HomeMy WebLinkAboutDraft EIR Terrabay 08-01-1982
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TERRABAY DEVELOPMENT
San Mateo County, CA
Draft
Environmental Impact Report
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(ZIP Corporation
August 1982
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Environmental Impact Planning Corporation
319 Eleventh Street
San Francisco, California 94103
(415) 864-2311
DRAFT ENVIRONMENTAL IMPACT REPORT
FOR THE
TERRABA Y DEVELOPMEI'IT PROJECT
San Mateo County, California
August 1982
E lP 1181-1 2 I
SCH 1182020211
CONTENTS
Page
I. SUMMARY I
II. INTRODUCTION 9
III. PROJECT DESCRIPTION II
IV. ENVIRONMENT AL SETTING, IMPACTS AND MITIGATION 45
A. Visual Qual ity 45
B. Geology and Hydrology 60
C. Air Quality 89
D. Land Use 96
E. Vegetation and Wildlife 103
F. Community Services 116
G. Noise 141
H. Energy 150
I. Archaeo logy 153
J. Wind and Climate 156
K. Economics 159
L. Traffic and Transportation 175
V. IMP ACT OVERVIEW 220
A. Growth-Inducing Impacts 220
B. Unavoidable Significant Environmental Impacts 220
C. Short-Term Uses Versus Long-Term Productivity 222
D. Irreversible Environmental Changes Occurring
as a Result of Project Implementation 222
VI. AL TERNA TIVES TO THE PROPOSED PROJECT 224
A. No Project Alternative 224
B. Concept Plan Alternative 225
C. Alternative Designed to Conform with the Sphere
of Influence Study 226
D. Alternative Designed to Conform with the
General Plan Amendment 227
VII. EIR AUTHORS AND PERSONS CONSUL TED 229
APPENDICES A-I
A. Traffic and Transportation
B. Fundamental Concepts of Environmental Noise
C. Plant Species Observed or Reported on T errabay
Development Site
D. Phase 11 Geotechnical Feasibility Study
E. General Geotechnical Summary
TABLES
Page
I. Residential Unit Mix
15
31
38
39
72
90
2. T errabay Development Phasing Schedule
3. Terrabay-General Plan Amendment: Housing Plans
4. Terrabay-General Plan Amendment: Land Uses
5. Geologic Impact Criteria
6. Number of Days Selected Pollutants Exceeded
State or Federal Regulations (1981)
7. Curbside CO Concentrations at Critical Intersections
92
94
101
125
8. Project-Generated Emissions (1990)
9. T errabay Land Use Data
10. City of South San Francisco
Fire Department 1981 Equipment List
II. South San Francisco Police
Department 1977-1981 Crime Statistics
130
12. Students-per-Household by Housing Type
13. Terrabay Students - Estimated Impacts
to School Districts
134
135
14. Results of Noise Measurement Survey
144
15. Changes in Traffic Noise Levels
(Hourly Leq and CNEL) Along Existing
Streets in the Vicinity of the Project
145
16. Projected Energy Consumption of Project in 1990
17. Wind Direction and Speed Distribution at the
San Francisco International Airport
152
158
18. Total Operating Revenues from T errabay Development
by Source: 1982-1995
160
i i
TABLES
continued
Page
19. Distribution of Property Tax Revenues 163
to All Jurisdictions: at Full Project Buildout
20. Distribution of Firms by Size and Type 169
21. Summary of Additional Annual Operating Costs 171
Attributable to T errabay Development
22. Summary of Major Fiscal Impacts 172
23. Proposed Project Sponsor Capital 173
Expenditures for Public Facilities
24. Definitions of Intersection Levels of Service 187
25. Existing Peak Hour Intersection Volumes 188
and Existing Levels of Service
26. 1990 Peak Hour Intersection Volumes 189
and Levels of Service (without Hillside Extension and
Terrabay Project)
27. 1990 Peak Hour Intersection Volumes and Levels 194
of Service (with Hillside Extension and but without
Terrabay Project)
28. Terrabay Development Gross Trip Generation 196
29. T errabay Trip Generation Adjusted for On-site Travel 198
30. Travel Orientation of T errabay Trips 199
31. Terrabay Traffic P.M. Peak Hour Distribution 200
32. 1990 Peak Hour Intersection Volumes and Levels 201
of Service (with Hillside Extension and Terrabay
Project)
33. Year 2000 Peak Hour Intersection Volumes and Levels 210
of Service
34. 1990 and 2000 Mitigated Peak Hour Intersection 217
Volumes and Levels of Service
i i i
LIST OF FIGURES
Page
I. Regional Location Map
/2
13
2. Site Location Map
3. Site Plan
16
4. a. TerrabayVillage- 181 TownhomeUnits
b. Terrabay Park - 136 Single Family Units
c. T errabay Woods - 200 T ownhome Units
d. T errabay Commons - 129 Terraced Un its
e. T errabay Point - 99 Condominium Units
18
19
20
21
22
24
26
28
29
47
48
49
53
5. Hillside Recreation Center
6. Commercial Area Site Plan
7. Offices and Restaurant
8. Hotel and Tech Center
9. View to South and West: Existing Development
10. View to Southeast: Existing Development
II. View to East: Existing Development
12. Section: Proposed Hillside Boulevard Extension
13. Terrabay Site Geology
62
14. Terrabay Site Slope Analysis
64
15. Active Fault Zones in Bay Area
67
68
78
97
100
142
176
181
182
16. T errabay Site: Potential Landslide Areas
17. T errabay Site Drainage System
/8. Existing and Proposed Land Uses
19. Limits of Disturbance
20. Noise Measurement Locations and 1990 Post-Project Noise Exposure
21. Local Street System
22. Existing Daily Traffic Volumes (1982)
23. Existing PM Peak Hour Traffic Volumes (1982)
iv
List of Figures
(continued)
Page
24. 1990 Daily Traffic Volumes without Hillside Extension and 184
without T errabay Project
25. 1990 PM Peak Hour Traffic Volumes without Hillside 185
Extension and without T errabay Development
26. 1990 Daily Traffic Volumes with Hillside Extension and 192
without T errabay Project
27. 1990 PM Peak Hour Traffic Volumes with Hillside Extension and 193
without T errabay Project
28. 1990 Daily Traffic Volumes with Hillside Extension and with 202
T errabay Project
29. 1990 PM Peak Hour Traffic Volumes with Hillside Extension 203
and with T errabay Project
30. Year 2000 Daily Traffic Volumes 209
v
I. SUMMARY
A. PROJECT DESCRIPTION
I. Site Location and Setting
The proposed project site is located within San Mateo County on the lower southeastern
slopes of San Bruno Mountain. The extension of Hillside Boulevard is anticipated and the
costs will be shared equally by San Mateo County and the project sponsor. The project
area is currently unincorporated, however, annexation to the City of South San Francisco
would occur in conjunction with the project approval process.
2. Project Characteristics
The Terrabay Development proposed by W.W. Dean Associates would consist of a mixed-
use residential and commercial development contained in approximately 179 acres of the
332-acre project site. The remaining acres would be preserved and dedicated to the
County as open space.
The residential portion of the Terrabay development would consist of 745 dwelling units
divided into five neighborhood groups of single-family detached homes, and single-family
attached townhomes, terraced units and condominiums. Hillside Recreation Center, a
four-acre community recreation complex located within T errabay, would provide indoor
and outdoor recreational facilities. The project a/so provides for playfield improvements
to Hillside Elementary School.
Commercial development would be located along Airport Boulevard and feature a
condominium office building, private health club, restaurant and hotel, and high-tech
trade center comp lex.
The project would be constructed in six phases over a minimum five- to six-year period.
3. Relationship to Plans
Several planning documents guide future environmental and development decisions with
respect to the proposed site. They include the San Mateo County General Amendment
Plan for San Bruno Mountain, the South San Francisco General Plan, the Association of
Bay Area Governments (ABA G) Regional Plan, and the San Bruno Mountain Area Habitat
Conservation Plan for San Bruno Mountain. The relationship of the project to these
planning documents is discussed in the EIR.
4. Community Concerns
Development proposals on San Bruno Mountain have generated significant public contro-
versy in past years. At the beginning of this EIR process, a public "scoping" meeting was
held in South San Francisco. As a result of the meeting several changes were instituted in
the focus and emphasis of the EIR scope of work.
B. VISUAL QUALITY AND URBAN DESIGN
The hillside's visual character would be changed from an open space setting to one of
expanding development. To mitigate visual impacts, development would be clustered in
separate neighborhoods in the Mountain's lower southeastern swales; the knolls and hillside
above would remain open. The entire project would not be visible at one time from any
location, nor would it break the ridgeline. The project sponsor has incorporated landscape
and architectural design features into the project to mitigate the transition between the
development and the surrounding urban and rural environments.
c. GEOLOGY AND HYDROLOGY
Most of the area proposed for development contains slopes between 5% and 30%.
Numerous landslides and soil creeps have occurred on the site which affect, to some
degree, all the areas proposed for development. Steep slopes and fairly impervious soils
produce high runoff volumes which the existing drainage system is unable to handle. Off-
site flooding would be reduced by the construction of a new storm drainage system. A
total of 159 acres would be graded, requiring the importation of about 50,000 cubic yards
of fill. Extensive excavation and backfilling would be necessary to complete the proposed
project. Grading would be completed in two phases to minimize disturbance of soil and
vegetation. A comprehensive erosion and sedimentation control plan would be developed
2
and implemented. Geot echn ica I invest igat ions would be con t inued and recommenda t ions
for rebuilding iandslides and unstable slapes would be fOllowed. Grading permits would be
required from the City of South San Francisco and reviewed by the County of Son Mateo.
(Grading permits may also be determined to be required by the County.)
D. AIR QUALITY
Air quality in the vicinity of the project is generally gOod due to the prevailing
northwesterly winds.
Wetting of exposed earth surfaces would reduce dust emissions during construction by
about 50%.
The project would not Cause violation of iacal or regional air quality standards, although it
would slightly increase the overall regional burden of air pollutants. The project would be
consistent with the 1979 Bay Area Air Quality Plan.
E. LAND USE
With minor exceptions, the entire site is undeveloPed. T errabay would replace the site's
open space with a mix of residential, commercial, recreational and open spaCe uses.
Residential and recreational uses on approximately 139 acres and commercial develop_
ment of approximately 39.8 acres would leave 153.2 acres of undeveloped apen space.
Resi dent i 01 cluster densities wau Id range from 4.1 to I/, 3 units per ac re. T errabay wou Id
supply approximately 41 % of South San Francisco's projected housing needs for 1980 to
1985.
Commercial development at the site's east end would be consistent with existing and
proposed land uses along the freeway corridor.
The San Bruno Mountain Hob ita t Conservat ion Plan (HCP) st Ipu lates ded i co t ion 0 f the pro j eo t 's
undevelaped Open space areas to the County at the time the first grading permits are granted
for the parcel of the project to which it pertains.
3
The undeveloped open space would be, therefore, dedicated to the County in conjunction
with the two grading phases: upon completion of the residential portion and upon
completion of the commercial portion. Dedication plans are as yet still proposed since
the HCP, at this stage, has not been finalized. Remaining open space, to be managed
according to the Habitat Conservation Plan, would be within jurisdiction of the City and
under the auspices of a homeowners' association.
F. VEGETATION AND WILDLIFE
Two rare butterflies are found on the project site: the mission blue (federally listed
endangered species) and the callippe silverspot (proposed but not, as yet, I isted as
endangered species). In response to concerns to preserve the habitat of these butterflies,
the affected public agencies and developers have created a Habitat Conservation Plan
(HCP) for San Bruno Mountain. The proposed project would conform to the extensive
guidelines required by the HCP concerning limits of grading and development. The
project would also be designed to preclude sudden loss of habitat and minimize habitat
disturbances.
G. COMMUNITY SERVICES
Water services would be provided by the California Water Service Company. The project
would require a new water distribution system including a new water storage tank. The
project sponsor has agreed to incur all costs for the system. The Water Service Company
would be able to accommodate the projected increase in services.
Sewage treatment services would be provided by South San Francisco's Public Services
Department. The project would increase wastewater flows by about 390,000 gallons per
day. The project sponsor has agreed to incur costs of a new on-site sewer system and
improvements to the existing system necessitated by the project. The Department would
be able to accommodate the projected increase in treatment services.
The South San Francisco Scavenger Company would provide solid waste removal and
disposal services. The company would be able to accommodate the additional service
impacts generated by the project's estimated 2,061 tons per year of solid waste.
4
Natural gas and electricity would be supplied by the Pacific Gas and Electric Company
and telephone services would be provided by Pacific Telephone. Neither company
anticipates any impacts associated with additional service demands created by the
pro ject.
The City of South San Francisco would assume responsibility for providing police and fire
protection services. The project would increase demand for both services. The Police
Department would request an expansion of staff and services if the project and other
proposed residential and commercial projects are approved for the area. The project
sponsor has agreed to donate land and construct a fire station within the T errabay
Development to mitigate impacts to fire services.
Approximately 286 school-aged children would live within the project and be served by
three school districts. All school districts would be able to accommodate an increase in
enro II ment .
The project also includes development of a community recreation center, linear park,
child care center and improvements to playfields at nearby Hillside Elementary School.
H. NOISE
The noise environment at the project site varies considerably with location. The project
would conform to California Noise Insulation Standards for acceptable interior noise
environments. Standard mitigation practices would be followed to reduce construction
noise impacts.
I. ENERGY
Annual energy consumption for the project is estimated at 71,000 BOE (barrels of oil
equivalent) for construction, 42,000 BOE for operation and 47,000 BOE for project-
generated traffic. In addition to complying with California's residential energy consump-
tion requirements (Title 24), the project sponsor would consider other features to improve
energy efficiency.
5
J. ARCHAEOLOGY
An archaeological evaluation indicated the presence of a potentially significant prehis-
toric site within the project's boundaries. The sponsor has proposed mitigating impacts by
placing a minimum of one foot of sterile fill over the site and sealing the area under
landscaping and/or parking areas.
K. WIND AND CLIMATE
The climate of the area is dominated by windflo'w through San Bruno Gap. Most of the
project would be located in areas at least partially sheltered from the wind. Care should
be taken in the building layout and landscaping to put wind-sensitive activities to the east
of development windbreaks.
L ECONOMICS
The project would increase property tax revenues and generate new revenues from the
sales and use tax, real property transfer tax, transient occupancy tax, business license tax
and the franchise tax. The City of South San Francisco would also receive greater
subventions from the State. Total annual revenues at full bui Idout of the project are
estimated at $1.0 million.
Additional operating costs for providing services to the project would be incurred by the
City of South San Francisco. These annual costs are projected to be $377,000 at full
project buildout.
Capital costs for increased facilities for fire protection, storm drainage, parks and
roadways would be $4.3 to $5.5 million. The project sponsor proposes to contribute $3.6
to $5.0 million towards necessary capital expenditures.
M. TRAFFIC AND TRANSPORT A TION
The proposed project would generate about 13,900 daily and 1,500 p.m. peak hour vehicle
trips at full project buildout. About 60% of peak-hour traffic would be generated by the
commercial development of the project and 40% by the residential areas.
6
The proposed project's projected share of year 1990 p.m. peak hour traffic would be about
20%-45% of the total cumulative volumes in the immediate vicinity of the site (Hillside
Extension) and less than 10% in areas further from the site (on Linden, west of Chestnut
and east of U.S. 101). It should be noted that several major roadway and freeway
interchange improvements are planned in the project vicinity, including the Hillside
Boulevard Extension and Oyster Point Interchange modifications.
The new Hillside Extension would effectively channel existing through traffic and project-
generated traffic away from existing residential areas south of Randolph Avenue and
downtown by distributing traffic directly onto major regional facilities such as Airport
Boulevard and U.S. 101. Future projected intersection service levels would be affected
only moderately by the proposed project, generally in the order of one-half service level
step. The most critical intersections (Linden/Airport, Hillside/Linden, Oyster
Point/Airport, Oyster Point interchange ramps, and freeway off-ramp/Airport) would be
overloaded by 1990 regardless of the proposed project unless improvements are made to
the Oyster Point interchange.
With the anticipated roadway improvements described earlier and with additional mitiga-
tion measures discussed in the EIR and incorporated in the project, the impacts resulting
from the project and other cumulative developments could be satisfactorily mitigated
under the "worst case" assumptions for cumulative land development in the area. With
the mitigated service levels, traffic conditions would be similar to current rush hour
operation on the Peninsula.
N. IMPACT OVERVIEW
The project would directly increase growth of the housing stock of the City of South San
Francisco by about four percent. Retail purchases by project residents and employees
would indirectly stimulate business growth.
The unavoidable environmental affects, irreversible environmental changes and the
relationships between short-term uses versus long-term productivity are discussed in
Section V of the EIR.
7
o. AL TERNA TIVES
Four alternatives are discussed in the EIR:
No Project Alternative
Concept Plan Alternatives
Alternative Designed to Conform with the Sphere of Influence Study
Alternative Designed to Conform with the General Plan Amendment.
A comparison of impacts in relation to the proposed project is discussed for each
alternative.
8
II. INTRODUCTION
This report provides an analysis of the likely environmental impacts of the proposed
Terrabay Development on the south slope area of San Bruno Mountain. The purpose of
this Draft Environmental Impact Report (EIR) is:
To meet the requirements of the California Environmental Quality Act (CEQA) of
1970, as amended, following the guidelines set forth by the Secretary of Resources
and the procedures approved by the County of San Mateo and the City of South San
Francisco.
To serve as an informational document for the public and City and County agencies
to assess the relative environmental impacts and growth considerations that could
occur if the proposed Specific Plan were implemented.
The report is the primary document in a process which began with the Concept Plan for
South Slope and will end with action on the Specific Plan by San Mateo County and South
San Francisco. As a part of this process, the environmental professionals preparing the
EIR have provided information and review comments on draft versions of the Specific
Plan leading to revisions and the incorporation of certain mitigation measures into the
Plan. Following publication of this report, the agencies listed below, as well as the
general public, are expected to use the EIR during the permit process.
Approval
Specific Plan
Prezoning and Access
Application
Agency
City and County
City
Subdivision Permit
Grading Permit
Development Agreement
Annexation Agreement
Architectural Permit
Building Permits
Service Distr ict (Water)
Boundary Change
City
City and County
City
LAFCO, City
City
City
LAFCO, PUC
9
Approval
Roadway Transfer
Encroachment Permit
Burning Permit
Section lOa Permit
On compliance with the
Endangered Species Act,
1973, as amended)
Agency
City, Brisbane
Potential EIR Users
Caltrans
Bay Area Air
Quality Management
District
u.s. Fish and
Wildlife Service
10
III. PROJECT DESCRIPTION
A. SITE LOCATION AND SETTING
The proposed project site is located within San Mateo County on the lower southeastern
slopes of San Bruno Mountain. It is curvalinear in shape and generally bounded by Hillside
-------- -
B~'tard.QlJg Randolph Avenue to the south, Hillside Elementary School to the west,
____ -'~'-_____..._____..___. __...... .._.n___-~.____.___'__________.~______.._.__"...___._._"',_ ~.._.___.____._____ ..._....._..___._._~__._.~,
~~iq~~':"..!_~~~I~,,~!d_!o.._!~~_e_a_~_~ and San Bruno Mountain State and County Park to the north
(Figures 1_'(]l1d, 2). ..
-------------
A Pacific Gas and Electric Company transmission line and authorized right-of-way bisects
the project site approximately opposite North Spruce Avenue.
Present access to the site is - from Hillside Boulevard, Randolph Avenue and Airport
Boulevard. Bayshore Freeway (U.S. 101) is located about one block east of the
easternmost portion of the project site.
Extension of Hillside Boulevard, north of Randolph Avenue and west of Airport Boulevard
is anticipated. The County of San Mateo and the project sponsor have agreed to share
equally the costs for the extension. Projected time of construction is contingent upon
project approval.
Juncus Ravine, a separate 157-acre parcel of land is located generally west of Hillside
Elementary School (Figure 2). The project sponsor has agreed to dedicate Juncus Ravine
to permanent open space pending development approval of the Terrabay Development.
The area is presently unincorporated, though immediately adjacent to the city limits of
South San Francisco. The Local Agency Formation Commission (LAFCO) has established
that the project area falls within the South San Francisco sphere of influence. According to
current San Mateo County policy, once urban development is approved for the Terrabay
site, the City of South San Francisco may annex site.
11
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T errabay Development
SITE LOCATION
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13
III. Project Description
B. PROJECT CHARACTERISTICS
The Terrabay Development proposed by W.W. Dean Associates would consist of a mixed-
use residential and commercial development contained in approximately 179 acres of the
332-ac[e-m~. The remaining undisturbed 153 acres in the project site would be preserved
--...-- -- _..~--_.-
and dedicated to the County of San Mateo as open space (Figure 3)~__ _In addition, a
separate I 57-acre parcel of land, Juncus Ravine, would be preserved and dedicated to the
County as open space.
The residential portion called Terrabay, would consist of a series of five separate
neighborhoods in development pockets along Hillside Boulevard and its planned extension.
Each neighborhood would have common areas and common facilities characteristic to the
neighborhood which would be owned, operated and maintained by homeowners
associations. A master association would own, operate and maintain facilities common to
the entire residential area.
A total of about 1,39 acres would be developed as dwelling units, roadways, parking and
recreation facilities. See Table 9 of this document for a breakdown of land use data.
A total of 745 dwelling units would be developed into groups of single-family detached
homes, single-family attached townhomes and terraced units and condominiums (Figures
4a-e). Projected cost per unit varies from $95,000 to $230,000. Table I lists development
units by neighborhood, residential type and associated costs. Overall density on the
residential portion excluding the area dedicated to open space, would be 5.4 dwelling units
per acre.
The proposed neighborhoods would feature pockets of development at the lower elevations
of the site, separated by grassy knolls. The neighborhood of townhomes adjacent to
Hillside Elementary School would reach the project's maximum elevation of 425 feet. The
adjoining single-family development would have a maximum 350-foot elevation.
Remaining residential units would be constructed below the 300-foot elevation level.
Residential pockets would be connected by a collector street generally parallel to Hillside
Boulevard. As a public thoroughfare, this street would be dedicated to South San
Francisco. All other roadways in the development would be private. Two access roads
14
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SOURCE:
DOUG DAHLIN AND COMPANY
Terrabay Development
SITE PLAN
FIGlJ~e: 3
16
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would connect Hillside Boulevard with the collector street--one opposite Jefferson Street
and the other opposite Chapman Avenue. A covered bus stop would be located on Hillside
Boulevard at each access road.
The Hillside Recreation Center, four-acre generally level park would be developed
directly south of T errabay Park and opposite Jefferson and Irving Streets. This
community recreation complex would feature a basketball court, tennis courts, playground
apparatus and an indoor facility, containing a swimming pool, weight room, dressing
rooms, multi-purpose room and an activity room with adjoining tot lot (Figure 5). A
parking lot contain 61 spaces would be located adjacent to the recreation center. The
Hillside Recreation Center would be deeded to the City and maintained as a community
park.
A child care center tot lot would be located within T errabay Village (Figure 4a). This
center would be designed to provide care for 40 children and would be operated and
maintained by a combined Terrabay homeowners organization.
A fire station would be located on the northwest portion of the Hillside Recreation Center
(Figure 5). This facility would be designed to specifications recommended by the City's
Fire Chief and erected in conjunction with T errabay Village. Dedication of the facility to
the City of South San Francisco would occur upon completion of 50% of the units in
Terrabay Village.
The project design also indicates improvement of the eastern portions of the Hillside
Elementary School site with an illuminated softball diamond and overlapping soccer field.
A linear park/greenbelt is proposed parallel to Hillside Boulevard connecting the school
site with the Hillside Recreation Center. Asphalt paths would be provided for pedestrians
and bicycle traffic.
The undisturbed 153 acres of open space located between the developed area and the
northerly and westerly properly lines would be dedicated to the County of San Mateo for
inclusion into the San Bruno Mountain State and County Park. All other open space areas
would remain within the jurisdiction of South San Francisco and under the purview of a
combined property owners association.
23
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III. Project Description
Two trailheads within the project area would provide access to the regional park's
proposed trail system. One trailhead would be located adjacent to Hillside Recreation
Center and the other behind the private health club in the commercial portion of the
development. A six-space parking lot would be provided adjacent to the trailhead near
the Recreation Center. Parking for the other trailhead would be accommodated at the
private health club.
Commercial development is proposed on the portion of the site facing Airport Boulevard.
A total of 40 acres would be developed into condominium office buildings, private health
club, restaurant, and hotel and tech trade center complex (Figure 6). Commercial uses
will ultimately be held in private ownership by arrangements which would be finalized
prior to the construction of commercial facilities.
A four story structure of office condominiums would be located immediately north of
T errabay Point. The office building would contain approximately 57,500 square feet of
owner-occupied professional services. Individual spaces would be available in units of
about 1,000 square feet. A single building restaurant located on the north side and
adjacent to the condominium office building would seat 150 (Figure 7).
Directly behind the office building would be a private health club with an indoor
swimming pool, six racquetball.courts and a weight and exercise room. Five tennis courts
on three terraced levels would step-up the hillside behind the health club. Membership
opportunities wOIJld be available to residents of Terrabay Commons and Terrabay Point.
'listing privileges would also be available to hotel guests. A pedestrian trail from the
promontory down to the health club would provide a link to the residential areas.
A collector street would connect the office, restaurant and health club area to a hotel and
tech trade center complex located in the ''bowl area" adjacent Airport Boulevard. Three
access points to Airport Boulevard are proposed. Refer to Figure 6 for access location
points.
The hotel and tech trade center complex would feature an 18 story, 400 room hotel
adjoining a 268,700 square foot high technology trade center. (Figure 8.) The hotel and
tech trade center would be built in separate phases but would be architectually linked by a
three-story atrium/entry lobby. Above the fourth floor, the two buildings would be
separate.
25
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SOURCE: DOUG DAHLIN AND COMPANY
Terrabay Development
COMMERCIAL AREA SITE PLAN
FIG:lR2: 6
26
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III. Project Description
The hotel would contain a combination of restaurant and banquet room facilities that
would seat about 500. A seminar center that seats up to 600 would also be located within
the hotel. It would provide flexible conference and seminar space for local and visiting
business needs. Three small units of retail space would be located within the hotel lobby
area to provide hotel guest-related services (i.e., gift/tobacco shop, barber shop, etc.)
The tech trade center would cater to high technology hardware manufacturers and
software suppliers. Of the tech trade center's total floor area, 240,900 square feet would
be utilized as showroom space and 27,800 square feet as permanent office space. Leased
space would be available to display products and provide space for their sales
representat ives.
At commercial build-out, a total of approximately 1,560 parking spaces would be
provided. Parking garages would contain expansion capabilities to allow for an increase in
parking requirements.
The project would be constructed in six phases of buildout over a minimum five to six-
year period. Grading operations would be separated into two phases which would span two
to three construction seasons. Residential development would be completed, proceeding
generally from west to east along Hillside Boulevard. Commercial development would be
completed in conjunction with improvements to Airport Boulevard and Bayshore Freeway
access. Table 2 shows the proposed schedule phases for operational buildout.
30
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III. Project Description
C. BACKGROUND OF PROJECT I
San Bruno Mountain, in northern San Mateo County, is a large expanse of undeveloped
open space amidst some of the most densely developed areas in the Bay Area (Figure 2).
Over the last two decades considerable attention and controversy has been focused on the
area by private developers, public agencies, concerned individuals and environmental
organizations. Extensive planning efforts have been made to balance protection of the
mountain environment with the increased demand for housing.
I. History of Recent Planning Efforts Affecting the Proposed Project
Before adoption of the 1976 General Plan Amendment for ~n Bruno Mountain,
planning considerations affecting the project site were addressed in the following San
J -
Mateo County General Plan Elements:
Master Plan for 1990, adopted by the Boord of Supervisors, 1960; last amended,
I 964. 2
Parks and Open Space Element, adopted by the Boord of Supervisors, 1969;
amended I 972. 3
Conservation and Open Space Element, adopted by the Boord of Supervisors, 1973.4
Portions of this element superseded the Parks and Open Space Element.
Parks and Recreation Element, adopted by the Boord of Supervisors in 1978.5 This
document replaced remaining portions of the Parks and Open Space Element not
already superseded.
In December 1973, an application for a General Plan Amendment was submitted to San
Mateo County by Visitacion Associates in an initial effort to develop 1,244 acres of
Crocker land Company land on San Bruno Mountain. This intensive project, known as
Crocker Hills, divided the property into six planning areas. One of the planning areas,
South San Francisco, encompasses all of the South Slope project site.
Due to the significance and ramifications of the proposed development, a Technical
Advisory Committee was organized in January 1974 to help San Mateo County.evaluate
the proposed development. The committee consisted of representatives from Brisbane,
Daly City, South San Francisco, Colma" San Francisco, local school districts, the San
Mateo Local Agency Formation Commission, San Mateo County and the developer.
32
III. Project Description
Visitacion Associates revised their development plan in response to concerns raised by the
Technical Advisory Committee and an EIR was completed in November 1975.6 Specific to
the South Slope project area, the plan proposed a combination of residential and
commercial development of 25% or 125 acres of the 4S0-acre South San Francisco area.
A fiscal analysi/ of the plan was examined along with the EIR and public hearings were
conducted by the San Mateo Planning Commission and Boord of Supervisors. This
extensive review process resulted in adoption of a General Plan Amendment in April 1976,
which would provide "a balance between economic growth and open space preservation,
and result in fewer adverse impacts than the applicants' proposal."S In accordance with
this objective, the Amendment limited development to three planning areas: the northeast
rid~:!__l?-rI$1:>ane, and South San F~ar1<:isco. The South Slope area (South San Francisco
---. , .... ... .,-.--- ..... --,--,
planning area}-wasdesig-OOte-d as a potential location for commercial and residential
development.
The presence of endangered butterflies had become a key ele!,""ent in the planning of San
Bruno Mountain. Subsequent to the adoption of the General Plan Amendment, portions of
the mountain were discovered to provide habitat for a federally listed endangered species.
In 1976 the U.S. Department of Fish and Wildlife (USFWS) had designated the mission blue
and San Bruno Elfin as "endangered" pursuant to the provisions of the Endangered Species
Act of 1973. Another butterfly, the callippe silverspot had been proposed for listing by
the USFWS in 1975. To ascertain the extent of these important resources, the County
commissioned an extensive biological study of the mission blue and callippe silverspot and
other species of concern.9,10 The major emphasis of this study focused on the mission
blue and callippe silverspot to determine their exact locqtion on the mountain, the
location of their food and larval resources and other information regarding their habitats
and life cycles. The findings of this study formed the basis of San Bruno Mountain Area
Habitat Conservation Plan (HCP).II An analysis of the project area 'was included in this
plan. The HCP and the biological studies that preceed it, form the basis of San Mateo
County's permit application under Section 10(0) of the Endangered Species Act, 1973 (as
amended). Such a permit is required to allow urban development of portions of the
mountain which provide habitat for endangered species.
Current County policy anticipates that a city may annex approved urban development
adjacent to that city. The San Mateo Local Agency Formation Commission (LAFCO)
designated the unincorporated South Slope area to be in the sphere of influence of South
33
'". Project Description
San Francisco. * Joint County and City cooperation was therefore initiated. In March
1981, a Letter of Understanding was adopted by the County and City of South San
Francisco to serve as a guide for joint review and approval of development proposals for
the South Slope area. Both jurisdictions would have to approve the final development
plan. The Letter of Understanding also established a joint South Slope Task Force
consisting of two members each from the City Council and County Board of Supervisors.
Members of the Task Force would serve as liaison to their respective legislative bodies
and oct as a steering committee for staff during the planning process.
A preliminary concept plan was submitted to the County by W.W. Dean and Associates as
a first step in developing a workable plan for the South Slope. Two public workshops were
held on June 20, 1981 and July II, 1981 in South San Francisco to offer an opportunity for
comments on the project design. As a result of issues and concerns raised at the public
workshops and after input from the Task Force, the preliminary concept plan was revised
by the project sponsor.
On August 26, 1981, a joint public hearing on the revised concept plan was held in South
San Francisco. Prior to the public hearings, the planhing staffs of the City and County
circulated a joint staff report to the City and County Planning Commissions as well as the
general public. The staff report recommended endorsement of the revised concept plan.
A document entitled "Analysis of Staff Report" and dated August 26, 1981 stated issues
and comments raised by concerned citizens in opposition to the proposed project. In
addition, a fiscal impact study on South Slope Concept Plan was completed and submitted
to the County in September 1981.12
A recommendation was made by the City and County Planning Commissions for approval
of the revised South Slope concept plan and on September 22, 198/ the City Council and
County Boord of Supervisors approved the plan. It was determined that a specific plan
and an EIR would be required to address all policies established by the General Plan
Amendment and all issues and concerns raised at the public hearings.
* The Terrabay Development was referred to as the South Slope Development up until the
publication of the Specific Plan, May 1982.
34
Ill. Project Description
Opponents to the South Slope concept plan organized a petition campaign and an initiative
was proposed to deny extension of South San Francisco municipal services to the South
Slope project. A special election was held in South San Francisco on October 6, 1981 and
the initiative was defeated 4,013 to 2,901.
Development of the South Slope area is presently contingent upon certification of the
Final EIR and approval of a specific plan of development. Should this occur, the South
Slope area would be annexed to the City of South San Francisco and subdivision approval
and building permits would be required and processed by the City.
I Unless otherwise noted, this section is based on San Mateo County Department of
Environmental Management Staff Report to the City of South San Francisco and San
Mateo County dated August 21, 1981 and on a telephone conversation on March 18, 1982
with Bill Rozar, Planner III, San Mateo County Department of Environmental
Management.
2San Mateo County, Master Plan -/990, January 1964.
3Regional Planning Committee of San Mateo County, Parks and Open Space Element of
the San Mateo County General Plan, May 1978.
4San Mateo County Planning Department, Conservation and Open Space Element of San
Mateo County General Plan, December 1973.
5San Mateo Department of Environmental Management, Planning Division, Parks and
Recreation Element of the General Plan, May 1978.
6URS Research Company, Final EIR - Application for a General Plan Amendment:
Crocker Hills, November 1975.
7Economics Research Associates, The Financial Effects of Crocker Hills on San Mateo
County, 1975.
8General Plan Amendment for San Bruno Mountain, 1976.
9Thomas Reid Associates, Phase I Re ort Endangered Species Survey, San Bruno
Mountain, Biological Study-I 80, prepared for San Mateo County, December 9, 9 O.
10Thomas Reid AsSOciates, Draft Endan ered S ecies Survey San Bruno Mountain,
Biological Study-1981, prepare or an Mateo County, Novem er 8.
I 'San Bruno Mountain Habitat Conservation Plan Steering Committee _ Chaired by San
Mateo County, Draft San Bruno Mountain Area Habitat Conservation Plan, May 1982.
12Recht Hausrath and Associates, San Bruno Mountain: South Slope Fiscal Impact Study,
September 198 I.
35
III. Project Description
D. RELATIONSHIP TO PLANS
A number of planning documents guide future environmental and development decisions in
respect to the proposed project site. They include the County General Plan Amendment
for San Bruno Mountain, the South San Francisco General Plan, the Association of Bay
Area Governments (ABAG) Regional Plan and the Habitat Conservation Plan for San
Bruno Mountain.
The following is a summary of these planning policies and their relationship to the
T errabay project.
I.General Plan Amendment, San Mateo County General Plan I
In April 1976, a General Plan Amendment was adopted by the Board of Supervisors in
response to a proposal submitted to develop portions of San Bruno Mountain. The
proposal, known as Crocker Hills, called for a high-density, mixed-use development
encompassing about 30% of the mountain.
The General Plan Amendment adopted by the Board provided for development of the
Mountain but for less development than specified in the Crocker Hills plan. Goals and
objectives were drafted to balance economic growth with open space preservation. The
following is a partial list of the Amendment's objectives relevant to the Terrabay project
area.
The general goals and objectives of the General Plan Amendment:
Provide for continued economic growth while meeting the needs for open
space in northern San Mateo County.
Provide a significant number of employment opportunities.
Aid in alleviating the general housing storage in San Mateo County by
providing for the construction of a significant number and variety of new
housing units.
Preserve and enhance the open space and environmental resources of San
Mateo County.
Reduce overall environmental impacts and preserve open space through a
compact development pattern.
Provide a wide-range of public and private services and facilities in the Plan
Area.
Minimize impacts on existing traffic and transportation systems.
36
III. Project Description
Minimize the impact of development in the Plan Area on the proposed
Regional Resource Park.
The Amendment designated several San Bruno Mountain planning areas as suitable for
development. The Terrabay project area is generally contained within the South San
Francisco planning area.
The objectives, policies and plan elements of the General Plan Amendment reflect
recommendations and planning strategies of documents prepared for the Crocker Hills
project. The proposed project differs in planning strategies from the Amendment,
although planning components are generally consistent.
The proposed project conforms to the General Plan Amendment with five exceptions:
The Terrabay plan does not provide for a high-rise housing complex for the
elderly.
The Terrabay plan does not provide for 20% low and moderate income housing.
The proposed project does not provide for warehouse development in the Sierra
Point subarea.
The Amendment calls for a community center located approximately in the
same location as the project's community recreation complex. The cultural
center, library, police station and religious facilities indicated in the
Amendment as elements of the community center are not provided for in the
project plan.
The project calls for development of areas which exceed at points the 30%
slope limitation on development listed in the Amendment.
Tables 3 and 4 illustrate these differences in development. The figures listed as "General
Plan Amendment" represent those listed for the "South San Francisco" planning area in
the Amendment.
The County's Department of Environmental Management has found the proposed project
plan is generally consistent with the General Plan Amendment. 2
37
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III. Project Description
2. South San Francisco General Plan
The South San Francisco General Plan was adopted by the City Council on April 21,
1969, and is currently undergoing revision. The General Plan calls for low-density
housing, a neighborhood park and an elementary school for the Terrabay area. The
proposed project conforms to the General Plan with two exceptions.
The Terrabay plan calls for commercial development along Airport Boulevard.
The General Plan has designated this land use as low-density housing.
The Terrabay plan does not provide for an elementary school site as designated
in the General Plan.
The two exceptions were among those impacts also identified for the Crocker Hills
(Visitacion Associates) development. In a letter prepared in response to the Crocker Hills
General Plan Amendment EIR, Richard A. Battaglia, Mayor of South San Francisco, made
the following comments with regard to mitigating conformance with the General Plan:
"Elementary School Site. The project plan does not provide the
elementary school site called for in the South San Francisco General Plan.
According to the South San Francisco Unified School District, surplus
capacities in existing classrooms in this area will amply accommodate the
projected increase in enrollment resulting from the proposed
development. Thus, no elementary school site is needed.
"Commercial Development. The project plan calls for commercial
development along Airport Boulevard, but the City's General Plan shows
none. However, the City desires to accommodate this proposed
commercial development and w~ld consider taking the necessary steps to
amend the City's General Plan."
3. ABAG Regional Plan 4
The Association of Bay Area Governments is a regional planning organization founded in
1961 by the cities and counties of the San Francisco Bay Area. Its purpose is to oversee
land control, plan for the future and promote cooperation on areawide issues. In 1980, an
updated version of the Regional Plan was prepared in an effort to provide inter-agency
coordination in regional planning efforts.
Regional goals of the Plan provide overall, long-range guidance in planning for the Bay
Area. The Terrabay project is consistent with these goals. The following is a partial
listing of the Regional Plan goals that are of particular relevance to the project area.
40
III. Project Description
Regional and subregional growth consistent with the city-centered concept of
regional development.
A permanent regional open space system that makes possible the range of
activities essential to the city-centered concept of regional development.
Protection and enhancement of San Francisco Bay and the major physical
features and environmental qualities of the region.
Maximum employment opportunities in the region.
Opportunity for all persons in the Bay area to obtain adequate shelter,
convenient to other activities and facilities, in neighborhoods that are
satisfying to them.
Active and leisure time opportunities for all the Bay area residents.
A physical environment pleasing to the senses.
4. San Bruno Mountain Area Habitat Conservation PlanS
An analysis of the Terrabay Development is included in the San Bruno Mountain Area
Habitat Conservation Plan (HCP). That plan and the biological studies that preceeded it
form the basis of San Mateo County's permit application under Section 10(a) of the
Endangered Species Act. Such a permit is required to allow urban development of
portions of the mountain which provide habitat for the endangered mission blue butterfly.
(Refer to Section IV.E. of this document for further discussion of the environmental
impacts to vegetation and wildlife.
The Terrabay Development is consistent with HCP objectives as they relate to specific
conservation needs. These objectives include project phasing to prevent sudden loss of
habitat, defining the interface of development and open space areas and minimizing
grading requirement to protect upslope habitat.
An apparent discontinuity exists between the operating program of the open space areas
as indicated in the HCP and as proposed by the project sponsor. The project area is
subdivided into two management areas in the HCP; 2-04-0 I which comprises areas of
permanent disturbance and 2-04-02 which comprises the temporary and undisturbed areas.
A temporary disturbance is defined in the HCP as "the portion of a development envelope
designated for grading at the time of development, but which will become reclaimed
habitat after a reclamation program is complete; area temporarily lost as habitat."S The
HCP stipulates that all lands within management unit 2-04-02 would be dedicated to the
County.
41
-~
III. Project Description
For dedication purposes, the project sponsor has divided the project site into two areas.
All undisturbed open space areas (approximately 153 acres) would be dedicated to the
County as conserved habitat upon issuance of the first grading permit for that parcel of
the project to which it pertains. In addition, Juncus Ravine, the separate I 57-acre parcel
adjacent to the project site would be dedicated to the County as permanent open space.
All temporary and permanently disturbed open space areas would remain within the
jurisdiction of the City of South San Francisco and under the purview of a combined
property owner's association (Figure 19). Recent litigation has focused attention on the
issue of liability for upslope lands. Areas which have been temporarily disturbed (i.e.
slopes which have been cut and filled) could provide a greater erosion risk than
undisturbed areas. It is the project sponsor's intent to retain a zone of continuous
jurisdiction in order to provide a unified zone of management and area of responsibility.
In accordance with the concern, therefore, the project proposes that temporarily
disturbed areas would not be dedicated to the County, but rather would be annexed, along
with the developed areas, into the City of South San Francisco.
Inasmuch as the 153 acres of undisturbed open space areas have not been specifically
designated, a mutually agreed-upon boundary would be determined at the time of
dedication.
The proposed project would generally conform to all other guidelines contained in the
HCP. The vegetation and wildlife section of this document (Section IV.E.) provide further
discussion of the mitigation guidelines as contained in the HCP.
I San Mateo County, General Plan Amendment for San Bruno Mountain, 1976.
2San Mateo County, Department of Environmental Management, Staff Report to South San
Francisco and San Mateo County Planning Commissions, August 26, 1981.
3URS Research Company, Final EIR - Application for a General Plan Amendment: Crocker
Hills, Volume 4, Response to Public Comment, 1975, page 238.
4Association of Bay Area Governments, Regional Plan 1980 - San Francisco Bay Area,
1980.
42
III. Project Description
E. COMMUNITY CONCERNS
Development of San Bruno Mountain's south slope has been the subject of controversy for
years. Throughout the history of proposals, planning efforts to balance development with
protection of the mountain environment have involved developers, public agencies, and
concerned citizens (see Section III.C., Background of Project). In light of such activity, a
public meeting was held at the beginning of this EIR process.
This meeting, held February 23, 1982, was advertised by the County and was attended by
representatives from San Mateo County, City of South San Francisco, EIP Corporation
(EIR prepared, PRC Voorhees, (traffic consultant) and about 15 citizens who came to
voice their concerns. Issues raised by the citizens focused on environmental and open
space and economic concerns as well as specifics of the planning process.
Storm drainage and possible flooding impacts of the proposed project were the major
environmental issue.s raised. Additional environmental concerns were fire hazards, slope
stability, loss of open space, and traffic impacts, including impacts on access from
existing residences onto Hillside Boulevard.
Economic issues include cost to the City of constructing and servIcing the project,
maintaining the recreation center, constructing the Hillside Boulevard extension, and the
economic viability of the hotel complex.
Planning issues included concern over the lack of information on which to base decisions,
whether or not the proposed project should be considered before or after the South San
Francisco 1969 General Plan is amended, impartiality of the Environmental Impact Report
preparers, and actual density of the development.
These issues were summarized in a compilation of letters and documents prepared by a
citizens action group and sent to EIP and others on March 9, 1982.' The key
environmental, economic and planning concerns expressed at the public meeting and in
this document have been addressed in individual sections of this Environmental Impact
Report.
I Analysis of Staff Report, submittal of citizens' comments to South San Francisco
Planning Commission, San Mateo County Planning Commission, and All Other Concerned
Citizens of South San Francisco, August 26~ 1981.
43
Ill. Project Description
F. OBJECTIVES OF SPONSOR
w.w. Dean and Associates, the project sponsor, wishes to construct a mixed use
development which would provide for community and economic growth while minimizing
environmental impacts and preserving open space. It is the intent of the sponsor to
achieve a reasonable return on its investment. The goals and objectives of the project
sponsor are discussed in detail in the Terrabay Specific Plan.
44
IV. ENVIRONMENTAL SETTING, IMPACTS AND MITIGATION
A. VISUAL QUALITY
I. Sett ing
a. Regional Character and Location
The project site occupies the south and east-facing, lower elevations of the San Bruno
Ridge. Smaller spur ridges run at right angles to the main ridgeline and divide the site
into eight separate swales (Figure 3). The swales are gently sloping near the southern
border of the site but become steeper, narrower ravines in higher elevations.
Site vegetation is predominantly grass interspersed with other non-woody species.
Upper elevation ravines contain some scattered chaparral while the only trees on the site
are at an abandoned 4-H facility. Overall, uniform vegetation of both ridges and swales
characterize the site. Aside from exposed rocks on the upper knolls and the few
scattered shrubs, there is little on the site to emphasize natural topography. Graded fire
trails and random dirt bike trails, which tend to run straight up and down slopes, criss-
cross the site.
The site, and the mountain behind it, form a natural backdrop for the intensively
urbanized area around the mountain. Hillside Boulevard and Randolph Avenue parallel
the site's southern boundary and separate it from existing residential development to the
south. These roads emphasize the present sharp division between urban and open space
areas.
b. Views
San Bruno Mountain is a regional landmark, visible from much of the northern peninsula.
At the mountain's lower elevations, however, distant views of the project site are
interrupted by Sign Hill, a prominent hill with "South San Francisco, the Industrial City,"
written on its southern slope.
45
IV. Environmental Setting, Impacts and Mitigation
A knoll at the site's western property line slopes sharply down to a complex of four
single-story elementary school buildings. Most of the site's other southward facing
ridges and swales can be seen from this knoll. A plantation of eucalyptus trees north of
Hillside Boulevard, and Sign Hill to the south, screen the western view. A new townhouse
project, in earthtone colors, and other multi-colored, single-family detached houses face
the site from across Hillside Boulevard. Noise from traffic on the four-lane boulevard and
from children in the schoolyard can be heard from the knoll.
The view south is dominated by the grassy, north face of Sign Hill with a water tower and
communications pylon at the top. One and two-story pastel-colored detached residences,
with associated trees and landscaping, occupy the base of Sign Hill (Figure 9).
Views east include additional residential development south of Hillside Boulevard and
Randolph Avenue, the grassy knolls and swales of the project site, and transmission towers
which cross the site near North Spruce Avenue. Further east, beyond the Bayshore
Freeway, lie industrialized bay fill lands with large one and two-story flat-roofed
buildings. Several vacant sites and the Oyster Point Marina are also visible along the Bay.
On clear days, there is a panoramic view from this point of the site, encompassing the
Bay, the San Mateo Bridge, and the East Bay Hills in the distance.
