *Salsola tragus Tumbleweed Convolvulaceae Calystegia occidentalis occidenta/is Morning-glory *Convolvulus arvensis Bindweed * Indicates non-native species Page 2 of 7 Crassulaceae Crassula connata Sandy pygmy-weed Dudleya farinosa Dudleya Cucurbitaceae Marah fabaceus Common man-root Fabaceae *Acacia melanoxylon Blackwood acacia *Genista monspessulana French broom Lathyrus vestitus vestitus Wild pea *Lotus corniculatus Birdfoot trefoil Lotus humistratus Woolly trefoil Lotus micranthus Least trefoil Lotus purshianus purshianus Spanish-clover Lotus scoparius Deerweed Lupinus albifrons collinus Bush lupine Lupinus bicolor Dove lupine Lupinus nanus Sky lupine Lupinus succulentus Arroyo lupine Lupinus variicolor Bluff lupine *Medicago polymorpha Califomia burclover *Melilotus indica Sour clover *Trifolium campestre .Hop clover *Trifolium dubium Suckling clover *Trifolium hirtum Rose clover *Trifolium incarnatum Crimson clover Trifolium willdenovii Tomcat clover *Vicia benghalensis Purple vetch *Vicia sativa nigra Common vetch *Vicia sativa sativa Spring vetch Geraniaceae *Erodium botrys Long-beaked filaree *Erodium brachycarpum Short-fruited stork's-bill Geranium bicknellii Bicknell's geranium *Geranium dissectum Cut-leaf geranium Hippocastanaceae Aesculus californica Califomia buckeye Hydrophyllaceae Phacelia califomica Rock phacelia Phacelia distans Fern phacelia Phacelia imbricata imbricata Rock phacelia * Indicates non-native species Page 3 of 7 Lamiaceae *Marrubium vulgare Horehound Monardella villosa Coyote mint Salvia spathacea Pitcher sage Stachys ajugoides rigida Rigid hedge-nettle Lythraceae *Lythrum hyssopifolium Grass-poly Malvaceae *Lavatera cretica Mavva rosa *Malva nicaeensis Bull mallow *Malva sylvestris Hight mallow Sidalcea malvaeflora malvaeflora Checker mallow Myrtaceae *Eucalyptus globulus Blue gum *Eucalyptus sp. Eucalyptus Onagraceae Camissonia ovata Sun cup , Clarkia rubicunda Farewell-to-spring Epilobium brachycarpum Summer cottonweed Epilobium ciliatum ciliatum Hairy willow-herb Oxalidaceae *Oxalis pes-caprae Bermuda buttercup Papaveraceae Eschscholzia califomica California poppy Plantaginaceae *Plantago coronopus Cut-leaf plantain Plantago erects Plantain *Plantago lanceolata English plantain Polygonaceae Eriogonum nudum Wild buckwheat *Polygonum arenastrum Common knotweed *Rumex acetosella Sheep sorrel *Rumex crispus Curly dock *Rumex pulcher Fiddle dock Rumex salicifolius Willow dock Portulacaceae Calandrinia ciliata Red maids Claytonia perfoliata mexicana Miner's lettuce Claytonia pen`oliata pen`oliata Miner's lettuce Primulaceae *Anagallis arvensis Scarlet pimpernel * Indicates non-native species Page 4 of 7 Ranunculaceae Ranunculus californicus Califomia buttercup Rosaceae Acaena pinnatifida californica Acaena Aphanes occidentalis Western lady's-mantle *Cotoneaster sp. Cotoneaster Heteromeles arbutifolia Christmas berry Oemleria cerasiformis Oso bent' Prunus ilicifolia ilicifolia Islay *Pyracantha sp. Pyracantha *Rubus discolor Himalayan blackberry Rubus ursinus California blackberry Rubiaceae *Galium aparine Goose grass Galium porrigens porrigens Climbing bedstraw Salicaceae Salix lasiolepis Arroyo willow Scrophulariaceae *Bellardia trixago Bellardia Castilleja densiflora densiflora Owl's-clover Castilleja exserta exserta Purple owl's-clover Castilleja subinclusa franciscana Indian paintbrush Mimulus aurantiacus Sticky monkeyflower Mimulus guttatus Common monkeyflower Scrophularia californica californica California figwort Solanaceae Solanum americanum Black nightshade Valerianaceae *Centranthus ruber Red valerian Violaceae Viola pedunculata ~ Johnny-jump-up Angiosperms -Monocots Cyperaceae Carex aquatilis dives Carex deweyana leptopoda Carex sp. Cyperus eragrostis Scirpus americanus Sitka sedge Short-scale sedge Sedge Tall umbrella-plant Olney's bulrush * Indicates non-native species Page 5 of 7 Iridaceae Iris douglasiana Douglas' iris Iris longipetala Long-petal ins Sisyrinchium bellum Blue-eyed grass Juncaceae Juncos bufonius bufonius Toad rush Juncos effusus pacificus Bog rush Juncos lesueurii Salt rush Juncos occidentalis Slender rush Juncos patens Common rush Juncos phaeocephalus phaeocephalus Brown-head rush Juncos sp. Rush Liliaceae Allium peninsulare franciscanum Wild onion Chlorogalum pomeridianum pomeridianum Soap plant Dichelostemma capitatum capitatum Blue dicks Triteleia laxa Ithuriel's spear Poaceae *Aira caryophyllea Silver European hairgrass *Avena barbata Slender wild oat *Avena fatua Wild oat *Briza maxima Quaking grass *Briza minor Small quaking grass Bromus carinatus carinatus Califomia brome *Bromus diandrus Ripgut grass *Bromus hordeaceus Soft chess *Bromus madritensis madritensis Compact chess *Bromus madritensis rubens Foxtail brome *Cortaderia jubata Pampas grass *Cynodon dactylon Bermuda grass *Dactylis glomerata Orchard grass Danthonia californica califomica Califomia oatgrass Deschampsia cespitosa cespitosa Tufted hairgrass Elymus multisetus Big squirreltail *Festuca arundinacea Tall fescue *Gasfridium ventricosum Nit grass *Holcus /anatus Common velvet grass Hordeum brachyantherum brachyantherum Meadow barley *Hordeum marinum gussoneaunum Mediterranean barley *Hordeum murinum /eporinum Foxtail barley *Hordeum vulgare Barley * Indicates non-native species Page 6 of 7 Leymus triticoides Creeping wildrye *Lolium mu/tiflorum Italian ryegrass *Lolium perenne Perennial ryegrass Melica californica California melic Nassella pulchra Purple needlegrass *Phalaris aquatics Harding grass *Poa annua Annual bluegrass *Polypogon interruptus Ditch beard grass *Polypogon monspeliensis Rabbit's-foot grass *Vulpia myuros hirsuta Zorro grass *Vulpia myuros myuros Zorro grass * Indicates non-native species Page 7 of 7 POTENTIAL SPECIAL STATUS SPECIES FOR TERRABAY, SAN BRUNO MOUNTAIN Species Status Blooming Common Name Fed/StatefCNPS Habitat Period Arabis blepharophylla Fed: None Coastal Bluff Feb-April Coast rock cress State: None Coastal Scrub CNPS: 4 Coastal Prairie Arctostaphylos montaraensis Fed: None Coastal Scrub Jan-March Montara manzanita State: None Maritime Chaparral CNPS: 1B Calandrinia breweri Fed: None Coastal Bluff Scrub March-June Brewer's calandrinia State: CEQA? Chaparral CNPS: 4 Calochortus umbellatus Fed: None Valley Grassland March-May Oakland star tulip State: CEQA? Chaparral CNPS: 4 Cirsium andrewsii Fed: None Meadows/Seeps June-July Franciscan thistle State: CEQA? CNPS: 4 Collinsia multicolor Fed: None Coastal Scrub March-May San Francisco collinsia State: CEQA? CLAPS: 4 Erysimum franciscanum Fed: None Coastal Scrub March-June San Francisco wallflower State: None Valley Grassland CLAPS: 4 Fritillaria agrestis Fed: None Ualley Grassland March-April Stinkbells State: None Chaparral CLAPS: 4 Fritillaria liliacea Fed: None Coastal Scrub Feb-April Fragrant fritillary State: None Valley Grassland CLAPS: 16 Grindelia hirsutula var. maritima Fed: None Coastal Scrub Aug-Sept San Francisco gumplant State: None Valley Grassland CLAPS: 16 Helianthella castanea Fed: None Coastal Scrub April-June Diablo helianthella State: None Valley Grassland CLAPS: 1B ~ecies Status Blooming Common Name Fed~State/GNPs Habitat Period Horkelia marinensis Fed: None Coastal Prairie May-Sept Point Reyes horkelia State: None Coastal Scrub CLAPS: 1B Lessingia arachnoidea Fed: None Coastal Scrub July-Oct Crystal Springs lessingia State: None Valley Grassland CLAPS: 1B Lessingia germanorum Fed: FE Coastal Scrub Aug-Nov San Francisco lessingia State: CE CLAPS: 1B Lessingia ho loleuca Fed: None Coastal Scrub June-Oct Wooly-headed lessingia State: CEQA? Valley Grassland CLAPS: 3 Lilium maritimum Fed: C Coastal Prairie May-July Coast lily State: None Coastal Scrub CLAPS: 1B Limnanthes douglasii ssp. sulphurea Fed: None Coastal Prairie March-May Point Reyes meadowfoam State: CE Meadows/Seeps CLAPS: 1B Linanthus acicularis Fed: None Coastal Prairie April-July Bristly Linanthus State: CEQA? Chaparral CLAPS: 4 Linanthus grand iflorus Fed: None Coastal Prairie April-July Large-flowered Linanthus State: CEQA? Valley Grassland CLAPS: 4 Coastal Scrub Lupinus eximius Fed: None Coastal Scrub April-July San Mateo tree lupine State: None Chaparral CLAPS: 1B Monardella undulata Fed: None Coastal Scrub May-July Curly-leaved monardella State: CEQA? CLAPS: 4 Pedicularis dudleyi Fed: None Valley Grassland April-June Dudley's lousewort State: CR Maritime Chaparral CLAPS: 16 Pe~tachaeta bellidiflora Fed: FE Valley Grassland March-May White-rayed pentachaeta State: CE CLAPS: 1B Species Status Blooming Common Name Fed/State/GNPs Habitat Period Perideridia gairdneri ssp. gairdneri Fed: None Valley Grassland June-Oct State: None Chaparral CNPS: 4 Plagiobothrys chorisianus var. Fed: None Coastal Prairie April-June chorisianus State: CEQA? Coastal Scrub Choris' popcorn flower CNPS: 3 Sanicula hoffmannii Fed: None Coastal Scrub March-May Hoffman's sanicle State: None Chaparral CNPS: 4 Silene verecunda ssp. verecunda Fed: None Coastal Prairie March-June San Francisco camp ion State: None Coastal Scrub CNPS: 1B Valley Grassland Triphysaria floribunda Fed: None Coastal Prairie April-May San Francisco owls-clover State: None Valley Grassland CNPS: 1B Ri~hard.a.:lrnad. Ph.D. f res~denc '_~r~mol_~ical Consi~ltin ~ervices, Ltd `loun[a~n '~ ie~c Coun. I I:~san[ Hill. C~ 9a5?3 i 101 321-3'8-# FA}C 82'-1809 6 April 1998 Mr. James A. Martin, Principal Environmental Collaborative 127 Western Drive Point Richmond, CA 94801 RE: Terrabay Development, Phases II and III Callippe Silverspot Butterfly Dear Jim: This letter presents my evaluation of various issues dealing with the endangered Callippe Silverspot butterfly at the Terrabay development site, located on San Bruno Mountain in South San Francisco, CA. My evaluation is for the update to the supplemental environmental impact report for Phases II and III of the Terrabay development project. Background Information. The Callippe Silverspot, known scientifically as Speyeria callippe callippe, is a nymphalid butterfly (Lepidoptera: Nymphalidae) that is endemic to the San Francisco Bay area. It is one of 16 subspecies of Speyeria callippe, a silverspot species that ranges from