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4.6 Hydrology and Water Quality
4.6.1 Introduction
Section 4.6, Hydrology and Water Quality, addresses the impacts that the 201 Haskins Way Project
(project) would have on water quality, groundwater supplies, stormwater, erosion, and flooding. This
section describes the existing hydrology on the project site and in the study area, and presents the baseline
conditions against which project impacts are measured. Project - specific impacts are presented for the
proposed project and mitigation measures, if any, are identified when feasible. A cumulative impact
discussion is identified for each subtopic.
4.6.2 Environmental Setting
EXISTING CONDITIONS
Climate and Topography
The project area is located in a relatively flat area east of U.S. 101, immediately adjacent to the San
Francisco Bay (Bay) shoreline, in the City of South San Francisco. The regional climate is typical of the
Bay Area and is characterized by dry, mild summers and moist, cool winters. Approximately 80 percent
of the total annual precipitation occurs during the months of November through March, and the average
annual precipitation is 20.25 inches. Average daily temperatures range from a high of 73.4 degrees
Fahrenheit in September to a low of 42.6 degrees Fahrenheit in January.'
The project area consists of eight parcels totaling approximately 18.2 acres of land, consisting of six
parcels with trucking, warehouse, and distribution uses, one parcel used for parking, and one parcel with
existing office /research and development (R &D) use. The surrounding area is largely developed with
light industrial manufacturing and distribution, biotechnology, waste collection and recycling service, and
open space uses. The majority of the site is hardscaped with a mix of asphalt parking and building
structures. The unpaved portions of the site are landscaped or ruderal areas between parcels. The site
slopes toward the southwest, with the direction of slope varying across the site. The site elevation ranges
from approximately 11 to 25 feet above mean sea level (MSL).
Regional Hydrology
The majority of the project area consists of fill material located east of the historic shoreline along the
Bay. As such, the site lacks natural surface drainages. A series of man -made structures provides drainage
of surface waters. The largest watershed in the immediate vicinity is the Colma Creek watershed, which
includes portions of San Bruno Mountain, as well as urbanized areas of South San Francisco, Daly City,
and the City of Colma. Most of this urbanized creek is channelized and/or conveyed underground to allow
' Western Regional Climate Center, 2016. Weather Station: San Francisco Intl AP, California (047769). Available online at:
https:// wrcc. dri.edu /cgi- bin/cliNMIN.pl ?ca7769. Accessed April 16, 2018.
201 Haskins Way Project Draft EIR 4.6.1 October 12, 2018
4.6 Hvdroloav and Water
for urban development. The percent of impervious surface area within the Colma Creek watershed was
estimated to be 63 percent, the highest in the County of San Mateo.2 Colma Creek is a flood control
channel maintained by the San Mateo County Department of Public Works that discharges into the Bay
just north of the San Francisco International Airport. In addition to the Colma Creek watershed, a series
of small watersheds runs along the shoreline in the vicinity of the site.
Groundwater
The California Department of Water Resources (DWR) defines state groundwater basins based on
geologic and hydrogeologic conditions. According to the DWR, the site is located within the Westside
Groundwater Basin.3 The Westside Groundwater Basin consists of bedrock and unconsolidated
sediments .4 Aquifer storage coefficients indicate unconfined conditions5 at depths less than 100 feet and
confined conditions' at depths in excess of 100 feet.' Unconsolidated materials overlying the bedrock
comprise the water - bearing formations. s
The project site was originally bayward of the historic shoreline and is on reclaimed land.9 In general, the
site is expected to be underlain by approximately 20 to 25 feet of fill.10 The fill is likely underlain by up
to 20 feet of marine clay, known as Bay Mud." Literature indicates there is no Bay Mud in the northern
portion of the site; therefore, the Bay Mud thickness likely varies from approximately 0 to 20 feet,
becoming thicker generally to the south and southwest. 12 Bay Mud is underlain by silty sand and sand
with silt and by sandy clay and clay. 13 Geologic maps indicate that the depth to bedrock varies from
approximately 20 to 70 feet below the ground surface (bgs); the depth to bedrock likely increases
generally to the south and the southwest. 14 Bedrock was identified in borings drilled south of the site at
approximately 64 to 78 feet bgs, although what was identified as bedrock may be very dense sand of the
2 City of Daly City, 2018. Source Control. Available online at:
http: / /www.dalycii,�oriz/City Hall/Dgparhnents /wwr /Divisions /waste_source.htm#4. Accessed April 16, 2018.