Proceeding east along the site, views to the west become focused along Larch and
Hemlock Avenues which run through Sterling Terrace subdivision. Distant views to the
east and west are restricted from the lower elevation swales proposed for development,
while the mountain behind and spur ridges to either side provide enclosure on three sides.
Views emphasize the foreground and middleground of Hillside Boulevard and adjacent
residential development. Each swale of the site affords a slightly different angle of the
views to the west, south and east; each is also framed somewhat differently by the
mountain behind.
Near the eastern end, a transmission line crosses the site and passes over Randolph
Avenue to a small developed hill east of Sign Hill. The terraced, unvegetated grading and
new development of this hill and the transmission towers on top dominate views south
from this end of the site. Views to the east focus on the industrial and freeway corridor
(Figures 10 and 11). The undeveloped, grassy knolls of the site bound the view to the
west.
46
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49
IV. Environmental Setting, Impacts and Mitigation
A steep-sided promontory forms the eastern edge of the site at the intersection of
Randolph Avenue and Airport Boulevard. A panoramic vista from this point includes the
distant ridge to the west, the peninsula and Bay to the southeast, and the East Bay Hills
from Oakland to Fremont. The proximity of the freeway and adjacent industrial
development make them the dominant features of the view. A level cut, midway down
the slope of the promontory, is an occasional dumping ground for auto parts and other
Ii tter .
The site's last two swales lie north of the promontory on east-facing slopes of the
mountain. These steeply-sided swales cannot be seen from each other or from the rest of
the site. Proximity to the heavily travelled Airport Boulevard causes this portion of the
site to collect litter and other debris from the road corridor. Views from these sites focus
on the freeway and adjacent industrial development. The upper elevations, corresponding
to upper stories of the proposed commercial buildings, offer more panoramic views of the
marina, San Francisco Bay, and the East Bay Hills.
2. Impacts
a. Project Description
The proposed project would consist of seven residential neighborhoods clustered along San
Bruno Mountain's southern slope. Two commercial centers are proposed at the base of the
mountain's eastern side, adjacent to the Bayshore Freeway. Five of the residential
clusters would be in low swales, and two of the neighborhoods, at the east and west ends
of the project, would be on prominent knolls. A recreation center complex, fire station,
and public athletic fields are also proposed in conjunction with a linear community park as
part of the development on the mountain's south side (see Figure 3, Section 111).
The project would alter the site's visual character from an open space setting to one of
expanding suburban development. The present sharp transition between urban and open
space along Hillside Boulevard would be changed. Grassy, undeveloped knolls would
continue down from the mountain to the site's southern boundary, breaking up the
development. Dense landscaping around the building clusters would create a pattern of
wooded swales and grassy knolls typical of the mountain's north side but contrasting with
the existing grassy south slope. Intensive landscape treatment near the building clusters
would emphasize fire resistant species. Open space areas more distant from the buildings
would be managed using fire resistant species. Architectural elements of the proposed
50
IV. Environmental Setting, Impacts and Mitigation
development would be visible within the context of existing topography and proposed
landscaping.
b. Regional Environment
The proposed residential buildings would appear similar in size to the existing one- and
two-story houses opposite the site. Because the proposed houses would be attached or
grouped together they would appear more dense within their clusters than the existing
houses which line up along the streets in a layout typical of earlier subdivisions. The new
development would respect the existing street pattern. Except for the proposed single-
family units, which would be laid out in a fan-shape, residential buildings would be parallel
to Hillside Boulevard and Randolph Avenue and parallel to the houses south of these
streets.
The townhomes and townhouses would share common walls. They would step back from
each other and rise or fall with the land contours in groups of two. This would break up
their linearity and reduce their bulk. The proposed project's larger buildings--the
condominium cluster, the hotel, and the mid-rise office structure--would be located on
the site's eastern border where they would be in scale with other existing large elements
and non-residential development along the freeway.
The hotel and office structure would contrast in mass and scale with the smaller
residential structures but would be separated from them by open knolls. The steep hillside
would form a background to these commercial structures and soften their appearance.
They would be tall, but would not break the ridgeline above them nor rise above the knoll
of the promontory condominiums. Those residences' views of the changing industrial lands
to the east (see Section 1'1.0., Land Use) would thus be preserved. Condominium
development on the promontory knoll would be very visible and would provide visual
identity for the rest of the project.
The architects seek to blend a proposed recreation center with the existing and proposed
development around it (see Figure 5, Section 111). Although the center would be large
(approximately 10,900 square feet), its small scale elements would help it to appear
smaller and more in scale with the residences. Like the houses, it would be two stories
tall, and they would have several design features in common: roofs, tight-colored stucco
walls, earth tone cement roof tiles, a southern exposure, and generous landscaping.
51
IV. Environmental Setting, Impacts and Mitigation
The proposed 70-foot wide Hillside Boulevard extension and the project's 60-foot wide
public residential collector road would separate nearby residents from the hillside
(Figure 12). Two steep, planted banks would add to this visual separation. For residents
at the site's east end who live north of Randolph Avenue, the site could no longer be used
as an extension to their backyards.
Separate pedestrian walkways would be provided to link on-site residential neighborhoods,
the linear park, recreational facilities and Hillside Elementary School. Pedestrian links
with adjacent existing neighborhoods would be provided at the intersection of Hillside
Boulevard with Jefferson Street, at the junction of Hillside Boulevard with Hillside
Extension, and near the Hillside Extension and North Spruce Avenue intersection.
Trailheads at two locations would tie existing and Terrabay neighborhoods to the mountain
trail system.
Views from the south to much of the proposed project, from El Camino Real, and portions
of South San Francisco, would be blocked by Sign Hill. Its southern slope obstructs views
of the site's lower areas where most development would occur. The proposed project
would be seen from Interstate 280 and from the residential areas on the flanks of the
ridge below the freeway. Portions of the develoment not blocked by Sign Hill or by the
adjacent hill to the east, would be seen from the extensive residential and industrial areas
southeast of the site.
The proposed hotel and tech trade center buildings and the promontory condominiums
would rise above the residential and industrial areas to the east and southeast and would
be visible from the Bayshore Freeway and from the urbanized corridor along it to the
south. They would be visible from the Bay, from San Francisco Airport, the San Mateo
Bridge, and, on clear days, from portions of the East Bay.
From a distance the hillside would look very different from its present natural state. The
developed swales would appear as alternating patterns of light and dark, sun and shadow,
according to each cluster's building arrangement. The undeveloped knolls would still
appear light, as they did before development.
At night, light from the street lamps, houses, outdoor spaces, and automobiles would
indicate development where a dark slope formerly existed. Street lights along roads and
52
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33
IV. Environmental Setting, Impacts and Mitigation
drives would be visible, especially those along uphill roads, perpendicular to the contours.
Except for the red flashing warning lights on transmission pylons, the rest of the hillside
(including the undeveloped knolls between clusters) would appear dark.
c. Local Environment
The buildings step up the slope, within their clusters, in east-west rows. Viewed from
residential areas south of Hillside Boulevard and Randolph Avenue, the south-facing
facades and roofs of the proposed buildings would be their most prominent feature.
Plantings and driveways between the east-west building rows would be less visible.
Perspective foreshortening would cause the building rows, especially in the townhouse
clusters, to appear close to each other, with roofs almost touching. T all trees if planted
on the slopes between the buildings, would soften the appearance of the roofs.
Parking and service roads running perpendicular to the hill's contours would be steep and
prominent. Roads running with the slope and parallel to Hillside or Randolph would be
less steep. They would more likely be shielded by plantings and buildings, and would be
less visually intrusive on neighboring residences.
Clustering development into neighborhoods would localize major grading operations.
Grading which does occur would be highly visible since existing vegetation and topography
would not screen views. Grading for roads and building pads would alter the existing
terrain and vegetation. The artificial shape and contrasting color of areas exposed by
grading would become less apparent after buildings were constructed and plant materials
matured. Incompliance with Hep guidelines, grading for the projectwouldoccur in two phases.
In order to reduce visual impacts a more restrictive phasing schedule could be required
subject to City and possibly County grading permits.
Individual buildings, their architectural details and colors, landscaping, and the outdoor
spaces between buildings would be apparent from existing residences and from nearby
vantage points. To unify the project and to create homogeneous neighborhoods within a
heterogeneous project, the architects intend to use a palette of related colors, similar
building materials and unified landscaping throughout the project. These unifying aspects
would include cream to light beige painted stucco exterior buildings and courtyard walls,
warm grey to brown earth tone cement roof tiles, clear to slightly bronze window glass,
brick and dark stained wood exterior trim, toned, patterned concrete courtyard paving,
natural concrete stairs and sidewalks, and black asphalt driveways. In addition,
54
IV. Environmental Setting, Impacts and Mitigation
ornamental street lights, sign posts, park benches, covered bus stops and stucco
walls/planters (with tile insets for names and numbers), would serve as unifying design
elements throughout the project.
The light colored residences would appear bright in the sunlight, and unless shielded by
plantings, windows may reflect low morning and afternoon sun as glare. Recessed entries,
roof overhangs, and articulated building facades and roofs would create shadow patterns
and some visual interest.
Residences would not have solar panels but would be properly oriented for solar
absorption. By using what the project architects call "The Zero Sideyard Concept,"
adjacent structures' blank exterior walts would define private outdoor courtyards for an
economical use of materials and maximum privacy. These outdoor spaces would occur on
the buildings' south sides, be wind protected, and look over the buildings below them on
the slope.
Commercial area buildings would incorporate architectual designs and materials that are
consistent with existing and proposed development along the freeway (see Figures 7 and 8,
Section 111). A condominium office building, sited in the bowl area northeast of T errabay
Point, would be a four-story concrete and glass structure with two adjacent surface
parking lots. A landscaped bank on the building's east side would slope down
approximately 12 feet to the main parking lot. A smaller building containing a satellite
restaurant would be visible on the office building's north side. The office and restaurant
buildings would block views from the rood of the proposed health club, thus enhancing the
club's privacy.
North of the office complex, and separated from it by a grassy knoll, the hotel and tech
trade center would be the site's northernmost development. An 18-story hotel, to be
constructed primarily of reflective glass, is proposed. This structure would be visible
from Airport Boulevard and the freeway, thus adding to economic viability. The building
would appear bright when reflecting morning sun and, in the late afternoon, would be in
the shadow of the mountain behind it. A three story glass atrium would architecturally
link the hotel to the eight-story tech trade center next door. Although the buildings
would be built in separate phases they would, when completed, appear to be one building
55
IV. Environmental Setting, Impacts and Mitigation
at the first three floors and would share the same atrium/lobby entrance. From the
fourth floor up, the buildings would appear as two separate towers. The tech center
building would be designed with alternating horizontal bands of concrete and glass. Two
large surface parking lots, with landscaped center medians, and a terraced parking garage
would be built at this site.
Landscape treatments for T errabay would vary according to location in the site. Medians
and buffers would define roads and allow selective screening of Terrabay buildings.
Intersections and access points to neighborhoods would contain planters and formal
arrangements of trees and shrubs.
A transition zone would be provided between the highly designed residential landscape
areas and the native grassland. This transition would be based on a 50-foot wide fire
break. The first 25 feet of this break would be permanently irrigated to sustain
ornamental plant species. A temporary irrigation system for the remaining 25 feet would
operate long enough to establish native and drought-tolerant species. This fire control
measure would contribute to the project's appearance of densely vegetated swales and
open, grassy knolls.
The buildings' colors and shadows would be visible against the green firebreaks and against
the hillside's natural grassy cover. These surroundings would change from golden brown in
summer to green in winter.
To save open space and to economically use the road system, residences would be
attached or grouped closer together than in single-family subdivisions. Garages for
townhomes and single-family units would be grouped around auto courts, and each court
would serve four garages to reduce paved driveway area. Exposed visitor parking would
be in the areas between buildings.
Residents' garages in the townhouses and condominium clusters would be under the
buildings. Individual units would be entered directly from the private parking spaces
within the garage. An open, raised, secured concrete deck would cover the garage and
provide separate pedestrian access to the units. Guests would park in widened bays
outside the garage at grade and walk up to the deck and to the units. Textured concrete,
potted plants, and exterior lighting would soften the deck's appearance.
56
IV. Environmental Setting, Impacts and Mitigation
The Hillside Elementary School is adjacent to the westernmost knoll proposed for
development. The townhome project on this knoll would overlook the school from the
formerly vacant knoll.
From trails in the San Bruno Mountain State and County Park and the open knolls above
the development, lights, tile roofs, cars, and paved areas could be seen, although
landscape buffer would soften and break up the mass of this developement.
3. Mitigation
a. Mitigation measures proposed as part of the project.
The project sponsor has incorporated the following mitigation measures into the project
design in an effort to mitigate visual impacts.
Development would be generally restricted to the swales; the knolls would remain
open. The development would appear as a series of clusters, not as a mass. The
entire project would not be visible at one time, nor would it break the ridgeline.
Residential structures would be oriented for solar absorption and for views, but
would not incorporate solar panels for hot water heating.
Auto courts would each serve four garages to reduce paved areas and would
preserve open space in the townhome and single-family unit clusters.
To save open space, the road system would be efficiently designed.
To unify the project, lower building costs and create homogeneously designed
neighborhoods within the project, restrained natural colors, unifying building
materials and landscaping would be used throughout the development.
To save open space, units would attach or group more closely together than in
standard subdivisions by using the "Zero Sideyard Concept."
Stepped buildings would break up the visual mass and reduce the amount of
required grading. The visual mass would be integrated into the hillside by
stepping, offsetting and rotating buildings were feasible and by providing tree
grove clustering in a naturalistic setting.
57
IV. Environmental Setting, Impacts and Mitigation
Articulated facades, recessed entries, roof overhangs, and courtyards would
create varying patterns of light and shadow to soften the residential buildings'
appearance and to create visual interest.
A uniform system of street furniture would tie together diverse clusters of the
project.
Pedestrian access would be provided at the intersection of Hillside Boulevard and
Jefferson Street, at Hillside Boulevard and Hillside Extension, and near the
intersection of Randolph Avenue and North Spruce Avenue.
Pedestrian walkways would be provided to minimize street widths as shown on the
walkway plan.
Rapidly growing trees would be planted around parking areas and on slopes
between building rows to break up the visual mass.
Street lighting would be kep low, as shown on the hardscape plan, to reduce glare.
The construction period would be kept as brief as possible to reduce visual
impacts and phased as indicated in the proposed Habitat Conservation Plan.
The natural, vegetated appearance of graded areas which would not be
permanently disturbed, would be hydro mulched just prior to the upcoming rainy
season. The natural appearing rounded knolls would be maintained by the grading
concept.
The above ground, one million gallon steel water tank would be located in a
disturbed open space area within the jurisdiction of the City (see Section IV.F.,
Community Services, Water Service) and painted with earthtone colors. Screening
would be provided by such methods as landscaping and mounding to reduce visual
impacts. If feasible, an underground tank would be utilized.
58
IV. Environmental Setting, Impacts and Mitigation
b. Mitigation Measures Recommended by EIR Consultant.
The following mitigation measures are recommended by the EIR consultant to assist the
project sponsor in designing a development which would be sensitive to the special visual
considerations posed by the T errabay Site.
Tall trees should be planted within parking areas and on slopes between building
rows to break up the mass of roofs and concrete decks when viewed from above.
These trees would also help to break up the mass of south-facing facades when the
project is viewed from the existing residences to the south.
Residences could incorporate into their south-facing roofs well-designed solar
panels for hot water heating.
Reflective surfaces on all buildings with the commercial portion of the
development should not exceed 40% reflectance to minimize glare impacts.
59
IV. Environmental Setting, Impacts and Mitigation
B. GEOLOGY AND HYDROLOGY
I. Sett ing
a. Topography
fhe site consists of rolling, gently to steeply sloping terrain on the south and east-facing
sides of San Bruno Mountain (Figure 13). Spur ridges, extending approximately
perpendicular to the main ridgeline create eight embayments on the site. These are fairly
. open, gently to moderately sloping swales along the lower, south and east, edges of the
site. They become steeper, narrower ravines at higher elevations along the north and
west si te boundar ies.
Along Airport Boulevard elevations range from approximately 125 feet above sea level
(as!) in the northeast corner of the site to approximately 25 feet asl at the Airport
Boulevard/Randolph Avenue intersection.' Elevations along Randolph reach 150 feet asl
at the conjunction with Hillside Boulevard, and 250 feet asl at the edge of Hillside
Elementary School playground. Across the top of the site elevations are slightly more
variable since the irregularly shaped development boundary crosses several spur ridges and
ravines. The east-facing portion of the site rises to between 450 and 575 feet asl. The
south-facing portions rise to elevations between 300 and 550 feet asl. The prominent
knoll near the Airport/Randolph intersection is 285 feet asl.
More than half the site contains slopes with gradients less than 30%.2 Most of this is on
---the south-facing side of the site. Generally the centers of the swales slope from 5% to
, "_..___.u.....__.^
I 5% and the walls slope from 1 5% to 30%. The ends of the spur ridges slope between 30%
and 50%. There are isolated areas of less than 30% slope along some ridgetops but they
are small and usually adjacent to very steep slopes (greater than 50%). On the east-facing
portion of the site the ravine sides generally slope between 30% and 50% with several
adjacent ridge walls sloping at more than 50%. The two swales have slopes generally
between 15% and 30%. The lowest areas along Airport Boulevard slope between 5% and
15%. A slope analysis map is shown in Figure 14.
b. Bedrock Geology
The bedrock geology mapped by previous investigations was reviewed and refined during
the geotechnical investigations of the project site.3 The text of the Phase II Report4
appears as Appendix D of this EIR.
60
IV. Environmental Setting, Impacts and Mitigation
The site is underlain by two units of the Franciscan Assemblage: sandstone with thin
interbeds of siltstone and shale (KJfss on Figure 13) and melange, a mixture of
sedimentary and metamorphic rock types (KJfm on Figure 13). Bedrock is discontinuously
exposed on the ridges and ravine walls throughout the site. It is buried by unconsolidated
sediments in the floors of the swales. The northern and eastern portions of the project
site are underlain by Franciscan sandstone. It is a hard, strong, erosion resistant rock
which has not been affected by major faulting. Much of the site is underlain by
Franciscan melange which contains deeply weathered claystone, siltstone beds, fragments
of sandstone, chert and metamorphic rocks such as serpentine, chlorite schist and
metasandstone.
Melange units are commonly considered to represent ancient fault zones. Exploration
trenches (Figure 13) dug through the melange units and serpentinized areas did not expose
evidence of major faults or shear zones on the site. Some evidence of minor faulting was
discovered but it was determined to be ancient activity with no movement in historic
time.
Both bedrock units could generally be excavated by conventional earthmoving equipment.
Some areas of exceptionally hard rock, particularly sandstone, metasandstone, and chert,
would be difficult to excavate and could require light blasting. This will be addressed in
further detail during a later phase of geotechnical studies.
c. Soils
The bedrock units are overlain by a discontinuous rocky loam soil mantle consisting of
colluvium (slope wash) alluvium (stream deposits) and a minor amount of artificial fill.
The natural soils are part of the Gaviota eroded Rockland association generally found on
steep slopes containing numerous exposures of bedrock. Thickness varies from less than
three feet on the upper slopes to approximately 20 feet in the lowlying swales around the
base of the site. Drainage is good to excessive at the surface but moderately slow in the
subsoil. The soil is prone to erosion since it saturates rapidly when wetted, producing high
~~,!~ff v~~es on steep slopes.5 This would produce gullied hillsides and sediment
blocked drainage ways if no erosion/sedimentation control plan were implemented during
construction or long-term area use (see B.2.d. Construction Impacts and B.2.f. Operational
Impacts of this report).
61
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SOURCE: DOUG DAHLIN AND COMPANY
Terrabay Development
TERRABAY SITE GEOLOGY
62
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TERRABA Y SITE: SLOPE ANALYSIS
64
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IV. Environmental Setting, Impacts and Mitigation
d. Seismicity
The project site, like the entire Bay Area, is in a region of high seismicity which annually
experiences low to moderate earthquakes epicentered along four major historically active
fault zones (Figure 15). The San Andreas Fault, approximately three miles southwest of
the site is the closest known active fault. The Seal Cove Fault is off-shore about ten
miles to the southwest. The Hayward Fault and the Calaveras Fault are about 15 miles
and 27 miles, respectively northeast of the site. In 1979 a minor earthquake (Richter
magnitude 4.2) occurred along the San Andreas Fault; one minor and one moderate
earthquake (Richter magnitudes 4.8 and 5.9) occurred along the Calaveras Fault.6 Three
moderate earthquakes of Richter magnitudes 5.5 to 5.9 occurred along the Calaveras
Fault in 1980.7
There are no known active faults crossing the site. There are several inactive faults near
the site. The San Bruno Fault (I Y4 miles southeast) the City College Fault (21f2 miles north)
show no evidence of historic activity. The Hillside Fault has been previously mapped as a
single or double trace northwest and southeast of the project site. Fault investigation
trenches across the extension of these traces revealed no evidence of the Hillside Fault on
the site. The site is not in an Alquist-Priolo Special Studies Zone, but it would experience
strong groundshaking during a major earthquake along the San Andreas Fault.
e. Landslides
A large number of landslides and soil creeps have occurred on the site (Figure 16). There
is no single factor, such as steepness of slope, which determines whether a hillside will
fail as a landslide or as soil creep, (a slower, less dramatic downslope movement). Depth
and composition of soil, degree of water saturation, subsurface and downslope support, as
well as ylope steepness all contribute to the landslide/soil creep susceptibility of a soil
unit. Depending on the orientation of planes of weakness within the rock, the Franciscan
sandstone on the project site is susceptible to slope failures on deeply weathered or
extremely (greater than 70%) steep slopes. The colluvium (slope wash) is considerably
more susceptible to soil creep, even at slopes as low as 5%, and susceptible to landsliding
at slopes greater than 30%. The Franciscan melange is susceptible to landsliding at slopes
greater than 15%.8 The General Geotechnical Summary9 in Appendix E of this EIR
indicates that all the areas proposed for development are affected by landslide/soil creep
66
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Terrabay Development
ACTIVE FAULT ZONES IN BAY AREA
67
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/ '\\" /, /, ,,-'-1
'"~~-----~::-- --" ---:::..-
-- '-.- ~
.-- :::;~;:-'
- -~.-
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, ---
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,,'~
...-----...
,,~
, "---::=--
-
'-,-
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- '
, ---=-
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-- -
",..::: = ~
--:;~-
-~
~',
~,
./ 1,/ '7":,-1
2J / /'''',1'
~.i"lJ~i
:z;i'l;'J ',I
//L/ "
/ //,1::// ,'/.
;;1 , r / // /
J, / " /1
_____ I / '
----" j
~ /,1/
/,'"
/ -
)~/ /1-
/ /~
"---
,~
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~~:;4 __~_
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":;~~~~.~/
4\11..... EXISTING LANDSLIDE
AREAS
+- SOIL CREEP AREAS
uuuuuu B 0 U N D A R Y 0 F PRO PO SED D EYE LOP M E ~ T
TERRABA Y SITE: POTENTIAL LANDSLIDE AREAS
-...." -
.gure: 16
----..... ---- -........ ~~
- ~ ~----'~~ '::-::-
" '-------.. '
~~s~=--=-,-/
'--- - - --- ---
~~",-~-.....
,~--=---= '-- ~- ~
,'-- ...--
.'- ..---
~~?-
" "-
---
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-:.
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,,,<..,/
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/l'
SCALE
o 250
500
N
FEET C:~
1 COO "---7
Terrabay Development
Figure: 16
TIIIII""A' .,TI: POTINT.AI. I.ANOSI.IOI AIII...S
69
IV. Environmental Setting, Impacts and Mitigation
conditions to some extent. Some of the major slides range in maximum depth from 25 to
55 feet, while numerous minor slides are 10 to 15 feet deep. In their present condition
these landslide deposits are susceptible to future sliding and would require stabilization if
they were in or near areas to be developed. 10
f. Surface Drainage
The site occupies the lower areas of two watershed subbasins on San Bruno Mountain.
From Hillside School to the Airport Boulevard/Randolph Avenue intersection the site is
part of a 552-acre watershed which drains to the South San Francisco-Paradise Valley
System. Northeast of the intersection the site forms part of a I 82-acre watershed which
drains directly to San Francisco Bay.
The slopes of San Bruno Mountain above the project site are very steep (greater than
30%). There are no major streams from these slopes which cross the site, but several
seasonal creeks have cut well defined drainage channels which appear as ravines on the
steep slopes and swales on the shallow slopes. Because of the steepness of the slopes, and
fairly impervious soils on the upper slopes, runoff is rapid and allows little time for
percolation into the soil. Some drainage channels discharge directly into the City storm
drain system. Studies conducted by San Mateo County have shown that the existing City
systems immediately downstream of the project site are inadequate to handle the flows
from the San Bruno Mountain watersheds in an undeveloped state.
The watershed area east of the Arden Avenue/Randolph Avenue intersection has no
defined City storm drain collection system. Currently storm drainage filters through
backyard drainage systems to Randolph Avenue and east to Airport Boulevard. The
subbasins which front on Airport Boulevard drain into roadside ditches which then feed
into small culverts under Bayshore Freeway. From these culverts, storm runoff flows
through a highway ditch parallel to Bayshore Freeway on the east side to San Francisco
Bay. This highway ditch could not transport flows of the magnitude which would be
generated by the proposed development without some form of improvement.
No part of the project site is within a IOO-year flood zone. However, much of the land
east of Bayshore Freeway and north of Oyster Point Boulevard is in a 100-year flood zone.
70
IV. Environmental Setting, Impacts and Mitigation
Rainfall in the area averages between 22 and 24 inches per year, with the majority falling
from October through March. I I Mean annual runoff in normal years has averaged
between 4 and 6 inches.12 This does not include the drought years of the past decade
during which average annual runoff was lower. The heavy rains of the 1981-1982 winter
produced more runoff than occurred during the drought and more than average runoff for
a non-drought year. The specific quantity of runoff is affected by the intensity and
frequency of rainfall, the steepness of slopes, the amount and type of vegetation and the
depth and grain size of the soils. Intense heavy rainfall and steep slopes increase runoff.
An undisturbed cover of grasses, herbs, flowers and trees reduces runoff. Coarse-grained
(sandy) soils absorb more runoff than fine-grained (silty or clayey) soils particularly if the
fine-grained soils swell when wetted. Deep soils generally have a greater water retention
capacity than shallow soils of similar grain size. Initial runoff coefficients for
undeveloped areas vary depending on the relationships among the previously mentioned
factors.l~ Under existing conditions of steep slope and easily saturated soil the project
site probably has an average runoff coefficient in excess of 50%.
g. Groundwater
The approximate locations of several springs and ponded drainage areas above landslides
are shown on the Figure 13 at the western end of the site. A minor amount of seepage
was encountered in each of the fault exploration trenches within ten feet of the surface.
Standing groundwater levels reported in the bore holes reviewed by the geotechnical
consultants varied considerably and represented shallow seepage of infiltrated surface
water rather than a true water table.14
2. Impacts
a. Geologic and Hydrologic Impact Criteria
In 1975 a table of criteria was developed to assess the potential adverse geologic/hydro-
logic impacts of the Crocker Hills development. 15 Since the proposed Terrabay
development occupies part of the same area covered by the study it is advisable to
consider that earlier evaluation (Table 5).
A "worst-case co,.,dition" rating (Degree of Impact) is described in Table 5 to point out
geologic problems that could result if mitigation measures are not applied. To put
potential problems into proper perspective a degree of mitigation difficulty (Mitigation
71
Oeqree of Impocta
Significant
Moderate
low
Significant
Moderote
Significant
l,Ioderate
low
Moderate
low
Significcnt
.''''oderate
GEOLOGIC II,IPACT CRITE?!A
TAFlLE 5
Mitigation
Rankinqb
I to V
IV
v
II to IV
III to V
III to V
v
v
IV to V
IV
Jescription of
?ot~tiol Adverse 1"."oactC
A. Potential conflicts ~etween proposed pro-
ject and ~atential geoiogic hazards at the
project site:
I. "'cult Oisolacement
a. Construction of residential, co,"-
mercial, or ,oublic buildings or 'T'lajor
utilities within SO feet of :In "octive
fault."
b. Construction of residential, c~mer-
cial, or public buildings or 'T'loior util-
ities within SO feet of (] "potentiallv
active fault."
c. Construction of residential.
commercial, or public buildings Qr
major 'Jtilities within 50 feet Qf a
"potentially active Foul t."
2. Eorthauoke Shakina
o. locating shallow foundation Hr'-lc-
tures or underground utilities in areas
de termine<1 to consti tute 0 poten-
tially high risk due to effects of
eartnQlXlke shaking Wquefoc tian.
lurcn crocks, slumping, densificotion,
lateral spreading, or landsliding).
b. locatina shalla'N Foundation str'JC-
/1Jres orunderground utilities in (]reas
of poteMiall', moderate risk due to
effects of eorthquol<e shaking.
3. 5 tatic Slooe Instobili tv
o. locating structures, roads, ,~ut
slopes, or underground utilities 'Nith-
in, at the t()o!, or at the crown of oJn
existing landslide deoosit, or I"~ Jreas
::leter'T1ined to constitute " >'Oten-
tiollv serious limitation for ::leve!op-
,."ent due to ;nnerent slope ''''stabil_
ity.
b. locating structures, roods, ':ut
slopes, or underground utilities within
areas determined to constitute (]
potentially moderate limitotion for
develOl)ment due to slope instaoility.
4. Erosion Activity
o. Locating S1'rvetures. roods, or
underground utilities in ereas pre-
sently undergoing erosion or sil tation.
S. Exoansbe Soils
o. Locating shal!ow fOlJndation str....:-
lures, concrete floor slcbs, pave-
ment, ,?r retaining walls in areas of
nigh shrink-swell potentiol.
b. locating shallo'N foundation struc.
tures, concrete floor slcb~, pave-
'Tlent, ?r retaining walls in ar~s of
moderate snrink-swell potential.
3. Effects of oroposed project on geolngie
condi tions/phenomena ot tne project si te
and in tl'le local setting: .
/. Incre<]se Slooe InSTobil! ty
a. Grading ac tivi ties 'not 'JnderC"Jt tne
supporting geological seooration
(plane .of 'Neakness) in a rock 'T'lCSS
and develooments whic;, 'Nill increase
infiltration of '1roundwoter or odd
static weight to potentiall., unstaole
slopes.
~.
Use of nil slooes steeoer than 2:: Jnd
over 25 feet ,ioh. 'Jse.of sliver F'J:s
:ess than 10 -feet wide on steep
slOl)es.
72
~eqree of Imoacta
,"litigation
Rankinqb
Descriotion of
Potential JJ.dverse i;,-,pactC
2. increase Rate a. Erosion Siltation
Significant
(Short-Term)
IV
a. Removing prote-=tive vegetal cover in
areas of high erosion potential during
'Ninter C"Ionths (~.Jovember - .l.pri Il.
Moderate
(Short- Term)
IV
b. Removing protective vegetal cover in
ore<]s of 'T1oderate erosion potential
juring winter mont,hs ('Iovember -
.l.pril).
L"w
(Short-Term)
III to V
c. .l.ccelerated rote of sll tation in oH-
si te drainage facilities and receiving
waters.
J. Creation of Foundation "'oblems
Moderate
v
a. Using oversized (larger than 5 inches)
rock material in .ill that 'Nill suopor!
strUCTures. thereby increasing poten-
tial for differential settlement.
4. Loss of .'Aineral Resources
Significant
a. Loss of mineral resource deposit (:lue
to loss of access, change in land 'Jse.
or change in zoning) which is of
regional, state, or '"IOtional signifi-
cance.
Moderate
b. Loss of mineral resource deeosi t
which is of significance on a local or
county level.
5. Loss of Uniaue Gealaaic F ectures
Significant
I to V
a. Loss of a regional/v 'Jniaue feature.
L.ow
I to V
b. Lass of laeall" unique feature.
a.
impacts are long-term unless otherwise noted.
b.
::xplanation of ""litigation Ranking" ~,Iototions:
Problems essentially impossible to overcome.
II Problem usually diffiC'Jlt to overcome. and mitigation aommon!'l ~ot feasible due
to expense.
III "r"blem 'JSU<ll/v can be overcome. but ditficul ty and ""xoense'T1av ~"na"r
mi tigation measures unfeasible.
IV Problem usually can be overcome Nith ",oderate difficulty and expense.
V Problem usual/y can be overcome Nith minor difficulty and expense.
c.
lJefinitions of Sefect'!<i T'!rms:
Active l:' QUI t
- fault of known historic activi ty or .:'owing
evidence of :"T1ovement within the ;-!olocene
(past 11,000 vears).
POTentiallv Active =-aul t
- fault snowing evidence of movement within
the ,')uaterncry (past 3,000.000 years).
Conditionallv Active =-cult
- fault t!'lat is ,~ot known to ':le ;lOtentially
crctive according to available geologic :jafo.
but that ;s considered condi tionally inactive
sub!ect to confirmarion by "'ore intensive
investigations.
73
IV. Environmental Setting, Impacts and Mitigation
Ranking) is given ranging from "minor difficulty and expense" (V) to "essentially
impossible to overcome" (I). The table indicates a majority of Moderate to Significant
adverse impacts with regard to development on San Bruno Mountain. Most mitigation
difficulties can be overcome, given sufficient financing. Notable exceptions are the
danger due to fault displacement and the potential loss of unique geologic features.
Applying Table 5 to the Terrabay project produced the following impact information:
Potential Geologic Hazards
Fault Displacement. Current investigation indicates fault displacement is
not a significant problem at the proposed project site.16
Earthquake Shaking. The area will be subject to seismic groundshaking (see
B.2.f. Operational Impacts).
Static Slope Instability. The numerous landslides which exist on the project
site (Figure 16) have been taken into consideration during the geotechnical
feasibility investigation (see B.2.e. Development Area Impacts).
Erosion Activity. Erosion potential at the site is high, therefore erosion/sedi-
mentation control measures are necessary during construction (see B.2.d.
Construction Impacts) and operation (see B.2.f. Operational Impacts).
Expansive Soils. No expansive soils were reported on the site (see
Appendix D. Geotechnical Feasibility Study).
Project Effects on Geologic Conditions
Increase Slope Instability. Grading plans would comply with City/County
requirements and should be evaluated for each development area within the
project (see B.3.b. Mitigation).
Increase Rate of Erosion/Siltation. An erosion control plan would be
implemented (see B.3.a. Mitigations).
74
IV. Environmental Setting, Impacts and Mitigation
Creation of Foundation Problems. Foundations should be constructed to
correct specifications under the supervision of a qualified engineer (see B.3.b.
M it igat ions).
Loss of Mineral Rights. No level of impact can be established for this possibility.
Loss of Unique Geologic Feature. The area of San Bruno Mountain proposed
for the development of T errabay is not a regionally or locally unique geologic
feature.
Hydrologic problems center around the increase of impermeable surfaces. This can
increase runoff, thereby effecting the surface drainage, and decrease groundwater
recharge, thereby effecting the water table. Runoff flow increases can result in damage
to the storm drainage system and flooding. Decreased groundwater recharge can lower
the water table resulting in saltwater intrusion, subsidence, or well failure. Groundwater
recharge problems are not of major concern at the project site. Inadequate storm
drainage and flooding are major concerns (see B.2.f. Operational Impacts and B.3.
Mitigations).
b. Grading Concept 17
The grading concept proposed for all development areas except T errabay Point (Area 7 on
Figure 13) would provide stepped building pads up the swales, leaving the knolls as distinct
landforms between the neighborhoods. At Terrabay Point stepped building pads would be
constructed on the knoll. Building sites and access roads have been designed to minimize
grading and to approximate a balance of earthwork (cut and fill amounts approximately
equal for the total project). Temporarily disturbed grasslands which are outside
permanent development areas would be reseeded with indigenous, low water consumption
plants. A 50-foot wide border of fire retardant plants would be provided between the
natural grassland and the developed areas. Slopes would generally be graded to 2: I
(horizontal to vertical) except where soil conditions permitted steeper slopes, or to
maintain existing landforms. These areas would be defined by site-specific, soil studies
during the design phase. Ditched terraces eight feet wide and 40 vertical feet apart
would be constructed to control debris fall and to direct runoff to the storm drainage
system.
Grading would occur in two phases. Phase I would include all road work along Hillside
Boulevard and Randolph Avenue as well as Development Areas I, 2, 3, 6 and 7 (Figure 13).
75
IV. Environmental Setting, Impacts and Mitigation
Phase II would include Development Areas 4, 5, 8 and 9. Approximately 159 acres of the
332-acre site would be graded, plus an additional 20 acres would be graded for the Hillside
extension and the proposed public road. About 1,870,000 cubic yards of material would be
cut and about 1,920,000 cubic yards of material used for fill. About 50,000 cubic yards of
fill would need to be imported.
The grading plans would adhere to the provisons of the Habitat Conservation Plan. There
are an insignificant number of trees within the proposed grading area. Abrupt transitions
between graded and natural slopes would be minimized.
c. Drainage Concept 18
The proposed storm drainage concept would provide an on-site drainage system and a
trunk line to intercept runoff from the open spaces upstream of the developed areas. No
porticn of the lowest parts of the site would discharge to the existing City system.
Siltation basins and trash/rock catchment basins would be provided at inlets for all major
storm- runoff channels.
The system would be designed to accommodate a 10-year storm and would transport
runoff directly to the Bay thus helping to alleviate existing capacity problems along
Hillside Boulevard and Randolph Avenue. The system would be constructed to the City of
South San Francisco standards and all capital costs would be borne by the project sponsor.
Upon acceptance of the facilities, the City would assume maintenance responsibilities for
the portion of the system which is designated as public facilities. The remainder of the
system will be maintained by private owners or homeowners associations.
A cost-benefit study of four alternate drainage systems was used to develop the proposed
system. 19 The system is illustrated in Figure 17 and described in the storm drainage study
as Alternative Number Three.20 That description has been updated by the supplement to
the Specific Plan as follows:
Under this alternative all flows from the slopes upstream of the subdivision as
well as the flow from the subdivision area will be intercepted and transported
along the contours through the subdivision to the crest of the hill just east of
the intersection of Arden Avenue and Randolph Avenue. At that point, the
storm drain trunk line enters the proposed alignment of Hillside Boulevard-
76
IV. Environmental Setting, Impacts and Mitigation
Randolph Avenue Extension and intercepts flows from the easterly portion of
the subdivision as it continues easterly in that alignment to Airport Boulevard.
At Airport Boulevard the trunk line passes under 8ayshore Freeway in a bored
and jacked 36" diameter reinforced concrete pipe which outlets into the
existing highway ditch parallel to Bayshore Freeway on the east side. This
ditch must be concrete lined to its terminus at the Bay in order to
accommodate the additional flow.
The runoff from the health club/restaurant/office condominium area fronting
Airport Boulevard is picked up in a separate interceptor and crosses under
Bayshore Freeway at an existing 36" pipe located north of the first crossing.
Runoff from the hotel and tech center is also collected separately and crosses
under Bayshore Freeway to three existing storm drains (one 48" and two 27"
drains).
This alternative will intercept the majority of flow from above and within the
proposed subdivision area and efficiently transport it to the Bay while relieving
the undersized City storm drain systems. The small amount of flow from areas
downsteam of the interceptors will feed into the City storm drain. Alternative
113 is the most cost effective alternative when the combined cost of on-site and
off-site drainage improvements are considered.
The system would drain a total basin area of about 530 acres which would produce a
cumulative flow of about 510 cubic feet per second during a rainfall of 1.5 inches per
hour.21
Installation of the storm drain system would require plan review by the City of South San
Francisco and a permit from Caltrans to bore and jack the storm drain trunk lines under
Bayshore Freeway. Approval would be needed from the Hydraulics Section of the local
Caltrans office to improve the highway ditch east of Bayshore Freeway. Caltrans is
currently planning (I) to bore and jack a storm drain across Bayshore Freeway at one of
the locations proposed for the T errabay drain crossing, and (2) to improve the Bayshore
Freeway east side ditch. Close coordination between Caltrans and the project sponsor
may be needed to assure optimum efficiency of the p"roposed drainage systems.
If the improvement work on the east side highway ditch stops short of the tidal zone no
permit would be required from Bay Conservation Department Commission. Intermittant
ditch flows normally do not require permit approval by the Corps of Engineers.
77
~---
I
/
~~< ~.:i~ ~
/
- PROPOSED STORM DRAINS
SOURCE: W.W. DEAN. ASSOCIA T!S
TERRABA Y SITE DRAINAGE SYSTEM
. 73
"tun: 17
,~~>
.~~--;',~
-~"
il
f_. '"
I -----------.
/------ i f
'~ I ;
/ /
',-'----, - I'.
.,,=-.. .:.:::..~_.
, ~.~, ---
. ~~I
/j/,:~~~~- ,
~, ......~ -~--
./ ',:\\,X;'~~---:'~:>;~'-
\ ",.~,-..:::.~~,
HEALTH CLUB
RESTAURANT
N
ffi
NOT TO SCALE
Terrabay Development
Figure: 1 7
T.''''A.AV OAAJHA08 SYST!M
IV. Environmental Setting, Impacts and Mitigation
d. General Construction Impacts
The proposed T errabay development would require extensiveexcovation andbackfHling_________
,- throughout the devefoped portion of the site in two phases of grading. Buildout would be
in six phases generally progressing from west to east (see Table 2) with the road
alterations along Hillside Boulevard and Randolph Avenue contained in Phase One. ~b~_
removal of vegetation during grading would expose the land surface to increased on-site
erosion potential and, consequently, increased off-site sedimentation of drainage systems.
Erosion potential is affected by degree and length of slope, soil properties (such as texture
and cohesiveness), duration of exposure and amount/intensity of rainfall. In general,
erosion potential increases with steepness even though slope length decreases. For
example; a 75-foot long, 15% slope has at least as high erosion potential as a ISO-foot
long, 7% slope. Loose sandy soils tend to erode more easily than compact clayey soils.
The longer a site is exposed to rainfall, the greater the amount of material which
potentially could be removed by erosion.
Sand-sized soil particles would have a more deleterious effect on drainage systems than
silt or clay-sized particles. Sand, being a larger, heavier particle would settle rapidly as
water velocities dropped and would clog channels and pipes. Silt and clay, which are
smaller, lighter particles would tend to be carried through the drain systems and deposited
in the bay.
The steep slopes of medium to fine grained soils on San Bruno Mountain would have hi~___
----._---~---------_._--~.^.-. --~ --
erosion potential if disturbed during the rainy season (November to March). Eroded soil
leaving the site would eventually clog the-existing storm drain system creating serious
storm water backups and overland flows.
The General Geotechnical Summary (Appendix E of this EIR) indicates that most of the
areas to be graded are "rippable to marginally rippable," that is, can be excavated with
conventional or heavy crawler tractor-ripper units. Light blasting may be necessary in
some non-rippable areas of Franciscan sandstone but these are all more than 200 feet
from the nearest residences and should produce no significant impacts.
80
IV. Environmental Setting, Impacts and Mitigation
Excavation of bedrock could produce some rock fragments over six inches in size. Since
a nearly balanced cut-and-fill concept is proposed, these oversized fragments would be
used on the site as fill. If left uncrushed they could eventually cause differential
settlement of fill surfaces that support buildings.
Slopes would generally be graded to 2: I (horizontal to vertical) surfaces using cuts or fills.
Steeper slopes or improperly designed slopes at this ratio could be subject to landsliding
during seismic shaking, heavy rainfall or from the weight of structures above them.
Depth and compaction of fill and subsurface drainage affect the stability of cut or filled
slopes. In general, artificial slopes are more susceptible than natural slopes to erosion and
instability unless specifically engineered to counteract the effects of leveling forces
(erosion, landsliding, settlement).
e. Development Area Impacts
Terrabay \lil.l~ge (Area IA and IB on Figure 13) has numerous landslides within the
..,----------...-----.--- ' ----.--- .---.--.----.-..
development area and is downslope from slides outside the area. Thebedrock is subject to
downhill creep. Overexcavation and subdrainage would be necessary to repair the slides
--illl-asfcibTJize the proposed cut slopes on the north (uphill) side of the Village. Most of
Terrabay Village would be built on fill in the southern (downhill) two-thirds of the area.
Road gradients would be up to 15% through the center of the Village. Some differential
.____---n.--..-_ _.~.,_.._.._____._
settlement would be expected between the cut and fill areas.
Terrabay Park (Area 2) has several deep slides within the area and is affected by slides
outside the area. Cuts proposed in the bedrock could increase the potential for downhill
creep. Springs (surface seepage) occur along the ravines. Three-fourths of T errabay Park
would be built on cut slopes, mainly in the uphill portions of the area. Slides would
require repair. Springs and slopes would need to be drained to prevent the development of
erosion or unstable soil conditions. Slight to moderate settlement would be expected in
the fill. Road grades would generally be low except for uphill access roads which would
be approximately 14%.
Terrabay Woods (Areas 3 and 4) has numerous shallow landslides and three deep slides
within its boundaries. Slides outside the boundaries affect the west part of the woods.
Soil creep is moderate but downhill creep in weathered bedrock is severe. Some bedrock
81
IV. Environmental Setting, Impacts and Mitigation
in the west Woods may not be rippable and may require blasting. Residences in both the
east and west would be built on fill and would be subject to moderate settlement. Access
roads around the edges would generally be on cut slopes. Road grades would be generally
below 6% but range up to 14%. Slide repair, slope stabilization and subdrainage would be
necessary.
T errabay Commons (Areas 5 and 6) has a few shallow slides in both parts of the area and
is affected by a large, deep slide above the east Commons which would need over-
excavation and repair. Soil and bedrock cuts may increase the potential for downhill
creep. The east Commons would be entirely on fill. The west Commons would be filled in
the center and on cut slopes on the sides. The fill would be subject to moderate
settlement. Grades of roods would be less than 14%.
T errabay Point (Area 7) would require extensive excavation to mold the top of the knob
and cut the hillside above the extension of Hillside Bol1levard. The road cut would be up
to 90 feet high and would have two benches (one at Elevation +65 feet asl and one at
Elevation + 105 feet asO to control debris fall and drainage. The knoll top would be
lowered about 100 feet to accommodate the buildings. Some of the bedrock may not be
rippable and could require blasting.
The Office Condominium/Health Club site (Area 8) would be almost entirely on fill. A
deep landslide is uphill from the site on the west side of the ravine. Numerous small
shallow slides line the east side of the ravine. Some settlement is expected in the fill
areas. Subdrainage would be necessary through the ravine. Overexcavation and benching
may be needed to repair the major slide. Rood grades would be less than 14%.
The Hotel and Tech Trade Center site (Area 9) would be entirely in cut areas with their
parking lots on fill. Several slides and soil slumps occur on the site and would need to be
excavated during grading. An area of loose fill would also require excavation and
backfilling to provide stable ground. Soil and weathered cut rock slopes may be subject to
downhill creep after grading. Some of the bedrock may not be rippable. The entrance
road grade would be about 14%.
82
IV. Environmental Setting, Impacts and Mitigation
f. Operational Impacts.
After construction is completed the project area would be subject to potential long term
impacts of erosion, groundshaking and slope instability. Long term off-site impacts from
drainage could occur downstream of the project site.
Erosional impacts would depend on the amount and type of exposed soil remaining after
complete build out. Unvegetated roadcuts, particularly very steep ones, can weather and
erode rapidly when subjected to heavy or frequent rainfall. Most open areas on the
project site would be vegetated to prevent erosion.
Strong groundshaking during an earthquake could cause cracks in masonry and brickwork
as well as create hazards from falling objects. Improperly protected structures could
slide off their foundations. Unstable soil or rock slopes could slide and some fills might be
subject to liquefaction under certain conditions. The current City Building Code provides
seismic safety standards for structures, slopes and fills but cannot provide for personal
safety from inappropriately placed heavy objects in the home.