the Rocky Mountains to the West Coast (Howe 1975; Miller and Brown 1981; and Scott 1986). Silverspots are also commonly referred to as fritillary butterflies. Although it is believed to have been formerly widespread throughout the grassland-covered hills of the San Francisco Bay area, today the butterfly is known only from San Bruno Mountain in San Mateo County and Joaquin Miller Pazk and Redwood Regional Parks in Oakland (Alameda County). Because of its shrinking geographic range and threats from poaching, the U.S. Fish & Wildlife Service (1997) recently recognized the Callippe Silverspot as an endangered species. Like many of the described subspecies of this Silverspot, Speyeria callippe callippe exhibits considerable phenotypic variation in its color, wing markings, and the amount of black scaling. Populations with more black scaling, a taxonomic characteristic used to distinguish S. callippe callippe from other subspecies, tend to be found closer to the coast, where the black scales probably aid in absorbing radiant energy from the sun. Inland populations, where temperatures are warmer and there is less fog, tend to have less black scaling. Additional populations of Speyeria callippe occur in the Sky Valley azea of southern Solano County and in the north central and northeastern portions of Alameda County (Arnold 1981). Although these populations have previously been treated by various entomologists (Murphy and Weiss 1990) and the U.S. Fish & Wildlife Service (1990) as the Callippe Silverspot, the recent rulemaking by U.S. Fish & Wildlife (1997) Callippe Silverspot Evaluation for Terrabay Phases II and III does not specifically identify these populations among those that are now recognized as endangered and protected pursuant to provisions of the federal Endangered Species Act. The Callippe Silverspot is not protected under the State of California's Endangered Species Act. The Callippe Silverspot occurs in grasslands where its sole larval foodplant, Johnny Jump-Up or violet, Viola pedunculata (Violaceae), grows. Adults tend to congregate on prominent hilltops, where they search for potential mates. Their flight season is usually from about mid-May through early July. Because of the length of the flight season, adults visit several different flowers to obtain nectar as these plants flower during the flight season. When available, favored nectar plants include mints, such as Monardella, and thistles, such as Silybum and Cirsium. Numerous other flowers may also be visited less frequently. Although the Silverspot occurs in hilly terrain with a mixture of topographic relief, areas where the larval and adult foodplants grow do not always coincide with areas where mate location and other behaviors occur. Temabay Proiect Description. The entire Terrabay project site, consisting of Phases I, II, and III, encompasses 332 acres. This development site is one of the original projects included in the Habitat Conservation Plan (HCP) for San Bruno Mountain (Thomas Reid Associates 1982), although it was known by a different name when the HCP was prepazed. Construction of the new homes contained in Phase I has neazly been completed. Some portions of Phases II and III were previously graded. As currently planned, 200 of the 332 acres will be developed, upon completion of Phases II and III, while 132 acres will remain as undeveloped open space that will be added to the conserved habitat acreage of San Bruno Mountain. Within the Phases II and III portions of the project, 104 acres will be developed, including approximately 80 acres that have already been disturbed by prior grading or other activities. Approximately 90 of the 132 acres that will remain as undeveloped open space, occur within the boundaries of the Phases II and III portions of the project; however, some of the open space acreage will be graded and subsequently revegetated. Existing Callippe Silverspot Habitat. Viola pedunculata, the larval foodplant of the Callippe Silverspot, grows within the boundaries of Phases II and III. The 1981 Biological Study (Thomas Reid Associates 1981) illustrates (Figure IV-11) the distribution and cover of the violet throughout San Bruno Mountain, including the Terrabay project site. Cover of the violet was generally found to be less than 0.05% within the commercial portion of the project site (Phase III) and between 0.05 and 0.10% in the residential portion (Phase II). In late January, 1998, Dave Kaplow, of Pacific Open Space, Inc., mapped the locations of V. pedunculata growing within the Phases II and III areas (Kaplow 1998}. He observed the violet growing in four locations, identified as A -Don the attached figure. He identified a single plant at location A, 60 plants at B, 58 plants at C, and 958 plants at D. Callippe Silverspot Evaluation for Terrabay Phases II and III On March 20~', 1998, Iperformed aground-truth survey to verify Kaplow's findings. Overall, I observed that Kaplow's mapping of the four V. pedunculata locations, A - D, was accurate. During my survey, I found two additional small clumps of V. pedunculata; one located in the Terrabay Commons portion of the project site (location E on the attached map), and the other located along the higher elevations in the proposed commercial area (location F on the attached map). These two, small clumps may not have been apparent at the time of Kaplow's survey. The attached figure illustrates six locations (A - F) within the boundaries of the project, where V. pedunculata was observed growing during our combined survey efforts. Violets at locations C and D are part of populations that extend into adjacent and upslope portions of the conserved habitat area at San Bruno Mountain. The numbers of Viola pedunculata growing within the boundaries of Phases II and III are difficult to accurately estimate. Violets reproduce both sexually and asexually, which can complicate how to define an individual plant. Indeed, different plants can grow together in the same clump of foliage and appear to be a single plant. At the Terrabay site, the violets were observed to range from solitary stems with a few leaves and no flowers to clumps with several hundred leaves and numerous flowers. Even though Kaplow's (1998) report on the violet refers to numbers of plants that he observed, I suspect that what he really observed were primarily clusters or clumps, consisting of one or more plants. During my ground-truth survey, I estimated the numbers of clumps at locations B and C, using a belt transect approach like Kaplow employed. I counted 176 clumps of V. pedunculata at location B and 228 clumps at location C. These numbers are three to four times higher than Kaplow's estimates of 60 and 58 plants. Clearly, part of this discrepancy has to do with how to define a violet plant or clump. Also, at the time of his late January survey, all of the violets may not have leafed out and been as appazent as they were in late March when I conducted my survey. No adult silverspots were observed in the Phases II and III areas at the time of my survey in March as their flight season does not normally begin until mid-May. A review of the past several annual monitoring reports of HCP activities, prepazed by Thomas Reid Associates, indicates that adults of Callippe Silverspot were rarely observed within the Phases II and III areas compared to other portions of the mountain; however, I presume that less time was spent monitoring the Silverspot in these azeas since they had been previously approved for development and were partially graded at some prior time. Larval feeding damage, characteristic of the Callippe Silverspot, was observed on several V. pedunculata growing at locations B, C, and D, as well as neighboring upslope areas within the conserved habitat during my ground-truth surveys. I did not attempt to undertake a more rigorous survey of larval feeding damage. At the time of my survey, a few of the lrnown nectar plants for the Callippe Silverspot were observed growing within the Phases II and III development areas. Observed nectar plants included Monardella, Horkelia, Silybum, and Cirsium. Callippe Silverspot Evaluation for Terrabay Phases II and III Evaluation of Project Impacts. Development of Phases II and III of the Terrabay project has the potential to cause both direct and indirect impacts on the Callippe Silverspot. Earlier grading of portions of the Phases II and III portions of the Terrabay project site, prior to the recognition of the Callippe Silverspot as an endangered species, probably resulted in some direct loss of the grassland habitat, including larval and adult foodplants, plus individuals of the Callippe Silverspot. The additional grading, which will be necessary to complete the proposed developments of the Phases II and III portions of the Terrabay project site, will also result in the direct loss of grassland habitat, larval and adult foodplants, and individuals of the endangered Callippe Silverspot butterfly. Indirect impacts on the Callippe Silverspot may also be realized beyond the boundaries of the Terrabay project, particularly in the conserved habitat areas immediately adjacent to violet locations C and D. Since the Callippe Silverspot is recognized as afederally-listed, endangered species, these direct and indirect impacts are considered significant under the California Environmental Quality Act (CEQA), pursuant to section 15065 of the CEQA guidelines. On March 11 `~, 1998, a meeting was convened to discuss~the need to amend the incidental take permit for the San Bruno Mountain Habitat Conservation Plan to include the recently listed Callippe Silverspot. An amendment is needed because when the original take permit was issued, the Callippe Silverspot was not recognized as an endangered species. Now that the Silverspot has been listed, the loss of its habitat at the Terrabay project site would be illegal without a permit for incidental take. Since development of the Terrabay project site was approved as part of the San Bruno Mountain HCP (Thomas Reid Associates 1982), an amendment to the existing incidental take permit is the preferred process rather than a separate take