3 California Department of Water Resources, 2018. Groundwater Information Center Interactive Map Application. Available
online at: hgps:Hgis.water.ca.gov/app /gicima/. Accessed May 7, 2018.
4 Phillips, Steven P., Scott N. Hamlin, and Eugene B. Yates, 1993. Geohydrology, Water Quality, and Estimation of Ground -
Water Recharge in San Francisco, California, 1987 -92, p. 5. US Geological Survey Water- Resources Investigations Report 93-
4019.
5 Unconfined aquifers are those into which water seeps from the ground surface directly above the aquifer.
' Confined aquifers are those in which an impermeable dirt/rock layer exists that prevents water from seeping into the aquifer
from the ground surface located directly above.
' Phillips, Steven P., Scott N. Hamlin, and Eugene B. Yates. 1993. Geohydrology, Water Quality, and Estimation of Ground -
Water Recharge in San Francisco, California, 1987 -92, p. 11. US Geological Survey Water- Resources Investigations Report 93-
4019.
8 California Department of Water Resources, 2006. California's Groundwater Bulletin 118, San Francisco Bay Hydrologic
Region, Westside Groundwater Basin, p. 1. Available online at: http://www.smcsustainabiliiy.org/download/energy-
water /groundwater /2- 35.pdf. Accessed May 7, 2018.
9 Langan, 2017, Preliminary Geotechnical Evaluation: 201 Haskins Way, South San Francisco, California, Langan Project No.:
750645101, pp. 2 to 3.
10 Ibid.
11 Ibid.
12 Ibid.
13 Ibid.
14 Ibid.
201 Haskins Way Project Draft EIR 4.6.2 October 12, 2018
4.6 Hvdroloav and Water
Colma formation, which can be cemented. 15 Groundwater was measured at nearby sites at depths varying
from approximately 8 to 15 feet bgs.16
Site Hydrology
The majority of the project area is currently covered by low permeability surfaces. The existing 201
Haskins site includes an area of compacted gravel that was used for truck storage. Due to the compacted
nature of this gravel, significant infiltration likely does not occur. However, as a conservative approach,
this area is considered partially pervious for the purpose of stormwater analysis.
Stormwater runoff from the project site is generally directed to the west and south, then flows to the
existing 24- inch - diameter storm drain line on East Jamie Court and the existing 48- inch - diameter storm
drain line on Haskins Way. Runoff flows south along Haskins Way and into a catch basin, then through
an existing approximately 48- inch - diameter outfall pipe before being discharged into the Bay. 17 The
outfall pipe is designed to operate throughout a range of high tide conditions in the Bay to prevent
flooding near the terminus of the system.
Within the 201 Haskins Way parcel, two existing 12- inch - diameter storm drains are located along the
parcel's northern and southern boundaries. These storm drains flow west from the parcel and connect to
the existing 48- inch - diameter storm drain line on Haskins Way. One connection from the southern on -site
storm drain to the East Jamie Court storm drain is also provided.
The National Wetlands Inventory indicates that there is an unnamed riverine wetland located
approximately 100 feet to the east of the project site which runs along the north side of the existing
recycling center located southeast of the project Site. 18 Stormwater is not directed toward this wetland.
Flooding
The majority of the project area is located outside the 100 -year flood hazard zone as delineated by the
current Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRMS). 19 A
portion of the southern border of the site, which abuts the Bay waters, is just north of the "VE" zone
designation, which defines areas with wave action in the 100 -year flood hazard zone.20
15 Ibid.
16 Ibid.
17 Personal communication with Carie Jung, South San Francisco Department of Public Works Engineering Division, (650) 877-
8550, May 7, 2018.