Seismic slope instability could result from improper drainage of hillside fills or from
static loads on incorrectly designed slopes. Landslides or downhill creep of soil or rock
could damage structures or roadways and create personal injury hazards. Design criteria
for drainage systems, slope stabilization, and foundations to support specific static and
live loads are set forth in the Code to reduce these hazards.
Downstream drainage impacts result from the interception and undergrounding of
storm flow from the developed area and from the slopes above the developed area.
Volume of storm water runoff from the developed portions of the site would be higher and
flows would be faster than if the area remained undeveloped. Off-site flooding would be
reduced since a new drainage system would be constructed to accommodate runoff from a
10-year storm for local development. The existing drainage ditch on the east side of
Bayshore Freeway would be improved to accommodate the IOO-year storm runoff. All
drainage from the site would pass through this ditch into San Francisco Bay. San Mateo
County is currently developing information regarding the effect this would have on the
I DO-year flood zone between the freeway and the bay.
83
IV. Environmental Setting, Impacts and Mitigation
Adverse effects on water quality would result from the increase in such contaminants as
lead, oil and dust which commonly are carried in runoff from urban areas. The increased
runoff and improved drainage would cause more of these pollutants to reach the bay. The
amount of additional contaminants may not be significant in itself, but it would add to the
cumulative pollutant load in San Francisco Bay.
Increased soil erosion from improperly maintained drainage facilities could also increase
the amount of siltation in the bay. This impact is two-fold. On-site land degradation
occurs due to soil loss and downstream water quality is reduced due to added sediment
load.
The addition of lorge amounts of impervious surfaces to the project site would reduce
what groundwater recharge does occur through the south slope at San Bruno Mountain.
Since current percola~ion is fairly low and the static water table appears to be very deep,
-and since no use of groundwater is proposed for the site, theirnp~ct of reduced recharge
---woufcf'~t-b~-~ig~ific~nt .
3. Mitiqation
a. Mitigation measures proposed as part of the project.
The project sponsor has included the following mitigation measures in the T errabay
Development Specific Plan which directly or indirectly relate to geologic and hydrologic
impacts.
The development plan would implement, where feasible, the recommendations of
the Phase II Geotechnical Study already completed (Appendix D of this EIR) and of
those proposed to be completed prior to the project design plan.
An erosion control plan would be incorporated in the project design which would
include on-site siltation basins to prevent downstream sedimentation and
construction techniques to prevent soil loss.
The construction period would be kept as brief as possible and phased to reduce the
duration of unprotected soil exposure and to minimize vegetation removal.
The graded areas which would not be permanently disturbed would be hydromulched
prior to the rainy season to further reduce soil exposure.
84
IV. Environmental Setting, Impacts and Mitigation
Sharp changes in slope would be reduced to eliminate areas where erosion could
begin.
Limits of temporary and permanent grading would be clearly delineated during
construction to prevent encroachment into areas to be left undisturbed.
Pedestrian and bicycle paths would be constructed to reduce the effects of
indiscriminate travel across the project site and adjacent upslope areas.
b. Mitigation Measures Recommended by EIR Consultant.
The following mitigation measures are specifically directed toward the development of
the steeply sloping project area at Terrabay. Many of them reiterate sound practices
which would be required by City regulations or followed by responsible engineers and
builders. They are recommended by the EIR consultant to assist the City and the project
sponsor in creating a development which would be sensitive to the special conditions posed
by the T errabay site.
The preliminary design criteria for each proposed development area provided in the
geotechnical feasibility study and general geotechnicaJ summary should be used as
- \ a guideline for planning. Detailed geotechnical investigation for each specific
project site should be conducted to provide design recommendations for each area.
The grading plans should be evaluated after detailed geotechnical information is
obtained from the investigation of each project development area.
All grading and site preparation should be done under the direct supervision of the
soil engineer in accordance with the guide specifications for engineered fill
supplied by the geotechnical consultant.
Weak or unstable soils should be over-excavated and replaced with sound material
properly keyed and compacted.
Fill slopes and cut slopes should be inclined no greater than 2: I unless specifically
reviewed and approved by a qualified soils engineer. Subdr~~~ge ~nd s~~~~ce
drainage should be installed to prevent sloughing or raveling of slopes. Cut slopes
should be designed on an individual basis and approved by the City/County.
85
IV. Environmental Setting, Impacts and Mitigation
High fi II slopes should be overfi lied and graded back to obtain stable surfaces. All
fill slopes must be compacted to City/County specifications with no loose outer
slopes.
Cut and fill slopes should be planted to reduce erosion. Cut slopes should be
terraces between benches for silt retention where appropriate.
. _~!<?r.r:n.dTQinage-9Dd_slJb9rainage should be installed and maintained to prevent
erosion of fill.
_.B~!aining walls should be subdrained. All retaining walls should be designed to
~ -
resist pressures appropriate to the size of the backslope.
After building sites are graded they should be inspected by a qualified engineer and
treated where necessary by over-excavation and backfilling. Moisture prevention
treatment should be used beneath building slabs where necessary.
Landslides should be repaired by over-excavation, installation of subdrains and
engineered backfilling or by the installation of retaining walls or by some other
appropriate method.
Disturbed areas should be stabilized as quickly as possible either by vegetation or
mechan ical methods.
During construction, limits of grading should be defined by fencing.
Both temporary and permanent erosion control measures should be employed.
Slope lengths and gradients should be kept to a minimum.
Runoff should be kept away from disturbed areas using water bars during
construction.
Construction sediment should be trapped before it leaves the site.
86
IV. Environmental Setting, Impacts and Mitigation
Adherence to grading principles and recommendations to reduce geologic and
hydrologic impacts should be made a condition of approval of the proposed project.
It should be the responsibility of the City/County to see that the recommendations
are carried out. Grading, drainage and erosion control plans should be submitted
to, and reviewed by the City/County for each final subdivision during the phased
development of the site. Site-specific soils and foundation studies for each
neighborhood would be necessary to complete these plans.
All landslides and areas of weak soil in or near proposed development should be
repaired.
Although all faults on the site are considered inactive, the maps for each final
subdivision located along a suspected fault trace should include verification of
inactivity. Setbacks should be provided as necessary.
The project sponsor should investigate the availability of landslide insurance
programs. Liability for the cost of damage from future landslides on the site to
on-site property or adjacent property, should be clarified.
Construction on hillsides should be designed to avoid areas of potential landslide or
erosion problems. Slides and soil creeps are shown on Figure 16.
Cut and fi II should be balanced within each project site, to the extent feasible.
Whenever possible, grading activities during the rainy season should be avoided.
Elevations taken from topographic map, prepared by J.F. Carrol and Associates,
Consulting Civil Engineers, San Mateo, CA, 1979, scale 1:2400.
2 Slope analysis made from URS Research Company, Draft EIR, Application for General
Plan Amendment: Crocker Hills, San Mateo, CA, 1975, Figure 2-2.5.
3 Perry R. Wood, CEG 711, PSC Associates, Inc., Geotechnical Consultants,
Geotechnical Feasibility Study, Phase I, South Slope San Bruno Mountain, South San
Francisco Area, San Mateo County, California, AprilS, 1982, /8 pages.
4 Perry R. Wood, CEG 711, PSC Associates, Inc., Geotechnical Consultants,
Geotechnical Feasibility Study, Phase II, South Slope San Bruno Mountain, South San
Francisco Area, San Mateo County, California, May 24, 1982,28 pages.
87
IV. Environmental Setting, Impacts and Mitigation
5
URS Research Company, Ope cit., pages 2-45 to 2-48.
6
U.S. Geological Survey, Earthquakes in the United States, 1979, Circular 836,
Washington, D.C., 1980-81.
7
U.S. Geological Survey, Preliminary Determination of Epicenters, Monthly listinqs,
Washington, D.C., 1980-81.
8 URS Research Company, Ope cit., pages 2-53, 2-54.
9
Perry R. Wood, Phase II, Ope cit., Table I.
10
Ibid., page 21.
II
ABAG, Manual of Standards for Erosion and Sedimentation Control Measures,
Berkeley, California, June 1981, page 21.
12 U.S. Geological Survey,
California, Miscellaneous
Ba
ion
13
ABAG, Ope cit., page 19.
14 Perry R. Wood, CEG 711, telephone conversation, June II, 1982.
15 URS Research Company. Ope cit., pages 3-27 to 3-32.
16 Perry R. Wood, CEG 711, Phase II, Ope Cit., page 17.
17
Resources Engineering & Management, Adminstrative Draft Specific Plan for T errabay
Development, May 1982, page 19 and figure 2.65.
18
Ibid., page 10.
19
Resources Engineering & Management, San Bruno Mountain, W.W. Dean Development,
Storm Drainage Study, March 1981.
20
Ibid., page 6.
21
Ibid., Hydrologic Plat.
88
IV. Environmental Setting, Impacts and Mitigation
c. AIR QUALITY
I. Setting
The Bay Area Air Quality Management District (BAAQMD) does not operate a monitoring
site in South San Francisco. Data from nearby sites are presented in Table 6. The table
indicates that air quality in the surrounding area is relatively good. Prevailing northwest
winds tend to carry pollutants toward the southeast Bay Area. Carbon monoxide is a
localized pollutant generated primarily by automobile emissions. Although both San
Francisco and Redwood City are in compliance with air quality standards, it is possible
that nearby locations which are not closely monitored could be in violation.
The violation of air quality standards in some locations in the Bay Area has resulted in the
development of an Air Quality Plan for the Bay Area, as part of the Environmental
Management Plan (EMP) prepared by the Association of Bay Area Governments (ABAG)
and other governmental agencies. The 1979 Air Quality Plan contains a strategy for the
long-term attainment and maintenance of the air quality standards. The plan includes
measures to reduce emissions from stationary sources and automobiles, and proposed
transportation measures to reduce automobile emissions. The air quality problems
addressed in the plan are photochemical oxidants, carbon monoxide and suspended
particulates. The plan is currently being revised, and a new version is expected in 1982.
2. Impacts
Air quality impacts would be due to dust generated by equipment and vehicles. Fugitive
dust is emitted during construction activity (clearing, earth-moving, grading) and as a
result of wind erosion over exposed earth surfaces. Earth-moving activities are the major
source of construction dust emissions, although traffic and general soil disturbance also
generate significant dust emissions.' i .
The effect of construction activities would be a temporary increase in dustfall near the
site. In the immediate area, this would mean that more frequent cleaning and washing of
exposed surfaces would be needed. Persons with respiratory problems could find them
aggravated by construction dust.
The project would affect local and regional air quality through automobile traffic. On the
local scale, carbon monoxide is the most important pollutant. To assess the project's
89
IV. Environmental Setting, Impacts and Mitigation
TABLE 6
NUMBER OF DAYS SELECTED POLLUTANTS
EXCEEDED STATE OR FEDERAL REGULATIONS, 1981'
Nitrogen
Dioxide
Carbon
Monoxide
Suspended
Particulates
Sulfur
Dioxoide
Monitoring Site
2
Ozone
San Francisco
0.0.
1.3
o
o
o
o
o
o
Redwood City
I The state's standards are specific concentration and durations of air pollutants that
reflect the relationship between concentration and undesirable effects. They are target
values and no timetable exists for their attainment. The federal primary standards
represent the level of air quality necessary for protection of public health with an
adequate margin of safety. The provisions of the Clean Air Act, as amended, require that
by December 31, 1987 the federal standards should not be exceeded.
21n early 1979 the U.S. Environmental Protection Agency adopted a new oxidant standard.
The previous standard of 0.08 parts per million for all oxidizing substances was replaced
by a standard of 0.12 parts per mi II ion for ozone alone, the most prevalent oxidant. The
new federal standard is based on a three-year average, known as the Expected Annual
Exceedance (EAE). An EAE of 1.0 is considered in complinace with the standard. For
ease of comparison the number of days with values greater than .12 ppm are shown.
Source:
Bay Area Air Quality Management District, Air Currents, Vol. 24, No.3,
March I 981 .
90
IV. Environmental Setting, Impacts and Mitigation
impact on carbon monoxide concentrations, a diffusion model2 developed by the
California Air Resources Board, CAlINE 3, has been applied to intersections affected by
project traffic. The analysis was for a worst-case assumption of traffic and weather
conditions. Peak-hour and peak eight-hour traffic volumes were superimposed upon
adverse weather conditions consisting of a one mps (meters per second) wind and highly
stable atmosphere for the one-hour averaging time and a two mps wind and moderately
stable atmosphere for the eight-hour averaging time.2 The results of this analysis
represent curbside estimates of carbon monoxide concentrations under adverse conditions.
Vehicles were assumed to travel at an average speed of ten mph for the peak traffic hour
and 25 mph during the peak eight-hour traffic period on local streets. Freeway travel was
assumed to be 15 mph for the peak hour and 45 mph for the peak eight hour period.
Emission factors were calculated using the computer program developed by the State of
California Air Resources Board, EMF AC6C. 3
Table 7 shows the results of the carbon monoxide modeling.~(]ckgrol![ld leyelsmQLJhree
and one ppm have been included in the one-hour and eight-hour average concentrations,
respectively. Predicted levels are to be compared to the federal standards of 35 and 9
parts per million for the one- and eight-hour averaging periods, respectively.
No violations of the CO air quality standards are predicted to occur with or without the
project. The highest concentrations would occur near the intersection of Oyster Point and
Airport Boulevard under southeasterly winds. Under such conditions emissions from
Highway 101 combine with emissions on local streets to produce elevated CO
concentrations. Concentrations at other intersections are predicted to be lower for all
other wind directions. Concentrations would be lower as a result of traffic mitigation
measures contained in the transportation section of this report. Concentrations in the
year 2000 would be about 10-15% lower than 1990 concentrations because the effect of
emissions limitations on new motor vehicles compensates for the predicted increase in
traffic volumes.
In addition CO concentrations at these intersections were calculated for a similar set of
assumptions using the model recommended by the Bay Area Air Quality Management
District. I The concentrations predicted by this model were slighly higher than those
predicted by CAlINE 3, although neither model predicts violations of air quality
standards.
91
IV. Environmental Setting, Impacts and Mitigation
TABLE 7
CURBSIDE CO CONCENTRATIONS AT
CRITICAL INTERSECTIONS (PARTS PER MilLION)'
19902 19902 1990 with2
1982 project and
no project with project mitigation
I-hour 8-hour I-hour 8-hour I-hour 8-hour measures
Hillside Extension/
Airport (Easterly winds) II. 2. 12. 2. II. 2.
Hillside Extension/
Airport (Wester Iy winds) 9. 2. 12. 2. 9. 2.
Hi Ilside/lrving
(Westerly winds) 7. 2. 7. 2. 8. 4. 7. 2.
Oyster / Airport
(Easterly winds) 14. 3. 18. 3. 20. 4. 16. 3.
I Conditions Modeled:
I-hour
8-hour
Winds (meters per second)
Stability c1ass*
Background concentrations (parts per
million)
Average vehicle speed on streets
(miles per hour)
Average vehicle speed on freeway
(miles per hour)
I
E
2
10
15
2
D
25
45
2Hillside Extension included
Wind angles are assumed parallel to Hillside Boulevard for both easterly winds and
westerly winds for I-hour average and for easterly winds for the 8-hgur average.
Westerly winds for the 8-hour average are assumed to be at an angle of 22.5 to the more
heavily travelled road at the intersection. If parallel westerly winds had been assumed for
the 8-hour average predicted, concentrations above ambient would have been larger
resulting in a worst-case value of 3 ppm at the Hillside Extension/Airport intersection,
with or without the project.
*Stability is an important measure of the tendency of the atmosphere to disperse air
pollutants. Class "E" has a lower potential for dispersal than does Class "0".
92
IV. Environmental Setting, Impacts and Mitigation
Examination of Table 7 reveals that CO would increase as a result of project-generated
traffic under some conditions. The largest increase would occur at the intersection of
Oyster Point and Airport Boulevard under southeasterly wind flows; the increase would be
four ppm for the one-hour average, one ppm for the eight-hour average.
A screening analysis of other intersections in the project area indicates that none would
have CO concentrations greater than those at the intersection of Oyster Point and Airport
Boulevard. This is the case whether or not the Hillside extension is completed. As the
predicted concentrations in Table 7 are worst-case, curbside concentrations under typical
weather and traffic conditions would be lower.
The proposed project would affect regional air quality through changes in total vehicle
miles travelled (VMT). The additional VMT generated by the project would be
approximately 165,000. Table 8 shows the emissions in tons per day that would result.
These emissions would not be of sufficient magnitude to result in a measurable
degradation of regional air quality. However, in combination with increases in emissions
from other sources, measurable air quality degradation could result.
The 1979 Bay Area Air Quality Plan 4 contains actions and policies designed to result in
the attainment and maintenance of air quality standards. Strategies include new controls
on stationary and mobile sources, and transportation controls. There are no apparent
conflicts between these measures and the proposed project. The project is also consistent
with the growth assumptions of the Air Quali ty Plan, however, the additional emissions
would result in some delay in achievement of air quality standards.
3. Mitigation
Wetting surfaces of unpaved roads and disturbed soils surfaces during construction is an
effective control for dust emissions, provided the surface is kept wet. Twice-a-day
application of 0.5 gallons of water per square yard of earth surface will suppress dust
emissions by about 50%. I
93
IV. Environmental Setting, Impacts and Mitigation
TABLE 8
PROJECT GENERATED EMISSIONS (1990)
Tons Per Day
Generated by
Projected Traffic
Regional I
Total
Sulfur oxides
3.6
0.33
0.31
0.04
2,300
Carbon Monoxide
Hydrocarbons
590
590
210
Nitrogen oxides
Total Suspended Particulates
0.42
550
I Source: Bay Area Air Quality Management District, 1979 Source Inventory, San Francisco,
California, 1981.
94
IV. Environmental Setting, Impacts and Mitigation
Measures which reduce traffic volume and/or congestion can result in improvements in air
quality. Transportation Systems Management (TSM) programs, as identified in Section
IV. L. (Traffic and Transportation), would result in a 15% decrease in CO emissions in the
area during peak hours, ten percent during peak eight hours; this would result in a
reduction in CO levels between five and ten percent after accounting for background
levels. The Sierra Point Interchange and connectors would reduce CO levels on Airport
Boulevard north of Linden by a similar amount. The Oyster Point interchange with a new
southbound on-ramp would decrease CO levels on Airport Boulevard by about 30%. Other
measures identified in the transportation section of this report would also have beneficial
effects, the magnitudes of which are not quantifiable.
I U.S. Environmental Protection Agency, Guidelines for Development of Control
Strategies in Areas with Fugitive Dust Problems, QAQPS 1.2-071, October 1977.
2California Air Resources Board, Research Division, Air Quality Modeling Section,
Lecture Notes for Workshop on Estimating Carbon Monoxide Concentrations for Hot
Spots Analysis, Sacramento, CA, May 1980.
3California Air Resouces Board, Procedure and Basis for Estimates On-Road Motor
Vehicle Emissions, January 1980.
4Association of Bay Area Governments, 1979 Bay Area Air Quality Plan, January 1979.
95
IV. Environmental Setting, Impacts and Mitigation
D. LAND USE
I. Setting
a. Project Site
The Terrabay project site contains 332 acres of open hillside. With the exception of some
decaying former 4-H buildings opposite Jefferson Street,the_~I'l!ir~ site is undeveloped. A
transmission line crosses the site approximately opposite North Spruce Avenue. The site
is presently used for a variety of unofficial uses'cc~){!sting trails, which roughly follow
ridgelines, provide access to San Bruno Park above the site. These trails are popular with
both pedestrians and dirt bike riders. The gently rolling, grassy lower slopes are
commonly used by local residents walking dogs, by children going to and from school, and
as an alternate pedestrian route along Hillside Boulevard. At the site's east end, residents
of homes on the north side of Randolph Avenue have established small garden plots on the
site. ~_ level cut, midway down the eastern promontory, is used for dumping auto parts
and other litter.
b. Land Use in the Project Area
San Bruno Mountain State and County Park adjoins the site on the north side. The 2,064-
acre park is a regional open space containing developed trails and recreation facilites with
informal access through the project site.
Aside from the park, most land in the area has been committed to urban uses (Figure 18).
The one-story, four-building Hillside Elementary School complex is adjacent to the site's
w~stern edge. Nearby development south of the site ise~imarily single-family residential
homes. Sign Hill contains the Sterling Terrace residential development near the base of
its north side. The south side of the hill is largely undeveloped and contains the sign
"South San Francisco, The Industrial City." ~ustrial uses on bay fill land lie east of the
Bayshore Freeway, which follows the site's eastern boundary.
Numerous proposals are being considered for further development of residential and
industrial lands. An additional 155 residential units were recently approved for the
Stonegate Ridge district on the northwest side of Sign Hill. Other proposals for the
Hillside Boulevard and Chestnut Avenue area include 25 townhouses, and 17 single-family
residences.
96
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IV. Environmental Setting, Impacts and Mitigation
Additional industrial development has been planned for land east of the Bayshore freeway.
The northernmost of these near Terrabay is the Sierra Point development which lies in
both Brisbane and South San Francisco. This project would tentatively include two 12-
story oiflc~_btJ!~~!_~9~ totalling 1.5 million square feet, approximately 630 boat slipsgnd
sev~!al~_to 4-story buildings to include a hotel and shops. Recl"_eational uses, parking and
related facilities would also be provided.
Proposals for the Oyster Point Business Park south of Sierra Point include two 5-story
office buildings (400,000 square feet), a 227-berth marina and roughly 500,000 square feet
of warehouses. Further plans under discussion for the existing Oyster Point Marina
include approximately 275 additional boat slips, commercial facilities and the
development of a shoreline park.
The Gateway Redevelopment Project southwest of the Oyster Point Marina is a 177 -acre
site for which 2.1 million square feet of office space and a 600-room hotel are proposed,
in addition to banks, restaurants and 500,000 square feet of Research and Development
uses. Buildings would most likely range from 2 to 18 stories.
The site of the existing 200,000 square foot Dubuque office building, south of Gateway,
has also been mentioned as a possible office building location, although no plans have been
submitted. Plans for development in the industrial area have been kept flexible to allow
for changing economic conditions. The overall result of the various proposals will be to
convert the existing industrial setting to one of ,r:nixed commercial and industrial uses in a
modern, landscaped setting.
2. Impacts
The proposed project would replace existing open space uses of the site with a mixture of
residential, commercial, recreational and open space uses (see Figure 3, Section 111).
Residential development would occupy approximately 139 acres. Commercial
development of an additional 40 acres would leave approximately 153 acres of
undeveloped open space.
Clustering residential development into neighborhoods would soften the present sharp
transition between urban and open space land uses at the site boundary. Trailheads
through the site to San Bruno Park, outdoor recreational facilities, and a linear park
linking the project site with the Hillside Elementary School, would further enhance the
98
IV. Environmental Setting, Impacts and Mitigation
transition. Development of the site would eliminate its use for dirt bike racing and
dumping litter. Steps at trailheads on the site and the proximity of residents would
regulate use of the open space areas. Approximately 153 undeveloped acres of the site, as
shown in Figure 19, would be dedicated to the County. The San Bruno Mountain HCP
stipulates that dedication to the County of the project's undeveloped open space areas
"\
would occur at the time the first grading permits are granted for the parcel of the project r'l
to which it pertains. Dedication would, therefore, occur in two phases: upon completion
of the residential portion and upon completion of the commercial portion. I Dedication
specifics are, as yet, proposed since the HCP has not been finalized by the County.
Remaining open space would be within jurisdiction of the City and under the auspices of a
T errabay property owners' association. Inasmuch as the 153 acres of open space have not
been specifically designated, a mutually agreed-upon boundary would be determined at the
time of dedication to the County. A water storage tank, to be located in a disturbed open
space area, would be maintained by the California Water Service Company. Terrabay
development would eliminate current use of the site by pedestrians along Hillside
Boulevard. Residents north of Randolph Avenue would no longer be able to use the site
for small garden plots due to construction of the Hillside Boulevard extension.
Proposed commercial buildings would be concentrated at the site's eastern end. These
buildings would be consistent with existing and proposed land uses along the freeway
corridor.
Project construction would be phased over a minimum five to six year period.
Construction would begin at the west end and proceed to the east end. The Hillside
Boulevard extension is expected to be constructed in an early phase (see Table 2, Section
111). Actual density of individual residential neighborhoods would range from 4.1 to 11.3
dwelling units per acre (Table 9).
The proposed project would help meet the current housing demand in the City. The
Housing Needs Report for the San Francisco Bay area estimates that an additional 1,327 (t/
households will be needed from 1980 to 1985 in South San Francisco. 2,3 A total of 745 ~, /~
~
dwelling units are proposed for Terrabay; 545 of these are scheduled for completion by ~
1985, representing approximately 41% of the anticipated need.4 The City Housing
Element expresses support for development of 325-400 units per year and the final 169
Terrabay units scheduled for completion in 1986 would represent approximately one-half
of this number for the year. 5
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3. Mitigation
Mitigation measures proposed as part of the project.
The undisturbed open space located between the developed area and the
northerly and westerly property lines would be dedicated to the County of San
Mateo for inclusion into the San Bruno Mountain State and County Park. All
other open space areas would remain within the jurisdiction of South San
Francisco and under the purview of a combined property owners association.
Community recreational facilities and trailheads to the park would be provided
by the developer on the project site. The City would most likely assume
maintenance of the recreation facilities.
Juncus Ravine, west of the site, would be offered by the developer to the
County as permanent open space if the project is approved.
A fire station to serve the site and nearby areas would be built by the
developer at the site's west end.
The developer proposes to build outdoor playing fields between the site and
Hillside Elementary School. These fields would be operated by the City and
could provide a source of revenue. This proposal would eliminate present use
of this area by dirt bikers.
I San Bruno Mountain Habitat Conservation Plan Steering Committee - Chaired by San
Mateo County, Draft San Bruno Mountain Area Habitat Conservation Plan, May 1982.
2CitY of San Francisco, Zoning Ordinance, 1981, pages 2-4.
3Association of Bay Area Governments, Housing Needs Report, San Francisco Bay Area,
December 1981, page 35.
4
County of San Mateo, Staff Report, August 26, 1981, page 7.
5CitY of South San Francisco, Housing Element, page 27.
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102
IV. Environmental Setting, Impacts and Mitigation
E. VEGETATION AND WILDLIFE
I. Sett inq
a. Vegetation
The project site spans the lower slopes of the southeast portion of San Bruno Mountain
which consist almost entirely of annual grassland. In spite of this apparent uniformity in
vegetation, significant floral diversity exists, generally related to topography and
exposure. Areas of sparse soft-chaparral clothe certain hillslopes while ravines and water
courses support a different vegetation type. In addition, the grasslands themselves can be
divided into those which are dominated by introduced plants and those retaining
substantial native plant components.
A botanical inventory of San Bruno Mountain was published in 1968 by Elizabeth
McClintock and Walter Knight of the California Academy of Sciences.' This flora lists
the occurrence of 542 vascular plant species on the mountain which includes the project
site. Because of the relatively uniform vegetative composition of the Terrabay
Development Study area, however, this site did not receive as detailed a survey as other
portions of the mountain.2 Appendix C of this EIR lists those species observed during
field work for this report as well as plants reported from the site in the 1968 flora
inventory.
Non-Native Grassland. The more level portions of the site are situated at lower
elevations (below 400 feet elevation approximately), and are composed almost exclusively
of introduced annual grasses and herbs, mostly of European origin. These gently sloping
alluvial areas contain deeper soils than the steep, often rocky, slopes above. In addition,
these areas receive water from the upslope areas. The better moisture holding capacities
of the soils in this area compared to the slope areas above allow a longer growing season
resulting in higher grassland productivity.
Conspicuous floral components of these areas include wild oats (Avena barbata), soft
chess grass (Bromus moll is), wild mustard (Brassica campestris) farmer's foxtail (Hordeum
leporinum), filaree (Erodium spp.) and many others. Few native plant species are present
in these areas. In certain locations, however, abundant moisture supports patches of
vernally wet type vegetation as in the northeastern segment of the site. Here, such plants
as rushes (Juncus spp.), and sedges (Carex spp.) mix with curly dock (Rumex crispus),
teasel (Dipsacus fullonum) and fennel (Foeniculum vulgare).
103
IV. Environmental Setting, Impacts and Mitigation
Native Mixed Grasslands. The upper slopes and ridges of the project site provide a variety
of different habitats for grassland and some chaparral species. Native plant species still
comprise a substantial portion of the vegetation on their ridges and upper slopes.
Although introduced annual grasses and herbs extend upslope, some remnant native bunch-
grasses remain. This includes purple needlegrass (Stipa pulchra), a perennial species
thought to have been characteristic of pristine California grasslands. Broad splashes of
springtime color on the hillsides are produced by varied lupine (Lupinus variicolor>,
California poppy (Eschscholtzia californica), escobita (Orthocarpus purpurescens), and
checker bloom (Sidalcea malvaeflora). Other native species intermixed in the grassland
include golden aster (Chrysopsis villosa var. Bolanderj), mule ears (Wyethia angustifolia),
johnny-jump-up (Viola pedunculata) brownie thistle (Cirsium quercetorum), footprints-of-
spring (Sanicula arctopoides), wooly-fruited lomatium (Lomatium dasycarpum) and
California buttercup (Ranunculus californicus). California dichondra (Dichondra
Donnelliana), a prostrate ground-cover previously reported from only one locale on San
Bruno Mountain, was found to be widely distributed in hard packed soils on the project
site. Also of interest, Microcala quadrangularis, a diminutive member of the gentian
family, was found to be well distributed on the site, mostly in disturbed areas. This is the
first record for this species on San Bruno Mountain, although it is reported from San
Francisco and other areas of the Santa Cruz Mountains southward.9
Soft Chaparral. On some slopes a variety of shrubby plants typical of soft-chaparral are
intermixed with the grassland at low densities. This shrubby element is best developed on
the steep slopes above the northeastern area, and the ridges surrounding the old 4-H Club
structures off of Hillside Boulevard. Common in these areas are California sage
(Artemisia californica), sticky monkeyflower (Minulus aurantiacus), pitcher sage (Salvia
spathacea), poison-oak (Toxicodendron diversiloba), coyote mint (Monardella villosa) and
California phacelia (Phacelia californica). Holly-leaf cherry (Prunus illicifolia) is an
infrequent associate in these "chaparral" areas.
"Riparian-like" Areas. The ravines traversing the site's upper slopes create a variety of
microclimates favorable for the growth of certain plants not found elsewhere on the site.
Some of the ravines on the eastern side of the site support California buckeye (Aesculus
californica) with a relatively rich understory consisting of California bee plant
(Scrophularia californica), California polypody fern (Polypodium californicum), stinging
phacelia (Phacelia malvaefolia), cow parsnip (Heracleum maximum), coffee fern (Pellaea
104
IV. Environmental Setting, Impacts and Mitigation
andromedaefolia) and toyon (Heteromeles arbutifolia). In certain locations, where
sufficient moisture is available in these ravines, willows and other riparian species such as
rushes and common monkeyflower (Mimulus guttatus) are found.
b. Wildlife
For the most part, wildlife use of the project site is typical of annual grassland areas
throughout the San Francisco Bay region. Two rare grassland butterflies, the Mission Blue
(Plebeius icariodes missionensis) and the callippe silverspot (Speyeria callippe callippe),
are conspicuous exceptions to this. These butterflies are generally restricted to San
Bruno Mountain and have been the focus of detailed studies over the last few years. Their
status on the site is discussed separately in the following section on rare and endangered
spec i es.
As a large area of contiguous open space San Bruno Mountain continues to support viable
wildlife populations in the midst of one of the most highly urbanized regions in the
country. The predominant vegetation communities on the mountain, grassland and
brush land, provide a variety of habitats available for wildlife with a resulting diversity of
species.
Since the project site represents a band of varying width along the urbanized edge of San
Bruno Mountain, much of the site's wildlife use directly relates to off-site source
populations. The mountain mass, and in particular the southeast ridge, form a wildlife
reservoir for the site. Although the home range and habitat requirements of certain small
mammals and birds may be contained entirely within the project boundaries, many animals
would be expected to range more widely, taking advantage of the space and additional
resources available off-site.
The expansive grasslands of the proposed project site afford prime foraging habitat for
raptorial birds. Red tail hawk, American kestrel, marsh hawk, great horned owl and
turkey vulture are all commonly seen hunting over the site for rodents, reptiles and even
large insects. Coopers hawks have also been reported in the area. These various raptors
probably do not nest within the project boundaries although the site may account for a
substantial part of the hunting territory for specific individuals. Other wide-ranging
carnivores include gray fox and long-tail weasel. An interesting record of mule deer on
the southeast ridge indicates that deer may occasionally reach the project site. Due to
the proximity of the site to urbanized areas, no significant deer use would be expected.
105
IV. Environmental Setting, Impacts and Mitigation
Additionally, tall vegetative cover, presumably a habitat prerequisite for prolonged deer
foraging, is not available on the site.
A variety of resident songbirds are found in the grasslands and more densely vegetated
ravines. Savannah sparrow, western meadowlark, red-wing blackbird, western kingbird
lesser goldfinch, cliff swallow and barn swallow all make extensive use of the grassland.
The shrubbery, especially when in flower, is frequented by Anna's and Allen's
hummingbird, house finch, white-crowned sparrow, brown and rufous-sided towhee and
various warblers. Willow thickets are particularly attractive to the latter. San Bruno
Mountain is also visited by migratory species. The relative paucity of trees and shrubs on
the site does not suggest extensive use of the project area by migrants as a "stop-over."
Further, the principal migratory route in the area passes on the ocean side of the
mountain where birds presumably can orient by the ocean. Records of migratory species
on the site, such as lazuli bunting, do indicate some use of the area however.
Reptiles include various snakes and lizards which are often associated with the more
rocky portions of the site. No significant amphibian populations are expected due to the
lack of long-standing water on the site proper. Small mammals would include black-tailed
hare, california vole and california ground squirrel.
c. Endangered Species
Among the organisms inhabiting San Bruno Mountain as a whole are a number of rare and
unusual species. The Mission Blue and San Bruno Elfin butterflies were designated as
endangered by the U.S. Fish and Wildlife Service in 1976. Another butterfly, the callippe
silverspot, was proposed for listing in 1978; it apparent ly exists nowhere else except San
Bruno Mountain. San Bruno Mountain also supports 17 plants that are regional endemics,3
and ten plants that reach distributional limits on the mountain. The California Native
Plant Society (CNPS) has listed ten plant species found on San Bruno Mountain as rare.
As part of San Mateo County's effort to plan for development which is compatible with,
and sensitive to, these important biological resources, an extensive study of the rare
species found on the mountain was recently conducted by Thomas Reid Associates. This
two year study focused on the Mission Slue and Callippe Silverspot butterflies. Other
species of concern were addressed as well, although not in as great detail. The findings of
that study form the basis of the Habitat Conservation Plan. For a complete accounting of
106
IV. Environmental Setting, Impacts and Mitigation
this definitive work on the endangered species of San Bruno Mountain the reader should
refer to the project reports for that study.4,5
Based upon the findings of the reports cited above, the project site does not appear to
have suitable habitat for the following rare and/or endangered animals known to occur on
San Bruno Mountain: San Bruno Elfin Butterfly (Callophrys mossii bayensis), San Francisco
Tree Lupin Moth (Grapholitha edwardsiana) and the San Francisco Garter Snake
(Thamnophis sirtalis tetrataenis). Information on the rare solitary bee (Dufourea stageD is
incomplete at this time to determine if the bee still occurs on the Mountain or its habitat
needs. The bay checkerspot butterfly (Euphydryas editha bayensis) was recently
rediscovered on San Bruno Mountain along the main ridge about one-half km. west of the
eastern transmission line.5 The bay checkerspot has two larval food plants, the primary
plant is Plantago erecta and the secondary foodplant, Orthocarpus densiflorus. The
Orthocarpus is found on the project site, thus indicating the site a potential habitat for
this butterfly even though no specimens have been seen on the site.
Mission Blue. The mission blue butterfly (Plebejus icarioides missionensis) a subspecies of
Plebejus icarioides, is known only from San Bruno Mountain, Twin Peaks in San Francisco,
and, at least historically, Fort Baker in Marin County. Because of this very limited
distribution, relatively small population sizes and the potential for extinction given
regional trends in 1976, the U.S. Fish and Wildlife Service afforded the mission blue legal
status as an endangered species under the Endangered Species Act of 1973.
The mission blue butterfly has very specific habitat requirements which must be present
to meet its basic life requirements (mating, nectaring and egg laying). The butterfly
larvae are restricted to feeding upon three species of perennial lupines that occur on the
mountain. These are la,te lupine (Lupinus formosus), silver bush lupine (Lupinus albifrons)
and varied lupine (Lupinus variicolor). The adult butterflies use a much wider variety of
plants as nectar sources. The primary nectar plants are wild buckwheat (Eriogonum
latifolium), golden aster (Chrysopsis villosa) and blue dicks (Dichelostemma pulchellum).
In addition, California horkelia (Horkelia californica), plumeless thistle (Carduus spp.) and
brownie thistle (Cirsium quercetorum) are known to be heavily used by the butterfly.5
Absolute dependence of the larvae on any of the three lupines creates a situation where
the distribution of the butterfly is closely tied to the distribution of those plants. As
noted in the Thomas Reid Associates study, "the mission blue butterfly can be found
107
IV. Environmental Setting, Impacts and Mitigation
nearly everywhere on San Bruno Mountain that at least one of the three perennial lupine
host plants is found. The denser congregations of mission blue inevitably correspond with
dense patches of lupine." However, there is not an absolute correlation between lupine
and mission blue densities; other factors are involved as well.
Two major colonies of mission blue were identified in the Reid studies. The larger is the
Southeast Ridge Colony comprising about 60% of the total mission blue population. This
colony is located above the project site, however suitable habitat for the species does
occur on the site. As discussed in the vegetation section of this report, several of the
mission blue host plants are frequent on the project site, mostly on ridges or upper slopes.
In particular, extensive colonies of Lupinus variicolor are located on the slopes of the
project site. Although not all of the apparently suitable habitat on the project site is
utilized, Thomas Reid Associates have concluded that approximately nine percent of the
entire mission blue population is dependent upon the 332 acre project site.6
Callippe Silverspot. The callippe silverspot (Speyeria callippe callippe) is a subspecies of
Speyeria callippe. This species is made up of a group of ten subspecies that range
throughout the Sierra Nevada and Coast Ranges of California to central Oregon. The
subspecies present on San Bruno Mountain has always been confined to the San Francisco
Peninsula. Due to habitat destruction, populations of this subspecies are apparently now
reduced and confined to San Bruno Mountain. The callippe silverspot was proposed for
listing as an endangered species by the U.S. Fish and Wildlife Service in 1978. Although
the subspecies was not officially listed, San Mateo County and other agencies consider the
callippe a species of concern. Accordingly, extensive investigation of this organism was
included in the Thomas Reid Associates endangered species study.
As with the mission blue, this butterfly has specific habitat requirements for mating, egg
laying and feeding. Johnny-jump-up (Viola pedunculata) is the larval host plant for the
callippe silverspot. Eggs laid on these plants during mid-summer revive and hatch the
following season; the larvae then feed upon the violets. . Adult butterflys are known to
feed upon a variety of nectar producing plants. Preferred nectar plants are brownie
thistle (Cirsium quercetorum), milk thistle (Silybum marianum), plumeless thistle (Carduus
spp.) and coyote mint (Monardella villosa). Other plants used by the callippes to a lesser
degree include golden aster (Chrysopsis villosa), wild buckwheat (Eriogonum latifolium),
and California buckeye (Aesculus californica).5
108
IV. Environmental Setting, Impacts and Mitigation
Two major populations of the callippe silverspot occur on the mountain. The Southeast
Ridge supports approximately 75% of the total callippe silverspot population.6
As discussed in the vegetation section, the project site contains populations of many of
the callippe host plants, including localized patches of johnny-jump-up, the larval host.
The distribution of these plants is generally on the slopes and ridges of the site. Thomas
Reid Associates estimates that approximately two percent of the total callippe population
is dependent upon the entire proposed project site.6
Plants of Concern. Of the ten species of plants on the mountain listed as rare by the
California Native Plant Society (CNPS), two have been reported from the project site.
These are the San Francisco owl's clover (Orthocarpus floribundus) and the San Francisco
wallflower (Erysimum franciscanum). The owl's clover is considered rare and endangered
(CNPS list 2) while the wallflower is listed as rare (CNPS list 3).7 The San Francisco
wallflower is relatively abundant on San Bruno Mountain; on the project site it is
infrequent to rare however.
The San Francisco owl's clover is a much more rare plant on the mountain, known only
from two collections: in a ravine north of the junction of Randolph Drive and Hillside
Boulevard, and at Point San Bruno. The location of the Hillside Boulevard collection is
apparently within the project site. Several field surveys of that area in recent years
failed to relocate the species. Rare plant surveys of portions of the site were conducted
April 4, 1981 by CNPS members; May 29, 1981 by Thomas Reid Associates staff; and
March 16, 28 and April 4, 1982 by EIP staff.
During the ElP field survey, two related species of owl's clover were found (Orthocarpus
purpurascens and Orthocarpus densiflorus), but no Orthocarpus floribundus was observed.
There are three possible explanations for this failure to relocate the plant. First, the
species may be extirpated from the site either due to natural factors, such as drought, or
man-caused factors, such as motorcycle disturbance or fire. A second possibility is that
seed for this annual plant is still present on the site but climatic conditions have not been
favorable for germination and establishment during the years that surveys have been
conducted. The exceptionally wet winter of 1982, and the abundance of the plant at other
known localities that year make this unlikely.
109
IV. Environmental Setting, Impacts and Mitigation
A third possibility is that the plant exists on the site in such small numbers and is so
localized that it was present but not detected during the field surveys. While each of the
surveys were conducted diligently, undoubtedly none covered 100% of the potential
habitat on the site. We must conclude that the continued existence of Orthocarpus
floribundus on the project site is unlikely but still possible.
2. I mpocts
Development of the proposed project site would have a number of biological impacts
varying in significance. The most noteworthy of these impacts is the elimination of
habitat currently used by a federally listed endangered species as well as another rare, but
not listed, butterfly.
An analysis of the South Slope Development (now Terrabay), is included in the San Bruno
Mountain Area Habitat Conservation Plan (HCP). That plan, and the biological studies
that preceeded it, form the basis of San Mateo County's permit application under Section
IO(a) of the Endangered Species Act. Such a permit is required to authorize the "taking"
of a limited number of mission blue butterflies in order to allow urban development of
portions of the mountain. This development would also include conservation and
maintenance of the remainder of the habitat in perpetuity through the establishment of an
Open Space Management District or some similar institutional arrangement and funding
mechanism. As a part of that process San Mateo County and their biological consultants
have worked with the project sponsor to develop a proposal that minimizes impacts on the
endangered species of San Bruno Mountain. Key elements contained in the HCP include
establishment of zones of permanent and temporary disturbance, minimum grading, and
replanting disturbed slopes with native plants including host plants for the rare
butterflies. The undisturbed open space located between the developement area and the
northerly and westerly property lines would be dedicated to San Mateo County for
inclusion in the San Bruno Mountain State and County Park. All other open space areas
would remain within the jurisdiction of the City of South San Francisco and under the
purview of a combined property owners association. In addition, the 157 -acre Juncus
Ravine parcel adjacent to the site would be dedicated to the County as permanent open
space.
The extent of proposed permanent and temporary disturbance on the site is illustrated in
Figure 19, Section IV.O. Zones of permanent disturbance are those areas that would be
110
IV. Environmental Setting, Impacts and Mitigation
removed from habi tat and replaced with urban development. These areas amount to
approximately 126 acres. Zones of temporary disturbance during grading activities are to
be reclaimed and revegetated. These areas constitute an additional 33 acres.
Thomas Reid Associates estimate that development of the Terrabay project, as currently
proposed, would eliminate 2.22% of the total mission blue population and 0.45% of the
total callippe silverspot population.6 Since the Terrabay project is not the only
development proposal considered by the Habitat Conservation Plan it is important to
review this reduct!on as it contributes to a cumulative trend. If all private lands on San
Bruno Mountain were developed under the conditions set forth in the Habitat Conservation
Plan, Thomas Reid Associates estimate approximately 13% of the mission blue population
would be eliminated as would about 7% of the callippe silverspot.6
The effect these estimated reductions in population size would have on the extinction
potential of either species is open to conjecture. Further, questions about the
methodological accuracy of the population estimates have been raised by other scientists
familiar with the butterflies. Due to time and budget constraints, the Reid studies
focused upon adult butterflies and did not perform detailed analyses of larval densities
and success ratios. Work by Dr. Richard Arnold indicates that mission blue larvae
distribution and densities may not directly correspond with that of adults. Rather, certain
areas indicated by adult surveys of the 1981 flight season as "low density" may be more
important to larvae than those adult density figures would suggest.8
The mission blue and callippe silverspot butterflies could be headed toward extinction
even in the absence of further development on San Bruno Mountain. However, the
reduction in habitat associated with the proposed project as well as the other proposed
projects, such as the Northeast Ridge Development, would have the effect of accelerating
this trend and increasing the probability of extinction. Thomas Reid Associates have
estimated this increase, assuming complete loss of all populations on parcels in private
ownership, at 8 to 15% for the mission blue and 6 to 11% for the callippe silverspot.6 If
the conservation and management techniques contained in the HCP are successfully
implemented this increase in extinction potential could be substantially reduced.
However, the success of that program is at this point still speculative given remaining
methodological problems, uncertainty about certain life requirements of the species, and
the inability to accurately predict future population and habitat trends.
111
IV. Environmental Setting, Impacts and Mitigation
Elimination of 126 acres of annual grassland would also have an impact on those other
wildlife species that occasionally use, or are dependent upon that habitat. In particular,
the amount of raptor foraging habitat would be reduced. Because of the wide ranging
nature of these animals, development of the site would probably alter hunting patterns but
would not cause direct mortalities. The carrying capacity of the mountain for raptors
would be decreased by a small percentage. Other carnivores such as gray fox would
experience a similar modification in available hunting territory, especially due to increased
human and potential domestic animal activity.
The avifauna currently found in the grasslands of the site would be replaced by more
urban-associated species such as house sparrow, Brewer's blackbird, mockingbird,
American robin and starling. These birds are able to reproduce and feed within the
context of residential development, such as the one proposed. The removal of some
riparian-type habitat (e.g. willows and rushes) would also reduce the available habitat for
certain other species of birds.
3. Mitigation
a. Habitat Conservation Plan Guidelines
The Habitat Conservation Plan provides explicit guidelines for mitigating adverse impacts
of the project on species of concern. Because that document would be responsible for
determining the manner in which the site is developed the relevant section of that plan is
reproduced here (HCP Volume II, pages VII-I 56 to 158).6 As a note of explanation, the
T errabay Development is referred to as the South Slope Parcel Management Unit 2-04
throughout the HCP. The developed portion of the project site (area of permanent
disturbance) is referred to as Management Unit 2-04-01 and the remaining portion
(temporarily disturbed and undisturbed areas) is referred to as Management Unit 2-04-02.
"HCP Objectives - Specific Conservation Needs: The HCP approach to the South
Slope is to prevent sudden loss of habitat all at once by phasing the project so that
reclamation of cut and fill slopes with host plant species can begin in the first phase
before the final phase of development takes place. Other objectives include defining
the interface of development and open space to minimize habitat disturbance,
especially in sensitive areas; minimizing grading requirements to protect upslope
habitat, and protecting future inhabitants from grassland fires, which are important in
maintaining grassland succession. The developer has designed the project to meet the
needs of these conservation objectives.
112
IV. Environmental Setting, Impacts and Mitigation
"Operatinq Program
Obligations: The landowner/developer will have the following obligations:
I. No construction or conversion to urban uses shall be permitted in the area
designated 2-04-02 on Figure 2-04 C. The boundary of area 2-04-02 may be
adjusted by the Landowner by not more than fifty (50) feet, however, that the total
area increased as a result of such adjustment does not exceed ten (10) acres.