permit. Attendees included representatives from U.S. Fish & Wildlife Service, San Mateo County, Thomas Reid Associates, and the project proponent. A summary of this meeting, prepared by attorney Robert Thornton, Esq., (1998), indicates that the only concern of the U.S. Fish & Wildlife, relevant to the Callippe Silverspot on San Bruno Mountain, is the posting of informational signs at heads of trails in the pazk to warn poachers of the violations associated with this illegal activity. Thornton's letter also notes that San Mateo County would have to propose this condition in the amendment to the take permit because the HCP implementing agreement prohibits the Service from imposing additional mitigation measures. As a result, I have assumed that the Service feels that the existing mitigation measures, as detailed in the San Bruno Mountain HCP (Thomas Reid Associates 1982), aze adequate to compensate for the loss of habitat, foodplants, and individuals of the Callippe Silverspot as a result of the Terrabay project, Phases II and III. My attempts to contact Mr. David Wright, Entomologist for the Service, by telephone, email, and fax, to confirm my assumption about the Service's position, have not been answered. Callippe Silverspot Evaluation for Terrabay Phases II and III q Mitigation Measures. Even though the U.S. Fish & Wildlife Service may not impose any additional mitigation on the Terrabay project, CEQA requires that any direct and indirect impacts of the project be mitigated to a less than significant level. For this reason, the following mitigation measures are recommended. 1) Redesign the project to avoid, if possible, or at least reduce the amount of grading at violet locations, B and C, and especially D, to protect more of the existing violets within the project's boundaries. 2) Salvage and transplant existing violets and nectar plants (especially natives such as Monardella), as appropriate, which would be lost due to the grading associated with Phases II and III to other suitable portions of San Bruno Mountain. 3) Develop propagation methods for V. pedunculata and native nectar plants of the Callippe Silverspot that can be used to reestablish these species in additional grassland habitat areas that lack these plants on San Bruno Mountain. 4) Project sponsors should continue to participate in the San Bruno Mountain Habitat Conservation Planning effort. 5) Project sponsors should assist the San Mateo County Parks Department to prepare informational signs and install them along trails and other appropriate areas within the conserved lands on San Bruno Mountain to warn park users of illegal activities, such as poaching. 6) During grading of Phases II and III, implement appropriate dust control measures, such as frequently watering the work area, equipment, and haul roads, to minimize dust and control its dispersal. If all of these measures are unplemented, then the potential direct and indirect impacts to the Callippe Silverspot butterfly should be mitigated to a less than significant level. References Cited. Arnold, R.A. 1981. Distribution, life history, and status of three California lepidoptera proposed as endangered or threatened species. California Department of Fish & Game, Inland Fisheries Branch. Final report for contract #S-1620. 39 pp. Howe, W. H. 1975. The butterflies of North America. Doubleday. Garden City, NY. Kaplow, D. 1998. Letter, dated Feb. 5~', 1998, addressed to Jim Sweenie of Sterling Pacific Management Services, regarding distribution of Viola pedunculata in Phases II and III portions of the Terrabay project site. 2 pp. & maps. Miller, L.D., and F.M. Brown. 1981. A catalogue/checklist of the butterflies of American north of Mexico. The Lepidopterists' Society Memoir #2. 280 pp. Callippc Silverspot Evaluation for Terrabay Phases II and III Murphy, D.D. and S.B. Weiss. 1990. Report on surveys for the Callippe Silverspot butterfly, Speyeria callippe callippe, at the proposed Sky Valley development site. 10 pp. Scott, J.A. 1986. The butterflies of North America: a natural history and field guide. Stanford University Press. Stanford, CA. Thomas Reid Associates. 1982. San Bruno Mountain azea habitat conservation plan. 2 vols. Thomas Reid Associates. 1981. Endangered species survey. San Bruno Mountain. Biological Study - 1981. Thornton, R.D. 1998. Letter, dated March 11 `~, 1998, addressed to Jim Sweenie of Sterling Pacific Management, regazding meeting on amendment to incidental take permit to include the Callippe Silverspot. 2 pp. U.S. Fish & Wildlife Service. 1990. Letter, dated Feb. 2"d, 1990, from Wayne S. White, Field Supervisor, addressed to Mr. Geoff Monk, Hazding'Lawson Associates, regazding the Callippe Silverspot butterfly. 1 page. U.S. Fish 8:. Wildlife Service. 1997. Endangered and threatened wildlife and plants; determination of endangered status for the Callippe Silverspot butterfly and the Behren's Silverspot butterfly and threatened status for the Alameda Whipsnake. Federal Register 62:64306-64320. If you ha~-e any questions about my report, please call me. Sincerely, Richard A. Arnold, Ph.D. President Callippe Silverspot E~•aluation for Terrabay Phases II and III 11I _ III'I' i II I. ~I~~ `\, ~~. ~. ,,~~I i {~ ',I 111 ~ ~ ~ ~ St7 . ~~ T Y ~! '' S ES ~ 1LL ~ ;I: } • - - ~, ~ %i. i. I,I I 1 1 ~ ' '~~Ij'' { ~ ! pCC41. Gina~'q 1Qrv~ 1 ` ' ` -~n2 ~ K~ an9 2r1~ I €, lv d o~ ,,11 (anf ~; ~~, : ~; fit..; ~. Q 0. ~ D ~,~ -:~ 1~1 ~ ~ , ;1,1,1 ~a ~ Y' a 1,, d~ ,C`II 11 . ~ ILA I,1{fit, tl~~ ~ t a ~ i _ 1 ~J 1 i~ 11 ,~~ 'r lit ~., s 1 11 '~ ., ~ ~ k r I~ f' ~~ I ~~iy~{~,I \ I I I •, J i .1 _ N ' I.. ~ ll `~ r I III'I,~ r~'If i,~' ~~J~+ll I,; ~ `jll Ii, ;. V 1 .~14 II I{I`li~ll sl 111 {''ill {j~; -- - ~ _ [ r III + \~1 ll~;'I~~`!II~{~. ~ ' .~~1 I~t{IIIIIIIII_ _' ':, _ ~~ ~~ '~ 7 .{I~ .. 1y '~11'I'~~i1 ~ 11I ~.! i I`~i fl" t - ~ ~ ~ .,~/, 141 1 ~ --- ~. •, ~~t,+t a l\I .' ~ !, ~~ ~i ~~1~;I,1~ : ~ "~,' _- ~ '\ U7, ~ - ~ , t ' - ~ i `` i ~, -` , - ` ~ - \' ~ ~ n' \ ~ ~ ~ ~`^ ~ 1 111 IIII~I~{`I 1 ~4L~ -~ `~_ ,r .. ~ _ ~~ ~~ t-, ~ .~ -~ \ _- t 11 III ~III~41~.•.\ .. ~ ~_ - 1 , I ~_ ,, Kr , ~ - - - - -_~ -. ~ y~ THE STATUS OF THE ENDANGERED SAN FRANCISCO GARTER SNAKE (Thamnophis sirta~is tetrataenia) AND THE THREATENED CALIFORNIA RED-LEGGED FROG (Rana aurora draytoni.i) AT THE TERRA BAY PHASE II AND PHASE III PROJECT SITES, SOUTH SAN FRANCISCO, CALIFORNIA. Prepared For THE ENVIRONMENTAL 127 Western Point Richmond, By C07.7.AP~RATIVE Drive CA 94801 Dr. Samuel M. McGinnis Biological Consultant 9699 Melton Road Manteca, CA 95337 (209) 599-2726 April 18, 1998 1 INTRODUCTION The current distribution of both the San Francisco Garter Snake (SFGS) and the California Red-legged Frog (CRF) in Northern San Mateo County is both sparse and fragmented. Although the largest single population of the SFGS still persists in a seasonal wetland area west of the San Francisco International Airport (Larsen, 1994; McGinnis, 1987; Wharton, 1989), all recent attempts to find the endangered snake north of this site and east of the Pacifica/Daily City area have been unsuccessful. Such attempts included trapping surveys of Owl and Buckeye Canyons on the east side of San Bruno Mountain a few miles north of the Terra Bay project site (McGinnis, 1987) and a permanent wetland site northwest of the intersection of San Bruno Avenue and Route 101 (McGinnis, 1997). Indeed, the only other surviving SFGS population remaining in the northern most segment of San mateo County appears to be a small, highly impacted one in the Mori Point/Sharp Park area of Pacifica (McGinnis, 1997). The current distribution of the CRF in northern San Mateo County and San Francisco County is also sporadic. The California Natural Diversity Data Base lists four 1966 reports of this species' occurrence at Lake Merced, Lincoln Park, Golden Gate Park, and the Persidio in the greater San Francisco area. However, the introduction of bullfrogs at one or more of these sites may have highly reduced or eliminated the native CRF. Zt does occur at the San Francisco International Airport SFGS habitat site (Larsen, 1994) and at the San Francisco County Jail facility in San Bruno (McGinnis, 1997). However, two attempts to locates it in a small seasonal wetland area in Brisbane have been unsuccessful (McGinnis, 1997). The purpose of this survey was to examine all seasonal wetland sites within and adjacent to the project site area to see if those habitat features necessary to support a resident population of either or both of these two protected species are present. FIELD SURVEY I~iETHODS In an initial survey of the Phase II and III project sites on February 13, 1998, several potential CRF spawning sites and SFGS foraging sites were located. These included three recently created detention basins, a small, shallow series of interconnected pools within the flow channel of a small spring, and a shallow wetland within a dense willow grove (Figure 1). Because of the record setting rainfall of the 1997-98 winter season, the detention basins were partially filled at this time and thus offered potential habitats for breeding amphibians. However, the general lack of shoreline and emergent vegetation at all three basin sites suggested that these might soon dry once the early spring rains ceased. The period of water impoundment is a crucial factor in the evaluation of any potential CRF breeding habitat since larval metamorphosis in this species does not occur until late July or August. One other feature of the three basins which hindered the first survey visit was the extreme muddy nature of the water. It contained a suspension of very fine silt particles which did not 2 settle out, and thus a visual search for amphibian egg masses and larva was not possible. In contrast to these conditions, the shallow spring flow channel was relatively clear as were portions of the shallow impoundments within the willow grove. However, no large egg masses characteristic of the CRF or tadpoles of any species were seen at that time. Because of these initial mid February conditions, a re-survey of all wetland areas on the projects site in spring after the heavy winter rains had abated was