18 U.S. Fish and Wildlife Service, National Wetlands Inventory. Available online at:
hM2s: / /www.fws.gov /wetlands /data/Mapper.html. Accessed May 10, 2018.
19 Federal Emergency Management Agency Flood Insurance Rate Maps, Map Number 06081 C0044E.
20 Federal Emergency Management Agency, FEMA Flood Map Service Center: Search by Address, 2012. Available online at:
https: / /msc.fema.goy/portal /search #searchresultsanchor. Accessed May 7, 2018.
201 Haskins Way Project Draft EIR 4.6.3 October 12, 2018
4.6 Hvdroloav and Water
Sea Level Rise
The National Research Council's (NRC) 2012 report, Sea Level Rise for the Coasts of California,
Oregon, and Washington: Past, Present, and Future (the NRC Report) provides a scientific review of sea
level rise for the West Coast and provides the most recent regional sea level rise predictions for 2030,
2050, and 2100, relative to the year 2000 sea level. In this report, the NRC projects that sea levels in the
Bay Area will rise up to 24 inches by 2050 and up to 66 inches by 2100.21 The extreme limits of the
ranges (e.g., 5 to 24 inches for 2050 and 17 to 66 inches for 2100) represent unlikely but possible levels
of sea level rise using both low and very high emissions scenarios and, at the high end, including
significant land ice melt that was not anticipated at the time of publication but acknowledged as having
potential to occur.22 These projections include the sum of contributions from thermal expansion of
seawater, wind - driven components, land ice melting, and vertical land motion.23
As of 2015, the California Coastal Commission (CCC) supported the use of the NRC report as the best
available current science. The CCC noted that because sea level rise science is continually advancing,
future research may enhance the scientific understanding of how the climate is changing, and thus there is
a need to regularly update projections.24 Therefore, for the purposes of conservative analysis, this
Environmental Impact Report (EIR) uses the NRC report's highest projected sea level rise scenario. The
following scenarios are used in this EIR analysis:
• A sea level rise of 24 inches by 2050
• A sea level rise of 66 inches by 2100
The project site would not be inundated with 24 inches of sea level rise, which is expected in 2050, but
the southwestern corner of the project site would be inundated with 66 inches of sea level rise, which is
expected in 2100. When the effects of a 100 -year storm surge are combined with sea level rises of 24 or
66 inches, the southwestern corner of the project site would be partially inundated by 0 to 2 feet and 0 to 6
feet, respectively, as shown in Figure 4.6.1: Project Inundation Depth in Feet by 2050 and Figure
4.6.2: Project Inundation Depth in Feet by 2100.25 The areas that would be inundated under the 24 -inch
projection include landscaping and parking areas, where no structures are proposed.26 The areas that
21 National Research Council, 2012. Sea -Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and
Future.
Available online at: http:// www .nap.edu/catalog_php ?record_id= 13389. Accessed April 17, 2018.
22 Adapting to Rising Tides, Bay Area Sea Level Rise Analysis and Mapping Project, 2017, p. 9. Available online at:
hM2: / /www.adotingtorisin tl¢ 'des.org/wp- content/uploads / 2016 /05/BATA -ART- SLR - Analysis- and - Mapping- Report- Final-
20170908.pdf. Accessed May 7, 2018.
23 Ibid.
24 California Coastal Commission, 2015. Sea Level Rise Policy Guidance: Interpretive Guidelines for Addressing Sea Level Rise
in Local Coastal Programs and Coastal Development Permits. Adopted August 12, 2015. Available online at:
hM2s:/ /documents.coastal.ca.gov / assets /slr/ guidance /August2Ol5 /0 Full Adopted _ Sea _ Level_ Rise_ Policy _Guidance.pdf.
Accessed May 9, 2018
25 Adapting to Rising Tides, San Mateo County Sea Level Rise Inundation Scenarios, 2018. Available online at:
http:// smcmaps. maps.arcgis.com/apps/MapSeries/ index. html? 4ppid= 51676b57ab5f4446aO3adl3a9432986d. Accessed April 17,
2018.