Outside area 2-04-02 construction and conversion to urban uses may occur subject
only to the conditions set forth in Paragraph 2 below.
2. Prior to any construction within Administrative Parcel 2-04, the Landowner shall
provide for the following:
a. Dedication of Conserved Habitat. The landowner shall agree to dedicate to the
County all lands within Administrative Parcel 2-04 within area 2-04-02 as
adjusted by the Landowner pursuant to Paragraph I. Such dedication shall be
offered by the Landowner at the time of receipt of the first grading permit
with respect to the parcel of the project to which it pertains.
b. HCP Funding Proqram. During the pre-development phase of the HCP, the
landowner/developer will contribute to a pre-development fund. During the
project development phase, the developer will enter into a contract with the
Plan Operator to pay the reasonable cost of supervising the HCP restrictions on
grading and supervising the reclamation of habitat. Finally, after development
the Landowner shall obligate future residents, through CC&R's and covenents
running with the land to an annual assessment of $20.00 per dwelling unit or the
equivalent adjusted for inflation to 1983 dollars. The funds will be paid to the
San Bruno Mountain Conservation Fund. See Chapter V-B (of the HCP) for
details of funding and timing.
c. Construction Provisions. In accordance with Paragraph I above, the Landowner
shall not disturb any land in area 2-04-02 except as provided in 2d below. In
addition, the Landowner shall not grade more than one phase per year.
d. Reclamation Provisions. With respect to any areas which are to be graded or
disturbed and thereafter dedicated as Conserved Habitat, the landowner shall
prepare a Reclamation Plan for approval by the City (or County, as the case
may be) in accordance with its normal standards and procedures for grading
permits. These provide for grading to be accomplished, erosion and run-off
controls, and revegetation with native grassland species approved by the Plan
Operator. In addition, the Landowner shall clearly define on the ground (by
snow or two strand wire fencing or other methods) the limits of disturbance
anticipated and shall limit construction disturbance to said limits as provided in
fencing and signing provisions of the MOU and Chapter 5 (of the HCP). The
fencing shall be constructed at the boundary between the temporarily disturbed
areas and the permanently disturbed areas. At the time of approval of the
reclamation plan(s), those plans shall substitute for the more generalized maps
referenced in this section.
113
IV. Environmental Setting, Impacts and Mitigation
e. Pesticide Control. The landowner shall establish convenants and restriction
encumbering Development Areas in favor of the County and/or City prohibiting
the use of aerial or large-scale spraying of pesticides without the approval of
the Plan Operator.
f. Buffer Areas. The landowner shall convenant in favor of the City of South San
Francisco and the County to establish and maintain a buffer area of up to thirty
(30) feet in width to protect urban uses within the Development Area from fire.
Native plants, which will not present an invasion threat to grasslands within the
Conserved Habitat, are preferred. These buffer areas will be maintained by the
Homeowners Association.
g. Inspection. The Landowner shall, in carrying out Reclamation Plans for
Administrative Parcel 2-04, contract for an inspector acting for the County as
Plan Operator to periodically monitor grading and revegetation activities
through completion of the reclamation activities and acceptance of the offer to
dedication.
"The Plan Operator will have the following obligations:
I. Prepare and execute an annual operating program for the Conserved Habitat within
Administrative Parcel 2-04;
2. Monitor the effect of all activities within Development Areas on adjacent
Conserved Habitat and provide advice and direction to the Landowner to assist his
compliance with the obligations described above with respect to Administrative
Parcel 2-04;
3. Designate vegetation materials for use in Reclamation Plans and review such
Reclamation Plans submitted by the Landowner with respect to Administrative
Parcel 2-04 in a timely fashion to avoid delays in the implementation of such Plans:
4. Accept dedications of Conserved Habitat within Administrative Parcel 2-04."
b. Mitigation measures proposed as part of the project.
The project sponsor has included the following mitigation measures in the Terrabay
Development Specific Plan which directly or indirectly relate to impacts on vegetation
and wildlife.
The development will be generally restricted to the natural swales. The natural
appearing rounded knolls will be maintained as much as possible. Development of
knoll areas will be terraced in an effort to maintain the natural topography of the
site.
The limits of temporary and permanent grading will be clearly delineated during
construction to prevent encroachment into areas that are to remain undisturbed,
as delineated in Figure 19, Section IV.D. of this document, and as required by the
Habitat Conservation Plan presently under review.
114
IV. Environmental Setting, Impacts and Mitigation
The grading schedule will be phased as shown in the phasing plan (see Table 2,
Section IIl.B. of this document) in order to minimize vegetation removal during
one season.
The developed areas and the temporarily disturbed areas will be limited to the
boundaries shown in Figure 19.
Permanent open space area will be annex~d to the City and then dedicated to San
Mateo County and included into San Mateo County's Habitat Conservation Plan.
IE. McClintock, W. Knight and N. Fahy, A Flora of the San Bruno Mountains, San Mateo
County, California, Proc. of the California Academy of Sciences, Vol. 32, N. 20,
November 1968.
2Walter Knight, California Academy of Sciences, telephone conversation, March 28, 1982.
3Restricted to a limited geographical area.
4Thomas Reid Associates, Phase I Report Endangered Species Survey, San Bruno
Mountain, Bioloqical Study-I 980, December 19, 1980.
5Thomas Reid Associates, Draft Endangered Species Survey, San Bruno Mountain,
Bioloqical Study-I 98 I , November 1981.
6San Bruno Mountain Habitat Conservation Plan Steering Committee - Chaired by San
Mateo County, Draft San Bruno Mountain Area Habitat Conservation Plan, May 1982.
7 California Native Plant Society, Inventor of Rare and Endan ered Vascular Plants of
California, Special Publication No. I (2nd edition April 1980.
8Richard Arnold, Research Associate, University of California, Berkeley Entomology
Department, telephone conversation, May 19, 1982.
9Thomas, John H., Flora of the Santa Cruz Mountains of California, Stanford University
Press, Stanford, California, 1953, 434 pp.
115
IV. Environmental Setting, Impacts and Mitigation
F. COMMUNITY SERVICES
Discussion of community services for the project area presupposes annexation to the City
of South San Francisco and municipal jurisdiction when appropriate. Information used in
analyzing impacts in this section was derived, in part, from Recht Hausrath's fiscal
analysis of public services for the proposed project area. I
I Recht Hausrath and Associates, San Bruno Mountain: South Slope Fiscal Impact Study,
September 1981.
I. Water Service I
a. Setting
Cl!rrently, water services are not provided to the undeveloped project area. Rou9hly
~/one-half of the project site is designated within the service area of the California Water
Service Company. The remaining portion of the site is not assigned to any water service
area. Upon project approval, California Water Service Company would request inclusion
of the entire project site in their service area. The request would require approval by the
California Public Utilities Commission (PUC) and the San Francisco Water Department
(SFWD).
The California Water Service Company is a private utility company subject to regulation
by the State PUC. It provides service to 19 districts statewide. Once incorporated into
the Company's service area, the entire project site would lie within the South San
Francisco District. Boundaries for the District roughly coincide with the City limits.
About 90% of the water supplied to the District is purchased from the San Francisco
Water Department. Approximately 10% is supplied by California Water Service Company
wells located within the District.
In 1980, the Company supplied an average of 7.3 million gallons per day (mgd) to the
South San Francisco District. The present capacity of the District system is 40 mgd.
This leaves a current (normal year) reserve capacity of 32.7 mgd.
Water mains are located along Hillside Boulevard~ Randolph Avenue and Airport
Boulevard.
b. Impacts
Based on the proposed uses of each building and associated landscaping, the total project
would consume an average of about 320,370 gallons of water per day, or .32 mgd.2 This
116
IV. Environmental Setting, Impacts and Mitigation
would represent about 0.8% of the total present system capacity. The Company has
indicated their ability to comfortably accommodate this increase to the system.
Existing water mains on Hillside Boulevard, Randolph Avenue and Airport Boulevard are
sufficient to service neighborhoods adjacent to the project site. However, the proposed
project would require a new water distribution system, independent of existing
neighborhood water mains. The entire cost for the new on-site system and improvements
to the off-site water system which occurred as a result of the on-site system would be
incurred by the project sponsor.
Specific design features and cost estimates cannot be provided by the California Water
Service Company until the project has reached a later stage of planning. However, the
Company has developed preliminary basic plans for the T errabay water distribution
system.
The new system would include a feeder transmission line that would start at the San
Francisco Water Department connection on Airport Boulevard and extend approximately
1,000 feet southerly to a location within the project boundaries and under the new Hillside
Boulevard extension. In the same vicinity, a pump station would relift water to a one
million gallon steel tank reservoir located at an as yet unspecified site at the 400-foot
elevation within the project area. Location of the water tank would coincide with a
disturbed open space area within the jurisdiction of the City to facilitate servicing. A
pressure system pump station would be required to provide adequate water pressure to
structures located above an elevation of 300 feet. The new system would be
interconnected to the existing water system to provide a continuous loop. The entire
water distribution system would be designed to comply with fire flow requirements set by
the City.
The initial cost of the water system installation would be the responsibility of the project
sponsor. Ongoing maintenance of the water lines from the meters to the individual
dwelling units would be the responsibility of a homeowner's association in the residential
areas and the property owners in the commercial areas. The California Water Service
Company would assume maintenance of the water tank and service mains following their
dedication.
117
IV. Environmental Setting, Impacts and Mitigation
c. Mitigation
Ca Ii forn ia Water Service Company has indicated that an above-ground tank would provide
maximum resistance to possible seismic forces. Screening provided by such methods as
painting the tank with earthtone colors and landscaping and mounding would be utilized to
reduce visual impacts, although an underground tank could be more easily designed to
minimize visual impacts and should be given serious consideration.
I This section is based on information provided by J.P. Pendergast, Assistant Chief
Engineer, California Water Service Company in telephone conversations on March 9 and
31, 1982 and in letters dated March 10 and April 2, 1982.
2A conservative (high impact) estimate of water consumption was calculated using the
following methodology:
Consumption rates:
15/gallons/day/employee
150/gallons/day/resident
Employees:
Residents:
1 per 250 square feet of nonresidential space = 2,728
2.5/dwelling unit = 1,863
Consumption:
(+)
15(x)
I 50 (x)
2,728
1,863
=
40 , 920
279,450
320,370 gallons/day
=
Source:
Rau, John G. and David C. Wooten, 1980, Environmental Impact
Analysis Handbook.
2. Wastewater 1
a. Setting
Upon annexation to South San Francisco, sewage treatment services for the project area
would be provided by the Sanitation Division of the City's Public Services Department.
The residential area in the western half of the City is served by the Colma Creek
collection system. This system consists of gravity sewers that intercept wastewater from
eight basins. The project site would be served by Basin 6 which contains 9,140 feet of
interceptor and trunk sewers varying from 6 to 21 inches. The Basin 6 network of sewers
joins a main interceptor sewer which parallels Colma Creek. This Colma Creek line
terminates at the San Mateo Avenue Pump Station. The wastewater is then pumped by
pressure through a force main to the South San Francisco/San Bruno Treatment Facilities.
118
IV. Environmental Setting, Impacts and Mitigation
The main interceptor line for Basin 6 parallels Airport Boulevard and connects to the
Colma Creek line south of Cypress Avenue. A 627-foot section of this main interceptor is
surcharged in the vicinity of Village Way. Also, excessive infiltration into trunk lines
along Hillside Boulevard and Hemlock Avenue often results in manhole covers being raised
during rainstorms.
The City has planned enlargement of the Colma Creek line from Colma to the pump
station to accommodate flows resulting from the addition of the town of Colma to the
system. To increase the line's carrying capactiy, a parallel line would be constructed
along the existing line. Enlargement of the system is tentively scheduled to begin in the
fall of 1982. Completion of the newly enlarged system would occur prior to development
of the project site.2.
The San Mateo pump station has a design capacity of 12 million gallons per day (mgd),
while current wastewater flows average 5 mgd. Wet weather infiltration into dilapidated
sewer lines often results in wastewater flows of 7 to 9 mgd. The Public Services
Department expects the wet weather infiltration to diminish when the Colma Creek line
is upgraded.3
The South San Francisco/San Bruno treatment plant has a design capacity of 13 mgd.
Current treatment flows average 8.5-9 mgd. The Department has indicated that
occasional wet weather infiltration problems would also be alleviated when the Colma
- 3
Creek line is upgraded.
For discussion of the proposed project's storm drainage system see Geology and
Hydrology, Section IV.B. of this document.
b. Impacts
The City sewer master plan estimated that adding 1,000 new houses in the project area
(255 more than the proposed project) would increase average flows to the Colma Creek
line by 250,000 gallons per day., Since enlargement of the Colma Creek line is still in the
planning stage, impacts to that line are undetermined at this time.2
The City has indicated both the pumping station and the treatment pl~could
comfortably accommodate wastewater generated by the proposed project.
,
119
IV. Environmental Setting, Impacts and Mitigation
Sewage service for the proposed project would be provided through a system of on-site
gravity sewer mains and interceptors which would connect to the existing sewer system in
~irport Boulevard. The existing system in Airport Boulevard is near capacity from the
intersection at Randolph Avenue to the manhole in the intersection at Armour Avenue. In
this section, a parallel interceptor would be constructed to carry the wastewater flows
from the project. A 627-foot section of the Basin 6 interceptor near Village Way is near
capacity and would be enlarged to accommodate project flows. Sanitary sewers would be
designed to handle wastewater flows of 200 gallons per day per residential unit with a
peaking factor of 3.0. Infiltration/inflow would be calculated at 500 gallons per day per
inch diameter per mile. Commercial wastewater flows would be calculated on a case-by-
case basis.
Costs of the on-site sewer system and any corrections or modifications to the existing
system that are required as a direct result of the project would be incurred by the
sponsor. Upon dedication of the facilities, the City of South San Francisco would assume
maintenance responsibilities for the sewer system.
c. Mitigation
The project sponsor would participate with the South San Francisco Public Services
Department and the City Engineer for the town of Colma to ensure that enlargement of
the Colma Creek line would also accommodate wastewater flows generated by the
proposed project.
I Unless otherwise indicated, information for this section is based on CH2:HiII, Sewer
Master Plan for the City of South San Francisco, April 1980.
2Robert Yee, Director, Department of Public Services, City of South San Francisco,
telephone conversation, May 26, 1982.
3Recht Hausrath and Associates, "Wastewater Treatment", San Bruno Mountain: South
Slope Fiscal Impact Study, September 1981.
3. Sol id Waste I
a. Sett ing
Solid waste and collection disposal services for South San Francisco are supplied by the
South San Francisco Scavenger Company. Upon annexation to the City, services would be
extended to the project area.
120
IV. Environmental Setting, Impacts and Mitigation
An average of 400 tons of solid waste are collected each day, or about 146,000 tons per
year. Collected waste is taken to the Oyster Point Boulevard transfer station, then
transported to the primary disposal site located at Ox Mountain near Half Moon Bay.
Because the disposal site may also be used by San Francisco on a short-term basis,
lifetime expectancy of the landfill site is undetermined at this time.
b. Impacts
The residential portion of the Terrabay Development area is expected to generate
approximately 4,470 pounds of solid waste per day. The commercial portion is expected
to generate approximately 6,831 pounds per day. 2 The total solid waste generated from
commercial and residential sources annually (2,061 tons) would represent 1.4% of the total
amount currently collected within the Company's service area. The Company does not
anticipate any adverse impacts on service or disposal capacity due to the project.
Ilnformation in this section is based on a telephone conversation with Carlo Franco,
Manager, South San Francisco Scavenger Company, March 31, 1982.
2California State Waste Management Soard, Solid Waste Generation Factors in California,
T echn icaJ Information Series No.2, July 8, 1974 for generation factors:
residential refuse: 2.4 Ibs/capita/day
2.4 Ibs x 745 dwelling units x 2.5 persons/unit = 4,470 Ibs/day
nonresidential refuse: I Ib/lOO sq. ft./day
116(x) 682,100 sq. ft. ~ 100 = 6,821 Ibs/day
4. Gas and Electricity I
a. Setting
Natural gas and electricity would be supplied by the Pacific Gas and Electric Company
(PG&E). The project area would be serviced by the Northern San Mateo District of
PG&E's San Francisco Division. Currently, the District supplies natural gas to 17,241
customers and electricity to 19,960 customers. Current District peak demand is 285
megawatts.
Natural gas would be extended to the site via an existing pipeline network which services
the entire District. A pipeline system right-of-way, parallel to Airport Boulevard, crosses
the site approximately opposite Gardner Avenue.
121
IV. Environmental Setting, Impacts and Mitigation
Electricity to the project site would be distributed through PG&E's Daly City Substation
located at East Market and Orange Streets. The substation has a total capacity of 88
megawatts. Current peak demand within the substation's service area is about 76
megawatts.
Gas and electricity will be supplied to the project site according to the guidelines for
rates and rules on file with the California Public Utility Commission at the time of the
request for services.
b. Impacts
It is estimated that the project would generate energy demands of 12.2 million kwh of
electricty and 979,000 therms of natural gas per year. The annual residential demands
would be about 3.7 million kwh for electricity and about 750,000 therms for natural gas.
Annual nonresidential demands would be about 8.5 million kwh for electricity and 353
therms for natural gas.2 PG&E has indicated that present facilities would be adequate to
provide service to the project area.
c. Mitigation
The proposed project would be designed in accordance with the energy conservation
standards of Title 24 of the California Administrative Code. The Code requires that
structures comply with specified prescriptive measures for such architectural details as
wall and ceiling insulations, climate control systems, water heating systems and
infiltrations.3
The project would also conform with the more stringent standards outlined in the
Conservation Design Manuals for new residential and nonresidential bUildings.4,5 Proposed
project compliance approaches, and specific design features are described in Section IV.
H. of th is document.
1 Unless otherwise noted, information in this section is based on a telephone conversation
with E.A. Carrera, Manager, South San Francisco Division Pacific Gas & Electric
Company, on March II, 1982.
2For derivation, see Section IV.H. Energy.
3California Energy Commission, Conservation Division, Regulations Establishing Energy
Conservation Standards for New Residential and New Nonresidential Buildings, as
amended July 26, 1978.
122
IV. Environmental Setting, Impacts and Mitigation
4California Energy Commission, New Residential Building Standards Energy Conservation
Manual, January 1982.
5California Energy Resources Conservation and Development Commission, Conservation
Division, Energy Conservation Design Manual for New Nonresidential Buildings, October
1977.
5. Telephone Services
a. Setting
Telephone service would be accommodated through Pacific Telephone's Burlingame
Business Service Center located at 27 17th Avenue in San Mateo. Installation of
telephone facilities in the area would conform to the guidelines outlined in Schedule 36T
of the California Public Utilities Code. Cost of the facilities network system would be
incurred by Pacific Telephone. Specific installation fees would be charged to the
individual telephone customer. I
As part -of an unrelated program to reinforce telecommunications between San Francisco
and San Jose, Pacific Telephone is currently proposing the installation of a fiber optic
network system. The system would parallel the west side of Airport Boulevard in six
ducts of four-inch conduit. In conjunction with the system, a 10 foot by 28 foot
subterranean controlled environment vault (CEV) would be installed in the undeveloped
portion of the project site, adjacent to Airport Boulevard and northeast of the parking lot
servicing the hotel and tech trade center complex.
b. Impacts
Pacific Telephone has indicated the South San Francisco Central Office facilities are
adequate to accommodate 1,500 additional phone numbers, an estimate exceeding that
expected for the proposed development.3
The fiber optic system is scheduled to be completed before the projected start-up date for
the proposed project development in that area. Visual impact of the system would be
limited to the manhole cover above the CEV. Pacific Telephone indicated that
maintenance of the CEV unit would be minimal.2
I Erica Volberg, Service Marketing Representative, Burlingame Business Service Center,
Pacific Telephone, telephone conversation, March II, 1982.
123
IV. Environmental Setting, Impacts and Mitigation
2Wayne Lagger, Right-of-Way Agent, Distribution Services, Pacific Telephone, telephone
conversation, March II, 1982.
3Patsy Kalman, Manager, Switching and Engineering Division, Burlingame Business
Service Center, Pacific Telephone, telephone conversation, March II, 1982.
6 Fo sol
. Ire ervlces
a. Setting
The Terrabay project area, as an unincorporated area, is currently provided fire service by
the California Department of Forestry's district office in Belmont. Response time to the
project site is estimated between 15 and 25 minutes.2
Upon annexation to the City of South San Francisco, the City's Fire Department would
assume responsibility for providing services to the project area.
South San Francisco Fire Department operates four stations. Department headquarters is
located in the Municipal Services Building at 33 Arroyo Drive, near EI Camino Real. Also
located in the Municipal Services Building is the communications center which provides a
combined dispatch service for both fire and police departments.
I
I
The Fire Department has a staff of 82, with a minimum of 21 firefighters on duty per
shift. Staff are assigned to the following divisions: 2 in Administration, 4 in Fire
Prevention Division (Fire Marshall and Deputy Fire Marshall), 62 in Operations Division
(firefighters), 13 Paramedics and 1 Training Chief. Fire stations are equipped with a
miniumum of one engine company. An engine company consists of one engine (pump
equipped) and at least three firefighters. A truck company consists of one truck (ladder
equipped) and at least three firefighters. The truck company responds with at least one
engine company to all alarm calls. Fire Department equipment is shown in Table 10.
The actual pumping capabilities of a fire department are contingent upon manpower (i.e.
the amount of equipment in service depends upon the available manpower capabilities).
Of the Department's theoretical pump capacity of 7,250 gallons per minyte, its actual
operating capability is estimated at 2,300 gallons per minute, based on current manpower
capabi lities.
Each fire station has a general area of primary responsibility. However, response
coordination, in terms of specific equipment and backup units, is contingent upon a
124
IV. Environmental Setting, Impacts and Mitigation
TABLE 10
CITY OF SOUTH SAN FRANCISCO FIRE DEPARTMENT
1981 EQUIPMENT LIST
line Equipment
Pump Capacity in
Gallons per minute
Engine I
Engine 2
Engine 3
Engine 4
Engine 5
Truck (90' elevated platform)
Chemica' Truck
Paramedic Van
1,500
1,250
1,500
1,500
1,500
N/A
N/A
N/A
Reserve Equipment
Engine I
Engine 2
Truck (75' aerial ladder)
Paramedic Van
1,250
1,000
N/A
N/A
Non-Line Equipment
2 Fire Chief's Cars
3 Fire Marshall's Cars
2 Pick-up Trucks
N/A
N/A
N/A
125
IV. Environmental Setting, Impacts and Mitigation
number of factors including the type of alarm set and equipment needed. The Department
responded to a total of 3,672 calls in 1981, of which 1,629 were paramedic-emergency
calls.
Fire stations are located as follows:
Station I (Central Fire Station), located at 201 Baden Avenue near Airport
Boulevard. Presently, this station services the majority of the area adjacent
to the unincorporated project site. It is equipped with two engine companies
and one truck company, and staffed with a minimum of ten firefighters,
including one Battalion Chief. Response time to areas adjacent to the
project area is estimated at three minutes.
Station 2, located at the intersection of Harbor Way and Mitchell Avenue.
This station generally provides response service to the area east of Sayshore
Freeway. It is equipped with one engine company.
Station 3, located in the Municipal Services Building at Arroyo Drive near EI
Camino Real. This station generally services a region which includes the
area adjacent to the western portion of the project site near Hillside
Elementary School. It is equipped with one engine company and the
Paramedic Rescue Unit.
Station 4, located on Gateway Drive. This station generally services the
West borough Area and is equipped with one engine company.
The South San Francisco City Planning Department recommends adherence to a policy
standard set by the Insurance Services Office (ISO) for the maximum distance a fire
station should be from the response site. The ISO standard3 recommends having a first-
due engine company within a maximum of 1.5 road miles from any built-upon area of the
City.4 The majority of South San Francisco lies within the recommended distance or a
firehouse. The incorporated area adjacent to the project site ranges in distance from 1.5
to 2 miles from Stations I and 3.
b. Impacts
Planned development in the project area and subsequent annexation would result in an
increase to the Fire Department's service area and an increase in calls for service.
126
IV. Environmental Setting, Impacts and Mitigation
The project sponsor has offered to donate the land and erect a firehouse as part of the
T errabay Development. The new station would be juxtaposed to the Hillside Recreation
Center and erected during Phase I of the proposed construction schedule. Staff for the
new station would be transferred along with one engine company from Station I. Based
upon the Department's preliminary recommendations for building and equipment needs,
estimated total capital cost is $183,400. Of this, the estimated cost for building the new
station ($141,000) would be contributed by the developer, reducing the capital cost to the
City of $39,000 for furnishings and additional equipment.5
Placement of a fire station in the Hillside Boulevard area would provide additional
services and an increase to fire protection levels in surrounding areas where present
services are currently below ISO policy standards. Quick east-west access would be
provided across the northern portion of the City via Hillside Boulevard. This increase in
mobility would allow a faster response time both for first and backup calls. Faster
response time is anticipated with the extension of Hillside Boulevard.
Fire Chief Drago anticipates a possible manpower shortage at Station I with the
relocating of one engine company plus its staff to the new station. To increase efficiency
and improve the station's ability to cope with more serious fires, the Chief recommends
the addition of one firefighter position to Station I. Around-the-clock staffing of this
additional position would require hiring four firefighters at an estimated annual cost of
5
$133,200.
Possible staff shortages could occur in the Fire Prevention Bureau which provides project
design assistance and inspection of new development sites. Fire Chief Drago has
recommended the addition of one staff person in the Fire Prevention Bureau as a result of
the Gateway Redevelopment Project.6 Whether this position will be filled on a temporary
or permanent basis is not determined. Chief Drago indicated cumulative impacts to Fire
Prevention Bureau staff due to additional proposed project development are unknown at
this time.
The proposed project would provide a new fire station in an area already below ISO
standards. Service to the northern area would be increased beyond that necessitated by
the Terrabay Development. Earliest construction phases of the project would be on the
western end of the project site. This portion of the project is located farthest from
127
IV. Environmental Setting, Impacts and Mitigation
present station facilities. To lessen the impact to services, the fire station would be
erected during the first phase of construction.
Final approval of the project would require conformance to existing South San Francisco
and California fire codes. This includes an on-site fire hydrant system, satisfactory
access to all structures, a water system designed for adequate water supply and pressure,
a sprinkler system in all buildings over three stories and installation of alarm boxes in the
commercial developed area to connect to the existing municipal fire alarm system. These
measures would reduce the proposed project's demand for fire protection services.
Cumulative impacts to the immediate area would be minimal due to the addition of a new
fire station. As a control factor for fire hazards associated with San Bruno Mountain, a
50-foot wide fire break between project structures and natural hillside vegetation would
be installed around the perimeter of the development. The first 25 feet of this break
would be permanently irrigated to sustain ornamental plant species. A temporary
irrigation system for the remaining 25 feet would operate long enough to establish native
and drought-tolerant species. This landscape buffer is designed to provide a transition
between the development landscape and the native vegetation landscape.
c. Mitigation
The proposed project would have to conform with all fire code provisions. The project
sponsor is currently working with the Fire Prevention Office to identify specific design
features necessary to confqrm to existing fire codes.
I Unless otherwise noted, this section is based on a telephone conversation with Jack
Drago, Fi re Chief, South San Francisco Fi re Department, March 16, 1982.
2David Westover, Battalion Chief, Urban Forestry, California Deportment of Forestry,
telephone conversation, March 16, 1982.
3Clifford Ommert, Supervisor, Public Protection, Insurance Services Office, telephone
conversation, March IS, 1982.
41nsurance Services Office, "Distribution of Companies" Fire Suppression Schedule:
Edition 6-80, June 1980, page 22.
5Recht Hausrath and Associates, "Service Issues and Costs," San Bruno Mountain: South
Slope Fiscal Impact Study, September 1981.
6Sourh San Francisco Redevelopment Agency, Final EIR - The Gateway Redevelopment
Protect. June 1981.
128
IV. Environmental Setting, Impacts and Mitigation
7. Police Services'
a. Setting
Presently the unincorporated Terrabay project area is provided police services from the
San Mateo County Sheriff's Department. Coverage for the area is supplied by roving
patrol cars dispatched from the Redwood City headquarters.2 Upon annexation to the
City of South San Francisco, the City's Police Department would assume responsibility for
providing service to the area.
City police headquarters is located in the Municipal Services Building at 33 Arroyo Drive
in South San Francisco. The communications center which provides a combined dispatch
service for both fire and police departments is also located in the Municipal Services
Building.
The Police Department has a staff of 96 assigned to the following divisions: 2 in
Administration, 73 in Operations Division (Patrol and Investigation Sections), and 21 in
Services Division. Of the total staff, 53 have field law enforcement responsibility.
The Police Department divides the City's 9.6 square miles into patrol districts called
beats. During periods of normal service demand, patrol coverage is usually organized into
five beats. Supplemental coverage is provided by floating patrol units which are not
ass igned to anyone beat.
Over the last five years, crime statistics have remained consistent for all categories
except robbery. In this same time period, the number of calls for police services have
increased significantly (Table 11).
b. Impacts
Proposed development in the Terrabay project area and subsequent annexation would
increase the Pol ice Department's service area and create more calls for service.
However, new demands for police services would also occur independently of the proposed
project.
Police Chief James Datzman indicates projected overall growth in the northern portion of
the City along with a general upward trend in service calls would result in an expansion of
police services. (See Appendix A, Table I for further discussion on local projected
growth).
129
IV. Environmental Impacts, Setting and Mitigation
TABLE II
SOUTH SAN FRANCISCO POLICE DEPARTMENT
1977-1981 CRIME STATISTICS
1977 1978 1979 1980 1981
Person Related Crimes:
Homicide 0 2 3 2 I
Rape 9 12 14 II 9
Robbery 47 60 68 70 79
Aggravated Assau It 48 57 85 44 56
Total Person
Related Crimes 104 131 170 127 145
Property Related Crimes
Burglary 707 855 856 872 813
Larceny 1,475 1,453 1,822 2,007 1,744
Auto Theft 216 225 263 275 227
Total Property
Related Crimes 2,398 2,533 2,941 3,154 2,784
Total Police Service
Calls 21 ,980 23,876 25,758 25,540 28,757
Source: South San Francisco Police Department, 1982.
130
IV. Environmental Setting, Impacts and Mitigation
The Department has previously determined that an increase of 4.3 officers would be
needed in conjunction with the Gateway Redevelopment Project to maintain the present
quality of police services. Should the Terrabay project area be developed, Chief Datzman
would recommend the previously determined estimate be increased to a total of five
patrol officers and one Supervisor-Investigator along with the creation of a new beat. The
Department would increase the six officers and institute the new beat over the next five
years to maintain existing levels of service as buildout proceeded. Tentatively, the
additional beat would be responsible for the newly incorporated project area, the
Stonegate area, adjacent residences east of Chestnut Avenue along Hillside Boulevard,
Randolph, Larch and Hemlock Avenues, the Pecks lots area and the area north of Oyster
Point Boulevard and east of Airport Boulevard. The Department would anticipate the
establishment of the new beat within the next five years. With the flexibility of having a
variable number of beats along with floating patrols, additional services would be added
gradually while maintaining existing service levels. The increase in services would occur
as bui Idout proceeded.
Additional development of any kind would increase the potential for criminal activity. The
potential for auto theft, larceny, and residential burglaries would increase with new
residential development. The new development, however, is not expected to create a
disproportionate number of requests for police services compared to other similar
residential areas.
Demands for police services in the non-residential areas are more difficult to predict
because specific security measures and systems are not available at this stage of the
design process.
c. Mitigation
Details of the project's security features are not currently available , but the project
would conform with specific restrictions and design requirements of the City's building
security ordinance. Further restrictions would be detailed by the Department during the _
use permit process.
Preliminary security design features were recommended in a memorandum dated July 31,
1981 by the City's Police Department to the Director of Community Development. The
following is a list of security design features recommended in that memorandum and
subsequently by the Department's Crime Prevention Unit.3
131
IV. Environmental Setting, Impacts and Mitigation
Proper lighting and pedestrian access should be provided to Airport Boulevard
from the proposed Hillside extension.
Adequate levels of high intensity pole lighting should be placed in any area
where there is pedestrian traffic.
All pedestrian walkways servicing inside areas not adjacent to roadways should
be designed to accommodate emergency vehicles.
All nonresidential facilities should have alarm systems.
The Fire Station should be relocated to a central location in the recreation
center complex to afford maximum supervision of the playground, bandstand,
lawn area and basketball courts.
The restroom located adjacent to the softball/soccer field should have security
lighting and a metal grate door that would be locked when not in use.
Private roads servicing the residential units should be looped to provide more
than one access point to each unit.
Private and collector roads should be developed before construction to afford
access for fire and police services.
Security lighting and gate-controlled access with automatic garage door
openers should be required for all private underground parking.
In the hotel and office complex areas, a security system should be considered
including card access control to the office buildings, a closed circuit television
system to monitor garages and public places, and a tenant alarm monitoring
capability. Placement of one security office for both office and hotel and
tech center complex should be adequate providing there is adequate television
surve i I lance.
Although this is not a complete list of recommended security design features,
incorporating the features described would reduce the security problems of the project.
(--The Department's Crime Prevention Unit indicated it would be desirable to work with the
sponsor in the early stages of developing more specific site plans to provide additional
design and security features to improve security measures.
I Unless otherwise noted, information in this section is based on a telephone conversation
with James Datzman, Chief, South San Francisco Police Department, March 18, 1982.
132
IV. Environmental Setting, Impacts and Mitigation
2Richard Platt, Lieutenant, Services Division, San Mateo County Sheriff's Office,
telephone conversation, March 19, 1982.
3Meeting between EIP and Lieutenant Dave Haskins, Investigation Division and Sergeant
Ron Petrocchi, Crime Prevention Unit, March 22, 1982.
8. Public Schools
a. Setting
The project area is served by three school districts: South San Francisco Unified School
District, Brisbane Elementary School District, and the Jefferson High School District.
Present boundaries indicate Brisbane Elementary and Jefferson High School Districts have
jurisdiction north of Randolph Avenue and east of the line made by extending Arden
Avenue northward.
Preliminary estimates based on jurisdictional boundaries indicate students from 520
dwelling units (roughly neighborhoods west of the PG&E Transmission Line) would attend
South San Francisco schools. Students from the remaining 225 units would attend schools
in the Brisbane Elementary and Jefferson High School Districts. Anticipated annexation
of the project site to South San Francisco would not indicate a mandatory change in
district jurisdictional boundaries. I
Students in the South San Francisco Unified School District would attend the following
schools:
Hillside Elementary School (K-6), located on Hillside Boulevard and adjacent to the
western portion of the project.
Parkway Junior High (7-8), located at 825 Parkway Avenue.
South San Francisco High School, located at 400 B Street.2
Students in the Brisbane Elementary District would attend the following schoo1s:
Brisbane Elementary School (K-3), located on San Bruno Avenue in Brisbane.
Lipman Intermediate School (4-8), located at I Solano Avenue in Brisbane.3
133
IV. Environmental Setting, Impacts and Mitigation
Students in the Jefferson High School District would be attending Jefferson High School
located at 6996 Mission Street in Daly City.4
To coordinate findings, estimates listed in Table 12 for students per household are based
on projection factors used in the Recht Hausrath Fiscal Study.5
Housing Type
Single-Family (136)
T ownhomes, Terraced Unit (510)
Condominiums (99)
TABLE 12
STUDENTS-PER-HOUSEHOLD BY HOUSING TYPE
Projected Students
Per Grade
7-8 9-12
. I 5 .25
.10 .10
. 10 .05
Projected Number of
T errabay Students
K-6
.25
.15
.10
Total Students
88
178
20
286
b. Impacts
Total number of students generated by the T errabay Development would be 286, with
224 students attending South San Francisco District schools. Estimated impacts to school
districts are shown in Table 13.
South San Francisco Unified School District has experienced a decrease of approximately
500 students for the 1980-1981 school year. As of January 1982 the decrease in students
has slowed to about one-half of this amount. The District has indicated that in spite of
this slowdown, it would be too early to deduce any ongoing trend.2
Hillside Elementary School enrollment may slightly exceed capacity as a result of
cumulative impacts from other approved residential development. The District indicated
that if this occurs, school boundaries may be shifted or portable classrooms added.
Portable classrooms are in use throughout the District. Hillside Elementary School is
designed to accommodate the addition of portable classrooms without overcrowding
existing multi-purpose facilities.
In spite of possible capacity excesses at Hillside Elementary School, the District could
comfortably accommodate enrollment increases generated by the proposed
development. 2
134
IV. Environmental Setting, Impacts and Mitigation
TABLE 13
TERRABAY STUDENTS - ESTIMATED IMPACTS TO SCHOOL DISTRICTS
Number of September
T errabay 1982 Additional
School District Students Enrollment Capacity
South San Francisco District:
Hillside Elementary 92 401 200
Parkway Junior High 59 520 600
South San Francisco High 73 1,773 200
TOTAL 224
Brisbane Elementary District:
Brisbane Elementary 28 105 145-195*
Lipman Intermediate 17 225 25 - I 00
TOTAL 45
Jefferson High School District
Jefferson High 17 1,350 250
TOT AL TERRABA Y STUDENTS 286
*Numbers represent optimum/maximum enrollment
Source:
135
IV. Environmental Setting, Impacts and Mitigation
The project calls for the improving the existing undeveloped portions of the Hillside
School site with a softball diamond and soccer field. Cost of improvements would be
incurred by the project sponsor. Responsibility for maintaining school fields are shared
between the school districts and the City Department of Parks and Recreation.
Brisbane Elementary District Superintendent has projected an increase of 800 students
over the next five years due to new residential developments. This increase in students
would exceed present school capacities. The District anticipates building another school
(K-5) within the next five years to accommodate this increase. Children would be
relocated within the District if an over-capacity situation occurs before the new school is
built. In lieu of the projected plans to expand, the District could comfortably
accommodate additional students generated by the Terrabay Development.3
Projected enrollment trends for Jefferson High School estimate a decline of 1,000
students over the next five years. Serramonte High School closed in June 1981 due to
declining District enrollment. The 17 projected students from the proposed project could
easi ly be accommodated.4
Preliminary discussions with all involved school districts have indicated a joint preference
for students within their jurisdictions to attend their schools. State funding is based upon
average daily attendance; therefore, an increase in enrollment is desirable.
Division of the project area into separate school districts would detract from an overall
sense of community. In addition, students living within the Brisbane Elementary and
Jefferson High School Districts would travel longer distances to attend schools outside of
their own neighborhoods. Inter-district transfer agreements, which would allow students
to attend schools in other districts, are handled on an individual basis. Currently, there
are no blanket transfer agreements between the involved school districts.
A complicated procedure does exist to change school district boundaries. To initiate
proceedings, a petition is filed with the County Superintendent of Schools. The petition
must be signed by either 25% of the registered voters residing in the area proposed for
transfer, the owner of the property if the area is uninhabitated, or a majority of the
members of the governing boards of each of the school districts involved by the transfer.6
136
IV. Environmental Setting, Impacts and Mitigation
Annexation of the project site to South San Francisco would not indicate a mandatory
change in school district jurisdiction boundaries. It appears unlikely that District
Superintendents would petition for a school district boundary change. The project sponsor
does not propose to process a change in school district boundaries. If a change is desired
by the residents of a district, initiation of the proper petition filing procedures would be
the responsibility of the residents in that district.
I James Cokas, Coordinator, Child Welfare and Attendance, San Mateo County Office of
Education, telephone conversation, March 18, 1982.
2Robert Dominge, Business Manager, South San Francisco Unified School District,
telephone conversation, March 17, 1982.
3Dr. Robert Lloyd, Superintendent, Brisbane Elementary School District, telephone
conversation, March 7, 1982.
4Dr. Floyd Gonella, Superintendent, Jefferson High School District, telephone
conversation, March 17, 1982.
5Recht, Hausrath and Associates, "Service Issues and Costs," San Bruno Mountain: South
Slope Fiscal Impact Study, September 1981.
6San Mateo Office of Education, School District Boundary Change Procedure (as of July I,
198 I).
9. Parks and Recreation I
a. Setting
The Terrabay project area lies directly south of the San Bruno Mountain State and County
Park (Figure 2). Presently this regional park encompasses 2,064 acres of state and County
land. San Bruno Mountain is unique in that it offers a large undeveloped recreational
resource, totally surrounded by intense urban development.
The master plan for San Bruno Mountain was adopted prior to the Park's acquisition of the
undeveloped land adjacent to the project area. An expanded initial study of the mountain
prepared by the County's Department of Parks and Recreation indicates topographical and
biological constraints would limit use of this adjacent area to recreational trails and fire
2
roads.
Headquarters for the South San Francisco Department of Parks and Recreation is located
in the Municipal Services Building at 33 Arroyo Drive. The City has six fully developed
137
IV. Environmental Setting, Impacts and Mitigation
community parks. A seventh park on Appian Way is slated for completion by October
1982. In addition to City parks, many recreational facilities are available on various
school sites.
Of the six existing parks, four do not have indoor facilities: Brentwood, Buri Buri,
Westborough and Winston Manor. Siebecker Center is a recreational building that offers
only indoor facilities. Paradise Valley and Orange Memorial Parks provide indoor and
outdoor facilities. The Department's only indoor swimming pool is located at Orange
Memorial Park. Nine tot lots are located within existing housing developments on small
(one-tenth to one-third acre) lots. The City has nine tennis courts in four park locations.
Five of these courts are illuminated for night use.
The Parks and Recreation Department budget allocates funds to staff 40 permanent full-
time employees plus a number of seasonal employees roughly equivalent to 37 full-time
positions.
The Department's responsibilities include the maintenance of parks and programming of
recreational activities. It also is responsible for the landscaping and maintenance of road
median strips and shares responsibility with school districts for maintaining the school
fields.
b. Impacts
I The project design designates approximately 46% (153 acres) of the site as open space.
Most of the open space is adjacent to the San Bruno Mountain State and County Park. The
project sponsor has agreed to dedicate all undisturbed areas of the project site to the
County as permanent open space. The San Bruno Mountain HCP stipulates dedication of
the project's undeveloped open space areas at the time the first grading permits are
granted for the parcel of the project to which it pertains. Dedication of the open space
areas would, therefore, occur in two phases. The first dedication of the area above the
residential portion of the project would occur upon completion of the residential
development. Similarily, the area above the commercial portion would be dedicated upon
completion of the commercial development. Inasmuch as the 153 acres of open space
have not been specifically designated, a mutually agreed-upon boundary would be
determined at the time of dedication to the County. Open space crees remaining would
fall under the jurisdiction of the City of South San Francisco with the purview of a
combined T errabay property owners' association.
138
IV. Environmental Setting, Impacts and Mitigation
The proposed project provides for trail access to San Bruno Mountain. A trailhead would
be located east of the recreation center and would provide six parking spaces for hikers.
A second trailhead would be located behind the private health club. Parking for this
trailhead could be accommodated at the health club parking facilities. Preliminary
designs indicate both trails would provided steps at the trailhead to discourage access by
off-road vehicles.
Juncus Ravine, a separate, 157 -acre parcel of land, is located west of Hillside Elementary
School (see Figure 2, Section 111). This area has been designated general open space on the
County General Plan and as a community park on the City's General Plan. Upon project
approval, the project sponsor has agreed to dedicate Juncus Ravine to the County as
permanent open space.
A 2,OOO-square-foot child care center would be located within T errabay Village (see
Figure 4a, Section 111). This center would be designed to provide care for 40 children and
would be operated by a combined Terrabay homeowners' organization. A tot lot with
playground apparatus will adjoin the child care center.
The Terrabay Development plan indicates development of Hillside Recreation Center, a
four-acre community park with both indoor and outdoor facilities (see Figure 5, Section
111). The recreation building would include a solar-heated 25-yard indoor pool, multi-
purpose room, activity room, weight room and dressing rooms. A tot lot would be located
next to the activity room. Outdoor facilities would include a basketball court, parcourse
system, children's playground apparatus, two illuminated tennis courts, and picnic,
barbeque and lawn game area. Parking for 61 vehicles would be provided.
The T errabay Development concept plan also indicates improvement of four acres of
Hillside Elementary School with development of an illuminated adult softball field, soccer
field, bleachers and a restroom. The improved school grounds would be connected to the
community park by a linear park/greenbelt parallel ling Hillside Boulevard. Asphalt paths
would be provided within the linear park for pedestrians and bicycle traffic. The
estimated 1.5 to 2 million dollar cost associated with Hillside Recreation Center and
Hillside School improvements would be incurred by the developer. Upon completion, the
park and recreation fields would be dedicated to the City. The Department of Parks and
Recreation would then assume responsibility for maintenance and services. Maintenance
139
IV. Environmental Setting, Impacts and Mitigation
of the linear park/greenbelt would be the responsibility of the development's homeowners'
association.
The Department estimates that 50% of the recreational programs offered at the new park
and playing fields will be used on a community-wide basis. The two illuminated tennis
courts of the Hillside Recreation Center would provide the only lighted public courts in
the northern portion of the City. Similarly, the City is presently accommodating 51 adult
softball teams at one facility. With an additional illuminated field, the City could easily
accommodate existing teams plus those now being turned away due to lack of facilities.
Concern has been expressed regarding the appropriateness of locating a softball field at
Hillside Elemtary School due to the wind environment of the site. The area is partially
sheltered by a ridge to the west and should be no windier than other locations in South San
Francisco. Wind does not hinder outdoor recreation at the Hillside Elementary School
now.3 The appropriate use of fencing and landscaping around the ball field would provide
shelter for players.
c. Mitigation
The County Department of Parks and Recreation has recommended that the open space
areas of the project site be deeded in fee to the County and fenced.4
I Unless otherwise indicated, this section is based on information supplied by Lyle Norton,
Director, South San Francisco Department of Parks and Recreation, telephone
conversation, March 24 and 25, 1982.
2Harry Dean, Chief of Park Planning and Development, San Mateo County Department of
Parks and Recreation, telephone conversation, March 25, 1982.
3Mary Meissner, Principal, Hillside Elementary School, telephone conversation, June 14,
1982.
4Harry Dean, Notice of Preparation Response Memo to Bill Rozar, Planner Ill, San Mateo
County Department of Environmental Management, undated.
140
IV. Environmental Setting, Impacts and Mitigation
G. NOISE
I. Setting
The noise environment at the project site varies considerably with location. The entire
site is exposed to aircraft noise. The eastern portion of the site is exposed to traffic
noise from Airport Boulevard, Highway 10 I and passing trains. The portion of the site
adjacent to Hillside Boulevard is exposed to traffic noise emanating from this arterial.
To quantify the noise environment at the project site, noise measurements were made on
Monday, April 5, 1982 at the five locations shown on Figure 20. The results of the noise
measurements are shown on Table 14.
Individual planes flying over the site were measured at all locations to emit maximum
noise levels of up to 90 dBA with 75-85 dBA being typical (persons not familiar with the
terminology and fundamental concepts of environmental acoustics are referred to
Appendix B). The jet planes represent the single loudest noise events on the site.
2. Impacts
This section describes the potential noise impacts associated with the development of the
site as proposed. Potential impacts are as follows: the impact on existing adjacent land
uses due to traffic generated by the project; the compatibility of the proposed uses with
the future noise environment; and the potential for noise impact on adjacent land uses
during construction.