undertaken. This second survey was conducted on April 9, 1998, after two weeks of relatively light rains interspersed with several days of dry, warm weather. RESULTS AND DISCUSSION By early April Detention Basins 1 and 3 had lost most of their water and were now being colonized by water tolerant species of introduced grasses and forbs (Figures 2 and 3). Basin 2 still held water to a depth of approximately two feet, but its receding shoreline was also being invaded by annual, non-aquatic plants (Figure 4). The water in all three basins was still opaque due to the suspended silt noted in the mid February visit. However, some clear water was present at the shore edge where tadpoles usual aggregate because of the warmer water in this region. However, no tadpoles of any species were seen here. Tadpoles of the Pacific Tree Frog (Hyla regilla) were discovered in the small pools within the spring drainage channel (Figure 5). These were near the metamorphosis size for this species, and a few already exhibited small hind legs. These were easily viewed from above at close range because of the clarity and shallowness of the spring water. All exhibited a head configuration in which the eyes are situated on the lateral head outline. In CRF larva, the eyes are well within the head outline, but none of the one hundred or so tadpoles observed here showed this condition. A search of the willow grove revealed the presence of a few Pacific Tree Frog tadpoles in one remaining small, cup-like depression, but once again no other species of amphibian larva was present. The small seepage area well up on the hillside above the grove which exhibited some small pools in February had now been reduced to wet soil. Unlike the diminutive Pacific Tree Frog which spawns in almost any shallow, clear, pool and then undergoes larval metamorphosis by late April or early May before the site dry, the large CRF required larger and deeper breeding sites which will hold water through its July/August metamorphosis period. Although the three detention basins presented the initial appearance of such a habitat in February, it was apparent by the April site visit that all would dry well before the mid summer period. It was also of interest to note that no Pacific Tree Frog tadpoles were seen in these basins. I have noted on numerous past occasions that silt- laden sites such as these rarely produce crops of tadpoles, and that again seem to be the case here. 3 Perhaps the most important reason why these basins do not function as CRF breeding habitats is that they are recently created habitats. Had such ponds existed for the past several hundred years, it is possible that some series of chance events may have brought a male and female CRF to this area to begin a new population. However, given the massive land use changes brought about by the new human inhabitants of this area, the probability of such an event occurring in the future is extreaely low. The potential for SFGS occurrence at this or any site in Sam Mateo County in greatly dependent on the presence of a foraging habitat for both adult and new born young throughout the spring and summer months. Because this snake is a frog feeding specialist, this means that both the Pacific Tree Frog and the CRF must be present, and in addition the SFGS must have as adequate vegetated shoreline edge habitat in which to forage for these prey. As a result of a survey of over 50 potential SFGS feeding sites in San Mateo County at which 30 populations were actually found, I constructed the foraging habitat evaluation system presented below (McGinnis, 1987). Table l: A habitat evaluation system for potential feeding habitats for the SFGS in the San Mateo County area. A score of 12 denotes a prime feeding site. Habitat quality decreases as the score approaches 6. In habitats with scores below 6 the SFGS does not normally persist on a permanent basis. 1. Impounded Fresh Water: (marsh, farm pond, vernal pool) A. Present all year; large shallow inshore zone ..... .3 pts. B. Present all year but shallow inshore zone dries to barren shoreline by late summer.......... .2 pts. C. Shallow productive pool in winter and spring; dries completely by late summer ................... .1 pt. D. Shallow winter-spring pool or surface water dried by mid to late spring ....................... .0 pt. (Note: Brackish water sites also receive 0 pt.) 2. Vege tative Cover: A. Dense reed-shrub cover throughout marsh or in a wide band around entire pond edge ............ .3 pts. B. Dense reed-shrub cover patchy in marsh or in narrow band around entire pond edge ............ .2 pts. C. Dense reed-shrub cover in small clumps along one half or less of a pond shore .............1 pt. D. Essentially no reed-shrub cover present in or around the edge of an aquatic site...........0 pt. 3. Available Food: A. Pacific tree frog and red-legged frog adults and larva; small fishes .................... 3 pts. B. Pacific tree frogs and larva only .................. 2 pts. C. Red-legged frogs and larva only ................... 1 pt. D. Small fishes only .................................. 4. Competitive Garter Snake Species: 0 pt. A. No other garter snake species present .............. 3 pts. B. Coast Garter snake present ......................... 2 pts. C. Santa Cruz garter snake present .................... 1 pt. D. Both Santa Cruz and Coast garter snakes present.... 0 pt. 4 Because a coast garter snake was seen in this area and Pacific Tree Frog tadpoles were present at two the wetland sites, two points from each of the two last categories are assigned. However, if the three detention basins do indeed dry completely by late spring and fail to produce any metamorphosed tree frogs, then a score of 0 must be assigned which in turn would render meaningless any consideration of the shoreline vegetation scores in category 2. Conversely, if the small spring-fed pools which presently contain tree frog tadpoles persist throughout the summer, then this condition along with current small stands of shoreline and emergent vegetation observed at this site would produce a habitat evaluation score of 8 or 9, well above the threshold score of 6 for possible SFGS presence. However, two additional factors must be considered. One is the size and potential productivity of the spring seepage tadpole habitat. Compared to the average Pacific Tree Frog breeding pond, it is very small, and even if both adult and young frogs remained in the near vicinity of this site throughout the summer, such a scant prey resource could probably not support more than a couple adult SFGSs, let along the large litter (20-30) of young which this species produced. The other reason for no probable SFGS occurrence here is the absence of any known near-by population of this snake. Although SFGS foraging at small tree frog spawning sites such as this has been observed, such instances are just one of several such feeding opportunities which a given snake takes advantage of during the course of a spring/summer foraging season. With no such population of SFGS within the greater San Bruno Mountain area, the probability is extremely low that a small, isolated number of this snake would exist here with total dependence on this meager food resource. As with the case of the CRF, it is equally unlikely that any future migration to this area would occur given the current blockage of nearly all potential movement routes by assorted human enterprises. CONCLUSIONS 1. Acceptable spawning habitat for the successful reproduction of the CRF is not present at the Terra Bay Phase II and III project sites, and no larva of this species were detected during an April survey of all standing water sites within this area. 2. Although the small, shallow, spring seepage pools exhibit features similar to those found in larger SFGS foraging habitats, their very small size and the lack of any nearby SFGS populations and supplemental feeding sites essentially negates the presence of the endangered snake in this area. 5 LITERATURE CITED California Natural Diversity Data Base, 1997. Calif. Dept. Fish & Game, Sacramento. Larsen, S.S. 1994. Life history aspects of the San Francisco garter snake at the Millbrae habitat site. Master's Degree Thesis California State University, Hayward. McGinnis, S.M., 1997. The status of the San Francisco Garter Snake and California Red-legged Frog within the Cupid's Row Canal right-of-way between San Bruno Avenue and Route 1. San Mateo County Dept. of Public Works, Redwood City, CA. 1997. The status of the San Francisco Garter Snake (Thamnophis sirtalis tetrataenia) and the California Red-legged Frog (Rana aurora draytonii) on the San Francisco Jail No. 3 Property, San Bruno, California. Baseline Environmental Consulting, Emeryville, CA. 1997. The current status of the San Francisco Garter Snake (Thamnophis sirtalis tetrataenia) and the California Red-legged Frog (Rana aurora~draytonii) at Mori Point, Pacifica, California. National Investors Financial, Inc., Newport Beach, CA. 1997. The status of the California red-legged Frog on the Lavine Property, Brisbane, California. Donaldson & Associates, Alameda, CA. 1987. The distribution and feeding habitat requirements if the San Francisco Garter Snake (Thamnophis sirtalis tetrataenia). Calif. Depart. Fish & Game Interagency Agreement Report C-673 and C-1376. Wharton, J. 1989. Ecology and life history aspects of the San Francisco Garter Snake Thamnophis sirtalis tetrataenia. Masters degree Thesis, San Francisco State University. 6 - ~= .~_~ ~i ~ ~ ..~ '4 ~,~ r-r-' ~! ~ ~-1 11 1 1 ! 11 ~ 1 --~._~-.ter r _ - _ •1.'1 11 's 1' '? ~•-. ~ ;i _ r . -- r ~ ~ f ~ . i ~ li I ~ ' _s~_ ~`~~I .r{ }'-L~~~. 1 l T i f~ •1 ~ ~II~ ' { 1 f I~ f r ~ ~ ' 1 , ~ ~ 1 ~ ~ ~ ~lx 11 1 f ~ (f ~ r .'- f t i~•` 1' 1 ~ ~ ~• 1 t. ~ 11 ~ ~ ~ 1 ~' r_. t f 1._« -Z1 ~ 1 ~ r ! : • 1 ~~ r,: __.a`~ ~ i tL ~ ~ 11 ~1 i s 1 ti.~'• ~ r'_'~' _ ars ~~ r ~ ?l 1`~ ~ t 1 ~ '~ .1!•~ ~ ~ ~ I ~ ~ f r~. ti s ~.t j r ~ f ! ~' ~ : 's ~ _- fr !' !' r ~ r ~ ;' 1 ! 1 , i j 1 ~~ ~ i. 1 } ~.~= ~ . ~ _ ~~ ti _ - _r..1 r Cr ! - ~ •_ ~- }+ - 1 1 ~ i ~{= ~ ~_, j l~ ~~ fl {~ lr -z _ ' 1 ~L _ '''. -'~ j 1r r- r' ti1•_ _~ i ~ 1 =./1. 