26 Ibid.
201 Haskins Way Project Draft EIR 4.6.4 October 12, 2018
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4.6 Hvdroloav and Water
would be inundated under the 66 -inch projection include landscaping, parking areas, and the southwestern
portion of the existing building at 400 East Jamie Court.27
4.6.3 Regulatory Framework
This section provides a summary of the plans and policies of the City of South San Francisco (City), and
regional, state, and federal agencies that have policy and regulatory control over the project site. These
plans and policies include the Clean Water Act (CWA), Executive Order 11988, Porter - Cologne Water
Quality Control Act, National Pollutant Discharge Elimination System ( NPDES) permit requirements, sea
level rise and Executive Order S- 13 -08, San Mateo Countywide Water Pollution Prevention Program, San
Francisco Bay Water Quality Control Plan, beneficial uses of surface waters and groundwater, East of
101 Area Plan, and City of South San Francisco Water Quality Control Plant NPDES requirements.
FEDERAL
Clean Water Act
The CWA was enacted by Congress in 1972 and amended several times since inception. It is the primary
federal law regulating water quality in the United States and forms the basis for several state and local
laws throughout the country. Its objective is to reduce or eliminate water pollution in the nation's rivers,
streams, lakes, and coastal waters. The CWA prescribed the basic federal laws for regulating discharges
of pollutants and set minimum water quality standards for all waters of the U.S. Several mechanisms are
used to control domestic, industrial, and agricultural pollution under the CWA.
At the federal level, the CWA is administered by the U.S. Environmental Protection Agency (U.S. EPA).
At the state and regional level, the U.S. EPA has delegated administration and enforcement of the CWA
in California to the State Water Resources Control Board (SWRCB) and the Regional Water Quality
Control Boards (RWQCBs). The State of California has developed a number of water quality laws, rules,
and regulations, in part to assist in the implementation of the CWA and related federally mandated water
quality requirements. In many cases, the federal requirements set minimum standards and policies and the
laws, rules, and regulations adopted by the SWRCB and RWQCBs exceed the federal requirements.
Executive Order 11988
Under Executive Order 11988, FEMA is responsible for managing floodplain areas defined as the
lowland and relatively flat areas adjoining inland and coastal waters subject to a 1 percent or greater
chance of flooding in any given year (the 100 -year floodplain). FEMA's overall mission is to support
citizens and first responders to ensure that the United States builds, sustains, and improves capabilities to
prepare for, protect against, respond to, recover from, and mitigate all hazards. With regard to flooding,
FEMA provides information, guidance, and regulation associated with flood prevention, mitigation, and
response. Under Executive Order 11988, FEMA requires that local governments covered by the federal
flood insurance program pass and enforce a floodplain management ordinance that specifies minimum
requirements for any construction within the 100 -year floodplain. Through its Flood Insurance and
2' [bid.
201 Haskins Way Project Draft EIR 4.6.7 October 12, 2018
4.6 Hvdroloav and Water
Mitigation Administration, FEMA manages the National Flood Insurance Program, which includes flood
insurance, floodplain management, and flood hazard mapping functions. FEMA maps 100 -year
floodplains within its jurisdiction and provides flood insurance rate information via flood insurance rate
maps.
STATE
Porter - Cologne Water Quality Control Act
The Porter - Cologne Water Quality Control Act establishes the SWRCB and the RWQCBs as the
principal state agencies having primary responsibility for coordinating and controlling water quality in
California. The Porter - Cologne Act establishes the responsibility of the RWQCBs for adopting,
implementing, and enforcing water quality control plans (Basin Plans), which set forth the state's water
quality standards (i.e., beneficial uses of surface waters and groundwater) and the objectives or criteria
necessary to protect those beneficial uses. The NPDES permit, described below, must be consistent with
the Basin Plan for the site region.
National Pollutant Discharge Elimination System Permit Requirements
Since its enactment in 1972, the CWA has regulated the discharge of pollutants to the waters of the
United States from any point source. In 1987, amendments to the CWA added Section 402(p), which
established a framework for regulating non -point source stormwater discharges under the NPDES. The
Phase I NPDES stormwater program regulates stormwater discharge from industrial facilities, large- and
medium -sized municipal separate storm sewer systems (those serving more than 100,000 persons), and
construction sites that disturb 5 or more acres of land. Under the program, the Legally Responsible Person
(LRP), typically the project applicant, is required to comply with the NPDES permit requirements.