To evaluate the potential for traffic noise impacts as a result of the project, changes in
noise levels along the streets in the vicinity of the project site were evaluated for two
conditions: the difference between the 1990 levels that would exist if Hillside Boulevard
were not extended and the project were not approved, and the difference between the
levels that would not exist in 1990 if Hillside were not extended and the project not
approved, and the 1990 noise levels that would exist if the project were approved and
Hillside were extended. Because the distribution of traffic throughout the day would
remain the same, whether or not Hillside is extended or the project approved, the hourly
noise levels would all change by the same amount. Table 15 shows the anticipated
changes along the existing streets in the vicinity of the project. As can be seen, the
changes range from 0 decibels to -3 decibels. The decreases are the result of traffic
141
---.-
,
TERRABAY VILLAGE
FIRE STATION
HILLSIDE RECREATION CENTER
TERR~BAY PARK
CNEL
40'/"'- CNEL AIRPORT ONLY
(j)NOISE MEASUREMENT SITE
SOURCE: EJP/CHARLES M. SALTER ASSOCIATES Terrabay Development
NOISE MEASUREMENT LOCATIONS AND
1990 POST - PROJECT NOISE EXPOSURE
FIGUR!: 20
142
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Figure:20
NOISI MeASURIMeNT LOCATIONS ANO 111110
POST -PROJECT NOISI EXPOSURE
143
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144
.......
TABLE 15
CHANGES IN TRAFFIC NOISE LEVELS (Hourly Leq and CNEL)
ALONG EXISTING STREETS IN THE VICINITY OF THE P~OJECT
Street Segment
Difference between 1990 Noise
Levels without Project and
without Hillside Extension and
1990 Noise Levels without Project
but with Hillside Extension
Difference between 1990 Noise
Levels without Project and
without Hillside Extension and
1990 Noise Levels with Project
and with Hillside Extension
Hillside Blvd.
west of
Chestnut Ave.
o dB
o dB
Hillside Blvd.-
Chestnut Ave.
to Randolph Ave.
Hillside Blvd.-
Randolph Ave.
to North Spruce
Ave.
o dB
o dB
-3 dB
-2 dB
Hillside Blvd.-
North Spruce
Ave. to Linden
Ave.
-2 dB
-2 dB
Chestnut Ave.
o dB
o dB
o dB
Linden Ave.
south of
Hillside Ave.
o dB
Linden Ave.
north of
Hillside Ave.
-2 dB
-1 dB
145
IV. Environmental Setting, Impacts and Mitigation
diverted to Hillside Boulevard. It can also be seen from the table that there is essentially
no difference in expected noise levels attributable to the project.
A three-decibel decrease in traffic noise is slight and would not result in a significant
improvement in the noise environment. The improvement is even less when compared
with the contribution of jet aircraft noise to the noise environment in the vicinity of the
project site.
Along the extension of Hillside Boulevard, traffic noise levels would increase. Existing
homes along the extension of Hillside Boulevard between the intersection at Randolph
Street and North Spruce Avenue would be exposed to a peak hour Leq and CNEL
(Community Noise Equivalent Level) of 63 dB. In the absence of jet aircraft noise, the
existing Leq in this area is about 56 dB. Traffic noise levels would therefore increase a
significant amount, and in the absence of jet aircraft noise would be expected to annoy
the neighbors. However, the contribution of aircraft noise in this area results in existing
peak hour Leq's ranging from 60 to 65 dBA. The overall noise environment therefore
would not be significantly affected by increased traffic noise.
Existing homes which would be adjacent to the extension of Hillside Boulevard between
North Spruce Avenue and Airport Boulevard would be exposed to peak hour Leqs and
CNELs from traffic noise of between 63 and 65 dB. Homes in this area are exposed to
traffic noise levels in the absence of aircraft ranging from about 56 to 63 dB. Again, in
the absence of jet aircraft noise, annoyance would be expected in this area. However,
because of the contribution of jet aircraft noise, the resulting overall noise level would
not increase a noticeable amount.
Due to the continuous nature of traffic noise as opposed to the sporadic nature of aircraft
noise, the extension of Hillside Boulevard might still annoy some of the homeowners in
this area. The resulting noise levels due to traffic on the extension of Hillside Boulevard
would be high enough to occasionally interfere with speech outdoors. This noise could be
mitigated by the erection of a sound barrier along the south side of the Hillside extension.
This is discussed further in the mitigation section.
a. Compatibility of the Proposed Project with the Existing and Future Noise Environment
Figure 20 shows the expected 1990 noise exposure on the project site assuming project
approval and the extension of Hillside Boulevard. It can be seen that the proposed
146
IV. Environmental Setting, Impacts and Mitigation
commercial development, and the condominiums are exposed to noise levels ranging from
65-70 dB. Some of the townhomes and terraced units are exposed to an Ldn ranging from
60-65 dB and the remaining townhomes are exposed to a CNEL of less than 60 dB. All of
the buildings would be exposed to maximum noise levels from occasional aircraft of up to
90 dBA.
The City of South San Francisco has adopted guidelines for exterior noise exposure levels.
The suggested guidelines are that residential development without anticipated outdoor
activities, including hotels, motels, and highrise apartment houses should not be exposed
to a total annual exterior CNEL of 70 dB of which up to 67 dB may be contributed by
aircraft and aircraft engine noise, with the exception that the nighttime hourly Leq should
not exceed 55 dB. For residential uses with anticipated outdoor activities, the annual
exterior CNEL should not exceed 68 dB of which up to 65 dB may be contributed by
aircraft and aircraft engine noise, with the exception that the nighttime hourly Leq should
not exceed 55 dB. For office buildings and other commercial establishments, the exterior
hourly Leq should not exceed 70 dB during hours of contemplated activity.
The State of California has adopted standards pertaining to the noise exposure of new
multi-family housing projects. The standard requires that interior noise levels due to
exterior noise sources must not exceed a CNEL of 45 dB. In those areas where the
exterior CNEL exceeds 60 dB, an acoustical report must be prepared prior to the issuance
of a building permit showing how the units will be designed to assure that interior noise
levels do not exceed a CNEL of 45 dB.
As can be seen from Figure 20, the project as proposed would be compatible with the City
of South San Francisco's suggested goals. However, a majority of the project is exposed
to a CNEL of greater than 60 dB and as noted previously, the entire site is exposed to
periodic maximum noise levels of up to 85 dBA. The portion of the project exposed to a
CNEL of greater than 60 dB will require the preparation of an acoustical report showing
how the residential buildings and the hotel will be designed to control interior noise levels
to or below an Ldn of 45 dB.
With windows closed, standard building constructions will reduce aircraft noise by about
25 dBA. The units with windows closed would maintain an indoor CNEL of 45 dB in an
exterior noise environment of up to 70 dB. If the units in this project are designed to be
mechanically ventilated so that the windows can remain closed for noise control, then the
147
IV. Environmental Setting, Impacts and Mitigation
entire project would meet the requirements for an interior noise level of a CNEL of 45
dB. If the units are not mechanically ventilated and rely on open windows for ventilation,
the building shell will only provide approximately a IS-decibel reduction in exterior noise
levels. In this case, only units exposed to a CNEL of less than 60 dBA would meet the
requirement for an interior CNEL of 45 dB.
Because the maximum noise levels emitted by individual jet aircraft as they pass over the
site reach 90 dBA, there is a possibility of sleep disturbance and interference with
watching television or listening to the radio. To minimize the possibility of annoyance or
sleep disturbance in this situation, the California State Office of Noise Control
recommends that noise levels in bedrooms not exceed 50 dBA. Maximum instantaneous
noise levels of up to 55 dBA are acceptable in other rooms. If the proposed project is of
standard construction, noise levels in bedrooms and other rooms of up to 65 dBA could be
expected. These noise levels could be controlled by modification of the building shell.
b. Construction Noise Impacts
In general, construction will be far from existing development. Maximum noise levels
during construction would range from 50 to 85 dBA at the nearest existing building. The
maximum noise levels of 85 dBA will be reached during construction of the Hillside
extension. The levels of construction noise would be at or below the levels of existing
aircraft noise in the area and would not be expected to result in a significant noise
impact.
3. Mitigation
a. Traffic Noise
Increased traffic noises along Hillside Extension could be mitigated by the erection of a
sound barrier on the south side of the extension. Detailed studies during the engineering
of the road would determine the required height and location of this barrier. As noted in
the impact section, the purpose of this barrier would be to maintain traffic noise levels at
their existing levels in the absence of aircraft noise.
b. Land Use Compatibility
Because the project is exposed to a significant amount of traffic and aircraft noise, steps
would have to be taken to assure that at the minimum, the project meets the
148
IV. Environmental Setting, Impacts and Mitigation
requirements of the State Noise Insulation Standards. Units exposed to an exterior CNEL
of greater than 60 dB would, at the minimum, require mechanical ventilation and closed
windows to meet the requirements of the Noise Insulation Standards. Because of the
potential for sleep disturbance, consideration should be given to reducing the maximum of
50 dBA in bedrooms and 55 dBA in other rooms. This would require the use of sound-rated
windows and the design of acoustically-rated ceilings, roofs, and walls.
c. Construction Noise
Although construction noise would not create a significant noise impact, the following
common practices should be followed. All equipment should be adequately muffled.
Construction hours should be limited to 7:30 a.m. to 5:00 p.m.
149
IV. Environmental Setting, Impacts and Mitigation
H. ENERGY
I. Setting
The project site is currently vacant. No energy is consumed on-site.
2. Impacts
Project implementation would require energy for the construction and operation of the
structures and associated site improvements, and for the fueling of project-generated
traffic. The impacts are summarized in Table 16.
a. Construction
Project construction would consume 400 billion BTU of energy primarily in the form of
electricity and diesel fuel with minor contributions from gasoline and lubricants. This is
the equivalent of 71,000 barrels of crude oil.
b. Operation
Annual energy use for project operation, not including traffic-related consumption, would
total 235 billion BTU, equivalent to 42,000 barrels of oil. The estimates of energy
consumption assume that the structures would conform to the provisions of Title 24 of the
California Administrative Code. Specific energy conservation features that are planned
to be incorporated in the project include:
favorable solar orientation
night setback thermostats
energy-efficient lighting
solar heat for swimming pool
Further details concerning energy-using features of the project are not available because
the design process is not yet complete.
c. Project Traffic
Based upon an estimated increase in daily vehicle miles travelled (VMT) of 165,000,
project-related traffic would consume approximately 2.1 million gallons of gasoline per
year.
150
IV. Environmental Setting, Impacts and Mitigation
3. Mitigation
The project sponsor has planned to include several design features which go beyond the
minimum requirements of Title 24; these options are listed above. In addition, several
more are under consideration:
greenhouse windows
concentration of glass on south side of structures
overhangs on south-facing windows
There are also additional options which would reduce energy consumption in the
residential buildings, although at increased cost. These include:
additional insulation
additional infiltration control measures
energy-efficient space and water heating equipment
energy-efficient glazing
These mitigation measures are among those which would be required in accordance with
the various compliance options under the proposed Title 24 residential regulations which
were certified in January 1982 and are scheduled to become effective, barring delays due
to legal action, in July 1982.' If adopted prior to issuance of the building permit, the
project design would be required to comply with the new regulations.
Conservation
151
IV. Environmental Setting, Impacts and Mitigation
TABLE 16
PROJECTED ENERGY CONSUMPTION OF PROJECT IN 1990 I
Electricity Natural Gas Total BTU
(millions Kwh) (thousands of therms) (billions of STU)
Resi dences 2 3.70 750.00 113.0
Office Structures 0.67 12.50 8.10
Restaurant 0.70 60.00 13.20
Hotel 3.80 216.00 60.50
Tech Trade Cen ter 3.17 59.00 38.40
Hillside Recreation Center 0.06 2.17 0.83
Private Health Club 0.09 3.30 1.30
Total 12.19 II 02 . 97 235.33
I Nonresidential energy consumption rates based on energy consumption data contained in:
California Energy Commission, California Energy and Demand 1980-2000' Revised
Forecast for Consideration in the Proceedin s on the Third Biennial Re ort, Volume II:
Detailed Appendices, cramento, CA, November 19 .
2Residential energy consumption based upon average annual energy bills per household in
South San Francisco and predicted energy consumption for projects in similar climates.
152
IV. Environmental Setting, Impacts and Mitigation
I. ARCHAEOLOGY I
I. Setting
An archaeological evaluation of the Terrabay site was conducted by Dr. Robert Cartier of
Archaeological Resource Management. The methodology used to determ ine the extent of
significant cultural resources included archival review, field reconnaissance and limited
subsurface testing.
Before surveying the subject area, the maps and records at the Northwest Information
Center of the California Archaeological Site Inventory were examined to determine if any
known cultural resources were reported in or around the subject area. rhe archival check
indicated that two prehistoric sites, CA-SMa-40 and CA-SMa-92, are located within the
boundaries of the subject area. CA-SMa-40 was recorded in 1950 by A. Pilling and was
described as a large shell mound. CA-SMa-92 was recorded in 1954 by D. F. McGee in and
was described as a smaller shell midden. According to local informants, historic resources
potentially located in the vicinity included remnants of an early San Francisco water
system and two mine shafts.
A general surface reconnaissance was conducted in March 1982. Prehistoric site CA-SMa-
40 was located and consisted of a dark brown midden soil with fire-cracked rock, a few
lithics, and a high content of shell. The area recorded as CA-SMa-92 was not located
during the survey due to erosion activity which has covered the site with soil.
Limited subsurface testing was carried out in April 1982 to determine the location of the
buried site, CA-SMa-92, and also to establish the subsurface boundaries of the major site,
CA-SMa-40. It was found that CA-SMa-92 was located in the vicinity of prior
underground construction which has seriously disturbed this small deposit. Boundary
testing of the major deposit, CA-SMA-40 revealed an extraordinarily rich subsurface
component slightly south of the surface component. This was remapped accordingly. No
samples were taken or controlled excavation were done at this level of testing.
A previously unrecorded prehistoric site has located during the survey. This site consists
of a smaller midden deposit with essentially the same constituents as CA-SMa-40. The
trinomial given to this site by the California Archaeological Site Inventory is
CA-SMa-234.
153
IV. Environmental Setting, Impacts and Mitigation
Few traces of the former historic activities on the project site were noted during the
survey. Only a section of the pipeline of the former water system and one of the mine
shafts are actually located within the project boundaries. Remnants of the mines were
difficult to detect without knowledge of their locations.
An evaluation of significance of these resources relies heavily upon our knowledge and
understanding about the individual sites. The role of the historic mine shafts and early
water distribution system can be readily comprehended from their socio-economic
function and archival data which would shed light on these resources. The water system
and mine shafts have minimal local significance, but not enough to be considered for the
National Register of Historic Places. The prehistoric sites, however, lack archival
explanations, evident chronology, or manifest evidence of function. Testing or sampling
of the prehistoric sites was not carried out and thus no definitive statement of the nature
or significance of the prehistoric resources is at this time available. CA-SMa-40,
however, could possibly be eligible for National Register status, judging from data
presently available.
2. Impacts
Based upon the archival records, the surface survey, and the limited subsurface parameter
testing, it is concluded that there are potentially significant cultural resources within the
project boundary. These resources must be taken into account during project design and
construct ion.
It does not appear that any of the sites of historic resources would be impacted by the
proposed project.
The three prehistoric resources identified in this study are in the immediate vicinity of
the commercial portion of the proposed project. CA-SMa-234 is just outside the zone of
proposed development activity, but CA-SMa-92 and CA-SMa-40 are in the direct location
of the development. CA-SMa-40 has been so disturbed that its integrity is substantially
minimized. CA-SMa-92 appears to be very rich and is assumed to be relatively intact.
Oral reports of human interments in this deposit make direct impacts most unadvisable.
However, due to the lack of significance testing, the possible presence of human burials
can only be fowarded as hearsay.
3. Mitigation
The project sponsor has proposed placing a minimum of one foot of sterile fill over site
CA-SMa-40 and sealing the area under landscaping and/or parking areas. Trenching
154
IV. Environmental Setting, Impacts and Mitigation
activities for underground utilities would be avoided on the site to minimize disturbances.
The necessary scarification for burying the site, as well as the movement of heavy
equipment over the site, will unavoidably create some direct impact to CA-SMa-40. A
small scale mitigation program of surface collection and minor sampling is recommended
prior to the onset of the placement of fill dirt and its compaction. Once the scarification
and earthmoving process begins, a qualified archeological monitor should be on-site to
observe for possible unearthing of human remains or other significant prehistoric
elements.
Because there would be some scarification of the site, this level of mitigation and the site
evaluation may not be acceptable to the National Park Service, if they are found to have
formal jurisdiction over the project. Their jurisdiction, if any, would follow from the
project's involvement with a section IO(a) permit under the Endangered Species Act.
Considering that plans for subsurface utility and drainage trenching are not finalized,
these should be inspected by a qualifed archeologist and comment should be made as to
whether they will intrude into native soil.
Any construction earthmoving into native soil at CA-SMa-40 should be mitigated by a
five-percent sample of that area to be directly impacted by hand-excavation by a
qualified archeologist. Any possible construction excavation into native soil at sites
CA-SMa-40 or CA-SMa-92 should be also monitored by a qualified archeologist and if
significant features/artifacts are unearthed, specific mitigation should be undertaken as
recommended by the Archeologist-In-charge. If human remains are encountered, then a
Native American Representative should be consulted regarding this deposition and
protection.
Because it does not appear that any of the historic sites will be affected, it is
recommended that a minimal research program be developed to determine the historical
background of the mines-their age, builder, and period of use.
I This section is based on the following document and subsequent field work.
Archaeological Resources Management, Cultural Resource Evaluation of the South Slope
Project on San Bruno Mountain in the County of San Mateo, March 1982. Actual site
locations cannot appear in this document in order to ensure the safety of archaeological
resources on the project site.
155
IV. Environmental Setting, Impacts and Mitigation
J. WIND AND a.JMATE
I. Setting
The project site is located on the southeastern slope of San Bruno Mountain. The climate
of the area is dominated by wind flow through the San Bruno Gap, the northwest-southeast
oriented gap in the coastal hills west of the site. The San Bruno Gap is a major break in
the coastal hills, resulting in a strong flow of marine air in spring and summer. 1 The
marine air is responsible for the cool temperatures and frequent stratus clouds typical of
the South San Francisco area.
Winds were measured at San Francisco International Airport near the project site.
Table 17 shows that winds blowing through the San Bruno Gap dominate with a west to
northwest direction occurring nearly 55% of the time. Winds from the west and northwest
are also strongest, on the average.
Winds on the site are similar to those at San Francisco International Airport. Local
terrain makes winds more westerly than northwesterly along Randolph Avenue. That
portion of the site facing U.S. 101 is sheltered from prevailing winds, with a much lower
average velocity and more variable wind direction.
The project is frequently affected by low clouds and fog, particularly in spring and
summer that would affect the potential for solar heating. At 9urlingame, located a few
miles south but still downwind from the San Bruno Gap, measured solar radiation levels
are 61 % of potential sunshine.2
The South San Francisco area averages about 20 inches of rain per year. This falls almost
entirely during the winter months. During the approach of winter storms, the
predominant wind direction is southwest to south. The effect of wind-blown rain is to
enhance rainfall totals on south-facing slopes and diminish totals on north-facing slopes.
Rainfall at the project, therefore, could be greater than the 20-inch average measured on
level terrain.
2. Impacts
The project would not have a significant impact on the microclimate of the area, but the
microclimate could impact proposed uses. Wind would have the most direct impact on
outdoor activities.
156
IV. Environmental Setting, Impacts and Mitigation
The western end of the project is located behind a ridgeline to the west that would
provide shelter. This area, although breezy, would not be unusually windy.
The clustered and terraced townhouses along Randolph Avenue lie along small valleys
protruding northward into the side of San Bruno Mountain. This location puts a low ridge
to the west and east of each townhouse area which would provide partial shelter from
west winds.
The condominiums near the intersection of Randolph Avenue and Airport Boulevard are
located on a ridge and would probably be exposed to strong westerly winds.
The proposed uses along the Airport Boulevard are extremely sheltered from prevailing
winds.
The residential portions of the project are located on a south-facing slope, giving good
solar access. Due to the sloping terrain shadows would not affect adjacent properties.
3. Mitigation
The current project layout locates most of the project in areas at least partially sheltered
from the wind. Nevertheless, the entire site would be breezy. Care should be taken in
the layout of buildings and the planting of vegetation to put wind-sensitive activities to
the east of some form of shelter. Vegetation such as trees and hedges are the most
effective wind shelter. Where this type of windbreak is not feasible, porous screens could
be used, such as the kind installed around tennis courts.
The exposed location of the proposed condominiums would require that wind influences be
accounted for in the design. Pathways, entrances and outdoor recreation spaces should be
laid out so that bui Idings, landscapes and fences are used to advantage in reducing winds.
I Gilliam, Harold, Weather of the San Francisco Say Region, 1962.
2California Department of Water Resources, California Sunshine-Solar Radiation Data,
Bulletin 187, August 1978.
157
IV. Environmental Setting, Impacts and Mitigation
TABLE 17
WIND DIRECTION AND SPEED DISTRIBUTION
A T THE SAN FRANCISCO INTERNATIONAL AIRPORT I
Direction Frequency Average
(% of time) Speed (mph)
N 1.3 9.2
NNE 1.2 8.0
NE 2.8 6.8
ENE 2.5 6.5
E 2.9 6.2
ESE 2.6 7.0
SE 4.3 7.2
SSE 2.6 7.4
5 3.3 7.4
SSW 2.9 11.9
SW 4.8 9.0
WSW 5.4 10.8
W 18.7 13.1
WNW 21.5 14.0
NW 14.2 12.1
NNW 1.6 10.3
Calm 6.8
1 California Department of Water Resources, Wind in California, Bulletin 185, 1978.
158
IV. Environmental Setting, Impacts and Mitigation
K. ECONOMICS I
I. Setting
The assessed value of the project site is currently $3,482,104 (Assessor's parcels 007-180-
130, 007-180-140, 007-180-150). The property tax levied on the project si te totals
$139,284 (four percent of assessed value) and is distributed to the County of San Mateo,
the City of South San Francisco, and various other educational and regional jurisdictions.
There are no improvements on the property and no other revenues or costs associated with
the si tee
2. Impacts
a. Revenues and Capital Benefits
The project would contribute to a variety of local revenue sources. 80th the residential
and the nonresidential development would add to the assessed value of the property tax
base. New residents, businesses, firms, and employees of the project would generate
additional fee and user charge revenue, initiate additional taxable transactions, and would
provide an expanded customer case for franchise service providers. Funds distributed on
the basis of population from other levels of government to local jurisdictions would also
increase with the addition of new residents of the project.
Revenue estimates are provided from the first phase of development through phase six in
order to provide a perspective on the rate of revenue flow in comparison to new service
demands. A primary assumption underlying the revenue projections is the project
sponsor's proposed buildout schedule (see Ill. Project Description). Unanticipated delays
beyond the project sponsor's control would inhibit this schedule. The effects of delays on
the revenue flow, barring other economic or fiscal changes, would be to decrease the
amount expected in anyone year during the buildout period and, overall, to extend the
projections for the level ing off of revenue flow even further into the future.2
Table 18 presents an overall view of the operating revenue sources on which the Terrabay
Development would have an impact. Revenues in constant 1981 dollars increase steadily
over the buildout period. The first year in which all building activity is estimated to be
complete and on the property tax rolls is the peak year for additional revenues. It is
estimated that the development would generate approximately $1,025,500 at that point.
159
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IV. Environmental Setting, Impacts and Mitigation
After this time, total operating revenues (expressed in constant dollars) from the
Terrabay development would be expected to decline each year, although at an even slower
rate. Sometime near the end of the century (to the extent that such a projection is
reliable) the City can expect the revenue to level off at a constant figure. The decline
reflected in the Table is due largely to annual decreases in the assessed value of real
property when measured in constant dollars (due to the effects of Proposition 13
limitations in inflationary times).3 The sales and use taxes are shown as constant after
project completion, but could fluctuate substantially, depending largely on factors beyond
the influence of the development of the City. The other major source of .revenue, the
transient occupancy tax, also appears as a mainstay for the general fund.
Property Tax. Maximum property tax levies under Proposition 13 are one percent of full
market value at the completion of construction or time of sale. Estimates of market
value include construction and related costs as well as the land cost.
The property tax estimates in Table 18 are based on the project sponsor's current
assessment of costs, design and the market. An important assumption in the analysis is
that the value of the developed property will appreciate with inflation, but at no faster
rate. For example, a luxury condominium sold in 1985 would be valued at no more in
constant 1981 dollars than it would be if built and sold in 1982.
Several additional assumptions are necessary to calculate assessed values and additional
property tax revenues from the project. Under Proposition 13, the assessed value of real
property can only increase two percent per year, unless the property is sold. This implies
that if inflation boosts a property's price eight percent per year, while the assessor can
only record a two percent year increase in valuation, that the property actually declines
in value for property tax purposes (when expressed in constant 1981 dollars). This effect
is especially clear when the property is considered as a source of revenue to meet public
service costs that increase each year with inflation. If the revenue source is only valued
two percent higher than in the preceding year, it buys fewer current services, the costs of
which have increased eight percent over that same period.
The exception to this two percent annual limitation occurs when property is sold. At this
time, property is reassessed at its full vlaue. For the purposes of this report, it is
.
161
IV. Environmental Setting, Impacts and Mitigation
assumed that houses are sold, on average, after eight years.4 In other words, it is
assumed that one-eighth, or 12.5 percent, are resold every year. Resale prices are
assumed to be equal to the cost of a new house constructed that year. Thus, each year,
the estimate of values for property taxes must account for new construction, resales, and
the annual decline of assessed value of properties not sold.
Office space, hotels, and restaurants do not change ownership as often as houses. The
projection of nonresidential property values consequently assumes that no sales would
take place. As with the residential component, nonresidential property values are
assumed to increase with inflation, but are similarly subject to the two percent
assessment limitation and thus also decline in value for tax purposes.
The law assumes that some portion of the property taxes currently allocated to the
County from the unincorporated South Slope would be shifted to the City upon annexation.
The City's share of property tax revenues would be the subject of a negotiated agreement
between the City and San Mateo County. The principal basis for the allocation is the
service responsibilities assumed by the City that would otherwise be the province of the
County. Based on this consideration, the County fire and library levies, which account for
7.3 percent and 3.9 percent, respectively, of the incremental property tax, would be
shifted to the City. Some shift also appears reasonable to reflect the City's assumption of
road maintenance (Hillside Boulevard) and sheriff tasks. The additional shift of tax
monies (above that for the fire and library levies) is here estimated to be 15 percent of
the 27 percent (about four percent) that the County now receives from incremental tax
dollars in the project area. The City's share of the incremental property tax is thus 15.3
percent of the total.
For comparative purposes, Table 19 shows the distribution of additional property tax
revenues to all jurisdictions claiming a share from the Terrabay development. The
distribution estimates are based on current formulas for the areas in which development
would occur.
The boundaries of five of the jurisdictions do not cover the entire Terrabay site. South
San Francisco Unified School District, Colma Creek Flood Control District and Colma
Flood Control District Sub-Zone 3 cover the western part of the site, while Brisbane
162
IV. Environmental Setting, Impacts and Mitigation
TABLE 19
DISTRIBUTION OF PROPERTY TAX REVENUES TO
ALL JURISDICTIONS AT FULL PROJECT BUILDOUT
( 1982 Dollars)
Jurisdiction
Genera I County
City of South San Francisco
San Mateo Junior College
Bay Area Air Quality
County Harbor
School Equalization
County Education Tax
South San Francisco Unified*
Brisbane Elementary**
Jefferson High School**
Colma Creek Floor Control*
Colma Creek Flood Control Zone 3*
Additional
Property Tax
Revenues
$ 381,700
254,000
127,800
3,300
6,600
6,600
61,400
433,200
156,000
205,800
9,200
13,300
* Based on 80 percent of residential assessed valuation.
** Based on 20 percent of residential assessed valuation plus 100 percent of non-
residential assessed valuation.
SOURCE: EIP, based on Recht Hausrath & Associates, San Mateo County Controller.
163
IV. Environmental Setting, Impacts and Mitigation
Elementary and Jefferson High School Districts cover the eastern part of the site. The
approximate allocation of development to each area assigns 80% of the residential
assessed value to the western part, and the remaining 20%, in addition to all the non-
residential assessed value, to the eastern part. The assumptions are the basis for the
estimates detailed in Table 19.
Real Property Transfer Tax. Local governments in San Mateo County collect a tax on the
sale of real property in the County. The tax rate is $1.10 per $1,000 of the market price.
The tax is split equally between the County and the City within whose jurisdiction the sale
occurs. Thus, South San Francisco receives 55 cents for every $1,000 of the price of
property sold. For the proposed project, this implies revenues from the initial sale of
homes during the buildout period in addition to revenues from subsequent resale of these
homes. The resale price of a house is assumed to equal its original sale price in constant
1981 dollars.
As noted, it is assumed that houses are resold on average after eight years, or at a rate of
12.5% per year. Thus, the real property transfer tax revenue base for the City of South
San Francisco consists (through phase six) of the initial sale of houses during that year of
the buildout period plus the 12.5% of houses sold in previous years. After project
completion, transfer tax revenue is based solely on the 12.5 % resale factor. Again, it is
assumed that nonresidential property would not change ownership. Finally, a transfer tax
would be assessed on the original sale of the 332 acres to the project sponsor. This figure
has not been calculated, but a modest amount would be expected before the development
phases begin.
Sales and Use Tax. The new residents of South San Francisco living at Terrabay would
make taxable purchases in the City. These expenditures are estimated according to the
incomes of new residents and those incomes are determined by the prices of the houses at
T errabay.
Incomes of those persons purchasing houses in the proposed development are assumed to
be three and one-third times the annual housing costs of the purchaser. Estimates of
housing costs include mortgage payments, property taxes and insurance. This income
requirement is a rule-of-thumb among lenders.
164
IV. Environmental Setting, Impacts and Mitigation
It is estimated that Terrabay residents would spend approximately 15% of their income on
taxable purchases in the City.5 The estimate accounts for the probability that the new
residents, with generally higher incomes than current residents of the City, would have
different shopping habits. They would be likely to travel farther for their purchases and
perhaps spend more near their place of work.
According to the County controller, the City receives approximately 95% of the one
percent local sales tax levied on taxable purchases within its jurisdiction. It is assumed
that taxable expenditures would remain constant over time as a proportion of income and
that the local sales tax rate would not change.
Office development at Terrabay would generate both additional sales tax revenue and
additional use tax revenue for the City of South San Francisco. Sales tax revenue flows
from the personal retail purchases made by employees in the office complex, as well as
from local retail purchases made by the offices located in the new development. The use
tax is the same tax rate as the sales tax and is assessed against machinery, equipment,
supplies, and other materials not normally subject to California retail tax because
purchased from out-of-state firms or distributors.
Estimates of personal retail sales tax are based on the number of employees in the office
development. The taxable expenditures made in South San Francisco by these employees
would be mostly restaurant meals. It is assumed that, on average, each employee would
spend $2 per day on taxable goods. There are about 250 working days per year, implying
$500 of taxable purchases per employee per year. At a share equalling 95% of one
percent of taxable sales, the City would expect approximately $5 of additional retail sales
tax revenue per office employee.
Taxable retail purchases (such as reproduction/printing services or stationery and office
supplies) made locally by the new Terrabay offices are more difficult to predict. At the
conceptual plan stage, the likely occupants of the office complex are not specified.
Moreover, such expenditures would vary considerably, depending on the type of firm and
the scale of in-house facilities on which each draws. Estimation is also complicated by
the fact that many such purchases may not be made in the City of South San Francisco.
Given these limitations, no attempt has been made here to predict taxable retail
165
IV. Environmental Setting, Impacts and Mitigation
purchases by firms moving into the Terrabay office complex. Total sales and use tax
revenues from the non-residential component of the development may thus be consider-
ably higher than the following estimates suggest.
The use tax is estimated on a per employee basis. Analysis of historical data from the
State Board of Equalization and employment data from the Employment Development
Department provide an estimate of $68 of non-retail sales tax revenue per non-retail
employee (J 981 dollars). Lack of more appropriate data requires this approximation.
The total additional sales and use tax revenue generated by each employee is thus
estimated at $73 (1981 dollars). With an average of 250 square feet per employee, there
would be approximately 230 employees in a fully occupied office complex at Terrabay.
All are assumed to be non-retail employees. Revenues would remain constant (in 1981
dollars) in the years after a full buildout as taxable sales increase with inflation. This is a
rough estimate and would range from near zero for firms that pay retail sales tax on
machinery or supplies to other California jurisdictions, to substantially more for a large
sales office.
Transient Occupancy Tax. The City of South San Francisco levies an eight percent tax on
the charges to hotel and motel patrons in the City. To estimate additional revenues to
the City from development of a new 400-room hotel requires both room rate and
occupancy assumptions.
At this stage of the project proposal, it is not known what type or quality of hotel will
eventually be built. With the reduction in the relative share of local tax revenues
contributed by the property tax, the transient occupancy tax becomes one of the most
significant revenue sources. Therefore, assumptions are critical and should be
conservative in light of the few specifics known at this time. The model for hotel
development at Terrabay is the Airport Holiday Inn (320 rooms) in South San Francisco.
Room rates there average $60 per night. Overall occupancy this year has been 95%,
according to the hotel's manager.
Room rates at the Airport Hilton average $68 per night for a single room and $82 per
night for a double room. The assumption that the Terrabay hotel would charge an average
166
IV. Environmental Setting, Impacts and Mitigation
of $60, as does the Holiday Inn, is on the conservative side. Similarly, the 95% occupancy
rate has been adjusted downward; average annual occupancy is assumed to be 80%.
An average fee of $60 per room per night and an overall occupancy of 80% would provide
revenues to the City as shown in Table 18. It is assumed that room rates increase with
inflation, so revenues would remain constant in 1981 dollars.
Business License Tax. The City of South San Francisco assesses an annual tax against all
firms and commercial establishments doing business in the City. Revenues from this tax
flow to the general fund. The assessment varies by the classification of the business.
However, in all cases it is a flat fee as opposed to a tax that varies with a firm's gross
receipts. For three of the five classes of use in the proposed nonresidential development-
-office, service station, and restaurant--the business license fee is based on the number of
firms and employment, specifically $50 per year plus $3 per employee for non-professional
offices and $100 per year plus $75 for each additional professional employee for
professional offices. The fee for hotels is based on the number of rooms ($50 per year
plus $4 per room) and the fee for the athletic club is a flat rate of $100 per year.
To estimate the business license tax revenues resulting from the proposed project requires
estimates of the number of firms and employment expected in the office complex, as well
as estimates of the number of employees in the service station and in each restaurant.
The latter two figures are the most readily available. The 1977 Census of Retail Trade
indicates an average of five employees per service station in California. A survey of
restaurants comparable in size to those proposed for T errabay suggests about 130
employees for the four restaurants.
Estimating firms and employment for the office development is more complex and
requires several simplifying assumptions. The business license tax differentiates between
professional and general office firms. Professional firms include physicians, attorneys,
engineers, architects, consultants and other licensed services. It is assumed that 20% of
the employees in the office development work in professional firms and that, of these
20%, half are professionals and half are non-professionals. To estimate the number of
such firms, it is necessary to assume that each professional firm has an average of four
professional employees. The distribution of non-professional or general office firms by
167
IV. Environmental Setting, Impacts and Mitigation
number of employees is assumed to mirror the distribution of all San Mateo County firms
by size, with the exception that there would be no firms over 250 employees in the
Terrabay office development. Finally, the standard allocations of 250 square feet per
office employee and 1000 square feet per employee in the tech trade center has been used
to estimate total employment for those developments. Table 20 details the distribution of
firms and employees according to these assumptions.
Franchise Tax Revenue. The City of South San Francisco levies an annual tax on the
providers of certain services in the City. The franchise tax ranges from one-half to two
and a half percent of a firm's gross receipts from business in South San Francisco. The
revenues from this tax accrue to the City's general fund.
The three current franchise holders are Pacific Gas and Electric Company (PG&E), the
gas and electric utility; South San Franciso Scavenger, a garbage pick-up service; and
Western T.V. Cable. As the customer base for each of these services expands, so do its
gross receipts, and, subsequently, the franchise tax revenue to the City. Estimates of
future revenue from each service are based on analysis of current consumption patterns
for households and nonresidential customers, together with trends in consumption and
prices for the service. Total franchise tax revenues are given in Table 18.
Other Revenues. The City of South San Francisco has several other operating revenue
funds. Neither the parking district nor the maintenance districts would be significantly
affected by the Terrabay project. The sewer rental fund and the debt service fund,
however, would register measurable benefits from the T errabay project.
The two primary sources of revenue for the sewer rental fund are sewer connection fees
and a user charge. F or the purposes of this report, the fund is considered an enterprise
fund in which assessments are set to cover costs. Therefore, sewer user charges are not
calculated because it is assumed there would no additional revenue to the City net of
sewer and waste treatment operations costs attributable to the new development. On the
other hand, sewer connection fees for both residential and nonresidential users would be a
substantial capital contribution to the system. For the Terrabay development, these fees
would be paid over the buildout period as development proceeded and would total $479,700
(constant 1981 dollars).
168
IV. Environmental Setting, Impacts and Mitigation
TABLE 20
DISTRIBUTION OF FIRMS BY SIZE AND TYPE
Number of Number of
Firm Size Firms Employees
General Office
1-4 18 45
5-9 7 49
10-19 4 60
20-49 3 105
50-99 3 203
TOT AL GENERAL OFFI CE 35 462
Professional Firms 15
Professional Employees 60
Non-Professional Employees 60
GRAND TOTAL 50 582
Source: EIP estimates based on U.S. Bureau of the Census, County Business Patterns,
1978, California.
169
IV. Environmental Setting, Impacts and Mitigation
The debt service fund consists of revenue from a pre-Proposition 13 property tax
assessment to support a bond for construction of the City's municipal services building.
The additional tax rate for the 20-year $2.4 million bond is $.05/$100 of assessed value.
Prior to Proposition 13's limitations on increases in assessed value, major additions to the
property tax base, such as the Terrabay project, would likely have allowed reducing the
tax rate for all City property owners. The City of South San Francisco, however, has had
to rely on deficit financing of this bond obligation because assessed value has not
increased as forecast before Proposition 13. The effect of the Terrabay Development on
the debt service fund would be to contribute to the reduction of the outstanding debt and
thus allow the $.05 tax to be terminated earlier for current City taxpayers.
b. Costs
This section summarizes the capital and operating costs associated with the proposed
project. The issues related to these costs are discussed in IV.J. Community Services and
Public Utilities.
One-Time Capital Costs. The City would potentially incur one-time capital costs
attributable to the project in several service areas. One is fire protection services. A
new fire station would cost $140,000. There is also a cost to equip the station. The fire
chief estimates this cost at $42,400, the majority of the amount being $25,000 for an
emergency generator.
The cost of the necessary storm runoff system for the site is estimated at $0.5 to $1.0
million. Park and recreational facilities projected for the site would cost an additional
$1.50 $2.0 million.
Finally, extension of Hillside Boulevard would cost $1.4 to $1.6 million, depending upon
the number of street signals desired by the City.
Improvements and replacements of sections of the sewer main system would be necessary.
Operating Costs. Annual municipal operating costs associated with the project are
summarized in Table 21.
170
IV. Environmental Setting, Impacts and Mitigation
TABLE 21
SUMMARY OF ADDITIONAL ANNUAL OPERATING COSTS
A TTRlBUT ABLE TO TERRABA Y DEVELOPMENT
(1981 Dollars)
Annual Cost I
$ I I 6 ,000
142,000
49 , 000
$ 60,000 2
10,000
$ 377,000
Function
Police Services
Fire Protection
Road Maintenance
Parks and Recreation
Programming and Maintenance
General City Services
TOTAL
lEst i mates based on I 98 I costs.
2These are net costs. Total operating costs would be approximately $91,000, but would be
partially offset by annual softball team fees of $30,000 -$35,000. Specific costs for the
swimming pool have not been est imated, but it is expected to operate at a 50% deficit the
first year, with increasing revenues in subsequent years.
171
IV. Environmental Setting, Impacts and Mitigation
c. Net Fiscal Impacts
Table 22 shows the revenue and cost categories addressed in this report. The Table should
be used as a capsule abbreviation of the estimates and issues discussed in the text.
Comparison of on-going costs and revenues at any point for a "bottom line" conclusion is
not the most appropriate use of this fiscal analysis.
.
TABLE 22
SUMMARY OF MAJOR FISCAL IMPACTS
(1981 Dollars)
Fiscal Category
Annual Operating Revenues
Full Project Completion
$1,025,500
Annual Operating Costs
$377,000
Total Capital Expenditures I
$4.0 - 5.2 million
N.B. Estimates must not be used for "bottom line" comparison.
For public facilities: amount depends on City and County policy as well as financial
feasibility of development. These expenditures would be made at some point in the
first phase of the buildout period.
Source:
Recht Hausrath & Associates
In spite of the caveats, Table 22 is an important summary tool. The first line shows the
general fund operating revenues projected for the City and the second line shows the
annual operating cost attributable to the Terrabay project net of any estimated fee
revenue. The third line shows the one-time capital costs as a lump sum range estimate.
Given the assumptions and attributions of cost described, it appears that the development
would generate more in additional annual general fund revenues than it would require in
172
IV. Environmental Setting, Impacts and Mitigation
additional annual general fund expenditures.6 The logic of the current property tax
situation helps explain how this happens. New development generally has a higher
assessed value than other properties in the City. It thus generates above average revenue
for a given type of property, particularly in the early years. Moreover, with specific
reference to Terrabay, the development would appear to be of above-average quality
compared to earlier development in South San Francisco. This implies that the new
development would be likely to maintain its value over the long term to a greater degree
than the average quality development in other parts of the City.
The capital costs associated with the project would be substantial and are the subject of
the section describing mitigations.
3. Mitigation
The project sponsor has offered to defray the major portion of the capital costs related to
the project. A summary of the project sponsor's portion of these costs is given in
Table 23.
TABLE 23
PROPOSED PROJECT SPONSOR CAPITAL EXPENDITURES
FOR PUBLIC FACILITIES
(J 981 Dollars)
EXPENDITURE
COST
(Millions)
$ 0.14
$ 1.14 - 1.6
$ 0.5 - 1.0
$ 1.5 - 2.0
$ 0.3
TOTAL $ 3.58 - 5.04
Fire Station
Hillside Boulevard Extension
(Developer Share)
T errabay Runoff Collection System
Hillside Recreation Center I
Sewer Main Improvement2
Ilncludes swimming pool, tot play lot, two
ballfield, and the linear park.
2Preliminary estimate subject to revision.
Source: W.W. Dean and Associates.
illuminated tennis courts, one illuminated
173
IV. Environmental Setting, Impacts and Mitigation
An observation regarding these benefits is appropriate. The project sponsor has proposed
them in the belief that the project in its present form can afford the costs. Substantia'
changes in the project, such as reductions in density, may be desirable for other reasons,
but may make the project no longer capable of affording all of the costs of these
facilities.
Capital costs remaining for the City would range from $0 to $250,000 for the extension of
Hillside Boulevard.
I This section is based upon information contained in Recht, Hausrath and Associates, San
Bruno Mountain: South Slope Fiscal Impact Study, September 1981. The figures have
been revised to reflect new project characteristics.
2 All the numbers presented here are best estimates given the current legal status and
practices for each revenue source; they are benchmarks for decisions, based on the
understanding that a change in conditions external to the Terrabay project or a change in
the basic proposal itself would cause a change in the revenues. Projections as far in the
future as 1995 must be viewed as giving a sense of the relative magnitude of the
different revenue sources--what portion does each contribute to the City's budget?--and
the future trend of that share-does it increase or decrease over time?
3This analysis assumes that the market value of the houses will increase at an annual rate
of 8% per year. However, Proposition 13 limits increases in assessed value to 2% per
year. Thus, in constant dollars, property taxes would decline 6% per year.
4There are no reliable statisics on average length of home occupancy in today's housing
market. Historical data compiled by the U.S. Census Bureau and banks indicate that
houses were sold every four to five years, on average. However, current high interest
rates and the rapid escalation of housing prices invalidates these figures. The most that
can be assumed with any degree of certainty is that houses do not "turn over" as often as
they did in the past.
5Th is estimate is based on the U.S. Department of Labor's Consumer Expenditure Survey
data (1972-1973) which provides statistics for various income groups on proportions of
income devoted to taxable expenditures and the California State Board of Equalization's
Taxable Sales in California.
6For the purposes of this analysis, it is enough to conclude that revenues would cover
expenditures; project uncertainties and future changes in both the revenue and cost
situation for local governments argue against even the statement that revenues appear
to be almost twice as great as expenditures. It should also be remembered that one
element, the hotel, provides $280,000, a sizable portion of the revenues.
174
IV. Environmental Setting, Impacts and Mitigation
L. TRAFFIC AN) TRANSPORT A TJON
I. Environmental Setting
The project site is strategically located near regional highway and transit facilities. It is
located adjacent to a major freeway, U.S. Route 101, and has di rect access to the freeway
via the Oyster Point Boulevard interchange. In addition, the site abuts two major arterial
streets, Airport Boulevard on the east and Hillside Boulevard on the south. Transit
service includes several Sam Trans bus lines which run adjacent to the site and the
Southern Pacific commuter rail service at the South San Francisco station about one mile
away.
Although the site is located close to the freeway and regional transit service, certain
short-comings exist in the local circulation system. The proximity of Airport Boulevard
to Highway 101 has resulted in substandard design of the freeway interchanges and their
associated intersections. These physical constraints cause peak period traffic to
concentrate in the freeway vicinity as traffic leaves and enters Highway 101.
Further, today's transportation conditions are expected to change as several major new
developments and associated roadway improvements are constructed in the area. The
assessment of the proposed project's impacts must consider not only today's local
transportation setting but also the changing environment in its vicinity.
a. Street and Freeway System
Regional Facilities. The project site is located adjacent to U.S. 101, the Bayshore
Freeway, an eight-lane divided facility which provides direct access to San Francisco, the
San Francisco Airport and the remainder of the Bay Area. Another regional highway
facility, Interstate 380, is located about two miles south of the site. This facility is a
connector freeway which provides access to the western part of the San Francisco
Peninsula and to Interstate 280 for regional travel. Figure 2 shows the location of the
project with respect to the regional freeways and principal elements of the local street
system.
Local Circulation Systems. The local street system and freeway interchanges serving the
site are illustrated in Figure 26. The project site has direct access to U.S. 101 via Airport
Boulevard. The eastern portion of the site fronts on Airport Boulevard and would connect
175
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IV. Environmental Setting, Impacts and Mitigation
to it via two proposed driveways. The western portion of the site has access to Airport
Boulevard, Linden Avenue and Randolph Avenue.
Airport Boulevard is the major north/south arterial in the area and is heavily used by
traffic heading to and from the freeway. It also connects the project area with the city
of Brisbane to the north and to central and southern areas of South San Francisco and the
airport to the south. Airport Boulevard is a four-lane facility with added left-turn and
right-turn lanes at major intersections. Major signalized intersections in the area are at
Oyster Point Boulevard, linden Avenue and Grand Avenue. Freeway ramp junctions on
Airport Boulevard are at Linden Avenue (a southbound on-ramp) and a southbound off-
ramp designed in a scissors configuration located immediately opposite the project site.
Hillside Boulevard is a major east/west arterial. From the South San Francisco boundary
on the west to its intersection with Randolph Avenue on the east (including the section
which abuts the project site), Hillside Boulevard carries four Janes of traffic. Hillside is
reduced to two lanes west of the South San Francisco boundary and alon~ the section
between Randolph Avenue and its eastern terminus at Linden Avenue. Hillside is posted
for a 35 mph speed limit west of Randolph and 25 mph east of Randolph. Partly to
discourage speeding and partly to allow access to and from residential driveways along the
south side of Hillside Boulevard east of Lincoln Street, all-way stop signs have been
installed on Hi IIside at three intersecting minor collector streets: Kearny Street, Irving
Street and Franklin Avenue. Traffic signals and lane channelization have been installed at
Hillside and Stonegate Drive and at Hillside and Linden Avenue.
linden Avenue is a two-lane minor arterial street connecting Hillside Boulevard with
Airport Boulevard and the freeway and also serving as a primary route between the site
area and the nearest major shopping area, the South San Francisco central business
district. Parking is permitted on both sides of Linden as well as along Hillside just west of
their intersection, and this, coupled with high levels of commercial activity in the area,
tend to reduce street capacity and restrict the flow of through traffic. (By contrast,
Airport Boulevard and Hillside west of Randolph, both wider four-lane streets, permit only
one-side parking, and little friction is evident between parking and through traffic.)