'i t~ til '' '1 'f • - Y t ' Z ~ + / ~~ ~ f • •;,+; •'1 1•+ •' • ••'•~ I ; 1 {: 1 I -~ ~_ 1 - l 1 1 j • , + 1 1 1' J r 11..1, ~ ~ ii ~ t 11f 1~ ~'.. _ .4~,'~t~ J Ilrr11 ~~ =_~-~ =f: ~t1 ~i ~ 1• '' 1 ~ i ; 1 . , ~+ i + 1 ~+ i ! Fr _ =- 1. i. ~''', ` l r~ ~~ •'.t• '',~ .,, ~ 1~ 7 ~ it 'I l ~1 ~ ~ -'L'am - ~~ -_~~ ' t '~ 'i ~. O 1 {' ' /i _ "s ~ 45 ~- _~~ ''1 :. ~ t ~ a n _~ -- ~.r j_ l r . ~ f 1+ ~ : `~ ' ;~ 1 t 1 _ ~ '6 f _ 1 __~ I 1 __. - 1 i .~ ~. r:f ~_ r'' J f.. i _T~ .. _ ~~l ___ _ :_ , 1, ors ... j~ .{ f. ~ti, ~ ~ - _~~ .r ~ ~~ _ ~ mil !t •1 • L 'i ~1.e - ~ ~ _ ~ ~ ~ ~ l f Figure 1. A.n enlarged segment of a 7.5 minute USGS topography map showing the the locations of detention basins 1, 2 and 3, the spring seepage pools, and the willow grove area. Note: The recent topographic alterations which have formed the detention basins are too new to be displayed on this map. Scale: 1" = 500' 7 8 Figure 2. A view looking northwest across Detention Pond 1 on April 9, 1998. The once half full basin had now dried to about a depth of about one foot. Figure 3. A view looking east toward Detention Basin 2. On April 9, 1998, it contained about two feet of water, but no amphibian larva could be seen along the shoreline. 9 Figure 4. A view looking southeast across Detention Basin 3 on April 9, 1998. It contained about one foot of water at this date and will probably dry by the end of this month. Figure 5. A view looking northeast across the small pools in the spring seepage channel where Pacific Tree Frog larva were observed. This small wetland may persist into the summer period. APPENDIX 7.5 TRAFFIC & CIRCULATION 7.0 APPENDICES Terrabay Phase ll and 111 SEIR APPENDIX 7.5 TRAFFIC & CIRCULATION As noted in Chapter 4, the impacts of traffic generated by the proposed Ten abay Phase II and III project components combined are discussed in the main text of this 1998 SEIR. In addition to identifying impacts of the entire Phase II + III Terrabay development ("the project"), the year 2000 analysis also determined impacts with Terrabay Phase II traffic only and with Phase III traffic only. The 2010 horizon impact analysis similarly was conducted for the same three Terrabay development scenarios with the results of the Phase II + III analysis presented in the main text of the 1998 SEIR and the Phase II only and the Phase III only analysis results presented below. Exhibits numbered Exhibits 4.4-# are presented in 4.4 Traffic and Circulation in the main text of this 1998 SEIR, and those numbered Exhibits 7.5-# are presented at the end of this appendix. YEAR 2000 Year 2000 Base Case Plus Project Phase Il Impacts and Needed Mitigation Year 2000 Project Phase ll Intersection Level of Service Impacts (see Exhibit 4.4-6) Phase II project traffic would not result in significant level of service impacts at any intersection analyzed. Year 2000 Project Phase ll Signalization Requirement Impacts Traffic from the Phase II project would produce a significant impact at the following location. Impact 7.5-7 Year 2000 Base Case plus Phase ll Signalization Impact Volumes at the Bayshore Boulevard / U. S. 101 Southbound Off--Ramp Intersection would remain below peak hour warrant criteria during the AM peak hour, but would be increased during the PM peak hour to meet warrant criteria levels. S Mitigation Measure 7.5-1 (see Exhibits 4.4-IO and 7.5-8) A signal shall be provided when warranted and signals shall be timed to preclude off-ramp backups to the freeway mainline. Alternatively, all- way-stop operation shall be maintained, and second off-ramp approach and departure lanes shall be provided. Significance after Mitigation Implementation of Mitigation Measure 7.5-1 would result in PM peak hour operation of LOS B (if signalized) and LOS C (if maintained as anall-way-stop with second off- ramp approach and departure lanes) and would reduce this impact to aless-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and Brisbane area development would be responsible for paying their fair share of the improvement(s) selected, and the City of South San Francisco Public Works Department would monitor implementation. 7.0 APPENDICES Terrabay Phase /1 and !1l SE1R Year 2000 Project Phase II Freeway Impacts (see Exhibit 4.4-7) Phase II traffic would significantly impact peak hour operation of the U.S. 101 freeway at one location. Impact 7.r2 Year 2000 Base Case plus Phase I! Freeway Impact Phase ll traffic would change operation of the U. S. 10i Freeway Northbound (from the Oyster Point on-ramp to the Bayshore Boulevard off-ramp) from LOS E to an unacceptable LOS F during the AM peak hour. SU Mitigation pleasure 7.5-2 Project sponsors shall reduce the amount of development proposed within the Phase II site. Significance after Mitigation Reduction of Terrabay Phase II development could accomplish the desired result of not changing freeway operation to an unacceptable level and would reduce the impact to ales-than-significant level. Alternatively, or in conjunction, local and regional development could be reduced along with significantly increased transit service to provide acceptable freeway operation. However, it is likely that this alternative would be infeasible, in which case the impact would remain significant and unmitigable. ' Responsibility and Monitoring The Terrabay Phase II project sponsor would be responsible for implementing Mitigation Measure 7.5-2 (reduced Terrabay development) and the City of South San Francisco would monitor implementation. Project Phase ll Freeway Ramp Impacts (see Exhibit 4.4-8) Neither Phase II AM nor PM peak hour traffic would significantly impact any of the U.S. 101 freeway ramps pro«ding primary access to the project site. Year 2000 Base Case Plus Project Phase 111 Impacts and Needed Mitigations Year 2000 Project Phase 111 Intersection Level of Service Impacts (see Exhibit 4.4-6) Development of the Phase III commercial site would provide for the construction of new U.S. 101 southbound on- and off- hook ramps connecting to Bayshore Boulevard at a signalized intersection about midway- between the two new signalized intersections providing access to the Phase III site (see Exhibi14.4-12).1 The ramp intersection would be located at about the same location as the existing southbound off-ramp connection to Bayshore Boulevard. Provision of a new southbound on-ramp along Bayshore Boulevard would remove a significant amount of Brisbane traffic bound for southbound t .S. 101 which previously traveled through the Oyster Point interchange to reach the southbound on-ramp connection at Dubuque Avenue. Thus, even with the addition of traffic from Phase III, volumes for some movements within the Oyster Point interchange would decrease. 1 The Phase III site also would be accessible via a right-turn-in /right-turn-out driveway on Bayshore Boulevard at the north end of the site. 7.0 APPENDICES Terrabay Phase I! and !ll SE1R Phase III project traffic would not result in significant level of service impacts at any intersection analyzed. Year 2000 Project Phase 111 Signalization Needs Impacts There would be no unsignalized intersection impacts in the vicinity of the Phase III site. Year 2000 Project Phase 111 Freeway Impacts (see Exhibit 4.4-7) - Impact 7.5-3 Year 2000 Base Case plus Phase 111 Freeway Impact Phase Ill traffic would increase volumes by more than one percent on segments of the U.S. i01 Freeway already operating unacceptably at LOS F.• • Southbound.• to the north of the off-ramp to Bayshore Boulevard (AM=1.12 percent increase). • Northbound: from the Grand Avenue on-ramp to the Dubuque off-ramp (PM=i.81 percent increase) and north of the Oyster Point on-ramp (PM=1.46 percent increase). Phase Ill traffic would change operation on the on the U.S. 101 Freeway from LOS E to an unacceptable LOS F.• • Northbound: from the Oyster Point on-ramp to the Bayshore Boulevard off--ramp during the AM peak hour. • Southbound: from the Dubuque on-ramp to the Grand Avenue off-ramp during the PM peak hour. These would constitute significant impacts. SU Mitigation Measure 7.5-3 Project sponsors shall reduce trip generation from development within the Phase III site by at least 45 percent. Significance after Mitigation Reduction of Terrabay Phase III development could accomplish the desired result of not changing freeway operation to an unacceptable level and would reduce the impact to ales-than-significant level. Alternatively, or in conjunction, other local area development could be reduced to provide acceptable freeway operation. However, it is likely that this alternative would be infeasible, in which case the impact would remain significant and unmitigable. Responsibility and Monitoring The Terrabay Phase III project sponsor would be responsible for implementing Mitigation Measure 7.5-3 (reducing Terrabay development) and the City of South San Francisco would monitor implementation. Year 2000 Project Phase 111 Freeway Ramp Impacts (see Exhibit 4.4-8) Neither Phase III AM nor PM peak hour traffic would significantly impact any of the U.S. 101 freeway ramps providing primary access to the project site. 7.0 APPENDICES Terrabay Phase ll and 111 SE1R YEAR 2010 Year 2010 Base Case Plus Project Phase ll Impacts and Needed Mitigations Year 2010 Project Phase ll Intersection Level of Service Impacts (see Exhibit 4.4-6) Phase II peak hour traffic would produce significant impacts at the following locations. Impact 7.5-4 2010 Base Case plus Phase 11 Intersection Impacts Phase Il traffic would increase 2010 AM peak hour volumes at the Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard Intersection by more than one percent over apre-existing Base Case unacceptable LOS E signalized operation and would change acceptable PM peak hour LOS D operation to an unacceptable LOS E. S Mitigation Measure 7.5-4 (see Exhibits 4.4-IO and 7.5-8 in the Appendix) The project sponsor shall provide a fair share contribution towazds restriping the southbound (Bayshore Boulevard) approach (to include an exclusive right, a shared through / right, an exclusive through, and two left turn lanes), construction of exclusive right-turn lanes on the eastbound (Sister