City and town agencies, the San Mateo County Flood Control District, and San Mateo County formed the
San Mateo Countywide Water Pollution Prevention Program. These agencies were previously subject to
NPDES Permit No. CAS612008 as amended by Order No. R2- 2011 -0083 to discharge stormwater runoff
from storm drains and water courses within their jurisdictions .28 On November 19, 2015, the RWQCB
reissued countywide municipal stormwater permits as one Municipal Regional Stormwater NPDES
Permit to regulate stormwater discharges from municipalities and local agencies in Alameda, Contra
Costa, San Mateo, and Santa Clara Counties, and the cities of Fairfield, Suisun City, and Vallejo.
Provisions of the permit prescribe requirements and schedules for permittees identified therein to manage
their discharges that may cause or contribute to violations of water quality standards for pesticides, trash,
mercury, polychlorinated biphenyls, and bacteria. In addition, one of the provision goals is for the
permittees to use their planning authorities to include appropriate source control, site design, and
stormwater treatment measures in new development and redevelopment projects to address stormwater
runoff pollutant discharges and prevent increases in runoff flows from new development and
redevelopment projects. This goal is to be accomplished primarily through the implementation of low
impact development techniques.
28 California Regional Water Quality Control Board, San Francisco Bay Region, 2015. Municipal Regional Stormwater NPDES
Permit — Order No. R2- 2015 -0049 (NPDES Permit No. CAS612008).
201 Haskins Way Project Draft EIR 4.6.8 October 12, 2018
4.6 Hvdroloav and Water
The NPDES Construction General Permit requirements apply to clearing, grading, and disturbance to the
ground such as excavation for construction sites that disturb more than 1 acre of land. The applicant is
required to submit a Notice of Intent (NOI) and other documents to the RWQCB using the Storm Water
Application Report Tracking System. The NOI includes general information on the types of construction
activities that will occur on the site. The applicant is also required to submit a site - specific Stormwater
Pollution Prevention Plan ( SWPPP) for construction activities. The SWPPP must include a description of
Best Management Practices (BMPs) to minimize the discharge of pollutants from the site during
construction. It is the responsibility of the LRP to obtain coverage under the permit prior to site
construction. An annual report must be submitted to the SWRCB each September 1 until a Notice of
Termination is filed.
Sea Level Rise and Executive Order S -13 -08
In November 2008, Governor Arnold Schwarzenegger issued Executive Order S- 13 -08. The order
indicates that future potential sea level rise associated with climate change may have a substantial effect
on coastal development, and provided for the formation of an independent panel to complete a California
Sea Level Rise Assessment Report by December 1, 2010. This panel, the California Adaptation Advisory
Panel to the State of California, published the required report in November 2010 titled Preparing for the
Effects of Climate Change —A Strategy for California .29 This study noted that the state requested an
assessment of defensible sea level projections for the West Coast from the NRC, which was published in
2012. The NRC projections are described above in "Sea Level Rise" on pp. 4.6.4 - 4.6.7.
REGIONAL
San Mateo Countywide Water Pollution Prevention Program
To comply with the CWA, San Mateo County and the 20 cities and towns in the County formed the San
Mateo Countywide Water Pollution Prevention Program, which holds a joint municipal NPDES permit
from the San Francisco RWQCB. The permit includes a comprehensive plan to reduce the discharge of
pollutants to creeks, the Bay, and the ocean to the extent possible.
San Francisco Bay Water Quality Control Plan (Basin Plan)
The San Francisco RWQCB is responsible for the development, adoption, and implementation of the
Water Quality Control Plan for the San Francisco Bay region. The Basin Plan is the master policy
document that contains descriptions of the legal, technical, and programmatic bases of water quality
regulation in the San Francisco Bay region. The Basin Plan identifies beneficial uses of surface waters
and groundwater within its region and specifies water quality objectives to maintain the continued
beneficial uses of these waters. As identified in the plan, the beneficial uses of groundwater in the
Westside Groundwater Basin include municipal and domestic supply, industrial process supply, industrial
29 California Adaptation Advisory Panel to the State of California, prepared by Pacific Council, 2010. Preparing for the Effects
of Climate Change —A Strategy for California.