Randolph Avenue is a local or collector street by design which, in practice, serves
arterial-street functions as well.' Although its eastern section is, by character, a
neighborhood street and its western section is extremely narrow (less than 18 feet wide,
177
IV. Environmental Setting, Impacts and Mitigation
serving two-way traffic), Randolph carries a certain amount of through traffic. It acts as
a short-cut between Airport Boulevard and western Hillside Boulevard for motorists
attempting to avoid signals and traffic congestion in the vicinity of Airport and Linden
and Linden and Hillside. Traffic controls along Randolph include stop signs at both
Hillside and Airport Boulevard termini. Left turns are not permitted at the
Hillside/Randolph intersection.
Another key street in the study area is Chestnut Avenue, a two-lane arterial which
connects Hillside Boulevard with the 1-280 freeway and major shopping areas to the south
and west. Chestnut is controlled by a stop sign at Hillside and all-way stop signs further
south at Sunset Drive and Commercial Avenue. Its major signalized intersections occur at
Grand Avenue and EI Camino Real. Because of insufficient street width and capacity-
constrained intersections, Chestnut currently experiences significant levels of traffic
congestion near EI Camino Real (about one mile south of Hillside).2 Similar conditions
exist near the northwestern terminus of Hillside Boulevard in Daly City, reducing its
usefulness as an 1-280 access road.
Freeway Interchanges. The freeway interchange which most directly serves the project
area is the U.S. 101 Oyster Point interchange adjacent to the site. A secondary access to
U.S. 101 is via the Grand Avenue interchange about a mile south of the site. There is
currently no interchange north of the site which is likely to carry any site-oriented
traffic.
The Oyster Point interchange includes on- and off-ramps serving the northbound freeway
lanes located at Oyster Point Boulevard just east of Airport Boulevard. The southbound
exit ramp feeds onto Airport Boulevard about one-half mile north of Oyster Point (and
opposite the project site), and the southbound entrance is located at Linden Avenue and
Airport Boulevard about one-quarter mile south of Oyster Point. All are one-lane ramps
and the two southbound ramps are of substandard length. Both off-ramps are controlled
by stop signs at their junctions with the local street systems. The southbound off-ramp is
designed in a scissors configuration, including a two-way stop sign at its intersection with
northbound Airport Boulevard and an exclusive acceleration lane for off-ramp traffic to
merge with the flow on southbound Airport Boulevard.
The East Grand Avenue interchange includes northbound on- and off-ramps and a
southbound off-ramp located on Grand Avenue just east of Airport Boulevard. The
178
IV. Environmental Setting, Impacts and Mitigation
southbound on-ramp is accessed via Airport Boulevard at a point about three-quarters of a
mile south of Grand Avenu~. Also at this location are another set of off-ramps and
another northbound on-ramp.
Planned Street and Interchange Improvements. In conjunction with planned development
projects in the area, severa' major improvements are planned for the local street system
and freeway interchanges. Most significant of the planned improvements and assumed to
be implemented by 1990 are the following:
East Grand Avenue grade separation and interchange modification.
Oyster Point Boulevard grade separation and interchange modifications.
Sierra Point interchange construction.
Gateway Boulevard construction.
The Grand Avenue project is a six-lane railroad overpass with freeway ramp connections
designed to provide access to the rapidly growing area east of the freeway. It is planned
to resolve existing and future traffic circulation problems along East Grand Avenue at the
Southern Pacific railroad grade-crossing, at the freeway ramp termini and at the Airport
Boulevard/Grand Avenue intersection. The project will also include an extended
southbound merge/diverge lane on the freeway between the Linden on-ramp and Grand
Avenue off-ramp to resolve current weaving problems and add capacity. The
improvement is scheduled for completion in the early- to mid-1980s.
The Oyster Point improvement is also a combination railroad grade separation/freeway
interchange project. It is to include a four-lane railroad/freeway overpass with a
modified ramp system. The project is to extend from a point on Oyster Point Boulevard
just east of the Southern Pacific tracks to a point on Airport Boulevard near the southeast
corner of the project site. Alternative design concepts have been developed for the
project and are currently being reviewed by the City of South San Francisco and Caltrans.
The nature of the alternative ultimately selected will have significant influence on traffic
circulation in the area. Of particular importance is the design of the interface between
the northbound on- and off-ramps at Oyster Point Boulevard, the design of the new
intersection at Airport Boulevard, and whether a new southbound on-ramp is constructed
to replace or augment the Linden Avenue on-ramp, and whether or not the southbound
"scissors" off-ramp will be modified. These issues are currently the subject of a special
study.3 The study is based on current information on cumulative traffic generation by
179
IV. Environmental Setting, Impacts and Mitigation
proposed new development including data developed in this EIR. The anticipated
construction date for the Oyster Point project is in the late I 980s or early 1990s.
The Sierra Point interchange is planned for construction in conjunction with on-going
development of the Sierra Point Peninsula, just northeast of the project area. The
interchange will connect the peninsula with U.S. 101 via a split pair of on/off ramps, with
access to central Brisbane and Airport/Bayshore Boulevards via a connection across the
northern edge of the Brisbane lagoon. The northbound ramp pair will be located at Sierra
Point and the southbound pair will be located about a mile further north at the Lagoon
connector roadway. Scheduled completion of the interchange is in the mid-I 980s.
Gateway Boulevard is a north/south major arterial street planned on the east side of U.S.
101. The four-lane roadway will connect Oyster Point Boulevard with East Grand Avenue,
and may reduce some of the impact of future development on the parallel section of
Airport Boulevard. Additional north/south arterials, such as an upgraded Harbor Way, are
also being considered for the east side of the freeway south of East Grand Avenue. These
may provide greater relief for Airport Boulevard. Completion of Gateway Boulevard is
scheduled for the early- to mid-I 980s and other improvements for the mid- to late-I 980s.
Another major improvement would be constructed as part of the proposed Terrabay
project. That facility would be a four-lane extension of Hillside Boulevard from its
current intersection with Randolph Avenue in an easterly direction to Airport Boulevard.
The Hillside extension would intersect Airport Boulevard at the southeast comer of the
project site just north of the Randolph/Airport intersection and near the planned
intersection of the new Oyster Point overpass with Airport Boulevard. The purpose of the
Hillside extension project is to provide continuity to the regional arterial network and
divert traffic from the Hillside/Linden Avenue area. The specific effects of this facility,
which would be completed prior to the completion date of the proposed project, is part of
the subject of this Environmental Impact Report.
b. Traffic Conditions
Existing Traffic Volumes. Recent counts of daily and peak-hour traffic volumes on the
streets and freeways near the project site are given in Figures 22 and 23. Traffic volumes
are current Iy as high or higher in the p.m. peak-hour than in the a.m. peak, and because
the proposed project would generate its highest levels of traffic in the p.m. peak, the
focus of the traffic impact assessment is the p.m. peak hour. However, at specific
180
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locations where a.m. conditions might be critical as well, separate analyses were done of
. t 4
a.m. Impac s.
As shown in Figures 22 and 23, traffic volumes adjacent to the site are considerably
higher in the north/south direction than east/west, with Airport Boulevard carrying one
and a half to twice as much traffic as Hillside Boulevard. The traffic level on Hillside is
in the range characterizing free-flow conditions, while Airport Boulevard traffic flow is in
the stable-to-restricted range. U.S. 101 carries about 145,000 to 150,000 vehicles daily in
the vicinity of the project site, and carries 1,600 to 1,700 vehicles per lane in the peak
travel direction during the peak hour. The most heavily used freeway ramp is the Linden
Avenue on-ramp which carries over 900 vehicles during the evening peak-hour.
Projected Traffic Growth Due to Other Projects. Traffic levels in the area are expected
to increase significantly by the time of completion of the proposed project due to
additional planned development projects. These include the Gateway and Sierra Point
developments, both major office/commercial projects just east of U.S. 101, and major
residential develoments on the northern slopes of San Bruno Mountain. A descriptive list
of major projects in the area considered likely to be completed by 1990 is given in
Appendix A, Table I. In addition to identifiable projects, general traffic growth is
expected to continue in the area due to smaller infill and re-use projects nearby, other
larger projects outside of the immediate area and growth in through traffic volumes. This----
background traffic growth is estimated to be about two percent annually on the local
street system and one percent annually on the freeway. Cumulative increases by 1990 are
estimated at 17% and eight percent, respectively. It should be emphasized that the
traffic impacts analyzed in this report represent "worst case conditions" assuming that 2.!.!.
cumulative projects are implemented by 1990. Prevailing market conditions may not
actually permit the projected development activities or delay implementation beyond
1990. If this is the case, the projected traffic impacts are overstated and, conversely, the
suggested mitigation measures would result in b€1"'.er future traffic conditions than
presented in this report. Figures 24 and 25 indicate the traffic volumes expe:: tee to
prevail in the project area by 1990. The figures account for background traffic growth
and traffic generated by identifiable major projects, but exclude traffic generated by the
Terrabay project. All of the major roadway improvements identified in the preceding
section were assumed to be in place except the Hillside extension and Oyster Point
interchange.5
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185
IV. Environmental Setting, Impacts and Mitigation
Figures 24 and 25 show traffic growth of about 50% to 60% is anticipated on Airport
Boulevard and streets further west. On streets east of Airport Boulevard and on the
freeway ramps, traffic increases of 100% and more are expected. Freeway volumes are
expected to increase to almost 200,000 vehicles per day, or well over 2,000 vehicles per
lane in the peak hour. 6
Levels of Service. The degree of congestion on roadways and at intersections is described
in terms of six levels of service, "A" through "F". Free flowing conditions are designated
as service level A, while saturation of an intersection is defined as level F. Levels B, C,
D, and E reflect various levels of degradation of service from high-quality to low-quality
flow. To compute the service level at an intersection, the volume of traffic through the
intersection is compared to its capacity, using the volume/capacity ratio. Table 24 shows
a description of flow conditions at each service level and specifies the corresponding
volume/capacity (V /C) ratio.
Table 25 gives the total volume using each of the key intersections in the project area in
1982 and the service level at which the intersection operates in the p.m. peak hour. Each
of the key intersections currently operate at acceptable levels of service (C or better),
except for the Hillside/Linden intersection which approaches unstable flow and intolerable
delay (D/E service level threshold).
Table 26 gives the projected peak-hour intersection volumes and levels of service which
would prevail in 1990 without the proposed proposed project . Traffic desiring to use most
intersections in the area would significantly exceed intersection capacities. Intersections
along Airport Boulevard, Linden Avenue and Oyster Point Boulevard would operate at
service level F assuming that no reconstruction of the Oyster Point interchange takes
place. It should be noted, however, that the planned improvements to the Oyster Point
interchange are expected to significantly improve the operation of all or most of the
over-capacity intersections depending on the specific design selected.
The traffic setting to which the Terrabay project and Hillside extension would be added
would, therefore, include already congested peak-hour conditions at the Linden/Hillside
intersection and, depending on the nature of the planned improvements at the Oyster
Point interchange, possibly at the Linden/Airport intersection at the southbound freeway
on-ramp and at the scissor off-ramp adjacent to the site on Airport Boulevard.
186
IV. Environmental Setting, Impacts and Mitigation
TABLE 24
DEFINITIONS OF
INTERSECTION LEVELS OF SERVICE
Level of
Service
D . t' I
escrJp Ion
Range of VolurT\f
Capacity Ratio
A
Conditions are such that no approach phase
is fully utilized by traffic and no vehicle
waits through more than one red
indication. (Very slight or no delay)
0.0 - 0.6
B
An occasional approach phase is fully
utilized; vehicle platoons are formed; this
is suitable operation for rural design
purposes. (Slight delay)
0.6 - 0.7
C
Stable operation; occasionally, drivers may
have to wait through more than one
indication; this is suitable operation for
urban design purposes. (Acceptable delay)
0.7 - 0.8
D
Approaching unstable
develop, but are
(Tolerable delay)
operation; queues
quickly cleared.
0.8 - 0.9
E
Unstable operation; the intersection has
reached ultimate capacity; this condition is
not uncommon in peak hours. (Congestion
and intolerable delay)
0.9 - 1.0
F
Forced flow; intersection operates below
capacity. (Jammed)
over I. 0
'TJKM, City of South San Francisco Traffic and Circulation Study, December 1981.
2For capacities expressed as maximum intersection carrying capacity, at E/F service level
threshold.
187
IV. Environmental Setting, Impacts and Mitigation
TABLE 25
EXISTING PEAK HOUR INTERSECTION VOLUMES
AND LEVELS OF SERVICE
1982 P.M. Peak Hour Conditions
I Intersection Volume/Capacity Level of
Control Volume Ratio Service
Hi II side/Chestnut SS 1,210 .40 A
Hillside/Kearny 3SS 1,025 A
Hillside/lrving 3SS 1,025 A
Hillside/ Jefferson SS 1,015
Hillside/Randolph SS 1,090 A
Hillside/Linden Signal 1,590 .89 D/E
Linden/ Airport Signal 2,335 .75 C
Oyster Pt./Airport Signal 2,320 .63 B
Oyster Pt ./Dubuque SS 1,130 .67 B
Scissor Ramp/Airport SS 870 .67 B
I Traffic control devices: SS = stop sign; 3SS = 3-way stop sign; signal = traffic signal.
188
IV. Environmental Setting, Impacts and Mitigation
TABLE 26
1990 PEAK HOUR INTERSECTION VOLUMES
AND LEVELS OF SERVICE
(Without Hillside Extension and Terrabay Project)
1990 P.M. Peak Hour Conditions
Without Hillside Ext. and Without Terrabay
I Intersection Volume/Capacity Level of
Control Volume Ratio Service
Hi I'side/Chestnut Signal3 1,845 .53 A
Hllside/Kearny SS3 1,725 A/B
Hillside/Irving SS3 1,725 A/B
Hillside/ Jefferson SS 1,715
Hillside/Randolph SS 1,825 B
Hillside/Linden Signal 2,435 1.37 F
Linden/ Airport2 Signal 3,850 1.21 F
Oyster Pt./Airport2 Signal 4,365 1.71 F
Oyster Pt ./Dubuque 2 SS 4,110 1.89 F
Scissor Ramp/ Airport2 SS 1,640 1.26 F
I Traffic control devices: SS = stop sign; 3SS = 3-way stop sign; signal = traffic signal.
2 Assumes existing interchange is still in place.
3Recommended change in traffic control.
189
IV. Environmental Setting, Impacts and Mitigation
c. Transit Services
Commuter Rail Services. The Southern Pacific Railroad (SPRR) commuter fail service
operates through the South San Francisco station about one mi Ie from the project site.
This service has recently been taken over by Caltrans and includes 44 trains per day
running between San Jose and downtown San Francisco. During each of the two daily peak
periods (one and three-quarters hours in the morning and one and three-quarters hours in
the evening), 10 trains pass the site, six of which stop at the South San Francisco Station.
During the off-peak periods, trains run at two-hour intervals (headways). Service begins
at 6 a.m. and ends at 8 p.m.
Caltrans' current plans call for the expansion of service from 44 to 52 passenger trains per
day by 1985. Ultimately, service would be increased to 68 scheduled trains per day and
current estimates are, that by 1990, about 60 train runs per day would be operated,
representing a 35 to 40 percent increase over today. Increases in the number of trains
stopping at the South San Francisco station and improvements to the station facilities
would depend upon the degree to which use of the station increases in the future.
Bus Service. The San Mateo County Transit District (Sam trans) operates a mainline bus
service between Redwood City and downtown San Francisco along Airport Boulevard. The
bus line (Line 7B) operates 35 trips northbound and 35 southbound daily, at about one-half
hour headways. Scheduled travel time from the project area to downtown San Francisco
is about 40 minutes. Scheduled travel time to Redwood City is about one hour.
Two other Samtrans lines serve the site directly. line 26H serves the south side of the
site (Hillside and Randolph Avenue) and provides service to downtown South San Ffancisco
and the 8uri Buri and Tanforan shopping centers. Line 248 serves the east side of the site
(Airport Boulevard) connecting it with Brisbane, downtown South San Francisco, and
Tanforan. Both pass within about 500 feet of the Southern Pacific station.
2. Impacts
Because the Terrabay residential/commercial development and the Hillside Boulevard
extension are considered mutually dependent they are analyzed below as two aspects of
the same project.
190
IV. Environmental Setting, Impacts and Mitigation
a. Hillside Boulevard Extension
The Hillside extension described above is considered part of the proposed Terrabay
Development project and a mitigation measure for potential negative traffic impacts.
The roadway facility would also affect prevailing traffic conditions in the area and change
'-------
the setting against which the project's impacts would be measured. The extension would
divert traffic away from the existing two-lane section of Hillside Boulevard (east of the
Randolph intersection) and from Linden and Randolph Avenues. In so doing it would
improve traffic levels of service at the Hillside/linden and Airport/linden and
Airport/Oyster Point intersections. -_________
To determine the amount of traffic which would be diverted to the Hillside extension, a
series of circulation pattern investigations were conducted. These included:
A license plate survey to trace the paths of vehicles currently using the
Hillside-Linden-Airport route.
Counts of traffic-turning movement volumes at intersections on Hillside,
Linden and Airport.
A review of traffic volume counts on Randolph Avenue.
Analysis of traffic assignments prepared in studies on major new projects
planned for the area.
Based on these evaluations it was determined that 35% to 40% of the traffic currently
using the section of Hillside Boulevard from Randolph to Linden would divert to the
Hillside extension, and that about 50% to 60% of traffic currently using Randolph would
divert to Hillside. The majority of new through traffic generated east of U.S. 101 would
also use the Hillside Extension, presuming it is conveniently aligned at Airport Boulevard
with the Oyster Point interchange.
The resulting 1990 traffic projections for the area are given in Figures 26 and 27, showing
a reduction of traffic in the vicinity of the Hillside/Linden intersection to about its 1982
levels. Table 27 gives the 1990 peak-hour intersection counts and service levels in the
area with the Hillside extension but without the Terrabay. Operation of the
Hillside/Linden intersection would improve considerably with respect to its condition
without the extension. It would operate at relatively high level E, within one-third of a
service level of its current level. The Airport/Linden and Airport/Oyster Point
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TABLE 27
1990 PEAK HOUR INTERSECTION VOLUMES
AND lEVELS OF SERVICE
(With Hillside Extension But Without Terrabay Project)
1990 P.M. Peak Hour Conditions
With Hillside Ext. But Without Terrabay
I Intersection Volume/Capacity level of
Control Volume Ratio Service
Hillside/Chestnut Signal3 1,845 .53 A
Hi Ilside/Kearny SS3 1,725 A/B
Hillside/Irving SS3 1,725 A/B
Hillside/ Jefferson SS 1,715
Hillside/Randolph Signal3 1,825 .62 B
Hillside/linden Signal 1,730 .92 E
linden/ Airport Signal 3,205 1.17 F
Oyster Pt./ Airport2 Signal 3,875 1.66 F
Oyster Pt ./Dubuque 2 55 4, 110 1.89 F
Scissor Ramp/ Airport 55 1,640 1.26 F
Hillside Ext./ Airport Signal 3,325 .70 B/C
I Traffic control devices: SS = stop sign; 3SS = 3-way stop sign; signal = traffic signal.
2 Assumes existing interchange is still in place.
3Recommended change in traffic control.
194
IV. Environmental Setting, Impacts and Mitigation
intersections would continue to operate within the F range unless appropriate
improvements are included in the Oyster Point interchange design.
b. T errabay Development
The impacts of the Terrabay project on traffic and transportation would be related to the
increase in area-wide traffic generated by the project's proposed residential and
commercial activities. Traffic would increase incrementally from about 1982 through
1987, in accordance with the project's proposed implementation program, concurrent with
traffic growth and circulation changes due to other area developments (described above).
By 1990 when the proposed project is scheduled to be fully built and occupied, it will have
contributed its full traffic load to the conditions that would otherwise prevail (Figures 24
through 27). The following sections discuss the level of traffic generation of the proposed
project, the traffic's distribution over the local street system and its impacts on traffic
volumes and levels of service that would otherwise exist in 1990, given the area's
anticipated cumulative development levels. A subsequent section addresses the area's
projected long-range traffic and circulation conditions, assuming a build-out scenario for
the northern part of San Mateo County by about the year 2000.
Trip Generation. Table 28 gives the phase-by-phase trip generation levels for the
Terrabay project. Upon completion and full occupancy (85% occupancy for the hotel), the
project would generate about 16,570 daily trips. About 6, I 00 of these (37%) would be
generated by the residential area and the remaining 10,470 (63%) would be generated by
the commercial part of the site.
The completed project would generate about 1,710 trips in the p.m. peak hour. Because of
the proposed mix of residential and commercial uses, the direction of peak hour traffic
flow would be roughly balanced, with about 45% of the traffic heading inbound to the site
and 55% heading outbound. The proposed land use mix of the project would, therefore,
have positive impacts on traffic generation by balancing peak-period traffic.
Because of the mutual compatibility of many of the on-site uses, it is anticipated that, of
total trips generated by each of the individual uses, some percentage would occur between
different on-site activities. This would include trips between the on-site hotel and private
health club, between businesses and residences, and between the restaurant, hotel and
seminar center, and office and tech trade center. Trips of this type would be either: (I)
walking trips, (2) fully on-site auto trips, or (3) auto trips between two ends of the site
195
IV. Environmental Setting, Impacts and Mitigation
TABLE 28
TERRABA Y DEVELOPMENT GROSS TRIP GENERATION
Phase Development Density I Trip Rates(per density unit)2 Traffic Generated
P.M. Peak Hour P.M. Peak HOl'"
Dei Iy Inbound Outbound Daily Inbound Outbou
T ownhomes (3.1 )3 181 D.U. 9.0 .65 .25 1,630 120 45
Single Family (3.7) 136 D.U. 10.0 .70 .30 1,360 95 41
Hillside Rec Center 500 Members .34 .02 .02 170 10 10
II Townhomes (2.6) 200 D.U. 9.0 .65 .25 1,800 130 50
III Terraced Units(l.6) 129 D.U. 5.0 .35 .15 645 45 19
Condominiums (1.8) 99 D.U. 5.0 .35 .15 495 35 15
Total Residential 745 D.U. 6,100 435 180
IV Office 57.5 KSF 15.0 .40 1.85 860 25 105
Private Health Club 600 members .34 .02 .02 200 10 10
Restaurant 150 seats 2.0 .08 .03 300 10 5
V Hotel 400 rooms 9.04 .38 .38 3,600 150 150
Seminar Center 600 seats 2.4 . II .25 1,440 65 150
Restaurants 500 seats 2.0 .08 .03 1,000 40 15
VI Tech Trade Center
Office Space 27.8 KSF 15.0 .40 1.85 420 10 50
Showroom Space 240.9 KSF 11.0 . 10 1.15 2,650 25 275
Total Commercial 10,470 335 760
Project Totals 16,570 770 940
'In dwelling units (D.U.), or thousands of gross square feet (KSF), unless otherwise
indicated.
2Trip rates developed from trip generation research counts published by Caltrans and the
Institute of Transporation Engineers.
3Values in parenthesis are estimated average dwelling unit occupancies.
4
Assumes 85% occupancy for hotel.
196
IV. Environmental Setting, Impacts and Mitigation
using only the immediately adjacent roadways. The first two types would not affect the
local street system and are, therefore, eliminated from the gross trip generation
estimates as indicated in Table 29. The traffic increase on area streets would be about
85% of the gross trip generation estimate.
Trip Distribution. The expected travel orientation of traffic generated by Terrabay
commercial and residential uses are given in Table 30. Recognizing local circulation
constraints (such as difficulty of peak-hour travel north and west to 1-280 discussed
above), these travel orientations can be translated to an estimated traffic distribution on
the local streets and freeway access system. The projected peak-hour distribution of
T errabay traffic is given in Table 31.
Traffic Impacts. Traffic increases that would be generated by the proposed project are
shown in Figures 28 and 29). The total 1990 daily traffic volumes along Hillside Boulevard
would range from about 12,000 to about 21,000 vehicles compared with 8,000 to 16,000
without the development. Daily traffic in the vicinity of linden and Hillside would
increase by about 1,500 vehicles to 11,000 or 12,000 daily trips. Along Airport Boulevard,
the largest increase (about 9,000 vehicles) would occur immediately in front of the
project's commercial area where traffic levels would reach over 36,000 average daily
traffic (odt). Elsewhere on Airport (beyond the nearest freeway ramps), traffic increases
would be considerably less, from 1,000 to 3,000 daily vehicle trips. __________
The proposed project's share of 1990 p.m. peak hour traffic (Figure 29) would range from
about 20% to about 45% of the cumulative volumes in the immediate vicinity of the site.
Further away (south of linden and Hillside, west of Chestnut or east of the freeway), the
project's share would be five to ten percent or less of the cumulative traffic. Freeway
traffic would increase by up to about four percent due to the project. For example, peak hour
southbound traffic on U.S. 10 I south of the linden on-ramp would increase from 9,985 to 10,385
(400 vehicles) as shown in Figures 25 and 27.
Table 32 indicates the traffic congest ion impacts of the proposed project. A t the key
intersections not already suffering over-capacity conditions, peak hour service levels
would worsen by between one-half to one grade. The Hillside/linden intersection would
continue to operate in the E service level range, but considerably better than without the
Hillside extension project. All other intersections west of Airport Boulevard would
continue to operate at service level C or better.
197
IV. Environmental Setting, Impacts and Mitigation
TABLE 29
TERRABA Y TRIP GENERATION
ADJUSTED FOR ON-SITE TRAVEL
Development Daily Trips Peak Hour Trips
Gross On-S i te Off-Site Gross On-Site Off-si te
Generation Walk Traffic Generation Walk Traffic
Residential Area 6,100 235 5,8651 615 30 5852
Dwelling Units
Hillside Rec Center
Commercial Area 10,470 2,450 8,0201 1,095 200 8952
Office
Private Health Club
Restaurant
Hotel
Seminar Center
Restaurants
Tech Trade Center
Total Project 16,570 2,685 13,885 1,710 230 1,480
(Off-Site/T otaJ) (84%) (87%)
I Includes about 200 vehicular trips between commercial area and residential area.
21ncludes about 45 vehicular trips between commercial area and residential area.
198
IV. Environmental Setting, Impacts and Mitigation
TABLE 30
TRA VEL ORIENT A TION OF TERRABA Y TRIPS
Residence locations of Employees in T errabay Office/Commercial
San Francisco, North Bay
Northern East Bay
32%
Southern and Mid Peninsula
So. Bay and Southern East Bay
55%
local (So. San Francisco,
Pacifica, Daly City)
13%
Work/Shop locations of Terrabay Residential Occupants
San Francisco, North Bay,
Northern East Bay
33-34%
Southern and Mid-Peninsula So.
Bay and So. East Bay)
33%
local (So. San Francisco, Pacifica,
Daly City)
33%
Sources of trip distribution projections: Survey of residence locations of employees at
the Bay Hill Offices in San Bruno; similar survey of employees of United Airlines
maintenance yard at San Francisco International Airport; tabulation of residence
locations of individuals employed in San Mateo County as reported in the 1970 census;
evaluation of travel orientations of employees at Cabot, Cabot and Forbes in South San
Francisco; and information provided by Terrabay project development team.
199
IV. Environmental Setting, Impacts and Mitigation
TABLE 31
TERRABA Y TRAFFI C
P.M. PEAK HOUR DISTRIBUTION
Outbound
Traffic
Inbound
Traffic
To/from North
U.S. 101
Bayshore Blvd.
30%
3%
29%
2%
To/from South
U.S. 101
Airport Blvd.
linden Ave.
52%
1%
3%
38%
10%
5%
To/from West
Hillside Boulevard
Chestnut Avenue
4%
5%
5%
6%
local
Hillside Boulevard
Oyster Point
0%
2%
2%
3%
100%
100%
200
IV. Environmental Setting, Impacts and Mitigation
TABLE 32
1990 PEAK HOUR INTERSECTION VOLUMES
AND lEVELS OF SERVICE
(With Hillside Extension and Terrabay Project)
1990 P.M. Peak Hour Conditions
I Intersection Volume/Capacity level of
Control Volume Ratio Service
Hillside/Chestnut Signal3 1,975 .57 A
Hillside/Kearny SS3 1,865 .61 A/B
Hillside/Irving 553 2,120 .74 C
Hillside/ Jefferson Signal3 2,170 .57 A
Hillside/Randolph Signal3 2,165 .71 B/C
Hillside/Linden Signal 1,850 .96 E
Linden/ Airport Signal 3,725 1.43 F
Oyster Pt./ Ai rport2 Signal 4,800 1.94 F
Oyster Pt ./Dubuque 2 55 4,580 2.28 F
Scissor Ramp/ Airport4 SS 2,750 .92 E
Hillside Ext./Airport Signal 4,485 5 5
I Traffic control devices: SS = stop sign; 3SS = 3-way stop sign; signal = traffic signal.
2Assumes existing interchange is still in place.
3Recommended change in traffic control.
4 Assumes off-ramp widened to two lanes.
5Depends on configuration of intersection and Oyster Point grade separation.
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IV. Environmental Setting, Impacts and Mitigation
At intersections along Airport Boulevard, including the linden on-ramp and the "scissors"
off-ramp, the project would reinforce the need for improvements before 1990. Service
levels would worsen by about 5% to 15% due to the project.
The Terrabay Development would also contribute, although only to a small extent, to a
worsening of peak period traffic conditions on Route 101 which already carries heavy
traffic. Without the project, the 1990 peak-hour demand for the freeway would
theoretically exceed its capacity by 10 to 20%. The project would increase total demand
by up to four percent.
Transit Impacts. The proposed project would generate about 400 public transit trips daily,
and this level could become considerably higher if Samtrans services are tailored to
encourage greater ridership. Even at the 400-trip level, transit impacts would be
noticeable. Samtrans would probably have to add bus runs through the area, and
additional commuter rail ridership would be attracted to the Caltrans/Southern Pacific
service.
With other major developments planned for the area, the cumulative transit ridership
growth by 1990 could be five to ten times the Terrabay level alone.
If appropriate improvements are made to Samtrans service, including more direct freeway
expresses to San Francisco and feeder service to the South San Francisco Southern Pacific
station, and if complementary upgrading is done to Southern Pacific service to the South
San Francisco station, and if aggressive Transportation Systems Management (TSM) and
transit promotion programs are introduced by new employers in the area, cumulative
transit ridership could be at least five times higher than these low-level estimates. To
the extent that new project-area riders would be reverse-direction commuters (living in
the area and working further south, or working in the area and living north) the new
transit demand would be relatively easier to service than would new peak-direction
commuters.
c. Special local Issues
In conjunction with the Hillside extension and Terrabay Development project, several
local traffic circulation issues warrant consideration. These concern potential
connections of North Spruce Avenue and Randolph Avenue to the Hillside extension and
possible design treatments for the existing section of Hillside from lincoln Street to
204
IV. Environmental Setting, Impacts and Mitigation
Randolph Avenue which would protect abutting residences from high levels of traffic
exposure.
North Spruce Avenue Connection. A connection has been proposed between North Spruce
Avenue and the Hillside Boulevard extension. This connection would be in conformance
with the South San Francisco General Plan which identifies the North Spruce Avenue,
School Street and South Spruce Avenue alignment as an arterial street. Advantages and
disadvantages of the proposed connection are noted below.
Advantages:
The connection would provide improved circulation and access for fire, police
and emergency vehicles to the proposed project. However, a new fire station
would be located inside the project so that under ordinary circumstances the
Spruce Avenue connection would not be used by fire fighting equipment.
The connection would, to a minor extent, reduce traffic on linden Avenue by
allowing traffic from this neighborhood to shift onto Hillside Boulevard
extension.
The connection would facilitate access for future T errabay residents to the
downtown commercial areas.
Disadvantages:
If the connection were open to all traffic (as opposed to emergency vehicles
only), increased traffic would occur on North Spruce Avenue and School
Street as traffic from the proposed project would filter through the existing
neighborhoods to downtown and areas south. It is estimated that up to 300
Terrabay vehicles and at least 500 non- Terrabay vehicles would be added to
the existing volumes on North Spruce Avenue and School Street daily.
School Street is not a publicly owned street and does not conform to City
design standards. Its present design (no sidewalks and a drainage dip that
slows down traffic) does not appear compatible with increased traffic.
Additional traffic would also have negative impacts on the residential
neighborhood along Spruce Avenue further south where steep grades and
parked cars result in reduced traffic capacity on this street.
A straight connection between North Spruce and the Hillside extension would
require a short but steep ramp between Randolph and the new Hillside
Boulevard extension due to the elevation difference between these two
streets. A more feasible connection could be provided 350 feet east of
Spruce Avenue where the project's internal circulation road feeds into
Hillside Boulevard extension.
205
IV. Environmental Setting, Impacts and Mitigation
The jogged connection and the closeness of Randolph Avenue and Hillside
extension at this point will result in an awkward and hazardous geometric
design. It appears likely that the connection would have to be signalized for
traffic safety reasons. Without such a connection this T -intersection would
not need to be signalized.
A limited connection, for emergency police and fire use, was reviewed, but is not
considered necessary. According to the Fire Department, the station on the project site
would house one engine, and equipment from other South San Francisco fire stations could
access the site via Airport and Hillside Boulevards.7 The South San Francisco Police
Department considers the project's two main Hillside Boulevard access points as adequate
access for police and other law enforcement vehicles.8
Treatment of Randolph Avenue at Hillside Boulevard and at Airport Boulevard. In order
to prevent through traffic on Randolph Avenue and to reduce the number of access points
on Airport Boulevard, Randolph Avenue should be made into a cul-de-sac at its east end.
local traffic to and from Airport Boulevard would use Butler, Gardiner and Chapman
Avenues instead. As an alternative, Randolph Avenue could be restricted to right-turn-in
and right-turn-out movements only at Airport Boulevard. The selection of the best
treatment for the east end of Randolph Avenue would depend on the selection of the
specific Oyster Point Interchange redesign alternative.
On the west end of Randolph, a cul-de-sac is also recommended. This should be just east
of the point where Randolph currently meets Hillside Boulevard. The cul-de-sac would
eliminate the need for a complex and inefficient design at the new intersection of the
existing Hillside Boulevard and the Hillside extension.
Treatment of Hillside Boulevard from lincoln Street to Randolph Avenue. Residences
abutting the south side of Hillside Boulevard currently experience higher levels of
exposure to fast moving traffic than is normally considered compatible with residential
environments. The high levels of traffic also reduce the ease and safety of access and
exit from driveways along the south side of Hillside. All-way stop signs have been
installed on Hillside at Kearny and at Irving Streets to reduce the impacts associated with
dense traffic flows and high speeds. However, these stop signs would not be compatible
with the function of Hillside as a major regional arterial.
Traffic along this section of Hillside Boulevard is projected to increase from 10,000 to
about 20,000 average daily trips by 1990. Beyond that, improved connectivity of Hillside
206
IV. Environmental Setting, Impacts and Mitigation
to the regional arterial street system would increase its prominence as a high-volume,
high-capacity major arterial. These prospects would both heighten the level of traffic
exposure for the street's residents and reduce the acceptability of the existing stop-signs.
For these reasons, the Specific Plan9 for the proposed project contains the construction of
a neighborhood traffic buffer zone along Hillside Boulevard to reduce the intensity of
traffic exposure and ease of access and egress for the adjacent properties. This buffer
zone will essentially provide an extensive eastbound lane on the south side of Hillside
Boulevard between lincoln Street and the "Y" intersection with the Hillside extension.
The additional lane will be physically separated by raised dividers with openings at the
intersections. This proposed treatment would sufficently separate local and arterial
street traffic and considerably mitigate the impact on the adjacent residential properties.
Parkinq for New Athletic Fields. As a mitigation measure, the Terrabay Development
project would provide a set of athletic fields for community use. The fields would be
located on Hillside Boulevard behind the elementary school at the west end of the site and
would be lit for night use. No separate parking area would be provided for the fields, and
no parking is currently permitted on the north side of Hillside.
Demand for parking at the fields is expected to be highest on evenings and weekends when
the school lots are unused. On occasions when parking demand generated by the fields
overflows the capacity of the school lot, parking could be accommodated at the nursery
school on the south side of Hillside, or could overflow into the adjacent residential
neighborhoods. A pedestrian overpass connects the nursery school area with the fields, to
facilitate safe pedestrian crossing of Hillside. Removing the parking prohibitions on the
north side of Hillside is not recommended.
d. long-range Impacts
Cumulative impacts of projects expected to be completed concurrently with the proposed
project are covered in the previous section. All known development projects and roadway
improvements scheduled for completion by about 1990 are listed in Table I of Appendix A
and included in the preceding assessment of project impacts. Beyond 1990, major
development is expected to continue, however, and the following sections summarize an
assessment of longer range transportation impacts.
207
IV. Environmental Setting, Impacts and Mitigation
lonq-ranqe Development. Development expected to take place in the project's area of
influence between 1990 and about the year 2000 are identified in Table 2 in Appendix A.
They include potential development on large holdings by U.S. Steel on the Oyster Point
peninsula and Southern Pacific in northeast Brisbane, and infill development on currently
undeveloped parcels in South San Francisco. Also assumed to continue through the year
2000 are general growth in background and though traffic at about two percent per year
on local streets and one percent per year on the freeway.
lonq-ranqe Circulation Improvements. Proposed long-range roadway improvements are
intended to improve the connection between Hillside Boulevard and the regional arterial
system. In addition to the Oyster Point interchange at the eastern end of Hillside,
upgrading is proposed for Chestnut Avenue as well as an extension of Hickey Boulevard to
better connect western sections of Hillside to EI Camino Real and 1-280.10
Other prospective street system improvements include North Canal Street (an east/west
collector south of Grand Avenue), Grand and Oak Avenue improvements near Chestnut,
and Westborough Boulevard (an extension of Chestnut Avenue) near 1_280.10
Lonq-range Impacts. The year 2000 traffic levels in the project area are given in
Figure 30. Traffic volumes are projected to increase by 30% to 40% between 1990 and
2000 on streets west of Airport Boulevard, and on the Hillside extension, growth would be
over 50%. Traffic levels on certain sections of Hillside Boulevard are forecasted to
exceed 28,000 vehicles per day by the year 2000. On Airport Boulevard, traffic is
projected to increase by 10% to 20% from 1990 to 2000, reaching levels about 60% to 70%
higher than today's volumes assuming continuation of today's travel patterns and level of
auto use. The unconstrained demand for travel on U.S. 101 is expected to exceed 200,000
vehicles per day by the year 2000.
Table 33 indicates traffic levels of service that would prevail in the year 2000,
reemphasizing the need for the currently considered major improvements along Airport
Boulevard in the vicinity of the Oyster Point interchange. The table also points out the
possible need for travel-demand reducing mitigation measures and/or for street
intersection improvements along Hillside at Randolph and Irving by the year 2000.
208
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IV. Environmental Setting, Impact and Mitigation
TABLE 33
YEAR 2000 PEAK HOUR INTERSECTION VOLUMES
AND lEVELS OF SERVICE
2000 P.M. Peak Hour Conditions
I Intersection Volume/Capacity level of
Control Volume Ratio Service
Hi IIside/Chestnut Signal3 2,775 .80 C/O
Hillside/Kearny SS3 2,460 .80 C/O
Hillside/Irving 553 2,845 .99 E/F
Hillside/ Jefferson Signal) 2,920 .77 C
Hi Ilside/Randolph Signal3 2,990 .98 E/F
Hillside/linden Signal 2,195 I. 14 F
linden/ Airport Signal 4,360 1.67 F
Oyster Pt./Airport2 Signal 5,750 2.34 F
Oyster Pt ./Dubuque 2 SS 5,155 2.57 F
Scissor Ramp/ Airport 4 SS 2,940 .98 E
Hillside Ext./ Airport2 Signal 5,500 1.13 F
I Traffic control devices: 55 = stop sign; 355 = 3-way stop sign; signal = traffic signal.
2Assumes existing Oyster Point interchange is still in place.
3Recommended change in traffic control.
4 Assumes off-ramp widened to two lanes.
210
IV. Environmental Setting, Impacts and Mitigation
e. Summary of Impacts
By 1990, cumulative development around San Bruno Mountain, including the proposed
project, will produce the following significant traffic and transportation impacts if not
mitigated:
Increased peak period traffic congestion at the following key intersections:
Hillside and linden
Airport and li nden
Airport and Oyster Point
Oyster Point interchange ramps (Dubuque)
Scissor Ramp from U.S. 10 I to Airport
Increased peak demand for travel on the U.S. 101 main line to levels greater
than the freeway's carrying capacity.
Increased traffic levels on Hillside Boulevard between Chestnut and Randolph
to levels requiring improved traffic controls.
Increased level of traffic exposure experienced by residents of Hillside from
lincoln to Randolph by 100%.
Increased dai ly transit ridership generated in the area by at least 2000 tr ips,
and possibly much more.
However, as is discussed in the following section, certain roadway improvements and
traffic reducing measures will allow mitigation of these impacts to acceptable peak
period service levels. Although slightly worse than today, such service levels would
result in traffic conditions that are not uncommon for rush hour operation on the
peninsula.
3. Mitigation Measures
The following sections discuss measures recommended to mitigate these impacts. It
should be kept in mind that several of the recommended mitigation measures are of
regional importance and go beyond the improvements required to accommodate local or
Terrabay-projected-generated traffic. Many of the proposed mitigation measures deal
211
IV. Environmental Setting, Impacts and Mitigation
with correcting substandard and incomplete freeway interchanges and providing railroad
grade separations and thus improving the overall circulation of this region of the
Peninsula.
a. Hillside Extension
The Hillside extension would help mitigate many of/the Terrabay and cumulative impacts
along lower Hillside and the critically impacted linden intersections. It would reduce
traffic at the Hillside/linden intersection by about one-third and enable it to operate at
less-than-capacity conditions through at least 1990. It would also reduce traffic at the
congested linden/Airport and Airport/Oyster Point intersections by up to five percent.
Traffic exposure levels for residents of lower Hillside Boulevard would be reduced by
about 40% and for residents of Randolph by about 60%.
b. Oyster Point Interchange
As is discussed in the following section, certain roadway improvements and traffic
reducing measures will allow mitigation of these impacts to acceptable peak period
service levels. Although slightly worse than today, such service levels would result in
traffic conditions that are not uncommon for rush hour operation on the peninsula.
This Oyster Point interchange improvement is needed to support planned development
east of U.S. 101. Alternative designs for the grade separation and interchange have been
prepared and are currently being reviewed by the South San Francisco City Council and
Caltrans. Up-to-date traffic projections for all development proposed for the area,
including the proposed project, have been incorporated in the design alternatives, and
although the selected alternative is not known at this time, it may be assumed that it will
provide adequate capacity to handle the projected traffic levels. It is, therefore, assumed
that the over-capacity conditions projected for the Airport/Oyster Point and Oyster
Point/Dubuque locations will mitigated by this improvement. If the selected alternative
includes a new southbound freeway on-ramp to either replace or augment the linden
ramp, significant improvements to the operation of the linden/Airport intersection will
also be achieved.
Four different designs for the reconstructed interchange are presently being studied by
the City of South San Francisco, all of which include a grade separation of the Southern
Pacific Railroad tracks. Three of the alternatives (Alternatives IE, 10 and 53) would
eliminate potential conflicts between major traffic flows (a.m. peak-hour northbound off-
212
IV. Environmental Setting, Impacts and Mitigation
movement toward the east and northbound on-movement from the west) that are inherent
in the present rather restricted design of that interchange. Two of the studied
alternatives would inlcude a reconstruction of the scissor freeway off-ramp at Airport
Boulevard and the provision of additional southbound on-ramps. Each of the three above-
mentioned alternatives would, in principle, serve the Terrabay project equally will
although Alternative 10 appears to accommodate the project traffic best.
c. Sierra Point Interchange and Bayshore Connectors
Much of the traffic which currently impacts Airport Boulevard in South San Francisco is
traffic bound for the linden Avenue freeway ramp from Brisbane and points further north.
The planned new freeway i~terchange at Sierra Point could not only serve traffic from
new developments in and north of Brisbane (as has been assumed in this study's traffic
forecasts) but could also intercept existing traffic which currently travels via Bayshore
Boulevard to Airport Boulevard and the linden on-ramp.
To intercept the existing traffic it would be necessary for the Sierra Point interchange to
present an attractive alternative to the accustomed Airport/linden route. This would
depend both on the projected increase in congestion along Airport and on the
establishment of uncongested direct access between Bayshore Boulevard and the Sierra
Point ramps. A well signed and high-capacity connection in the vicinity of the Lagoon
crossing could potentially divert 450 peak-hour vehicles from Airport Boulevard in 1990,
or about 3,000 daily trips. The measure has even greater potential long term benefits,
diverting about 530 peak-hour vehicles (3,700 daily) in the year 2000. This would reduce
peak-hour traffic on Airport by about 10% to 15% and ease congestion accordingly.
d. Redesign of Scissor Ramp (Freeway 101 at Airport Boulevard).
Even without the proposed project, the U.S. 101 off-ramp to Airport Boulevard in front of
the project site will reach operational capacity by 1990. The existing scissor
configuration with two-way stop signs would not have sufficient capacity to handle peak
demands and traffic could back up onto the freeway. This location would have to be
redesigned to support Terrabay and other cumulative development.
The Specific Plan for the project outlines a proposed re-design which would ultimately
relocate Airport Boulevard slightly to the west onto project property to facilitate a re-
designed off-ramp and a new on-ramp. In the interim, the new Airport Boulevard right-
of-way would accommodate an internal circulation roadway for the proposed commercial
213
IV. Environmental Setting, Impacts and Mitigation
development. The regulating of the scissor ramp reconstruction and its ultimate design
would be consistent with the current Oyster Point interchange reconstruction plans.
The reconstructed freeway ramp terminal and entrance to the project would be signalized
and would also include a southbound on-ramp. The commercial development of the
proposed project would be served by the signalized main entrance/exit and two secondary,
unsignalized entrances/exits on Airport Boulevard. These measures and the re-design of
the scissor ramp would adquately mitigate projected capacity and safety impacts along
this section of Airport Boulevard.
e. Installation of Traffic Controls
As a result of traffic increases from cumulative development, including the proposed
project, traffic signals should be installed at the following locations before 1990:
Hillside Boulevard/Chestnut Street
Hillside Boulevard/Hillside extension
Hillside extension/Airport Boulevard
In addition, depending on final design decisions, one or more signals will probably be
warranted in connection with:
Oyster Point interchange
Scissor ramp connection to Airport Boulevard.
Signalization would be necessary at two additional locations primarily due to the Terrabay
project. Their installation should be scheduled in accordance with the phasing of
development on the relevant access points:
Hillside Boulevard at Jefferson St.
Terrabay commercial area main driveway at Airport Boulevard (in
conjunction with the freeway ramp reconstruction).
In conjunction with these signalization projects, the existing all-way stop signs on Hillside
Boulevard at Kearney and Irving Streets should be removed. The signals would produce
suitable gaps in Hillside traffic to permit turns to and from the side streets, and
additional protection may be provided for driveway access if the other mitigation
measures are implemented.