Cities Boulevazd) and westbound (Oyster Point Boulevard) intersection approaches. This latter measure will require widening the Oyster Point Boulevard freeway overpass. Significance after Mitigation Implementation of Mitigation Measure 7.5-4 would result in LO.S D AM and PM peak hour operation and would reduce this impact to aless-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and other local area development would be responsible for paying their fair share of the improvement and the City of South San Francisco would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. Impact 7.5-5 2010 Base Case plus Phase 1I Intersection Impact Phase ll traffic would increase 2010 AM peak hour volumes at the Oyster Point Boulevard /Dubuque Avenue / U. S. 101 Northbound On-Ramp Intersection by more than one percent over pre-existing Base Case unacceptable LOS E operation and would change acceptable PM peak hour LOS D operation to an unacceptable LOSE. S Mitigation Measure 7.5-5 (see Exhibits 4.4-1 D and 7.5-8 in the Appendix) The project sponsor shall provide a fair share contribution toward a second exclusive right-turn lane on the westbound (Oyster Point Boulevard) approach and a second exclusive left-turn lane on the northbound (Dubuque Avenue) intersection approach. Significance after Mitigation Implementation of Mitigation Measure 7.5-5 would result in LOS D AM and PM peak hour operation and would reduce this impact to ales-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and other local area development would be responsible for paying their fair share of the improvement and the City of South San Francisco would monitor implementation. As part of this process, the City of South San 7.0 APPENDICES Terrabay Phase 1l and ll/ SEIR Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. Impact 7.5-6 Year 2010 Base Case plus Phase !! Intersection Impact Phase l! traffic would change acceptable 2010 PM peak hour LOS D operation at the Bayshore Boulevard / U. S. 101 Southbound Off-Ramp (all-way stop) Intersection to an unacceptable LOS E operation. S Mitigation Measure 7.5-6 (see Exhibits 4.4-IO and 7.5-8 in the Appendix) The project sponsors shall provide a fair share contribution toward a second off-ramp approach lane and second off-ramp departure lane shall be provided. Alternatively, the intersection shall be signalized when warranted, and the signal shall be timed to preclude off-ramp backups to the freeway mainline. Significance after Mitigation With full implementation of Mitigation Measure 7.5-6, anall-way-stop with two off-ramp lanes would operate at LOS D in the PM peak hour. Alternatively, Signalization with one off-ramp lane would result in PM peak hour operation of LOS C and with two off-ramp lanes would result in LOS B. Either alternative would reduced this impact to ales-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and other local area development would be responsible for paying their fair share of the improvement(s) selected, and the City of South San Francisco Public Works Department would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. Year 2010 Project Phase ll Signalization Requirement Impacts Traffic from the Phase II site would produce a significant impact at the following location Impact 7.5-7 Year 2010 Base Case plus Phase 11 Signalization Impact Phase ll traffic at the Bayshore / U. S. 107 Southbound Off-Ramp Intersection would aggravate the PM peak hour Base Case warrant criteria need for signals. Project traffic would increase AM peak hour volumes by more than one percent at this location which would have volumes already exceeding warrant criteria levels. S Mitigation Measure 7.5-7 (see Exhibits 4.4-IO and 7.5-8 in the Appendix) The project sponsor shall provide a fair share contribution towards a signal when warranted. When installed, the signal shall be timed to preclude off-ramp backups to the freeway mainline. The City should also consider requiring provision of a second off-ramp approach and departure lanes. Significance after Mitigation Implementation of Mitigation Measure 7.5-7 would result in PM peak hour operation of LOS C with one off-ramp lane and LOS B with two off-ramp lanes and would reduce this impact to ales-than-significant level. Responsibility and Monitoring Project sponsors of Terrabay Phase II and area development would be responsible for paying their fair share of the improvement(s) selected, and the City of South San Francisco Public Works Department would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. i. u Hrrtrvu ~.c~ Terrabay Phase ll and 111 SEIR Year 2010 Project Phase lI Freeway Impacts (see Exhibit 4.4-7) Phase II traffic would not sia ificantly impact peak hour operation of the U.S. 101 freeway. Year 2010 Project Phase ll Freeway Ramp Impacts (see Exhibit 4.4-8) Traffic from Phase II would produce sign~cant impacts at the following locations. Impact 7.5-8 Year 2010 Base Case plus Phase I! Ramp Impact Phase ll development would increase 2010 PM peak hour Base Case over-capacity operation by 1.1 percent at the northbound On-Ramp from Oyster Point Boulevard. S Mitigation Measure 7.5-8 The project sponsor shall reduce Phase II development by approximately 9 percent. Alternatively, the sponsor shall provide a fair share contribution towards construction of a second on-ramp lane connection to the U.S. 101 freeway. Significance after Mitigation Either reduction of Terrabay Phase II development to produce a less than one percent increase in traffic or completion of the full improvement would reduce this impact to aless-than-significant level. The latter would require Caltrans approval. Responsibility and Monitoring The project sponsor would be responsible for implementing Mitigation Measure 7.5-8, and the City of South San Francisco Public Works Department would monitor implementation. Alternatively, the project sponsor and other local area developers would be responsible for contributing funds for towards construction of the second on-ramp lane, which would require Caltrans approval. Impact 7.5-9 Year 2010 Base Case plus Phase 11 Ramp Impact Phase ll development would increase 2010 PM peak hour Base Case over-capacity operation by 1.3 percent at the southbound On-Ramp from Dubuque Avenue. S Mitigation Measure 7.5-9 The project sponsor shall reduce Phase II development by approximately 23 percent. Alternatively, the sponsor shall provide a fair share contribution towards construction of a second on-ramp lane connection to the U.S. 101 freeway. Significance after Mitigation Either reduction of Terrabay Phase II development to produce a less than one percent increase in traffic or completion of the full improvement would reduce this impact to aless-than-significant level. The latter measure would require Caltrans.approval. Responsibility and Monitoring The project sponsor would be responsible for implementing Mitigation Measure 7.5-9, and the City of South San Francisco Public Works Department would monitor implementation. Alternatively, the project sponsor and other local area developers would be responsible for contributing funds for towards construction of the second on-ramp lane, which would require Caltrans approval. 7.0 APPENDICES Terrabay Phase ll and 111 SEIR Year 2010 Base Case Plus Phase III Impacts and Needed Mitigations Year 2010 Project Phase 111 Intersection Level of Service Impacts (see Exhibit 4.4-6) Impact 7.5-10 Year 2010 Base Case plus Phase Ill Intersection Impact At the Sister Cities Boulevard /Bayshore Boulevard /Airport Boulevard /Oyster Point Boulevard Intersection, Phase /l/ traffic would change AM peak hour operation from an unacceptable LOS E to an acceptable LOS D (a beneficial impact) but would change an acceptable 2010 PM peak hour LDS D operation to an unacceptable LOS F. S Mitigation Measure 7.5-10 (see Exhibits 4.4-10 and 4.4-IS) The project sponsor shall provide a fair shaze contribution towards restriping the southbound (Bayshore Boulevard) intersection approach (to include an exclusive right, a shared through /right, and exclusive through, and two left turn lanes) and construction of an exclusive right-turn lanes on the westbound (Oyster Point Boulevard) intersection approach. This latter measure would require widening of the Oyster Point Boulevard freeway overpass. ' Significance after Mitigation Full implementation of Mitigation Measure 7.~-10 would reduce this impact to aless-than-significant level and result in PM peak hour LOS D operation. Responsibility and Monitoring Project sponsors of Terrabay Phase III and other local area development would be responsible for paying their fair share of the improvements, and the City of South San Francisco Public Works Department would monitor implementation. As part of this process,'the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. Impact 7.5-11 Year 2010 Base Case plus Phase 111lntersection Impact Phase Ill AM peak hour operation would change from an unacceptable LOS E to an acceptable LOS D at the Oyster Point Boulevard/Dubuque Avenue / U.S. 101 Northbound On-Ramp Intersection (a beneficial impact) but would change acceptable 2010 PM peak hour LOS D operation to an unacceptable LOS F. S Mitigation Measure 7.5-11 (see Exhibits 4.4-10 and 4.4-15) The project sponsor shall provide a fair share contribution towards a second exclusive left-turn lane on the northbound (Dubuque Avenue) intersection approach. Significance after Mitigation Full implementation of improvements .would result in PM peak hour LOS D operation and would reduce this impact to aless-than-sib ificant level. Responsibility and Monitoring Project sponsors of Terrabay Phase III and other local azea development would be responsible for paying their fair share of the improvements, and the City of South San Francisco Public Works Department would monitor implementation. As part of this process, the City of South San Francisco should review modifying their existing capital improvements program to include fair share funding mechanisms for major roadway improvements. 