201 Haskins Way Project Draft EIR 4.6.9 October 12, 2018
4.6 Hvdroloav and Water
supply, and agricultural supply.30 Projects are required to adhere to all water quality objectives identified
in the Basin Plan.
f119Zd_1
City of South San Francisco General Plan
The City of South San Francisco General Plan (General Plan) contains policies designed to protect
people and development from damage associated with flooding. Policies applicable to the project are as
follows.
Open Space and Conservation Element: Water Quality
Policy 7.2 -G -1: Comply with the San Francisco Bay Regional Water Quality Control Board
regulations and standards to maintain and improve the quality of both surface water and groundwater
resources. 31
Policy 7.2 -G -2: Enhance the quality of surface water resources and prevent their contamination. 32
Policy 7.2 -G -3: Discourage the use of insecticides, herbicides, or toxic chemical substances within
the Clty.33
Policy 7.2 -I -1: Continue working with the San Francisco Bay RWQCB in the implementation of the
NPDES, and continue participation in STOPPP for the protection of surface water and groundwater
quality.
Health and Safety Element: Flooding
Policy 8.2 -G -1: Minimize the risk to life and property from flooding in South San Francisco.34
Policy 8.2 -I -1: Continue working with the Regional Water Quality Control Board ( RWQCB) in the
implementation of the San Mateo Countywide Stormwater Pollution Prevention Program (STOPP).
Policy 8.2 -I -2: Use the City's development review process to ensure that proposed development
subject to the 100 -year flood provides adequate protection from flood hazards, in areas identified in
Figure 8 -3.35
City of South San Francisco East of 101 Area Plan
The East of 101 Area Plan provides design -level planning policies that complement the development
standards established under policies of the adopted General Plan. In particular, Policy CON -7, with
30 San Francisco Regional Water Quality Control Board, Basin Plan, Chapter 2: Beneficial Uses, Table 2 -2: Existing and
Potential Beneficial Uses in Groundwater in Identified Basins. Available online at:
https: / /www.waterboards.ca. og v/rwgcb2/ water_ issues / programs /basin plan/docsBP_CH2 +tables.pdf. Accessed May 8, 2018.
31 General Plan, Chapter 7, Open Space and Conservation Element, p. 7 -12. Available online at:
http: / /www.ssfnet/home /showdocument ?id =480. Accessed May 8, 2018.
32 Ibid.
33 Ibid.
34 General Plan, Chapter 8, Health and Safety Element, p. 8 -11. Available online at:
http: / /www.ssfnet/home /showdocument ?id =472. Accessed May 8, 2018.
35 General Plan, Chapter 8, Health and Safety Element, p. 8 -12. Available online at:
http:// www.ssfnet/home /showdocument ?id =472. Accessed May 8, 2018.
201 Haskins Way Project Draft EIR 4.6.10 October 12, 2018
4.6 Hvdroloav and Water
respect to hydrology and water quality, aims to ensure that runoff from development does not adversely
affect the biotic values of adjacent wetlands or other habitat areas.36
City of South San Francisco Water Quality Control Plant National Pollutant
Discharge Elimination System Permit Requirements
The City of South San Francisco Water Quality Control Plant requires source control measures of
stormwater pollutants to comply with their NPDES permit, including methods for managing pollutant
sources. Applicable control measures include utilization of stormwater pollution prevention devices,
management of refuse areas, management of pesticide /fertilizer application for landscaping, use of
treatment devices for interior -level parking garage flood drains, and marking of on -site storm drains.37
4.6.4 Impacts and Mitigation Measures
This section describes the impact analysis related to hydrology and water quality for the proposed project.
This section also describes the methods used to determine the impacts of the proposed project and lists the
thresholds used to conclude whether an impact would be significant. Measures to mitigate (i.e., avoid,
minimize, rectify, reduce, eliminate, or compensate for) significant impacts accompany the discussion of
any identified significant impacts.