214
IV. Environmental Setting, Impacts and Mitigation
f. Treatment of Hillside Boulevard Residential Interface
Impacts of increased traffic exposure on residences along the south side of Hillside
Boulevard between lincoln Street and Randolph Avenue would be mitigated by creating a
frontage road, or traffic free zone along the south side of the street. The treatment
would involve a partially landscaped buffer separating local access movements from the
higher speed traffic along Hillside Boulevard.
g. Transportation Systems Management
In view of the mid- and long-range traffic demand levels projected for the project area
and the entire U.S. 101 travel corridor, it is evident that measures which increase
transportation system supply cannot be expected to keep pace with an unrestrained
growth in demand. Measures will also be needed to reduce travel demand. Such
measures, generally referred to as Transportation Systems Management (TSM) strategies,
include:
Measures to increase vehicle occupancy, such as van pool programs, carpool
matching and ride-sharing incentives.
Measures to improve transit access, such as feeder bus services and fare
subsidies.
Measures to disperse peak-hour travel, including flex-time and staggered
work hours.
Measures to improve transit service, such as expanded service coverage, and
increased frequency.
Measures to improve high-occupancy-vehicle operations, such as ramp
metering and exclusive lanes.
Parking controls, including limiting parking supply and introducing parking
fees.
Other major developers in the project area have committed themselves to implementing
TSM programs to help mitigate their projects' impacts, and it is expected that a
coordinated area-wide program could have significant benefits. Essential elements would
include working with Caltrans and Sam trans to upgrade transit service in the area and
working with RIDES for Bay Area Commuters to implement an aggressive area-wide ride
sharing program. It is estimated that a coordinated effort, involving full commitment to
at least three or four of the types of measures identified above by all of the area's major
employers could result in a 10% to 20% reduction in peak-hour traffic generation.
215
IV. Environmental Setting, Impacts and Mitigation
Concurrent efforts throughout the region could affect the project area's residentially
generated and through traffic as well, and it is estimated that a 15% reduction in
area-wide peak-hour traffic could be achieved through coordinated TSM action.
h. Cumulative Effects of Mitigation Measures
Taken as a group, the measures suggested above can successfully mitigate the cumulative
traffic impacts in the project area through at least 1990. Table 34 summarizes the 1990
and year 2000 peak-hour service levels that would result from full mitigation, showing
that acceptable traffic conditions could be maintained through 1990. long-range
developments, proposed during the 1990 to 2000 time period, should be evaluated at the
appropriate times in terms of their traffic impacts. Suitable mitigation measures could
then be devised to preserve acceptable traffic conditions through the year 2000.
i. Phasing of Mitigation Measures
The proposed project is scheduled to be implemented in six phases starting with the
westernmost residential developments and ending with the tech trade center in the
northernmost area along Airport Boulevard. For purposes of this analysis, phasing would
refer to blocks of development rather than chronological sequence as shown in Table 2,
Section III. According to the Draft Specific Plan phasing would be consistent with the
anticipated roadway and capacity movements in the area. Phases IV and V, comprising
the commercial development could conceivably progress simultaneously with Phases I, II
and III. In terms of p.m. peak hour traffic impacts, each of the six development phases
will contribute the following proportions of the ultimate build-out level:
Phase I
Phase II
Phase III
Phase IV
Residential
Residential
Residential
T entat ive
Completion Individual Cumulative
1984 21% 21%
1985 12% 33%
1986 7% 40%
1984 9% 49%
1985 31% 80%
Beyond 1985 20% 100%
100%
(1,480 off-site
vehicle trips)
216
Office, Private Health
Club, Restaurant
Phase V Hotel/Seminar Center
Phase VI Tech Trade Center
Total Build-Out
IV. Environmental Setting, Impacts and Mitigation
TABLE 34
1990 and 2000 MITIGATED
PEAK HOUR INTERSECTION VOLUMES
AND lEVELS OF SERVICE
1990 and Year 2000 Mitigated
PM Peak Hour Conditions
1990 2000
I 1990 Service 2000 Service
Control Volume level Volume level
Hillside/Chestnut Signal3 1,670 A 2,360 B/C
Hillside/Kearny 553 1,585 A 2,110 A
Hi Ilside/lrving SS3 1,810 A 2,425 B
Hillside/ Jefferson Signal3 1,855 A 2,490 B
Hi Ilside/Randolph Signal3 1,830 A/B 2,535 C
Hillside/Linden Signal 1,565 D/E 1,880 F
Linden/ Airport Signal 2,7854 E4 3,2454 E/F4
Oyster Pt./Airport2 2 3,7002 2 4,4252 2
Oyster Pt /Dubque 2 2 3,8402 2 4,3252 2
Scissor Ramp/AirportS Signal3 1,955 A/B 2,035 B
Hillside Ext./Airport Signal 3,4802 2 4,2152 2
I Traffic control devices: SS = stop sign; 3SS = 3-way stop sign; signal = traffic signal.
2Depends on design of Oyster Point Interchange and Hillside Connection.
3Recommended change in traffic control.
4Can be improved by two service levels if Oyster Point Interchange includes southbound
on-ramp.
5 Assumes development's main commercial driveway located opposite redesigned ramp
terminus, as per Specific Plan.
217
IV. Environmental Setting, Impacts and Mitigation
Based on these incremental traffic impacts, and assuming that other developments in the
area are built as shown in Appendix A, Table I, the previously discussed mitigation
measures should be implemented in accordance with the following approximate schedule:
Mitigation Measure
Implementation Timetable
Prior to Completion of Phase I
At completion of Phase VI or earlier
Independent of proposed project
a. Hi IIside Extension
b. Oyster Point interchange
c. Sierra Point interchange
d. Re-design of Airport Boulevard
scissor ramp
At completion of Phase V or earlier
e. Traffic Controls
f. Hillside Traffic Buffer Zone
g. Transportation System Management
A t Phases I through VI
At completion of Hillside Extension
Starting with Phase II and primarily
during Phase IV, commercial development
j. Mitigation measures proposed as part of the project.
As listed in Exhibit 12 of the Draft Specific Plan, the project sponsor has agreed to the
following mitigation measures which would directly or indirectly affect traffic and
transportation impacts. Many measures reflect recommendations indicated in the
previous analysis. The proposed phasing schedule for these improvements and techniques
is shown in Table 2, Section III of this document.
"Roadway and Signalization Improvements
Construction of Hillside Blvd. Extension II
Signalization of the Intersection of Hillside Boulevard and Jefferson Avenue
Signalization of the Intersection of Hillside Boulevard Extension and Bayshore
Boulevard
Signalization of the Intersection of Sayshore Boulevard and the project commercial
area entrance 12
Financial participation in the Proposed Oyster Point Interchange Improvements
Construction of Scissors Ramp Modications on Bayshore Boulevard as part of the
Phase III of the development schedule
Construction of residential buffer zone along existing Hillside Boulevard
Transportation System Management Techniques
limousine Service will be provided from the San Francisco International Airport to
the Hotel/Seminar Center
Bus pullouts and bus shelters will be provided along Sayshore Boulevard and Hillside
Boulevard
Carpool preferential parking will be provided in the commercial area where
appropriate
Staggered work hours will be encouraged in the office space
Vanpooling and carpooling will be encouraged through homeowners' association and
the office space management
218
IV. Environmental Setting, Impacts and Mitigation
Expanded transit service will be sought through the appropriate agencies."
I For definitions of street functional classifications, refer to Appendix A, Table 3.
2T JKM, Traffic and Transportation Study, Circulation Plan for the City of South San
Francisco, December 1981.
3George S. Nolte and Associates, Oyster Point Grade Separation Study, (ongoing).
4PM peak-hour traffic volumes in the study area are, on the average, about 25% higher
than a.m. peak-hour traffic and proposed project development is expected to generate
10-15% higher traffic volumes in the p.m. peak than in the a.m. peak.
5The Oyster Point interchange is the subject of an on-going special study, and selection of
a final project alternative has not yet taken place. The general implications of that
project will be discussed in a separate section of this EIR, but for a more detailed
treatment, the forthcoming Oyster Point Interchange Study by George S. Nolte Assoc.
should be consulted.
6These volumes represent travel demand levels. Volumes significantly greater than 2,000
vehicles per hour would exceed the freeway's capacity and could not actually be carried.
Actual future traffic levels on the freeway will depend on development throughout the
region and particularly downtown San Francisco, as well as on changes in regional travel
patterns, such as diversion to under-used facilities and flattening of peak periods and
measures applied on a regional basis to effect these development and travel patterns.
For the purposes of this study, it has been assumed that U.S. 101 will continue to
operate at capacity through at least 1990. This volume/capacity balance is reflected in
current peak-hour traffic volumes and is related to existing upstream traffic constraint
points (outside the project area), and on currently obtaining traffic systems controls and
transportation systems management programs.
7Telephone conversations with Deputy Fire Marshall Fred Logomarsino on March 22,
1982, and with Fire Marshall Ed Simpson on AprilS, 1982.
8lieutenant Dave Haskins, South San Francisco Police Department, telephone
conversation, on March 23, 1982.
9Supplement to the Administrative Draft, Specific Plan, for the Terrabay Development,
by Resources Engineering & Management, May 1982.
Study, Circulation Plan for the Cit of South San
II
By Agreement between Sponsor and the County of San Mateo.
12Cost Participation proposed to be on the prorata share of traffic contributed by the
project.
219
V. IMPACT OVERVIEW
A. GROWTH-INDUCING IMP ACTS
The project would increase the housing stock of the City of South San Francisco by 745
units or about four percent. Public infrastructure and services would be extended to the
site. In many cases this would be a growth-inducing impact, however, in this instance the
opportunity for additional new development to utilize this increased capacity is not
available as the surrounding vacant lands would be dedicated to permanent open space.
The project, therefore, would not induce growth in the immediate vicinity.
Retail purchases by project residents and employees would stimulate business growth
throughout the City and in surrounding communities. It has been estimated that purchases
would reach nearly $90 million (see Section IV.K. Economics), which represents the
average amount of business handled by about 100 retail employees in the U.S.. This added
retail business activity would stimulate limited additional employment in other sectors,
though not necessarily in the local area. To the extent local businesses can handle
increased revenues with existing levels of staffing, fewer new jobs would be created.
In summary, the project would have few direct growth-inducing impacts and limited
secondary impacts.
B. UNAVOIDABLE SIGNIFICANT ENVIRONMENTAL IMPACTS
As proposed, the T errabay Development would to existing environmental conditions on-
site and within the vicinity of the project. They include the following:
332 acres of generally vacant open space on the site would be replaced by 745
housing units and approximately 680,000 square feet of nonresidential uses. Views
of undeveloped hillsides would be replaced by mixed development land uses and a
road network modified by landscaping and design features.
220
V. Impact Overview
Should movement occur along one of the region's earthquake faults, associated
groundshaking would occur at the site.
During site preparation, exposure of soils and excavation would increase erosion
potential and thus potential for siltation of the drainage system. After the project
is completed, stormwater runoff would contain urban pollutants.
Fugitive dust generated by clearing, earthmoving and grading activities would
create air quality impacts.
Use of the project facilities would create noise impacts. The degree of
significance would vary with the type of activity (i.e. movement, starting and
stopping of vehicles, children's voices, etc.) and the location of the receptor.
Construction equipment would also create noise impacts.
There would be some habitat loss on the residential area of the 332-acre site. The
habitat of two rare butterflies, and other species indigenous to the site would be
disrupted and/or displaced. The proposed project would eliminate approximately
2.22% of the total mission blue population and 0.45% of the total callippe
silverspot population.
Artificial lighting sources introduced to the site would create a newly illuminated
area at night.
The project would change the visual quality of the area, although the entire project
would not be visible from one place, nor would it break the ridgelines.
Increased traffic would be generated by project users with an associated increase
in vehicle emissions.
Demands for water, electricity and natural gas, fire and police protection,
telephone, education, sewage and solid waste disposal services would increase
slightly.
Construction and operation of the proposed project would consume gasoline, diesel
fuels, electricity and natural gas, which are non-renewable resources.
Archaeological resources would be disturbed, including one prehistoric site having
potential significance.
The environmental effects previously described have varing degrees of significance. Some
may be reduced by adopting of appropriate mitigation measures. For instance, while loss
of butterfly habitat is inevitable, the impact could be reduced by phasing the grading
schedule. to reduce the suddenness of the loss. This also applies to potential changes in
the quality of stormwater runoff which could be reduced by cleaning the roads and
221
V. Impact Overview
driveways, controlling erosion and landscaping. Visual effects would be reduced by
unifying architectural design features and generous landscaping. Also, by grouping the
residential development in pockets located generally within swales of the mountainside,
the transitional impacts from an urban to a rural landscape would be reduced.
c. SHORT -TERM USES VERSUS LONG-TERM PRODUCTIVITY
The project sponsor proposes at this time to successfully implement a mixed-use
development. Such a project would preclude further options for development of the
project site including the 153 acres to dedicated to the County of San Mateo as permanent
open space. The construction phase of the project would be relatively short-term
compared to the long-term period over which the project would exist.
Site development would have cumulative long-term effects in that it would consume
irreplaceable fossil fuels. It would contribute to cumulative traffic and community
service increases.
The project would replace existing open space in the areas proposed for project
development. Its economic productivity would be determined by employment generated
during construction periods and lifetime of the nonresidential activity of the development,
and the secondary economic effect on the local economy. The project would incur
operating costs from the City of South San Francisco and capital costs for increased
facilities; however, the project sponsor has agreed to contribute toward necessary capital
expenditures. New revenues would also be generated by sales and use tax, real property
transfer tax, franchise tax, transient occupancy tax and the business license tax. Further,
the City of South San Francisco would receive greater subventions from the State.
D. IRREVERSIBLE ENVIRONMENTAL CHANGES OCCURRING
AS A RESLL T OF PROJECT IMPLEMENTATION
Irreversible environmental changes resulting from implementation of the proposed project
would include loss of endangered species not otherwise mitigated by the Habitat
Conservation Plans modification of the topography and visual appearance of the site. The
332 acres now generally open space would be committed to a mixed-use development.
222
\/. Impact Overview
Another irretrievable commitment of resources associated with the project would be
gasoline consumption by residential and nonresidential activity.
No irreversible damage is anticipated as a result of possible environmental accidents
associated with the project.
223
VI. AL TERNA TIVES TO THE PROPOSED PROJECT
A. NO PROJECT Al TERNA TIVE
The no project alternative would not involve any change to the undeveloped project area
as it now exists. Private ownership would be retained and future options would remain
available for development of the planning area as allowed in the General Plan
Amendment.
The no project alternative would not create any additional environmental impacts.
Current levels of noise, air pollution, energy consumption and water quality would remain
unchanged. Existing soils, vegetation, wildlife, and archaeological resources would not be
disturbed. This alternative would have the least impact on the physical environment.
Existing views of the area as an open space site would remain. Adjacent neighborhoods
would maintain their present residential environment and views of the site.
The no project alternative would not require an increase in demand for local services and
utility systems. The City housing stock would not be increased by 745 units. This
alternative would not provide sponsor-related funds associated with Hillside Boulevard
extension, the community recreation complex, child care center, fire station, and Hillside
Elementary School and sewer system improvements.
The no-project alternative would not provide additional employment opportunities. The
City would not experience an increase of accrued taxable revenues, however, costs for
supplying services would also not be increased.
An option exists for permanent open space with this alternative. The project site is
currently under private ownership and the project sponsor would have to release his option
on the property before any action could occur. Either San Mateo County, another
governmental agency or private coalition would then have to acquire the land to
implement this alternative.
224
This alternative was rejected by the project sponsor because it would not exercise the
available option to develop the site as allowed in the General Plan Amendment. Further,
this alternative would fail to provide a reasonable return on the investment potential of
the site.
B. CONCEPT PLAN AL TERNA TlVE
This alternative would conform to the Concept Plan proposed by W.W. Dean Associates
which would include mixed residential and commercial uses on approximately 130 acres of
the 332-acre site.
This alternative would include 745 dwelling units arranged in clusters of single family
detached homes, townhouses, and condominiums along the site's south slope. The
residences, roads, parking and recreation facilities of the site's residential area would
require approximately 105 acres.
like the proposed project, this alternative would concentrate development in lower
elevations of swales, separated by undeveloped grassy knolls. The apparent density and
layout of the residential portion would be similar to the proposed project. This
alternative would also include a fire station, a recreation center, improvements to the
Hillside elementary school site and a linear park as part of the residential development.
Commercial development would be concentrated in two east facing swales overlooking
Airport Boulevard. A mid-rise hotel complex, in the southernmost of these swales, would
include an eight-story 200-room hotel over two levels of parking (250 spaces). The hotel
would contain a ISO-seat restaurant/bar and connect to a private athletic club directly
behind.
Two restaurants would be located north of the hotel, on Airport Boulevard. The larger of
these would seat 300 and would have 70 parking spaces, while the smaller restaurant
would seat 150 with 50 parking spaces.
A private collector road would connect the hotel complex and restaurants with an office
complex to the north. The office complex, totalling 210,000 square feet, would feature a
mid-rise seven-story building over two parking levels, and a two-story building with
adjacent surface parking. A service station would be located on Airport Boulevard, north
225
VI. Alternatives to the Proposed Project
the office complex. Access to Airport Boulevard from the collector road would be
provided near the restaurants as well as near the service station.
Impacts generated from the residential portion would not differ substantially from those
of the proposed project. The commercial area development, is, overall, less intense than
that proposed and would generate fewer traffic, noise, water and air quality, and energy
impacts. This alternative would disturb an archaeological site by erection of the office
complex in that location as indicated in the Concept Plan. Although this alternative
would have significant archaeological impacts, it would appear that after the no-project
alternative, Alternative B would be environmentally superior to the other alternatives.
Subsequent to development of the Concept Plan, an economic feasibility study for the
commercial area resulted in rejection of this alternative by the project sponsor. In
addition, Alternative B does not incorporate responses to comments received during
review of the Concept Plan.
c. ALTERNATIVE DESIGI'ED TO COf'FORM WITH n-E SPI-ERE OF INFLUENCE STUDY I
This alternative would involve development of the site as indicated by the Preliminary
Site Utilization Plan in the South Slope Sphere of Influence Study.
This alternative would provide 555 single-family units and 481 multi-family units for a
total of 1,036 residential units on 98.8 acres. This represents an increase of 291 units
over the proposed project and 51 units over that allowed in the General Plan Amendment.
A continuous band of residential development would occur on knolls and swales. Single-
family development would be mainly concentrated on the western portion of the project
site and layout and density would be generally consistent with surrounding neighborhoods.
Overall, residential development would create a sharp visuar transition from the open
space areas of San Bruno Mountain to adjacent existing neighborhoods.
This alternative would introduce a 10.4-acre shopping center and two high density
residential areas in a single-family neighborhood along Hillside Boulevard. As with the
proposed project, commercial development would also occur along Airport Boulevard.
New industrial land uses would occur with this alternative.
A 39% increase in residential units would result in additional impacts in transportation,
energy consumption, noise levels, water and air quality. A larger demand would also be
226
generated for community services and to utility systems. lJevelopment of the project site
and subsequent impacts to vegetation and wildlife would not reflect management
guidelines of the Habitat Conservation Plan. Oevelopment of the commercial portion of
the project site would not reflect findings of potentially significant archaeology sites.
This alternative was rejected by the project sponsor because development of the site as
described would result in denser residential development and a greater visual impact on
the existing landscape. Further, the sponsor believes that alterations in project land uses
and components were necessary to incorporate specific recommendations addressed in
community and task force meetings, and data compiled during preparation of this EIR and
Specific Plan.
D. Al TERNA TIVE DESIGNED TO CONFORM WITH THE GENERAL PLAN AMENDMENT2
Development of the site in this alternative would conform to all goals, objectives, policies
and plan elements of the General Plan Amendment for San Bruno Mountain. Tables 3 and
4 illustrate major differences in development between this alternative and the proposed
project. No development would occur on existing slopes generally exceeding 30%.
This alternative would provide 985 dwelling units, 240 more than the proposed project.
The Amendment provides for a greater density of residential development with 30% of the
units contained within a high-rise housing complex for the elderly. Further, 20% of all
residential units would qualify as low and moderate income housing.
Various differences in overall land use would exist for this alternative although residential
and commercial areas would occur in the same general areas. Overall, commercial land
uses would be more intense and warehouse development would occur that is not called for
in the proposed project. Acreage would be set aside for pre-school grounds and a
community center would be developed within the residential area which would
accommodate a cultural center, library, fire station, police station and religious facilities.
Visual impacts associated with the residential development would be similar to
Alternative C. A dramatic exception would be the introduction of a high-rise housing
complex which would create an even sharper transition from open space areas to adjacent
exist ing neighboroods. The townhouses and garden apartments would provide higher
227
density development than the proposed project and would not be consistent with the
single-family neighborhoods located south of the site.
An increase in residential units and a greater intensity of commercial uses would result in
greater impacts in energy consumption, noise levels, water and air quality. In addition to
the general increase to traffic impacts, further impacts would result from the increase in
vehicular trips associated with the centrally located community center. Impacts to
existing vegetation, wildlife and archaeological resources would be similar to Alternative
C.
This alternative was rejected by the project sponsor because development of the site as
described would result in denser recreational development and a greater visual impact on
the existing landscape. Further, the sponsor believes that alterations in project land uses
and components were necessary to incorporate specific recommendations addressed in
community and task force meetings, and data compiled during preparation of this EIR and
Specific Plan.
I San Mateo Local Agency Formation Commission, Sphere of Influence Study: San Bruno
Mountain South Slope, May 1977.
2San Mateo County, ~eneral Plan Amendment from San Bruno Mountain, 1976.
228
VII. EIR AUTHORS AND PERSONS CONSULTED
A. PROPOSED PROJECT AND EIR
lEAD AGENCY
County of San Mateo
Department of Environmental Management
County Government Center
Redwood City, California 94063
(415) 363-4161
Planning Director: David C. Hale
Development Review Manager: Roman Gankin
Planner III, Specific Plans: Bill Rozar
ENVIRONMENTAL IMP ACT REPORT
Environmental Impact Planning Corporation
319 Eleventh Street
San Francisco, Californ ia 94103
(415) 864-2311
Project Manager: Douglas Donaldson
Assistant Project Manager: Suzanne Davalos-McAdams
with:
PRC Voorhees, Traffic Engineers
Charles M. Salter Associates, Consultants in Acoustics
Archeological Resource Management, Archeological and Historical Analyst
Don Ballanti, Meteorologist
Robert Meyers Associates, Visual Analyst
PROJECT SPONSOR
W. W. Dean and Associates
151 West 20th Avenue
San Mateo, California 94403
Mailing Address: P.O. Box 5527
San Mateo, California 94402
(415) 349-8811
President: Bill Dean
229
VI. EIR Authors and Persons Consulted
PROJECT ARCHITECT
Doug Dahlin and Company
375 Diablo
Danville, California 94526
(415) 837-8286
President: Doug Dahlin
PROJECT ENGINEERS
Resource Engineering and Management
343 EI Camino Real
South San Francisco, California 94080
(415) 873-1284
Executive Vice President: Bob Eppler
B. PERSONS CONSULTED
Harry Dean, Chief of Park Planning and Development, San Mateo County Department of
Parks and Recreation .
James Cokas, Coordinator, Child Welfare and Attendance, San Mateo County Office of
Education
Richard Platt, Lieutenant, Services Division, San Mateo County Sheriffts Office
louis dell Angela, Director, Community Development, South San Francisco
Bob Yee, Director, Public Works, South San Francisco
Philip Gorny, Senior Planner, South San Francisco
lyle Norton, Director, South San Francisco Department of Parks and Recreation
Dr. Robert Lloyd, Superintendent, Brisbane Elementary School District
Dr. Floyd Gonella, Superintendent, Jefferson High School District
Robert Dominge, Business Manager, South San Francisco Unified School District
James Datzman, Chief, South San Francisco Police Department
lieutenant Dave Haskins, Investigation Division, South San Francisco Police Department
Sergeant Ron Petrocchi, Crime Prevention Unit, South San Francisco Fire Department
Jack Drago, Fire Chief, South San Francisco Fire Department
David Westover, Battalion Chief, Urban Forestry, California Department of Forestry
230
VI. EIR Authors and Persons Consulted
Clifford Ommert, Supervisor, Public Protection, Insurance Service Office
Erica Volberg, Service Marketing Representative, Burlingame Business Service Center,
Pacific Telephone
Wayne lagger, Right-of-Way Agent, Distribution Services, Pacific Telephone
Patsy Kalman, Manager, Switching and Engineering Division, Pacific Gas & Electric
Company
E.A. Carrera, Manager, South San Francisco Division, Pacific Gas & Electric Co.
Carlo Franco, Manager, South San Francisco Scavenger Company
J.P. Pendergast, Assistant Chief Engineer, California Water Service Company
Deputy Fire Marshal Fred lagomarsino, South San Francisco Fire Department
Fire Marshal Ed Simpson, South San Francisco Fire Department
231
APPENDIX A
TRAFFIC AND
TRANSPORTATION
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A-4
References for Tables 1 and 2
(1) PRC Voorhees, Traffic Report on the Gateway Project, included in the
Gateway Final EIR, June 1981.
(2) TJKM, Traffic Impact Analysis of the Proposed Oyster Point Business
Center, December 1981.
(3) George S. Nolte & Assoc., assumptions used in Oyster Point Grade
Seperation Study, January 1982.
(4) City of South San Francisco, Master Plan for Oyster Point Marina
Park.
(5) TJKM, City of South San Francisco Traffic and Circulation StUdy,
September 1978.
(6) Telephone conversation with Susan Gryte, City of Brisbane Assistant
Planner, March 10, 1982.
(7) Telephone conversations with Lin Lee, Sierra Point Development Corpi
and Chris Kinzel, TJKM, March 8 and 9, 1982.
(8) Telephone conversation with Bill Rozar, San Mateo County Planning
Department, March 12, 1982.
(9) Telephone conversation with Phil Gorny, City of South San Francisco
Planning Department, March 16, 1982.
(10) Information provided by W. W. Dean Associates development team,
February 1982.
(11) TJKM Traffic and Transportation Study Circulation Plan, City of
South San Francisco, December 1981.
A-5
Table '3
FUNCTIONAL CLASSIFICATION OF STREETS
Functional classification is a way of describing the design and purpose of
each street according to the type of service it is intended to provide (and
in some cases, according to the capac i ty of the street). The hierarchy of
service (or capacity) forms the functional classification system. The five
basic components of such a system, applicable to South San Francisco,
include 1) freeways, 2) principal arterials, 3) minor arterial streets, 4)
collector streets, and 5) local streets.
1) Freeways are divided highways with full control of access and grade
separation for all intersecting traffic. There are no intersections at
grade, no traffic signal s, no pedestrians, and no parking on freeways
to 1nterfere with the continuity of high-speed traffic flow on the high
capacity roadway. Freeways provide for the rapid and safe movement of
large volumes of traffic over relatively long distances.
2) Major Arterials are the routes which serve large volumes of through
traffic between sections of the urban area and/or prov ide access to
fr~eways. While principal arterials may provide access to abutting
properties, their primary function is to provide for the movement of
t h r 0 ugh t r a f f i c . We s t b 0 r 0 ugh Bo u 1 e v a r d and E 1 C ami noR e a 1 are
examples. Approximate traffic capacities of 20,000 to 36,000 vehicles
per day (vpd) or greater are common.
3) Minor Arterial Streets serve heavy vol umes of traffic destined for or
generated from business and commercial establishments. The main
difference between principal and minor arterial s is the character of
traffic served. The primary function of a minor arterial street is to
provide for local traffic movement and land access, not through
traffic. Mission Road and Linden Avenue are examples. Approximate
traffic capacities of 10,000 to 20,000 vpd are common.
4) Collector Streets connect neighborhoods with arterial streets. They
usually serve a dual purpose by providing a means for through traffic
movement within a limited area and giving direct access to abutting
property. For design purposes, it is desirable that no residences face
collector streets expected to carry relatively high volumes of traffic.
Examples of collectors include Arroyo Drive and Galway Avenue.
Approximate traffic capacities of 4,000 to 10,000 vpd are common.
5) Minor Streets provide access to abutting properties, usually
residential land use. Examples are subdivision streets (other than
collectors). IITolerable" or environmental capacities of approximately
4,000 vpd or less are used for roadways with single-family residential
frontages.
Source: TJ~1, Traffic and Transportation Study, Circulation Plan for the
City of South San Francisco, December 1981.
A-6
APPENDIX B
Fundamental Concepts of Enviro~~ental Noise
This section provides background information to aid in under-
standing the technical aspects of this report.
Three dimensions of environmental noise are important in deter-
mining subjective response. These are:
a. the intensity or level of the sound;
b. the frequency spectrum of the sound;
c. the time-varying character of the sound.
Airborne sound is a rapid fluctuation of air pressure above
and below atmospheric pressure. Sound levels are usually
measured and expressed in decibels (dB), with 0 dB corres-
ponding roughly to the threshold of hearing.
The "frequency" of a sound refers to the number of complete
pressure fluctuations per second in the sound. The unit of
measurement is the cycle per second (cps) or Hertz (Hz). Most
of the sounds which we hear in the enviro~~ent do not consist
of a single frequency, but of a broad band of frequencies, di=-
fering in level. The quan~itative expression of the frequency
and level content of a sound is its sound spectrum. A sound
spectrum for engineering purposes is typically described in
terms of octave bands which separate the audible frequency
range (for human beings, from about 20 to 20,000 Hz) into
ten segments.
Many rating methods have been devised to permit comparisons
of sounds having quite different spectra. Fortunately, the
simplest method correlates with human response practically as
well as the more complex methods. This method consists of
evaluating all of the frequencies of a sound in accordance
with a weighting that progressively and severely deemphasizes
the importance of frequency components below 1000 Hz, with
mild deemphasis above 5000 Hz. This type of frequency weighting
reflects the fact that human hearing is less sensitive at low
frequencies and extreme high frequencies than in the frequency
midrange.
The weighting curve described abo~le is called "A" weighting,
and the level so measured is called the "A-weighted sound
level", or simply "A-level".
The A-level in decibels is expressed "dBA"; the appended letter
"A" is a reminder of the particular kind of weighting used for
A-7
the measurement. In practice, the A-level of a sound source
is conveniently measured using a sound level meter that in-
cludes an electrical filter corresponding to the A-weighting
curve. All U.S. and international standard sound level meters
include such a filter. Typical A-levels measured in the en-
vironment and in industry are shown in Figure A-l.
Although the A-level may adequately describe environmental
noise at any instant in time, the fact is that the community
noise level varies continuously. Most environmental noise
includes a conglomeration of distant noise sources which
creates a rel~tively steady background noise in which no
particular source is identifiable. These distant sources
may include traffic, wind in trees, industrial activities,
etc. These noise sources are relatively constant from
moment to moment, but vary slowly from hour to hour as natural
forces change or as human activity follows its daily cycle.
Superimposed on this slowly varying background is a succession
of identifiable noisy events of brief duration. These may
include nearby activities or single vehicle passages, air-
craft flyovers, etc., which cause the environmental noise
level to vary from instant to instant.
To describe the time-varying character of environmental noise,
the statistical noise descriptors L10, LsO, and L90 are
commonly used. The L10 is the A-weighted sound level equaled
or exceeded during 10 percent of a stated time period. The
L10 is considered a good measure of the "average peak" noise.
The LsO is the A-weighted sound level that is equaled. or
exceeded 50 percent of a stated time period. The LsO rep-
resents the median sound level. The L90 is the A-weighted
sound level equaled or exceeded during 90 percent of a stated
time period. The L90 is used to describe the background noise.
As it is often cumbersome to describe the noise environment
with these statistical descriptors, a single number descriptor
called the Leq is also widely used. The Leq is defined as
the equivalent steady-state sound level which in a stated
period of time would contain the same acoustic energy as
the time-varying sound level during the same time period.
The Leq is particularly useful in describing the subjective
change in an environment where the source of noise remains
the same but there is change in the level of activity.
Widening roads and/or increasing traffic are examples of
this kind of situation.
In determining the daily measure of environmental noise, it
is important to account for the difference in response of
people to daytime and nighttime noises.
During the nighttime, exterior background noises are gen-
erally lower than the daytime levels. However most house-
A-8
~
A-WEIGITED SOL'ND
PRESSt'RE LEVEL,
IN DECIBElS
140
130
CIVIL DEFENSE SIREN (100')
JET TAKEOFF (200') 120
RIVETING MAQiL'iE
DIESEL BUS (15')
BAY AREA
RAPID '!R.L\}1SIT 'mAIN P.4SSBY (10')
p!-"EUM.4.TIC DRIlL (50')
SF ~ruNI LIGiT-RAIL VEHICLE (35')
FREIGHT ~..RS (100')
V ACli'LlM CLEA.L'lER (10')
SPEECH (1')
AUIO 1RAFFIC NEAR FREEWAY
LARGE TRANSFORMER (200')
AVERAGE RESIDENCE
SOFT WHISPER (5')
Rt"SILING LEAVES
nmESHOLD OF HE.A.RING ~
110
100
90.
80
70
60
so
40
30
20
10
o
,
) 'ffiRESHOLD OF PAIN
.~
RCCK MUSIC BAND
PILEDRIVER (50 I )
AMBt.lI.AJ.'l:E SIREN (100 r )
rolLER RCOM
PRINTING PRESS PLA."i"T
GARBAGE DISrosAL IN HOME (3')
INSIDE SroRTS CAR, 50 MPH
DAT.o. PRO:ESS ING CEt-i"TER
DEPAR'IMB.n' STORE
PRIVA1E BUSINESS OFFICE
UGHT TRAFFIC (100 I )
TYPICAL ~fL.'m>fUM NIGHTrn1E
rn"ELS--RES IDENTIAL ARE..4S
RECORDING STh1)IO
1OSQUI'ID (3')
(100 ') = DISTANCE IN lUT
BE'IWEEN SOLKE
A.~ L!STENER
FIGt.'RE A-I: TYPICll. SOuW mn.s MEASt"RED IN mE BNIRONMExr Al\1) I~USTRY
-
A-9
12/81
-"
hold noise also decreases at night and exterior noises be-
come very noticeable. Further most people are sleeping
at night and are very sensitive to noise intrusion.
To account for human sensitivity to nighttime noise levels
a descriptor, Ldn, (day-night equivalent sound level),was
developed. The Ldn divides the 24-hour day into the day-
time of 7 am to 10 pm and the nighttime of 10 pm to 7 am.
The nighttime noise level is weighted 10 dB higher than the
daytime noise level. The Ldn, then, is the A-weighted average
sound level in decibels during a 24-hour period with 10 dBA
added to the hourly Leqs during the nighttime. For highway
noise environments the Leq during the peak traffic hour is
approximately equal to the Ldn.
The effects of noise on people can be listed in three general
categories:
1. subjective effects of annoyance, nuisance,
dissatisfaction;
2. interference with activities such as speech,
sleep, learning;
3. physiological effects such as startle, hearing
loss.
The sound levels associated with environmental noise, in
almost every case, produce effects only in the first two
categories. Unfortunately, there is as yet no completely
satisfactory measure of the subjective effects of noise,
or of the corresponding reactions of annoyance and dissat-
isfaction. This is primarily because of the wide variation
in individual thresholds of annoyance, and habituation to
noise over differing individual past experiences with noise.
Thus, an important parameter in determining a person's
subjective reaction to a new noise is the existing noise
environment to which one has adapted: the so-called "ambient"
noise. "Ambient" is defined as "the all-encompassing noise
associated with a given environment, being a com~osite of
sounds from many sources, near and far". In general, the
more a new noise exceeds the previously existing ambient,
the less acceptable the new noise will be judged by the
hearer s.
with regard to increases in noise level, knowledge of the
following relationships will be helpful in understanding
the quantitative sections of this report:
a) Except in carefully controlled laboratory
experiments, a change of only 1 dBA cannot
be perceived.
b) Outside of the laboratory, a 3-dBA change is
considered a just-noticeable difference.
A-l0
c) A change in level of at least 5 dBA is required
before any noticeable change in community
response would be expected.
d) A lO-dBA change is subjectively heard as approx-
imately a doubling in loudness, and would allnost
certainly cause an adverse change in community
response.
A-l1
Cupressus macrocarpa
Pinus radiata
Aesculus californica
APPENDIX C
PLANT SPECIES OBSERVED OR REPORTED
ON TERRABA Y DEVELOPMENT SITE
Trees
Monterey Cypress
Monterey Pine
California Buckeye
Shrubs
Poison-Oak
California sage
Coyote Bush
Toxicodendron diversi loba
Artemisia californica
Baccharis pilularis
var. consan uinea
Eriop yl um confertiflorum
Grindelio camporum
Grindelia hirsutula
Marrubium vulgare
Monordella villosa
lupinus albifrons
lupinus arboreus
Rhamnus californica
Heteromeles arbutifolia
Prunus iIlicifolia
Solix coulteri
Salix lasiolepis
D"fjjTOcus aurantiacus
Equisetum telmateia
Polypodium californicum
Pteridium aquilinum
Amaranthus powelli
Amsinckia intermedia
Silence gallica
Spergulo arvensis
Spergularia rubra
Ach i Ilea mi lIefolium
var. californica
Artemisa douglasiana
Chrysopsis villosa
var. bollonderi
Cirsium quercetorum
Cirsium vulgare
Filago californica
Yellow Yarrow
Gum Weed
Gum Weed
Hoorhound
Coyote Mint
Silver Bush lupine
Bush lupine
Coffeeberry
Toyon
Holly-leaved Cherry
Coulter's Willow
Arroyo Willow
Sticky Monkeyflower
Herbs
Giant Horsetail
California polypody
Bracken Fern
Pig Weed
Fiddleneck
Campion
Spurry
Sand Spurry
Yarrow
Mugwort
Golden Aster
Brownie Thistle
Bull Thistle
A-13
~i1ago gallica
emizonia corymbosa
Hypochaeris radicata
lasthenia chrysostoma
Madia sativa
Silybum marianum
Sonchus oleraceus
Wyethia angustifolia
Convolvu Ius occ idental is
Dichondra donelliana
Dudleya cymosa
Sedum spathulifolium
Brassica campestris
Erysimum franciscanum
Raphanus sativus
Nasturtium officianale
Marah fabaceus
Dipsacus fullonum
Microcala quadrangularis
Erod i um botr ys
Erodium cicutarium
Phacelia californica
Saliva spathacea
Stachys rigida
ssp. quercetorum
lathyrus vestitus
Lotus scoparius
cuprnus ~
lu~inus variicolor
Me ica~o p<;>lymorpha
var. vu garls
Trifolium gracilentum
linum bienne
Cammisonia ovata
Clarkia rubicunaa
Epilobium sp.
Eschscholzia californica
Plantago erecta
Plantago lanceolata
Eriogonum latifolium
Rumex crispus
Rumex pulcher
Calandrinia ciliata
var. menziesii
Montia perfoliata
Anagall is arvensis
Ranunculus californicus
Acaena californica
Horkelia californica
Potentilla glandulosa
Ga Ii um apar i ne
Gal ium nuttall ii
Castilleja affinis
T arweed
False Dandelion
Goldfields
Coast Madia
Milk Thistle
Sow Thistle
Mule-Ears
Western Morning Glory
Bluff lettuce
Pacific Sedum
Field Mustard
Franciscan Wildflower
Wild Radish
Water-Cress
Wi Id Cucumber
Tease I
long-Beaked Fi laree
Red-Stemmed Fi laree
California Phacelia
Pi tcher Sage
Hedge Nett Ie
Pacific Pea
Deerweed
lupine
Varied lupine
Bur Clover
Clover
Flax
Evening Primrose
Winecup Clarkia
California Poppy
California Plantain
English Plantain
Wi Id Buckwheat
Curly Dock
Fiddle Dock
Red Maids
Miners lettuce
Scarlet Pimpernel
California Ruttercup
California Horkelia
Cinquefoi I
Bedstraw
CI imbing Bedstraw
Indian Paintbrush
A-14
Castilleja franciscana
Castilleja wightii
Mimulus guttatus
Orthocarpus densiflorus
Orthocarpus floribundus
Orthocarpus purpurascens
var. latifolium
Scrophularia californica
Solanum furcatum
Daucus pusillis
Foeniculum vulgare
lomatium caruifolium
lomatium dasycarpum
Sanicula arctopoides
Sanicula bipinnatifida
Viola pedunculata
C'Cirex barbarae
Aira caryophyllea
Avena barbata
Ariza minor
BromusmoTl is
Hordeum brachyantherum
Hordeum leporinum
Lolium multiflorum
Mellica californica
Phalaris californica
Poa annua
~tipOj)UlChra
ris longipetala
~yrinchium bellum
Juncus bufonius
Dichelostemma pulchella
Chlorogalum pomeridianum
Franciscan Paintbrush
Wight's Paintbrush
Common Monkeyflower
Owl's Clover
San Francisco Owl's Clover
Escobita
California 8eeplant
Nightshade
Rattlesnake Weed
Sweet Fennel
Alkali Parsnip
lace Parsnip
Footsteps-of -Spr i ng
Purple Sanicle
Johnny-Jump-Up
Sedge
Silver Hair Grass
Wi Id Oat
little Quaking Grass
Soft Chess
Meadow 8arley
Farmers F oxtai I
Italian Rye Grass
Canary Grass
Annual Bluegrass
Purple Needle Grass
Iris
Blue-Eyed Grass
Toad Rush
Blue Dicks
Soap Plant
Sources: EIP field survey conducted by Bruce Stein, botanist, March 16, 28 and April 4,
1982; E. McClintock and W. Knight, A Flora of the San Bruno Mountains, San Mateo
County, California, Proc. of the Ca. Acad. of Sci., Vol. 32, No. 20, November 1968;
Thomas Reid Associates, Draft Endan ered 5 ecies Survey, San Bruno Mountain,
Biological Study - 1981, prepare for an Mateo ~ounty, Novem er , page -.
A-15
APPENDIX D
GEOTECHNICAL FEASIBILITY STIIDY, PHASE II
sourn SLOPE SAN BRUNO MJUNrAIN, SOlIDI SAN FRANCISCO AREA
SAN MATEO COUNTY, CALIFORNIA
FOR
W. W. DEAN AND ASSOCIATES
SUMvlARY OF CONCLUSIONS AND RECa.1MENDATIONS
The Hillside Fault was mapped as a single trace by Bonilla (1971)
and as two traces by Brabb and Pampeyan (1972), and by Berlogar,
Long & Associates (1979). The fault is not known to be active.
No surface displacement has been recognized in the CoL~ Formation
of late Pleistocene age which covers the fault zone west and north-
west of the project area. There is no evidence suggestive of
geomorphic features such as fault-line scarps, shutter ridges, sag
ponds, offset drainage courses, linear ridges or linear valleys along
the mapped fault in the project development area.
Fault investigation during Phase I and Phase II study, totalling a
1585 feet of trenching at strategic locations, did not indicate the
presence of Hillside Fault.
The Franciscan Sandstone (Kjfss) is not separated from the melange
tmit (Kjfm) by a major fault. The Colma formation which covers the
Franciscan Assemblage west and northwest of the project area has not
been offset by faults or shear zones that have cut through Franciscan
rock. Jherefore, minor faults and shear zones that may have ruptured
Franciscan rocks in the project area were inactive when, and have
remained inactive since, the Colma was deposited.
The melange tmits in the Franciscan Assemblage commonly described as
being ancient fault zones did not indicate any major shear zone or
fault. This unit underlines much of the project area.
The serpentine intrusions normally associated with ancient faults
or shear zones were very few and these units did not exhibit any
major shear or fault activity. Minor amount of sheared serpentine
and sheared siltstone was encountered in some trenches. These zones
differed conSiderably in each trench and in addition, no slickensided
rocks or clay gouge were noted. The serpentine probably is a part
of the Franciscan Assemblage, had invaded an ancient shear zones
and has not been active in historic time; and that the shear zone is
not a serious threat to the proposed project development area.
It is recommended that detailed geotechnical investigation for each
specific project site be conducted in order to provide design recom-
mendations for foundations, grading, drainage, erosion control, cut
and fill slopes etc. Preliminary design information is provided in
our previous reports which can be utilIzed as a guidelIne durIng
the planning stages.
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Resources Engineering & Management
W.W. Dean & Associates
Job No. A82103
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INTRODUCTION
In accordance with your request and authorization, we have completed the Phase II
work of the Geotechnical Feasibility Study for a proposed residential and
commercial development of about 350 acres along the South Slope of San Bruno
r.1otmtain, adjacent to'the City of South San Francisco, San Mateo COlmty, California.
We have earlier provided a report on our Phase I study ~ted April 5, 1982. No
major faults or shear zones were noted during this study. Additional work was
authorized to check the trends of some minor shear zones and to evaluate the
significance of Serpentine intrusions that were reported by others.
This report has been prepared in accordance with the proposal dated _~ri1 12, 1982,
except that some test pits locations and lengths were modified based on our latest
findings.
Purpose and Scope
PSC Associates, Inc., provided a Phase I study, dated AprilS, 1982, which included
a review of available geotechnical reports; a geologic reconnaissance; excavation
and logging of 3 long fault-exploration trenches; seismic soundings of soils,
weathered rocks, and moderatelY hard to very hard bedrock; summary of geotechnical
information for an environmental impact report; and preparation of a report outlining
our findings.
Because logs of test pits made by Berlogar, Long & Associates (1979) indicated that
serpentine had been encountered in TP 5, 10, 13, 18, 19, 37, 40, 55, 57, 63, and
65 (Plate 1) and because narrow serpentinized shears were logged in our fault-
exploration trench 1 ( Plate 2, our Phase I report) and trench 2 ( Plate 3,
0' )S~ ASSOCIATES, INC.
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Resources Engineering & ~.lanagement
W.W. Dean & Associates
Job No. A82103
~.1ay 24, 1982
Page 3
our Phase I report), we wanted to evaluate the importance of serpentine in the
melange unit and determine if the occurrence of serpentine reflected intrusions
along shear zones that had cut through the melange unit in ancient time.
Phase II included the excavation, examination, and logging of a backhoe trench
in the vicinity of TP 63 (Ber1ogar, Long & Associates, 1979, Plate 1) to evaluate
the occurrence of serpentine noted in their test pit log and to determine the trend
and relative importance of a narrow shear zone logged in our fault-exploration
trench no. 2 (Plate 3, our Phase I report); the excavation, examination and
logging of backhoe trench segments near TP 37 and TP 40 (Berlogar, Long & Associates,
1979, Plate 1) to evaluate the occurrence of serpentine noted in their test pit logs
and determine if faults or shears were related to the possible OCCtlrrence of
serpentine; the excavation, examination and logging of backhoe trenches loeated
near TP 18 and TP 19 (Berlogar, Long & Associates, 1979, Plate 1) to evaluate
serpentine noted on their test pit logs in those areas and to determine if faults or
shears in the melange \vere related to possihle serpentine occurrences. Back~oe
test trenches were not excavated near TP 55 and TP 57 (Berlogar, Long and
Associates, 1979, Plate 1) because large patches of Lupin, a flowering plant,
prized by a species of rare butterflies \vere in full bloom and we would have
destroyed many of the plants. However, Ive did make geologic reconnaissance and
examined rocks exposed at land surface in those areas.
The basis for our investigation during Phase I and Phase II \vas a topographic map,
~)S1
~e JASSOCIATES, INC.
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Resources Engineering & ~1anagemen t
N.W. Dean & Associates
Job No. A82103
Hay 24, 1982
Page 4
scale 1 inch == 200 feet, contour interval 2S feet, prepared by J. F. Carroll and
Associates, Consulting Civil Engineers, San ~~teo, California. The same map was
used as a base for a geotechnical report prepared by Ber1ogar, Long & Associates,
1979. The topographic map, with geologic and geophysical features mapped by
Berlogar, Long & Associates, was used in Phase I and Phase II of our investigatil?n
and was reported as Plate I in our Phase I and Phase II reports. Plate I (Geologic
Map) shows geologic features, test pit locations, test boring locations, geo-
physical test sites, fault~exploration trench locations, principle geologic hazards,
areas of proposed development, and other geologic features. Plates 2, 3, and 4
of our Phase I investigation slumnarized geologic information obtained from the
inspection and logging of 3 long fault-exploration trenches. Plates 2, 3, 4, and
S of our Phase II investigation summarizes geologic information obtained from the
inspection and logging of S backhoe excavations made to evaluate potential geologic
hazards associated with possible faults, shears or serpentine noted on logs of
test pits made during an earlier investigation by Berlogar, Long and Associates
(1979).*
Figures 3 through 12 ln our Phase I report showed the results of seismic soundings
that PSC .~sociates, Inc. made at sites A, B, C, D, E, F, and G (Plate I, Phase
I and Phase II). Logs of test pits and borings shown on the map (Plate I, Phase
I and Phase II) can be found in the Berlogar, Long & Associates report (1979).