7.0 APPENDICES Terrabay Phase !l and 111 SEIR Year 2010 Project Phase 111 Signalization Needs Impacts There would be no major unsignalized intersections in the vicinity of the Phase III project. Year 2010 Project Phase 111 Freeway Impacts (see Exhibit 4.4-7) Phase III traffic would significantly impact peak hour operation of the U.S. 101 freeway at the following locations. Impact 7.5-12 Year 2010 Base Case plus Phase 111 Freeway Impact Phase Ill traffic would increase volumes by more than one percent on segments of U.S. 101 freeway already operating unacceptably at LOS F.• Southbound: north of the off-ramp to Bayshore Boulevard (PM=1.29 percent increase), and south of the Dubuque on-ramp (PM=1.67 percent increase (Segments 1 and 4 in Exhibit 4.4-2). Northbound: from the Grand Avenue on-ramp to the Dubuque off-ramp (AM=1.33 percent / PM = 1.58 percent increases), from the Oyster Point on- ramp to the Bayshore Boulevard off-ramp (PM=1.15 percent increase) and north of the Bayshore Boulevard off-ramp (PM=1.26 percent increase) (Segments 5, 7 and 8 in Exhibit 4.4-2). This would constitute significant impacts. SU Mitigation Measure 7.5-i2 Project sponsors shall reduce trip generation from development within the Phase III site by at least 37 percent. Significance after Mitigation Reduction of Terrabay Phase III development could accomplish the desired result of not changing freeway operation to an unacceptable level and would reduce the impact to aless-than-significant level. Alternatively, or in conjunction, other local area development could be reduced to provide acceptable freeway operation. However, it is likely that this alternative would be infeasible, in which case the impact would remain significant and unmitigable. Responsibility and Monitoring The project sponsors of the Terrabay Phase III would be responsible for implementing Mitigation Measure 7.5-12 (reduction of project development) and the City of South San Francisco would monitor implementation. Year 2010 Project Phase 111 Freeway Ramp Impacts (see Exhibit 4.4-8) Traffic from the Phase III project would produce significant impacts at the following location. Impact 7.5-13 Year 201 D Base Case plus Phase 111 Ramp Impacf Phase 111 development would increase PM peak hour Base Case over-capacity operation at the Northbound On-Ramp from Oyster Point Boulevard by 5.7 percent. S Mitigation Measure 7.5-13 The project sponsor shall reduce Phase III development by approximately 83 percent. Alternatively, the sponsor shall provide a fair share contribution towards construction of a second on-ramp lane connection to the U.S. 101 freeway. 7.0 APPENDICES Terrabay Phase ll and 111 SElR Significance after Mitigation Either reduction of Terrabay Phase III development to produce a less than one percent increase in traffic or completion of the full improvement would reduce this impact to aless-than-significant level. The latter measure would require Caltrans approval. Responsibility and Monitoring The project sponsor would be responsible for implementing Mitigation Measure 7.5-13 (project reduction), and the City of South San Francisco Public Works Department would monitor implementation. Alternatively, the project sponsor and other local area developers would be responsible for contributing funds for towards construction of the second on- ramp lane, which would require Caltrans approval. 7.0 APPENDICES Terrabay Phase ll and 111 SEIR Exhibit 7.5-1 Terrabay Phase l Remaining Development Trip Generation AM Peak Hour Trips PM Peak Hour Trips Type a Units Inbound Outbound Inbound Outbound Rate Volume Rate Volume Rate Volume Rate Volume Detached 62 0.22 14 0.64 40 0.75 47 0.41 2~ Attached ` 94 0.07 7 0.37 35 0.36 34 0.18 17 Total 1~6 21 75 81 42 Source: Crane Transportation Group and Trip Generation - 6th Edition, Institute of Transportation Engineers, 1997. Single-family units remaining to be built or occupied (attached and detached) Trip rates 15 percent above average to reflect potential generation from mix of four- and five-bedroom units. Townhouses. 7.0 APPENDICES Terrabay Phase /l and 111 SEIR Exhibit 7.5-2 Year 1998 to 2000 Expected Cumulative Development Trip Generation a Trip Generation t P Land Use Size ~ AM Peak Hour PM Peak Hour rojec Rate 2-Way Trips Rate ~ 2-Way Tri s South San Francisco - East of 10 i Area Bay West Cove Auto Nation Hotel 20 ac 9.05 615 rooms 0.67 181 413 12.40 248 0.76 468 Brittania Biotech R&D ~ 127,000 sf ~ 1?3 156 1.07 ~ 137 Ham ton Inn Hotel 100 rooms 0.67 67 0.76 76 Gateway Lot 9 Office ~ 201,000 sf I 1.40 281 1.30 i 261 Athena R&D 55,000 sf I 1?3 68 1.07 I 59 Heidelberg Site Hotel ~ 280 rooms I 0.67 188 0.76 I 213 Gatewa Lot 2C Hotel ! 112 rooms I 0.67 75 0.76 85 Gatewa Lot 2B Office 50,000 sf ~ 1.91 95 1.36 I 93 Trammel Crow R&D 105,000 sf I 1.23 129 1.07 ; 113 Point Grand Business Park Office 154,000 sf 1.45 224 1.35 209 MRF Office Li ht Industrial 14,500 sf 100,000 sf 2.97 0.92 43 92 3.10 45 0.98 98 Genentech Addt'1 Em to ees 195 em to ees i 0.43 '84 0.41 80 South San Francisco -West of 101 Area ` Chestnut Estates Single-Famil Resid. 80 units 0.96 ~ 77 1.32 106 Heather Heights Single-Famil Resid. 34 units ~ 0.74 26 1.O1 I 36 El Camino Cotridor Redevelopment Program Variety of uses; does not include BART station 6 2000 _ I _ 155 _ i 410 Brisbane Potential Develo ment and Traffic Generation b the Y,~ar2000 Sierra Point Office Hotel Restaurant 352,400 sf 600 rooms 8,000 sf 1.40 0.67 3.32 495 405 30 1.32 0.76 4.73 465 460 40 Southeast Bavshore n/a no land use i, n/a - n/a 1 - Southwest Bayshore Retail Office Trade Commercial 4,300 sf 1,200 sf 7,400 sf 0.67 1.40 0.98 3 2 8 2.93 ! 15 1.32 2 1.24 ~ 10 Brisbane Acres Single-Famil Resid. 4 units 0.74 3 1.01 4 Central Brisbane Single-Family Resid. Townhouses 38 uniu 16 units 0.74 0.44 30 7 1.01 40 0.55 9 OwUBucke e Can ons n/a ` no develo ment n/a -- n/a -- ^ n/a no develo ment ~ n/a -- n/a - Crocker Park Health Club Retail Outlet Restaurant Warehouse 2,500 sf 2,500 sf 3,000 sf 164,452 sf 0.12 0.36 3.32 0.57 1 1 10 95 1.70 2.14 4.78 0.74 5 6 15 1?5 Northeast Ridge Single-Family Resid. Townhouses A artrnents 87 units I 268 units 187 units 0.74 .44 0.67 65 120 125 ].O1 0.55 0.82 90 150 155 Northwest Ba shore Trade Commercial 168,000 sf 0.98 165 I?4 i 210 Northeast Ba shore n/a no develo ment n/a - n/a -- Baylands Retail R&D/Education 450,000 sf 200,000 sf 0.77 1.07 350 215 3.34 0.94 ; 1,505 190 Candlestick Cove n/a no develo ment n/a -- n/a -- Brisbane Subtotal 2,130 I Source: Crane Transportation Group Footnotes on following page. 7.0 APPENDICES Terrabay Phase 11 and 111 SEIR a Not including Terrabay. b Trip Generation Source: Route I01 /Bayshore Boulevard Hook Ramps PSR / PR, CCS Planning and Engineering, February 2, 1998. c Trip Generation Sources: (1) Traffic Impact Report Chestnut Estates Subdivision, Crane Transportation Group, February 1996, (2) Stonegate (Heather Heights) Initial Study, Wagstaff & Associates and Crane Transportation Group, 1994, (3) E! Camino Corridor Program Draft EIR, Wagstaff & Associates and Crane Transportation Group, January 1993. d Sources: (1) 1994 General Plan EIR; City of Brisbane, (2) CCS Planning and Engineering, Inc., (3) Crane Transportation Group. ., n/a = no net additional development planned. 7.0 APPENDICES Terrabay Phase 11 and 111 SEIR Exhibit 7.5-3 Year 2001 to 2010 Exaected Cumulative Development Trip Generation a Trip Generation Project ~ Land Use S/ze AM Peak Hour PM Pealr Hour Rate ~ 2-Way Trips Rate 2-Way Trips South San Francisco - East of 101 Area ° Bay West Cove Retail ~ 209,660 sf Hotel 610 roams 0.60 139 0.67 408 2.51 ~ 0.76 526 463 Brittania Biotech R&D ~ 43,000 sf I?3 ~ 53 1.07 ~ 46 Gatewa Lot 9 Office 201,000 sf ~ 1.40 ~ 281 1.30 261 Gatewa Lot 2B ~ Office ~ SQ000 sf ~ 1.91 ' 95 1.86 93 King Ventures Hotel ~ 165 rooms Office 20,000 sf 0.67 111 2.73 I SS 0.76 2.84 126 57 Raiser Or anization Hotel 400 morns I 0.67 268 0.76 304 Hazbor Wa Parcels Office 225,000 sf I.60 359 ~ 1.51 340 Gallo ~ Li ht Industrial ~ 57,000 sf 0.92 52 ~ 0.98 56 Maniaz ~ Li ht Industrial I 131,000 sf ~ 0.92 ~ 131 0.98 129 Fuller O'Brien R&D 296,000 sf 1.23 36-3 1.07 316 Genentech Addt'I Em lovees ~ 650 em lovees 0.43 i 280 OAI 267 South San Francisco -West of 101 Area ` El Camino Corridor Redevelo ment Area Variety of uses; includes I - Hicke BART station I -- 465 - 1,220 Summerhill Homes Sin le-Famil Resid. ~ 160 units 0.75 120 1.01 162 Brisbane Potential Develo ment and Traffic Generation 2001 to 2010 ° Sierra Point Retail Office Hotel 42,000 sf 1,294,590 sf 500 rooms 0.67 1.40 0.67 ~_8 1,813 335 2.93 1.32 0.76 1?3 1,709 380 Southeast Bavshore n/a` n/a n/a ~ - n/a -- Southwest Bayshore Retail Office Trade Commercial I 30,700 sf 2,300 sf 59,100 sf 0.67 1.40 0.98 21 3 58 2.93 1.32 1.24 90 3 73 Brisbane Acres Sin le-Famil Resid. I 205 units 0.74 ~ 52 1.01 207 Central Brisbane Sin le-Famil Resid. i 101 units 0.74 75 1.01 102 OwUBuckeye Canyons n/a n/a n/a - n/a - Crocker Park rt/a n/a pia - n/a -- Northeast Ridge n/a I n/a rt/a - n/a - Northwest Bayshore Trade Commercial ; 60,000 sf 0.98 59 1?4 75 Northeast Bayshore n/a n/a n/a - n/a -- Baylandsr Retail 1,550,000 sf 0.77 ( 1,19= 3.34 5,177 Office I 500,000 sf 1.40 700 1.32 660 R&D/Education 490,000 sf 1.07 I 5'_5 0.94 460 Restaurant 75,000 sf 3.32 249 4.78 359 Hotel i 2,000 rooms 0.67 I 1,3-0 0.76 1,520 Subtotal I (app. 1 million .rf) -t.008 8,176 Candlestick Cove n/a ~ n/a n/a I - n/a - Brisbane Subtotal ~ I 6.579 10,976 source: crane 1 ransportaUOn Group a Footnotes on the followinJ paje. 7.0 APPENDICES Terrabay Phase ll and 111 SE/R a Not Including Terrabay b Trip Generation Source: Route 101 /Bayshore Boulevard Hook Ramps PSR/PR, CCS Planning and Engineering, February 2, 1998. c Trip Generation Sources: (1) El Camino Corridor Program Draft EIR, Wagstaff & Associates and Crane Transportation Group, January 1993, (2) Trip Generation-6th Edition, Institute of Transportation Engineers, 1997. d Sources: (1) 1994 General Plan EIR, City of Brisbane, (2) CCS Planning and Engineering, Inc., (3) Crane Transportation Group. e n/a = no net additional development planned. f Baylands land uses shown are estimated land uses to match maximum high generating traffic increment reported in the General Plan EIR traffic analysis. The range of development currently considered feasible by the City of Brisbane would be 1.0 million square feet of high traffic generating uses to 4.2 million square feet of low traffic generating uses by buildout a ~ h w~ ~4 W~ Q G7 Q~ N d y m O N i _~ Vm ~ ao t O 0 N t ~ m Co Z O •- n tf1 O f- m ~~ CAD r r u~ ~ -~ O ~ ~ -~ t 00 m y N ~` ~ m m ~ L ~ Lo r o ~ ~ .