* A bibliography of agencies and authors cited herein is included in "References
Cited" at the end of this report.
e:. )S~ASSOCIATES,
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Sierra POInt
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Scale: 1" == 2UOO'
LOCATION ~lA.P
South San Bruno ~1oun ta in Project
San ~1ateo County, California
For
W.W. Dean and Associates
Base: Portion ot U.S.G.S. San Francisco, South, California
7.5-1-1inute Topographic Quadrangle, Pnotorevised 1968
and 1973, scale 1:24,000.
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DATE: 5-24-82
JO 8 NO: A82103
FIQJRE 1
Resources Engineering & ~hnageMent
W.W. Dean & Associates
Job No. A82l03
~1ay 24, 1982
Page 5
The results of seismic soundings made along seismic lines Sl, S2, and S3 (Plate I,
Phase I and Phase II) and the results of magnetometer traverses made along rvn,
M2, M3, and M4 (Plate I and Phase II) can be found in the Berlogar, Long ft
Associates report (1979). Seismic sounding lines CClO, CCll, CC13 and CC14
(Plate I, Phase I and Phase II) were made by Cooper-Clark & Associates (1972).
Their data were presented in a geotechnical report prepared by Harding-Lawson
Associates (1974). A geotechnical summary of various areas proposed for develop-
ment was presented in Table I of our Phase I report.
Location
The South San Bruno ~buntain project area is along the lower south side of San
Bruno ~~untain near the city of South San Francisco. The project area is bounded
on the east by the Bayshore Freeway and on the south by Randolph Avenue and
Hillside Boulevard. Figure 1 (location map) outlines project boundaries, and
shows general topography, drainage and other cultural features, at a scale of
1 inch = 2,000 feet. Plate I shows more detailed, but still generalized
topography and drainage at a scale of 1 inch == 200 feet.
REGIONAL GEOLOGY
This summary of regional geology is from our Phase I report and is restated
here to maintain the continuity of the report. The San Bruno ~Iountain
Project area is in the Coast Ranges Geologic Province of California.
Two main bedrock units have been distinguished in this province: The Franciscan
~ 1S~ASSOCIATES.
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Resources F~gineering 0 ~~agement
1'1.1'1. Dean & Associates
Job No. A82l03
t-1ay 24, 1982
Page 6
Assemblage and the Great Valley Sequence. Both units are Jurassic to Cretaceous
in age (about 90 to 180 million years old).
In the Central Coast area, the Franciscan Assemblage is composed of north to
northwest trending lithologic belts. These belts are characterized by the
following rock assemblages:
1) moderately well-bedded graywacke (a type of sandstone) and shale with
minor interbedded chert and volcanic rock;
2) metamorphosed graywacke, chert, siltstone and greenstone with
associated faint to strong development of a metamorphic fabric;
3) massive arkosic (feldspar-rich) sandstone and shale; and
4) melanges composed of a mixture of graywacke, siltstone, greenstone,
chert, serpentine and metamorphic rock inclusions in a matrix of
contorted and sheared shale, and siltstone.
These lithologic belts commonly are fault bounded and all exhibit substantial
lateral variation in lithology, mineralogy and structure. For these reasons
strict correlation among exposures of the Franciscan Assemblage generally is
not possible. ~lany workers, however, have divided the Franciscan A.ssemblage
into major geologic belts based on similarities in lithology or structure, or
both.
The Great Valley Sequence was deposited in a tectonically quieter environment
Gc lS'
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W.W. Dean & Associates
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Page 7
than the Franciscan Assemblage, which resulted in its greater continuity of
bedding and its relative lack of deformation. In our opinion, rocks in the
South San Bnmo Mountain Project area have too varied a lithology and are too
discontinuous to be considered a part of the Great Valley Sequence. We consider
rocks in the project area to be a part of the Franciscan Assemblage, or
Franciscan Formation.
During the interval between Cretaceous and Quaternary time l60 million years)
the Great Valley Sequence generally is interpreted to have been moved over
the Franciscan Assemblage along a low angle, east-dipping thrust fault called
the Coast Ranges Thrust. Also, during this period (60 million years), the
tectonic and depositlonal regime Which produced and disrupted the Franciscan
Assemblage evolVed to the present day San Andreas Rift Zone system. The
present tectonic system involves the Pacific Plate (ocean and coast area)
moving to the northwest relative to the North American Plate (inland area)
along several northwest-trending, right-lateral faults. Figure 2 shows the
location and trend of known active and potentially active faults in the San
Francisco Bay region. Rocks on the west side of the named faults tend to move
northward and northwestward in relation to rocks located on the east side of
the faults. The dominant fault in the present tectonic system is the San
Andreas Fault which is located about 3 miles \.,rest of the San Bnmo ~lcuntain
Project area. Another major fault of this tectonic system, the Hayward Fault,
~ )S~ASSOC4IATESI INC.
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Explanatlan
..;..---
Quaternary fault
'.
r.,.n.....l.~
..._ .......c..co c.r
South San Bruno
Mtn. Project
Source: Helley, E. J., and Herd, D. G., 1977
FIGURE 2. --KNOWN FAULTS IN THE S~ FRAJ.JCISCO BAY REGIO~ lliA.T SHOW EVIDEJ'~CE OF
MOVEMENT IN TIrE lAST 2 MILLION YE6JtS ( THE QUATERNARY PERIOD) .A..ND
LOCATION OF TInS INVESTIGATION
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~~~:;_ JASSOCIATES, INC.
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DATE: 5-24-82
JOB NO: A82l03
FIGURE 2
Resources Engineering & ~1anagement
W.W. Dean f.. Associates
Job No. A82l03
May 24, 1982
Page 8
lies about 15 miles east of the project area. Risks associated with activity
on these faults have been discussed by Harding-Lawson .~sociates (1974) and
Berlogar, Long & Associates (1979).
Deposition of deposits in Quaternary time (last 2 million-3 million years)
was closely related to global fluctuations in sea level related primarily to
climate and sea level changes controlled largely by periods of glaciation and
local tectonic movements. The Colma Formation (not exposed ~ the project
area) was deposited during late Pleistocene time, (more than 11,000 years and
quite possibly more than 30,000 years ago).
The Colma Formation is important, however, because it overlies and covers the
Franciscan Assemblage west and northwest of the project area and because the
Colma has not been offset by faults or shear zones that have cut through Franciscan
rocks. This fact suggests strongly that faults and shear zones that have ruptured
franciscan rocks in the project area were inactive when, and have remained inactive
since, the Calma was deposited.
PROJECf SITE GEOLOGY
General
In this report and in our Phase I report, bedrock in the SOllth San Bruno Mountain
Project is considered to be a part of the Franciscan .~semblage or Franciscan
Formation. Unconsolic1ated deposits that mask bedrock tmi ts \.;ere derived from the
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Job No. A82l03
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Page 9
bedrock and have reached their present location, thickness and extent as a result
of normal processes of disintegration, erosion, and deposition.
Geologic maps of the project area and vicinity have been prepared by Bonilla
(1965, 1971); Brabb and Pampeyan (1972); Schlocker (1974); Harding-Lawson
.~sociates (1974) and Berlogar, Long & Associates (1979). These workers
determined that rocks of the Franciscan Asse~blage, colluvial deposits, slope
debris, landslides, and alluvium are important geologic units in the project
area. Plate I, Geologic ~1ap, shows the approximate location and extent of the
various units as mapped by Berlogar, Long and Associates (1979). Logs of fault-
exploration trenches 1, 2, and 3 (Plates 2, 3, and 4, Phase I report) and logs
of backhoe trenches 4, 5, 6, 7 and 8 (Plates 2, 3, 4, and 5, this report) outline
near-surface geologic features. Other geologic information used in our analysis
included logs of 13 test borings, 90 backhoe test pits, data from 3 seismic
sounding lines, and 4 magnetometer traverses, which were found in a geotechnical
report by Berlogar, Long and Associates (1979) and logs of 5 test borings and 5
seismic sounding lines \vhich were prepared by Cooper-Clark Associates (1972) and
included in a geotechnical report by Harding-Lawson Associates (1974).
In the project area, the Franciscan .~semblage can be divided into DvO units;
sandstone, (KJfss, Plate I, Phase I and Phase II) with thin interbeds of siltstone
and shale,and melange (KJfm, Plate I, Phase I and Phase II).
~
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Resources Engineering f, Management
W.W. Dean & Associates
Job No. A82103
May 24, 1982
Page 10
Sandstone (KJfss)
Sandstone (KJfss, Plate I, Phase I and Phase II) with interbedded thin black
shale constitutes bedrock in the eastern and northern parts of the project area.
Generally speaking, hard, medium brown to gray, erosion-resistant sandstone occurs
along a line marked by an abrupt change in slope. Information gained from an
examination of fault-exploration trenches I and 2 (Plates 2 and 3 in our Phase I
report) indicated that faulting was not an important feature in forming the abrupt
change in slope and that, in areas tested, the sandstone unit (KJfss) is not
separated from the melange unit (KJfm) by a major fault.
Sandstone and thin bedded black shale OCCllrs along the north border and higher
parts of proposed development areas 2 and 3; the northern 2/3 or 3/4 of proposed
development areas 4 and 5 and nearly all of proposed development areas 6, 7, 3,
and 9 (see Plate I, Phase I and Phase II). In all these areas the sandstone
unit is hard and strong where little weathering has taken place. The weathered
surface of the sandstone unit and the thin soil zone is of lower strength. The
thickness of the lower strength zone varies from place to place depending upon
presence of joints, degree of fracturing, presence of secondary clay, and extent
that weathering and decomposition of rock constitllents. However, except for local
soil slumps, which can be removed and reworked by grading operations, the lOKer
strength zone poses no serious problem to development.
In general, the Franciscan sandstone unit (KJfss, Plate I, Phase I and Phase II)
rB JS'
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has a high bearing capacity and has the capability of providing adequate foundation
support for most structures. Variations in strength depend on degree of weathering,
and intensity of fracturing. Slope stability is generally good, even in weathered
rock. However, local conditions such as fracturing, presence of minor faults, water
seepage, secondary clays, and bedding orientation may require local changes in cut
slope design. \iJhere these conditions are not a factor, natural slopes as steep as
one horizontal to one vertical (1:1) are common. In general, the erodability of the
unit is relatively low, except in areas of intense alteration and deep weathering.
Generally, the sandstone and thin shale unit can be excavated with conventional
earthmoving equipment. Areas of fresh, unweathered rock without close fractures, may
require blasting. More information on rippability will be provided at a later date
when additional work is performed under a separate authorization.
Me lange (KJ fin)
The melange (KJfm, Plate I, Phase I and Phase II) includes relatively thick severely
and deeply weathered claystone and siltstone beds containing randomly located
subangular to angular fragments, cobbles, and bOlllders of severely weathered
sandstone; hard massive-appearing siltstone, hard, fracttlred black shale and
contorted red-bro"~ to black shale; discontinuous beds and lenses and inclusions
of hard sandstone, metasandstone, chert and minor amounts of chlorite schist,
ultrabasic rocks, and serpentine. ~1elange units in the Franciscan Assemblage
commonly are described in geologic literature as being ancient fault zones.
Interpretations of their present-day regional structural relationships often
are difficult when limited areas of the Franciscan rocks, such as the South
e:, )S~ASSOCIATES,
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Resources Engineering ft r.1anagement
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Job No. A82103
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Page 12
San Bruno Mountain Project are investigated. Therefore, few conclusions about
geologic structure and sources of deposition can be drawn.
As mapped by Ber1ogar, Long & Associates (1974), the melange occupied most of
proposed development area 1A and 1B and a relatively narrow band through the
central parts of proposed development areas 2, 3, 4, and 5 (see Plate 1, Phase I
and Phase II). Apparently, Berlogar Long 0 Associates restricted the melange
: . to a hard black contorted shale and associated metasandstone and minor serpentine
unit in proposed development areas 3, 4, and 5 (Plate I, Phase I and Phase II)
and expanded .~he area to include isolated chert, schist, metasandstone and black
shale in proposed development area 1 (Plate I).
Because the melange generally is considered to be fault related, our Phase I
study included 3 fault-exploration trench sites located in places where bedrock
could be excavated and examined to determine rock types, their relationship to
one another, and possible evidence of shearing or faulting. Our fault-exploration
trenches (Plates 2, 3, and 4, Phase I report) and backhoe trenches excavated and
logged during our Phase II activity indicated that the melange unit underlies
much of the project area west of proposed development area 5 (Plate I).
The fault-exploration trenches (Plates 2, 3, 4, Phase I report) and the backhoe
trenches (this report) did not expose evidence that a major fault or shear zone
cuts through the melange unit. Evidence of minor faulting \vas noted in trenches
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1 and 2 (Plate 2 and 3, Phase I report) but no evidence of faulting was noted
in trench 3 (Plate 4, Phase I report). Backhoe trench no. 4 (Plate 2, this
report) was excavated and logged to determine if sheared serpentine noted in
the log of TP 63 (Berlogar, Long & .~sociates, 1979) was an important
shear zone, or if the sheared serpentine was part of an old shear zone exposed
in our fault-exploration trench no. 2 (Plate 3, our Phase I study). lve did not
log serpentine in the upper part of backhoe trench no. 4 (Plate 2, this study).
However, '~e did log severely weathered serpentine in the bottom of the lower part
of the trench. The serpentine and sheared siltstone noted in the 30 to 40 foot
interval of trench no. 4 (Plate 2, this study) probably is part of shear zone
logged in the 7S to 8S foot interval of fault-exploration trench no. 2 (our
Phase I report). The shear zone noted in each trench differed considerably and
there was no indication of movement in historic time. The absence of slicken-
sided rocks and clay gouge suggests strongly that there has been no movement
in historic time. We found no surface indications or topographic eA~ressions
of faulting in the area or along a deeply entrenched drainage course west of the
trenched sites. Thus, on the basis of Ollr trenching activities and on our field
observations, it is our opinion that serpentine, probably a part of the Franciscan
Assemblage, had invaded an ancient shear zone, that the shear zone has not been
active in historic time; and that the shear zone is not a serious threat to the
proposed development.
Backhoe trenches S and 6 (Plate 3, this report) were excavated to determine if
serpentine noted in logs of TP 37 and TP 40 (Berlogar, Long & .~sociates, 1979) "as
,-m )S'
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Job No. A82103
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Page 14
part of, or related to, a fault or shear zone. 1~e had not logged serpentine or
an important shear zone in the upper part of our fault-exploration trench no. 1
, -
(Plate 2, our Phase I report). The logs of backhoe trenches 5 and 6 (Plate 2,
this report) indicated that siltstone and shale units contained minor narrow
shears but no major shear zone or fault was noted. In our opinion, probably
during the logging of TP 37 and 40 (Berlogar, Long & Associates, 1979), the black
contorted shale unit was interpreted as serpentine. This shale unit also was
noted in backhoe trenches 6 and 7 (Plates 4 and 5, this report) and along bulldozed
fire breaks that traverse ridges and steep slopes in the western part of the property.
On the basis of information obtained from our fault-exploration trenches made in
our Phase I study and on backhoe trenches made during the Phase II study, it is our
opinion that no major shear zone or fault is located in the melange unit. It is
also our opinion that the melange unit underlies much of the project area.
In most places, the melange can be excavated with conventional earthmoving equipment.
Locally, discontinuous beds of hard to very hard sandstone, metasandstone, chert,
and metamorphic rocks may make excavation difficult. Known areas of very hard
rocks occur along trench 1 above seismic line $-F and on the ridge top near the
south end of trench 3. In these areas, excavation will be difficult and blasting
may be required. ~lore information on rippability will be provided at a later date
when additional work is performed under a separate authorization.
~" ,-,.
, '.'"
'~.;.;.Y' .
JS'
J ASSOCIATES,
A-32
INC.
Resources Engineering & ~1anagement
W. W. Dean & ..<\ssociates
Job No. A82l03
~1ay 24, 1982
Page 15
FAULTS
The San Andreas Fault (Figure 2) about 3 miles west-southwest of the west
boundary of the project area is the closest knmm active fault. Earthquakes
generated by movements on this fault caused extensive damage in the San
Francisco area in 1906. This fault is capable of generating destructive
earthquakes that could seriously damage the project area. Habitable structures
and commercial buildings should be designed to resist seismic shaking generated
by large (8 ~1agnitude) earthquakes. Cuts and fills should be engineered and
constructed to minimize the possibility tor the insoak and storage of water
and provisions should be made to minimize move~ent of rocks or softer materials
that may be dislodged fram cut banks as a result of seismic shaking caused by
a large earthquake.
The Ha~ard Fault and Calaveras Fault, both active and potentially dangerous
faults are located IS miles and 27 miles respectively northeast of the project
area. Either of these faults could generate a major earthquake. However,
because of the distance to a possible earthquake epicenter and because of the
consolidated nature ot rocks in the project area, damage caused by seismic
shaking probably would not be excessive.
The San Bruno Fault, in the valley of Colma Creek, about l~ miles southeast of
the project area is little known. The fault is covered by alluvial and colluvial
~' )S~ASSOCIATES,
A-33
J N C.
Resources Engineering ~ ~1anagement
\<I. W. Dean & Associates
Job No. A82l03
May 24, 1982
Page 1)
deposits and there is no record of activity in historic times. The City College
Fault, north of San Bruno Mountain, and about 2~ miles north of the project
area, is not known to be active and no evidence of faulting has been noted in
Pleistocene and Holocene deposits that cover much of the zone of sheared rocks.
The Hillside Fault was mapped as a single trace by Bonilla (1971) and as two
traces by Brabb and Pampeyan (1972), and by Berlogar, Long & Associates (1979).
The fault is not known to be active. No surface disp1ace~ent has been recognized
in the Colma Formation of late Pleistocene age which covers the fault zone west
and northwest of the project area. There is no evidence suggestive of geomorphic
features such as fault-line scarps, shutter ridges, sag ponds, offset drainage
courses, linear ridges or linear valleys along the mapped fault in the project area.
Fault-exploration trench 1 (Plate 1 Phase I) crossed the Hillside Fault trace mapped
by Bonilla (1971). The same trench crossed a line that would mark an extension
of the north trace of the Hillside Fault, as napped by Berlogar, Long &
:\ssociates (1979). Our trench did not expose an extensive zone of sheared or
faulted rocks. In our opinion no major fault crossed Trench 1.
Fault-e~~loration trench 3 (Plate 1 Phase I) \\as excavated across a prominent
topographic saddle on a ridge above the northeast of Hillside School to determine
if a zone of sheared or faulted rocks crossed that area. ~~o evidence of f~llting
was noted in the excavation which was more that 400 feet long (Plate 4 Phase I).
~c )S~ASSOCIATES.
A-34
IN C.
Resources Engineering & ~~agement
W.W. Dean & Associates
Job No. A82l03
May 24, 1982
Page17
lvork done by lvoo~vard-C1yde Consultants (1976) on property located south of
Randolph Avenue and generally south southwest of proposed development area 5
indicated a general absence of highly sheared rocks and fault gouge (highly
plastic gray to black clay).
On the basis of our investigation, (Phase I and Phase II) and on our examination
of the walls of about 1585 feet of backhoe trench excavations it is our opinion
that the Hillside Fault is not present in the project development area and other
minor shear zones noted in the exploratory trenches are not a serious threat to
the proposed South Slope, San Bruno Mountain Project.
CONCLUSIONS
Based on information obtained in our Phase I and Phase II reports and on our
review and evaluation of geotechnical reports listed herein, it is our opinion
that the proposed South San Bruno ~1ountain Project is feasible from geologic and
geotechnical standpoints.
In our opinion, the Hillside Fault is not present in the project development area
and other minor shear zones noted during the investigation are not a serious
threat to the proposed development.
The Hillside Fault was mapped as a single trace by Bonilla (1971) and as DvO
traces by Brabb and Pampeyan (1972), and by Berlogar, Long & Associates (1979).
~~ JS'
~g - J ASSOCIATES, INC.
- A-35
Resources Engineering & ~1anagement
W.W. Dean & Associates
Job No. A82103
May 24, 1982
Page 18
The fault is not known to be active. No surface displacement has been recognized
in the Calma Formation of late Pleistocene age which covers the fault zone west
and northwest of the project area. There is no evidence suggestive of geomorphic
features such as fault-line scarps, shutter ridges, sag ponds, offset drainage
courses, linear ridges or linear valleys along the mapped fault in the project
area.
Fault-exploration trench 1 (Plate 1, Phase I) crossed the Hillside Fau1t.trace
mapped by Bonilla (1971). The same trench crossed a line that would mark an
extension of the north trace of the Hillside Fault, as mapped by Berlogar, Long
and Associates (1979). Our trench did not eA"Pose an extensive zone of sheared
or faulted rocks. In our opinion no major fault crossed Trench 1.
Fault-exploration trench 3 (Plate 1, Phase I) was excavated across a prominent
topographic saddle on a ridge above the northeast of Hillside School to determine
if a zone of sheared or faulted rocks crossed that area. No evidence of faulting
was noted in the excavation which was more than 400 feet long (Plate 4, Phase I).
The geologic trenching during Phase I and Phase II has revealed that the Colma
Formation overlies and covers the Franciscan Assemblage west and northwest of
the project area and has not been offset by faults or shear zones that have cut
through Franciscan rocks. This fact suggests that minor faults and shear zones
that have ruptured franciscan rocks in the project area were inactive, when and
have remained inactive since, the Colma was deposited.
~
~ ....--..;;.=--=--_-_;..--'~1 -
)S'
J ASSOCIATES,
A-36
INC.
Resources Engineering & ~tanagement
W.W. Dean & Associates
Job No. A82103
May 24, 1982
Page 19
Information gained from an examination of fault-exploration trenches 1 and 2 (Plates
2 and 3 in our Phase I report) indicated that faulting was not an important feature
in forming the abrupt change in slope and that, in areas trenched, the sandstone unit
(KJfss) is not separated from the melange unit (KJfm) by a major fault.
Melange units in the Franciscan Assemblage are commonly described in geologic
literature as being ancient fault zones. The fault-exploration trenches as
shown on Plates 2, 3, 4, of Phase I report and the backhoe trenches included
in this report did not expose evidence that a major fault or shear zone cuts
through the melange unit. Evidence of minor faulting was noted in trenches 1 and
2 (Plate 2 and 3, Phase I report) but no evidence of faulting was noted in trench
3 (Plate 4, Phase I report).
Further investigation the findings of trenches 1 & 2, (Phase I) additional trench
4 (Phase II) indicated minor amount of sheared serpentine and sheared siltstone.
The shear zone noted in each trench differed considerably and the absence of
slickensided rocks and clay gouge suggests strongly that there has been no move-
ment in historic time. We found no surface indications or topographic e^~ressions
of faulting in the area or along a deeply entrenched drainage course west of the
trenched sites. Thus, on the basis of our trenching activities and on our field
observations, it is our opinion that serpentine, probably a part of the Franciscan
Assemblage, had invaded an ancient shear zone, that the shear zone has not been
active in historic time; and that the shear zone is not a serious threat to the
proposed development.
~~ )S'
~/. J ASS 0 C I ATE 5, I N C .
A-37
Resources Engineering & ~tlnagement
W.W. Dean & Associates
Job No. A82l03
May 24, 1982
Page 20
Furthermore, additional trenches #5 and #6 (Plate 3 this report) did not encounter
any serpentine as reported earlier by others. Some siltstone and shale units with
minor narrow shears were encountered but no major shear zone or fault was noted.
On the basis of information obtained from our fault-exploration trenches made In
our Phase I study and on backhoe trenches made during this Phase II study, it is
our opinion that no major shear zone or fault is located in the melange unit which
underlies much of the project area.
RECorvMENDATIONS
The recommended preliminary design criteria for each proposed development area are
provided iIl our feasibility study report and summary matrix dated April 21, 1981.
This information is preliminary and is to be used as a guideline for planning.
It is recommended that detail geotechnical investigation for each specific project
site be conducted at a later date in order to provide design recommendations for
each such area.
Recommendations including preliminary slope angles for cut and fill slopes, shrinkage
factors, fill subsidence, "R" values for soil, and other pertinent information
useful during preparation of preliminary grading plans was provided in our letter
report dated ~~y 4, 1982. Additional investigation for rock rippability character-
sitic, sandstone mapping, etc., may be needed to evaluate the depth of proposed
cuts and can be performed at a later date, if necessary.
@
_' 6"_- .
)S'
J ASSOCIATES,
A-38
INC.
Resources Engineering & Management
l\'. W. Dean & Associates
Job No. A82103
May 24, 1982
Page 21
It is also recommended that the grading plans be evaluated after detail geotechnical
infonnation is obtained from
the investigation of each project development area.
Due to the absence of active faults and major shear zones at the proposed project
development area no specific building setbacks are recommended, although certain
setback requirements due to proposed slope grading may be necessary.
A comprehensive plan for drainage and erosion control will have to be implemented
in the final development plans. These should be closely coordinated with the updated
information available from the detail investigation of each project development area.
Subdrains that will be used to carry runoff on the south slopes of San Bruno
l-olotmtain should be designed and constructed so as to minimize the opporttmity
for rocks and debris to pile up and clog entrances to drains.
Landslide areas must be stabilized if they are in, or near, areas to be used
as building sites. Specific recommendatioP5 for these will be provided in
subsequent investigation reports.
INVESTIGATION LIHITATIONS
Our services consist of professional opinions and recommendations made in
accordance with generally accepted geologic and geotechnical engineering principles
and practices. No other warranty is expressed or implied. Our conclusions were
based on our site reconnaissance, our exarrlination of materials exposed in
fault-exploration trenches, and on our review of geotechnical reports listed herein.
r--m-..... . )S'
-... ----'
~..' ...:, / ' J ASS 0 C J ATE 5, I N C .
---~ A-39
Resources Engineering & Hanagement
W.W. Dean & Associates
Job No. A82103
May 24, 1982
Page 22
The geologic information used in our analysis is believed to be representative of
the entire area; however, geologic features and geologic units may vary consider-
ably between randomly located test pits, borings, trenches and other points
of examination.
This report is issued with the understanding that it is the owner's responsibility
to ensure that the information contained herein is called to the attention of
the designer for the project, and that necessary steps are taken to see that
the recommendations are carried out in the field.
The findings in this report are valid as of the present date. However, changes
ip the conditions of the property can occur with the passage of time, whether
they be due to natural processes or to the works of man, on this or adjacent
properties. In addition, ch~Lges in applicable or appropriate standards occur,
whether they result from legislation or from the broadening of knowledge.
Accordingly, the findings in this report might be invalidated wholly or partially
by changes outside our control. Therefore, this report is subject to'review
by controlling government agencies and is valid for a period of one year.
Respectfully submitted,
P S C ASSOCiATES, INC.
Reviewed by:
q;:ri~
R.C.E. 24227
PRW: jbj
~
~
)S"
JASSOCIATES,
A-40
INC.
Job No. A82l03
Page 23
REFERrnCES CITED
Bailey, E.H., Irwin, W.P., and Jones, D.L., 1964, "Franciscan and Related
Rocks and Their Significance in The Geology of Western California":
California Div. Mines and Geology. Bill 183.
Bonilla, M.G., 1971, "Preliminary Geologic ~fap of the San Francisco South
Quadrangle and Part of the Hunters Point ~adrang1e, California,": U.S.
Geol. Survey, Misc. Field Studies Map MF-311.
Bonilla, M.G., 1961, "City College Fault, San Francisco, California",
Short Papers in the Geologic and Ifydrologic Sciences: U.S. Geol. Survey
Prof. Paper 424-C.
Brabb, E.E., and Pampeyan, E.H., 1972, "Preliminary Geologic Map of San
Mateo County, California": U.S. Geol. Survey, Misc. Field Studies 1>lap
MF-328.
Brabb, E.E., and Pampeyan, E.H., 1972, "Preliminary Map of Landslide
Deposits in San Mateo County, California": U.S. Geol. Survey Misc. Field
Studies Map MF-344.
Brabb, E.E., Pampeyan, E.H., and Bonilla, M.G., 1972, "Landslide Susceptibility
in San Mateo County, California": U. S. Geol. Survey Field Studies Map
MF-360.
BrO\vn, R.D. Jr., and Lee, W.H.K., 1971, "Active Faults and Preliminary
Earthquake Epicenters (1969-70) in the Southern Part of the San Francisco
Bay Region": U.S. Geol. Survey Misc. Field Studies Map ~fF-307.
Brown, R.D. Jr., 1972, "Active Faults, Probable Active Faults and Associated
Fracture Lones, San Mateo County, California": U.S. Geol. Survey Misc.
Field Studies Map MF-35S.
Berlogar, Long ~ Associates, 1979, "Geotechnical Investigation South San
Bruno ~1ountain Property, San Mateo County, California": UnPub. consulta.."1ts
report, Job 708-100.
Cooper, Clark & Associates, 1972, "Preliminary Soil EngineerIng and Engineering
Geologic Studies Re: Development Feasibility and Construction ConsIderations,
Proposed V is i tacion Rancho Res idential Development, San BTI1I1o ~Iountain,
San Mateo County, California": October 20, 1972, Job No. 542 G.
Cooper, Clark & Associates, 1971, "Consideration of Seismic a.."1d Other
Geologic Hazards, Visitacion Kancho, San Mateo County, California":
October 19, 1971.
Harding-Lawson Associates, 1974, "Geologic Stud)', VisitacIon Rancho Project,
San Bruno Mountain, San Mateo County, California": San Francisco unpublished
report, Job No. 9037,001.04.
A-41
Job No. A82103
Page 24
Helley, E. J., and Herd, D. G., 1977, "Faults with Quaternary Displacement
Northeastern San Francisco Bay Region, California:" u.s. Geol. Survey
Misc. Field Studies ~~p ~~-881.
Hsu, K. J., 1968, "Principles of r.-le1anges and Their Bearing on the Franciscan
Knoxville Paradox": Geo1. Society America Bull., v. 79, No.8, p. 1063-1074.
PSC Associates, Inc., 1982, Geotechnical Feasibility Study, Phase I, South
Slope San Bnmo ~1ountain, South San Francisco Area, San Hateo County,
California: unpub. report to REH and W. W. Dean and Associates, Job No. A82103.
Sch1ocker, Julius, 1974, "Geology of the San Francisco North Quadrangle,
California": u.S. Geol. Survey Prof. Paper 782.
Wcodward-C1yde Consultants, 1976, "Geologic Study, Bocci Property, South
San Francisco, California": San Francisco, unpublished letter rept., 5 p.
A-42
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Log of Backhoe Trench No. 7
Near Berlogar, Long and Assoc., TP 19
Trend N55~v, Slope 55 Percent
PLATE 4
Phase II
o
Shale, (Sh), hard, gray to black,
chert fragments but no distinct
beds. Very difficult to excavate.
No serpentine; no shears.
o
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-0
Soil, thin, rocky clay and rock
fragments
_5
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(Ch) , hard, gray to red
fractured. Trend N5SoE,
5_
7 - 1- 6!2 '
Sandstone, fine grained,
gray brown, hard, large
sandstone was enclosed
by moist yellow brown clay
I~rd, massive contorted black shale (Sh)
containing many hard rOlmded to elliptical
10- nodules and kernels of hard shale in casts
of the shale matrix. No indication of
movement of nodules, kernels or casts;
occasional beds of hard fractured sandstone.
No slickensides.
. Bag Sample and Number
Scale 1 inch = 5 feet
(horizontal and vertical)
"~:ez~ )5'
~.!f~ JASSOCJATES, INC.
Logged By: Perry R. Wood, CEG #711
DATE: 5-12.:82
JOB NQ: A82l03
A-4S
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A-46
APPENDIX E
TARLE 1
GENERAL GEOTECH~ICAL SUMMARY
SOUTH SA~ 8RUNO MOU~TAI~ PROJECT
ABOVE HILLS IDE BOULEVARD AND RMIDOLPH AVelUE
SOUTH SMI FRANCISCO, CALlFOR~IIA
INFORMATION SYNTHESIZED FROM REPORTS PREPARED BY:
COOPER, CLARK & ASSOCIATES, 1971, 1972
HARDING-LAWSON ASSOCIATES, 1974
BERLOGAR-LoNG & ASSOCIATES, 1979
BONILLA, M.G" 1971
AND
WORK DONE BY PSC ASSOCIATES, [NC., 1982
30UNOARIES OF AREAS PROPOSED FOR DEvELOPMENT AND THEIR IDErlTIFICATION NUMBERS ARE SHOWN ON PLATE I.
~~PSC
~~:~ ASS 0 C I ATE S. IN C. DArE: ..\pr. 1981 JOB NO. ,\82103
A-47
..""
GF.01T:CI-tIl C\I. :;lJ-NMY
GEOLOGIC FAULTS
Sheet 1 of 3
AREAS
curs
(PROPOSED)
TYPE OF SOIL AND
SOIL CONDITION
Franciscan Sandstone
A Franciscan ~~lange
IA AREA 1 KJfss, KJfm - some Sou them trace
(8-1,2) ; (TP-l, 2, Qsr (colluviUIII) Hillside faul t
5, 6, 7, 8, 19, 16)
Trench 3, seismic Qsr-Quaternary
18 lines S- 1 , S-E,
CC-IO B colluvium Southern crace,
~Iagnetometer Gravelly clay and Hillside fault
~1-1, 101-4 Gravelly sandstone
Qsr-Sandy silt, sandy
AREA 2 clay, clayey gravel. Northern trn.ce,
(8-6) ; (TP-24, 26, Some Qal and Qaf in Hillside fault
27, 35) Trench 2, the ravine. Some
seismic line S- 2, KJ fss and KJ fm noted
CC'll, SoD, S-F at sa end of area
~lagnetometer Ml,
~12
I [..\NDSJ.lDES I
i (Designated by Letters) I
I
I
I
I KJfm and JKfss subject
i .'M end !las slides A 8 ! to downhill creep
I B (25 to 30 feet Jeep)
OOWNHI LL CREEP
POTENTIAL
KJfm and :(Jfss to
be cut
! Shallow landslides to
: be reworked by grading
i Slide C (15' to 30'
deep) outside proposed
11<:;P-
I KJfm and JKfss subiect
I to downhill creep .
'1orth of the area
(outs ide the proposed
use)
i
'Slides 0, E, F, G, !I. ,'lone in Qsr, low inQal~
!1lOstly outSlde the areal or Qof. Proposed cuts i Some of the sa end
Toe of slides may 'w1ll lncrease potential I ',;here KJfm md KJfss
affect the area. Depth, for creep in KJfm and i are noted
10 to 50 feet; small KJ fss area I
shallow slides a long
ravine
AREA 3
(8-7); (TP-38 , 39,
41, 37, 40); seismic
line S-C
4
AREA 4
(TP-42, 48, 49, 50,
51, 52, 53, 54);
(B- 8); seismic line
S-C, S-8
AREA 5
(B-9); (11'-56, 58,
59, 60, 61, 62);
seiSllic line CC '12,
Trench Z
Qsr
Sandy silt, sandy
c lay serpentine and
!\Jss
Southern & northern
traces or Ilillside
faul t; or shear cone
in /1elange; not
confi nned by
trenching activities
I
I
Slides J and K, _(15 to
Z5 feet deep) enter
the area.
I Other slides 5 toll
feet deep in the area.
'~1o<.lerate in soil and
severely weathered
rocks
'1orth and west end to
be cut, slides J S K
IlIOstly Qsr; '1W end
has some graywacke
sandstone
Mostly Qsr (colluviUIII)
Some Qal (alluvium)
along the ravine.
Bedrock not mown
but hard fractured I
sandstone at 12 feet.
Soil & colluviUIII I'
propably 10 or more
feet. Thick in South i
& Central parts I
I
Southern & northern ! Slide
traces of Hillside I Jeep)
fault or shear -one in I area
Melange; not.coofinned i
by Trench l or Trench I
2
~I (20 to 30 feet
in sa part or
i
Moderate in soir'; at Ii
'1W and sa ends proposed
cuts will increase
potential ror downhill
creep
'111 and sa parts of
area
Slide M may be removed
by grading operations
AlluviUIII (Qal and
colluviLIII (Qsr) in
and near drainage
course; KJfss on
high ground.
AREA 6
(B-lO, 11); (TP'67,
68, 69, 70)
Sandy clay (Qsr)
over sandstone
bedrock. Depth jQ'
to bedrock. Hard
at about 20 reet.
Southern & Northern
traces of Hillside
01.' shear cone in
~1e lange; were not
confinned by Trench
:-./0. 2. Minor
faul ting noted.
I i
Sawll shallow land- ' Soil mass over bedrock
slides in northwest has moderate potential
area will be removed for creep in ~1~ and 'IE
during grading; larger I parts or area. Cut
moderately deep slides: area on slopes in 'IE
in southeast part or part or area wUl
area to be corrected i increase potential for
by grading and , JOlollhill creep
engineered rill
CutS in hard sandstone
, in 'IE part or area
No known fault wi thin
the area
Some cuts along east
Slide l' (15 to 25 feet side in KJfss may
deep) \forth end - movesl increase creep
into upper half or ,potential. Rest to be ;
the area. Underlain ; raised with engineered
by sandstone, probably, fi 11.
hard a t depth. :
Nominal cuts in \:Jfss
at the east side
AREA 7
Seismic lines S- 3,
S-...", S-Az, S-A3
KJfss
sandstone
little soil in moSt
places
AREA 8
(B-13): (TP-75)
Qsr . NW side, valley
area
Lower portion is
KJfss. Small amounts
of Qaf (Ii 11) noted
in the ravine
Qsr over bedrock
,
.':0 knO\olll fault within !.':o landslides in the I Soil mantle over
the area i general area. I sandstone - But 0I0st
Slide Q (40 to 55 feet' or ,his willJe
deep) !1lOves at the : e.<cavated
north end away (~'E)
from area
:-./0 known fault wi thin
the a rea
ilestern 2/3 or the areal
fs ':0 be cut
(Sandstone expected
'.mder soil mantle)
,
Landslide Q (40 to 55 : Soil mantle over-
feet deep) west or the: lying sandstone will
~rea; Small 6 to 10 , be covered by
teet deep slllllps In I engineered fill
the soil mantle i
i
sa ,ortion K.: fss to
! "e excavated
9
AREA 9
(11'.77, 78, 79, so,
81, 82, 83, S4, 85,
86, 87, 88) Seismic
lines CC-13, CC'14,
S-G
Qsr, Qal and Qaf
Possibly underlain
by !(Jfss
Soil mantle (sandy
clay, gravel) 10 to
20 reet thick.
.':0 known fault within
the area
A-48
Slides R (15 to ZS
reet deeo). S (20 to
:5 feet Jeep), 'T (10
to 15 feet deep) and
small s lLDl1ps in the
soil mantle over sand,
stone. '105t slides
: \'4ill he t:xcavateU
durin\! t!r:.h.iin~
Soil mantle and
weathered cut surraces
mav creep after the
a rea ;,as been
~raded
~1ajority or thi. area
is to be excavated.
Q5r 3nd .ome underlyin~
sandstone will :,e - 1
reworked. I
GECYl'EO-!NICili, Slr.MARY
SPRINGS/SUBDRAINS
Sheet 2 of 3
FILLS
(proposed)
SETILEME.\'l'S
1A
Fill proposed west
sect ion
18
Fill proposed for
I1IJCh of the area
2
Fill proposed for
most of area; SE end
has IOEm and IOfss
on low ridge
Yes. Significant
amount of engineered i
fill to be placed '
for housing area
4
Significant amount
of engineered fill
in middle part of
the area.
Part of drainage
course and lower
gl'OUJId in west and
$Ii parts of area to
be graded with
engineered fill
6
Southern 2/3 of area
to be filled with
engineered fill.
Small area to be
filled in northeast
part of area.
Strellll valley in
western half of
area to be filled
OVER- EXCAVATION
Toe of slides A and B
to be over-excavated
and then filled under
sUDervi~ion
Two or three shallow
slides to be
removed
No springs
Subdrains under fill
areas and in drainage
course
No springs
Subdrains under fill
areas
SLOPES arT/FILL
i
I
i No
!
significant amount
ROCK RIPPABILITY .~
EXCAVATION CONDITIONS
I
I
i Seismic soundings
I 3300, 6600, 8000,
I 14800 ips KJEm and
JKf s s may pose a
problem but most of
areas shOUld be
rippable
Differential bet',;een
cut and fill
Fill will settle I
slightly to moderately!
i
,
Yes - deep slide area
in the stream
, drainages
Yes. Shallow slides
to be removed and area
along clrainage
course to be
i graded.
Yes. Several
shallow slides along
the raviJ1e to be
removed and parts of
deep slides L and M
to be graded and
drained.
None anticipated
Over excavate lower
half of slide P and
over excavate
southeast end of area
where SIIlIlll slide
has occurred.
None anticipated
Slide debris
including slide Q
(40 to 55 feet deep)
to be over excavated
and rec~ac1:ed
I
I Cut slopes north of
! proposed development
I wi 11 need benches and
I surface drains
I
Yes - temporary springl Cut slopes, nor1:h of
Subdrains required proposed developmen1:
under fill areas and Will need terraces
in drainage courses. and surface drains
No springs noted
Subdrains to be
placed in drainage
under fill
No springs noted
Subdrains to be
placed in drainage
course under
engineered fill.
No springs
Subdrains to be
placed in drainage
course under
engineered fill
No springs
Subdrain to be
located at bottom of
ravine under
engineered fill
No springs
No subdrains planned
No springs
Subdrain to be
placed in drainage
charmel.
Cut s lopes proposed
for the north and west
parts.
Fill proposed for the
central and southern
parts.
Cut slopes in north-
west and southeast
parts will increase
downhill creep
Cut slopes in NE part
of area in sandstone;
in southern part of
area cuts may be
largely in colluvium
Some cut slopes at
NE end of area
Cut slopes at the
north eiui of area
:-lone known
Seismic soundings
3200, 4500, 7200,
7700 ips
KJfm and IOfss may
pose a problem. ~tOst
of area should be
rippable.
! Seismic soundings
1400 to 7000 fps
Rippable in most of
area; probably
marginal in IW ss in
i north and west parts.
Seismic soundings
not made but no solid
rock enoclJll tered;
should be easily to
moderately rippable.
SeismiC soundings
1500, 5500, 6500 fps
rippable in most 0 f
area, probably
moderately rippable
at depth in hard
sandstone.
I
i
i Sandstone
I Probably rippable
at depths required
I for cuts.
Seismic soundings I
1300, 1800, 3800,
5000, 5700, 8300 fps :
Rippable to marginally!
rippable. I
!
Should be rippable
Fill will settle
slightly to moderately
I
i
I Fill will settle
moderately and
differential between
cut and fill areas
j
Differential
settlements in cut
and fill area,
fill will settle
I moderately.
I
I
!
Fill areas will
settle moderately
and differential
between cut and
fill areas
Fill areas will
settle moderately
Fills should
settle slightly
Settlement in fi 11 I
areas and
differential between ;
cut and fill '-'nits I
9
Small area along
frattage road to
be filled
Over excavation of
an existing poorly
compacted fill
(Qaf)
No springs
No subdrains
planned
A-4~
Cut slop~s in Qsr
and IOfss have low
to roodera te creep
poss in i li ty
Seismic soundings
2000, 2500, 6000,
8000, 9000, 20,000
ips.
Rippable to
non ripl'able
:-10 settlement !
problems anticipated i
'1
i
I
Gr:O'l'F.O'lNtC\J. stJ.foWtY Sheet 3 of
OEPlll TO aalRCClC oorstDe SLIDES FOl.lNOI\TtONS GEOLOGtc.o\L ffAL\JU) G""c:OlOGtC \\ORK
(approx. ) AfFECT niE .'JlEA ('l'ypic:1l) 'lEEDED
I
!
I Yes, but ~inl Possible fault
10 to 30 feet in Conventional irade Possible tnce location,
weathered shale, and I operatiOlls, drains ! beam and pier; Hillside faul t; not width or snear tone,
1 sandstone and subd:-ains should peT'ilIIeteT' foundations ~onrirmed by '!'renc!\ Jlld setback distJllces
6 to 10 feet in ! lllinimi:e in area of competenl: i ~. 3. Landslide :0 be evaluated.
1IlOCientely wellt!Wred benchecl rock. and soil slumps Trench ~. 3 did not
siltstone, at surface evalu:lted and e:cpose an ac~ive
in IUEm and IUfs cOn"eCted during fault.
trr-1n;n~
Possible fault
Exceeds 4S feet near Yes, but ~inl Canventional beOlll Possible, north tnce location,
Z borina 6, less than operatlons, surr:u::e and pier; perimeter Hillside fault; not width of snear tone
1 foot to about 6 drains and subdrains foundations in arell confirmed by Trench and .etback dist3l\ces
feet near Sl: border should lIIiniJIIi.:e of compet.:mt '10. 1 ; lands lilles :md to be evaluated on
benched rock .oil slumps :0 be basis of Trenches and
cOn"eCted by ~ding research. Trenc.'l 1
did not eX1lOse an
active fauit.
15 to Z5 feet, ucept Yes, but grading Grade beam and pier ~T'th and south tnces ~ Possible fault
in north and west opentions, surface type o of Hillside fault; 10catlon, width of
3 edges drains and subdnins or snear tone in shellr tone :Uld
should minimi:e ~le lange setbllck distances;
Trenches 1 Jlld Z did landslide and .oil
not confinn active slumps evaluated.
faulting
I Hillside fault or .he:1l1
Not known, but No major slides Grade beam and tone in ~telnnl:e co I Possible fault
indication frtel borina known to enter area pi8T' type be evaluated , Trench ! location, width of
4 8 suuesu I depth of No. Z did not eXl'Ose shear tone and '!'rench
9 to lZ feet in evidence of IIIlIjor bedrock for setb:U::K
central part of area faulting, distanCes
Bednlclt abolt 30 feet
(sandstoae) in thll
centnJ. part; and
less tlwl S feet on
ltighet' slopes above
tlla drainaie
MinoT' shallow slides
Slide 0 extends into
the Sl: part of area
Grade be_ and
pin type
raIlside fault or shella
:one in ,Ie l.:mge
be eVlUU&ted 3ru:! any
Trench No. Z did not
e:cpose evidence of
major faulting
Fault exploration
Trench ~lo. Z did
not eX1lOse evidence
or an ~tive faul:.
6
lledt'IXk may be at:
30 feet bu~ pTllbably
less ~ about
%0 f..t .
Slide P affects the
northern half of tile
area
Grade beam and
pier type
Probably no re31 Little needed
iecloaic ha:ard ~xcept:
for lands lides 0 f
shallow and r:lOder:1te
depths
7
UnIalawn .
Mticil'ated to be
less than lO feet of
tlla surface
None
Grade beam .:md
pier :ype
.'Ione lI1Iown ~lone (?)
!
!(JEss probably 10 to
l5 fee~ below surface
in the Sl: side
Other area is :0 be
engineered fill
Slide Q may affec-:
fill are:l; over-
i excava~icn and
I benc!tina may be
necessary
Grade beu and
pler type
None known ~e
Possibly 10 to ZO feet ~.
Gracie beam 3llli
pieT' tne
I
I
i
I
I
A-50
!
g
None known
~ne
....