~ 1 4 r~ ~l~ rN ~ m ~ ~ in ~' ~ ?b'a~n9nO a c ~ E ~ ~ _~ ~ v 1° -- o n o ~ ~ Q O W ~tl'f ~ IA 07 o p m y °~ c a ~ Z ~ O _ ~ •~ M ~ ~ Z ~ ~- N N ~ . , ~ C° ~ c a m ~ ~ o ~ o t ~ c ,e ~ 00~ y ~ tD v `~ ~ ~ ~„- o ~ l~ r~ 9 aroy e8 $ ~ v ~ t °' ~ m v ~ ~ ~ °' m z '- U m y ~~ ~~ ~y am o ~l ~, ~ Q Q ° ~ ~ 1 , ~ ~~ o~ ~~ L ~ a0 ~~~~~ N 14 ~ 0 m h 0 ~ N 111 ~ 0 a ~ _: _ ~ m ~ ~ ~ ~ ~ ~ am ~ 1~. r~ .a Q c ~ ~ ~ ~~ uavaya~ Fm ~ ~ ~ ~ o 0 a N O ~, ~ ~ v v \ N O v y~/ ~ N ~V m i~ ^ °' cn ~ N ~7 ~~ PM8 a 0 C7 c 0 m r O a y C F m C U m 7 O ~ ; ~~ k4 W~ a Q1 /~ V H O N a `m ~ ao r H _ ~ m 00 Z O ~.-- O O ~~ m ~ 0~1 ~ ~ ~ m O N O e{ ~ O ~ ~- fr b ~ N .~ 1 ~. r< IA O .~1~. r° a ~ ~ ~ ~ ~ anyanbngnp ~ v a ~~ m c ~ ~~ ~ --- N I ~ ~ 40 N O ~ N ~ r by ~ Z c ` N ~ ~ ~ C O m N Z ~ O ~ _ ~ f- ~ . 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O ~ U r ° r _ m °~ ° ° > 00 a ~ ~ A f0 ~ ~L f7 O N N ~ ~1 t_ ~ N N ~- N ~1~. rm a ~f1 y ~ ~ r tO ' U ~ l7 _ m y m y '~ y t y am o • ~~ .a Q o ~, ~ 1 p -~ o m ~ a ~~ m a0 ,~ ~ N f`7 r j 4 ~ ~ N C ~ 0 W ~ m v _ ~_ = ,~ O m y ~ o ~ N ~ •_ ~ U Q ~ ~ ~ ~ ~ ~ uos~ayap --- ~ m ~ Z a 0 c7 ^ c _ ` o ~ ~ m r c ~ rn o m u~ ~ ~ c ~ Hillside ~ ~ U ~ o ~ m ~ ~ O m U j ~ N ~ 00 4h k W m H V y O w N L m 3 a= a ~ ~ m r ~ Z O a c n o >; t~ o~ ~~ ~~ T !C ~ ~ o m a ~ r o ~ Z '~ ~ --- PN8 aioysdee -- -.. ~C ~~ ~ ~~ I a m H a H ~~ ~Q u ~`~~~~ i- ~ ~ 'itt~ ~ ~ ~ ~ 0:~ N a~,a ~~~ ~ Ott ~ °' ~ ° ~ '' ~o ~' w ~ 3 ~ ~ ~ ~~0 z b. t 4. ~ ' a o °~ c ~ ~ I a i tt "~ ~ o m L O ,~ ~ m ~ O ~ ~ ~ ~ a .~ .b C O ~ ~> U a m ~~~~ ~ a o~ ~ V Q ~ ~ ~~{ar ~~~ a.+ ~ •R m ~, 'o w cn a ~ ~ ..~ L L ~~ \^ ~ ~ _ \ ~ ~ ~ ~ ~ ~ C .y .L ~ h ~ .~ .~ .~ w w w it II II ~ (- T an y anvngn~ ~ ~~ ~ ~ o m ~ ~ o ~ ~ ZO ~a a ~ L ~' O C ~~ a~ N ~ C ~ O ^-~ ~~ ~ 3 Q~ ~ ~ ~ m `" N ~ R Q' v ~ a~ ~ ~ u m .~s t 0 z L ss. o it a * ~ ,OR V 0 m t 0 a c R F m U m 0 ~ 0 ~ n ~ ~ k a ~ m ~ T ~ ~,~ a =E° ~ o ~Om m~ o C ~ Z m op r c Z~ m y Q Z O G O ~ ~ (~j c a m ~ ~ ~ a mm ~ O O ~ N ~ ~ Z ~ ~ =' O O ~ a ~ ~-. ~~ 00~ N H 1 r~0 ~ P~+18 ab4 e8 m ~O~ ~ ~ ~ ~ ~ so d F = m 0 _ m y ~ ~ r y ,J a~ G Q `E ~ ® ~' '1 . 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II II x~ a 0 C7 c 0 m r 0 a c H m c U m O Exhibit 7.5-12 Maximum Queue Lengths at Intersections a A M Peak Hour P M Peak Hour Movement Storage Length ° Lanes Volume Maximum Queue Len th Vo/ume Maximum Queue Length All Stop ` Partial Stop ° All Sto Partial Sto v Bayshore / Terrabay North Access NB Left 48 m 1 174 60 m 53 m 231 76 m 60 m NB Throu h 180 m 2 406 68 m 23 m 665 98 m 38 m SB Throu~ 230 m 2 1,462 195 m 83 m 1,219 165 m 90 m SB Right 90 m 1 27 15 m 8 m 32 15 m 15 m Bayshore / SB 101 Ramps NB Throu Risht 92 m 2 504 83 m 68 m 817 120 m 98 m NB Left 120 m 1 450 128 m 90 m 520 143 m 105 m SB Through 185 m 2 1,141 158 m 75 m 905 128 m 75 m WB Left 260 m 1 394 113 m 83 m 695 180 m 120 m WB Ri ht 80 m 1 117 45 m 38 m 182 60 m 45 m Bayshore / Terrabay South Access NB Left 95 m 1 137 53 m 45 m 148 53 m 45 m NB Throu h 296 m 2 463 75 m 23 m 713 105 m 30 m SB Throu 92 m 2 1,489 195m 75 m 1,554 203 m 83 m SB Ri t 40 m 1 46 23 m 145 m 46 23 m 15 m Bayshore /Oyster Point SB Left 105 m 2 704 158 m l28 m 391 98 m 83 m SB Throu 295 m 2 ' 545 128 m 90 m 513 120 m 83 m SB Ri ht 105 m 1 258 120 m 68 m 725 300 m I80 m Source: CSS Planning and Engineering, Inc., March 1998. a Poisson Arrival Pattern, 95 Percent Probability. 6 Metric measurement in meters. One meter = 39.37 inches (3.28 feet). c Maximum Queue All Stop =Maximum Queue length (95 percent) if all vehicles must stop at signal. Numbers in bold italic type indicate that queue length calculated exceeds storage length. d Maximum Queue Partial Stop =Maximum Queue length (95 percent) if vehicles arriving during green sigrtal indication do not get added to queue. Numbers in bold italic type indicate that queue length calculated exceeds storage length. C f. 71 _u• "~ 09 c, is _: r r,. i ^,---~----- r. f oS ~~ ~ .n iJC1 1 1) 1 I I, ---' T~ _ ~ _ f;) -~ :' 00 r.'. - ~, Ir .. - I I -- - •_ ~.. - I dy n ~ r~ I ~ `~ • I ~. U _. 4 r• iii ni :n N ~' I ~ ~ ' ~. rTl N O ! ' n - '- _--~ ~ I ~ N :9 t t: I a r r' i. I; ; r. ~ to f ~ t . ---_ - -~ . ui - N __- J l): ~i 9~ P, f,j fT' i , )- 7 ni '~' 4;:1s of D t ~-0 ~~ ~ V ~ r' 04 I ' a --- -- - V~ (k7 I ~ ~ -~ • :D n' :4 ; <, D O - _ - _ O N ~ C ~\ :s~.U .~ \ ~_\ vl\ r,~ y r n m ,,/; „~ le Y n s' _ ~ ~ ~•' a ----'r-- O I ±9 I Y. k O ~, A r~ ~ O s ~ __..-- rn y-±--- f. !'~ ~' U ~. n~ ~~ J I --- - .U L __ ~. I N n c~ U U 1 --~ f rl 11 ~1 O O c,7 t~ U 1` C) ri .I n'~: ti ~.~ w -- - _', s--- -- I of -I w p it I _. V n, D i l -U~ --- - m ^I v L I -i- 1 ~ \\ __ `\\ .~ c~ .P~~ ~ , ,\ .~ U \`\\9 ~' ~' \ J` C~\9. :~\ ~ .~ In 1. C~ :rl 1> c~ i/j:!~ _ e 9 1~ := O cn ay N I~ to --- t O .D I ~ 09 T m I - ' z~ N ~ oq .i r ~ ~~`\ f ' _ '7i '~, ~J ~~ C> D x n c~ m ,'~'. . 04 r _~ a v N ~ ~ __ _ I ~ l•+ m I i~ .u N ..9 r ------ -o ~ } U O ^~ W `Q y fb ~¢ /'~ ~D 0 r"- V +~.. .7 ~ V (/I ~'C v APPENDIX 7.6 AIR QUALITY 7.0 APPENDICES Terrabay Phase lI and Ill SE1R APPENDIX 7.6 A/R QUALITY DESCRIPTION OF LOCAL AND REGIONAL AIR QUALITY MODELING Localized Air Quality Modeling Carbon monoxide concentrations associated with buildout of the Terrabay project were modeled using the CALINE4 model and adding the model results to background levels. The CALINE4 model is the latest in a series of line-source dispersion air quality models developed by Caltrans. It is based on the Gaussian diffusion equation and employs a mixing zone concept to characterize pollutant dispersion over a roadway. The purpose of the model is to assess air quality impacts near roadways. Given the source strength (volume of traffic and emission factors), meteorology, and site geometry, the model can predict pollutant concentrations at receptors within 500 meters of the roadway. The model has the ability to predict concentrations of pollutants resulting from vehicles in different stages of operations at an intersection (idling, accelerating, and cruising). The CALINE4 model is recommended for evaluating air quality impacts from roadways by the Bay Area Air Quality Management District (BAAQMD) and the California Air Resources Board. Both Caltrans and the BAAQMD have conducted extensive research into the worst-case meteorological conditions which are most conducive to the build-up of carbon monoxide levels in the Bay Area. This assessment assumed worst-case conditions -that is, conditions most conducive to high carbon monoxide concentrations. These conditions included the following: • Peak-hour traffic levels • Wind speed of one meter per second • Worst-case wind angle (out of 36 different directions) • Stability of F Category (most stable) • Standard deviation of wind direction (or fluctuation of wind direction) of ten degrees • Surface roughness of 100 centimeters • Mixing height of 1,000 meters Emission factors produced by the EMFAC7 version 1.1 model for average cruise speeds and idling were included in the CALINE4 modeling. To produce these emission factors, the Caltrans' version of the EMFAC7 model (ENV028) was used. The appropriate vehicle mix and cold start percentage are taken into account in the EMFAC7 model. For the freeway and off-ramps, a cold start percentage of five percent was used. On other roadways and freeway on ramps, a cold start percentage of 40 percent was used. Carbon monoxide emission factors for appropriate wintertime conditions were used. To predict the total carbon monoxide concentration, the modeled concentration was added to the background concentration. The background concentration was estimated from CO Isopleth Maps published by the BAAQMD. Rollback factors which account for the forecasted improvement in air quality were applied to future background carbon monoxide levels. For this 1998 SEIR, the 1997 background carbon monoxide levels are 5.0 parts per million (ppm) for the one-hour averaging period and 3.4 ppm for the 8-hour period. These levels were adjusted appropriately for the future using rollback factors recommended by the BAAQMD. As a result, future background carbon monoxide levels were as follows: 7.0 APPENDICES Terrabay Phase /l and 11l SEIR Year One-Hour Level Eight-Hour Level 1997 5 ppm 3.4 ppm 2000 5 ppm 3.0 ppm 2010 3 ppm 2.3 ppm 2020 3 ppm 2.3 ppm The model predicts one-hour average levels for the peak-traffic period. To predict the eight-hour average level, a persistence factor of 0.7 recommended by the BAAQMD was used. One- and eight- hour carbon monoxide concentrations are predicted as follows: One-hour concentration =modeled impact + one-hour background level Eight-hour concentration = (modeled impact x 0.7) + eight-hour background level Regional Emissions Daily air pollutant emissions from traffic which could affect air quality throughout the Bay Area were calculated using the URBEMISS model and methodology recommended by the Bay Area Air Quality Management District which is published in the District's CEQA Guidelines. This methodology involves combining daily trip generation data provided by the 1998 SEIR's traffic engineer and default travel activity for the Bay Area and San Mateo County with vehicle emission factors. This is combined with emission factors generated by the EMFAC7F (version 1.1) model to produce the daily emission rates. The daily emission rates account for tail pipe exhaust emissions, hot-soak emissions (reactive organic gasses), and fire weaz. An additional factor was applied to the PM,o emission results to account for roadway dust reintrainment. URBEMISS emissions of total organic gases were converted to reactive organic gases (the ozone precursor portion) by using a factor of 0.92. South Coast Air Quality Management District screening emission factors which account for air pollutant emissions from water space heating and energy consumption were applied to each proposed land use.