SIGNIFICANCE CRITERIA
Per the CEQA Guidelines, Appendix G, a hydrology and water quality impact is considered significant if
project implementation would result in one or more of the following:
a. Violate any water quality standards or waste discharge requirements;
b. Substantially deplete groundwater supplies or interfere substantially with groundwater recharge
such that there would be a net deficit in aquifer volume or a lowering of the local groundwater
table level (e.g., the production rate of pre- existing nearby wells would drop to a level which
would not support existing land uses or planned uses for which permits have been granted);
c. Substantially alter the existing drainage pattern of the site or area, including through the alteration
of the course of a stream or river, in a manner which would result in substantial erosion or
siltation on- or off -site;
d. Substantially alter the existing drainage pattern of the site or area, including through the alteration
of the course of a stream or river, or substantially increase the rate or amount of surface runoff in
a manner which would result in flooding on- or off -site;
e. Create or contribute runoff water which would exceed the capacity of existing or planned
stormwater drainage systems or provide substantially additional sources of polluted runoff;
f. Otherwise substantially degrade water quality;
36 City of South San Francisco, 1994. East of 101 Area Plan, pp. 45 -46. Available online at:
hM2: // www .ssf.net /home /showdocument ?id =508. Accessed April 17, 2018.
37 San Francisco Regional Water Quality Control Board, 2014. Order No. R2- 2014 -0012, NPDES No. CA0038130. Available
online at: hgps: // www. waterboards .ca.gov /sanfranciscobU!board_ decisions /adopted orders /2014/R2- 2014- 0012.pdf. Accessed
April 17, 2018.
201 Haskins Way Project Draft EIR 4.6.11 October 12, 2018
4.6 Hvdroloav and Water
g. Place housing within a 100 -year flood hazard area as mapped on a federal Flood Hazard
Boundary or Flood Insurance Rate Map or other flood hazard delineation map;
h. Place within 100 -year flood hazard area structures which would impeded or redirect flood flows;
i. Expose people or structures to a significant risk or loss, injury, or death involving flooding,
including flooding as a result of failure of a levee or dam; or
j. Inundation by seiche, tsunami, or mudflow.
APPROACH TO ANALYSIS
Construction of the proposed project does not include housing and therefore would not place housing
within a 100 -year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood Insurance
Rate Map or other flood hazard delineation map. Therefore, criterion (f) does not apply to the proposed
project and is not discussed further under "Impact Evaluation."
This analysis evaluates the project's potential effects related to hydrology and water quality. Water
quality impacts are assessed with respect to the potential for the project to result in an exceedance of
water quality criteria or an exceedance of waste discharge requirements, including NPDES permit effluent
limitations. In addition, the impact analysis assesses potential impacts related to groundwater depletion
and recharge as well as changes in stormwater flows and flooding (including flooding as a result of 100 -
year flooding under existing conditions, future flooding as a result of sea level rise, and flooding as a
result of a tsunami). The impact analysis assumes that all construction and operations would be completed
in compliance with applicable NPDES regulations and City permit requirements, including sewer and
storm drain systems or a discharge to surface waters (i.e., the Bay). If compliance with these standards
would ensure that impacts related to water quality would be less than significant, then no mitigation is
necessary.
Sea level rise is analyzed in relation to other natural phenomena that contribute to the risk of flooding.
Several factors must be considered in evaluating flooding risk at the project site. These include
stormwater, tides, waves, seiche, and tsunami. In the analysis of impacts, the impact of the proposed
project is first discussed in relation to these events without assuming future sea level rise. In combination
with these tsunami, seiche, and storm surge events, future potential climate- induced sea level rise could
pose risks of inundation to existing and proposed development located in low -lying areas close to the Bay
such as the project site.
The science of estimating sea level rise continues through a process of refinement. The rate of potential
future sea level rise is difficult to project, and estimates vary substantially among numerous scientific
studies available on climate change and sea level rise. The analysis considers whether people or structures
on the project site could be exposed to a significant risk of loss, injury, or death involving flooding as a
result of sea level rise in combination with storm surge and extreme tides. The impact is considered less
than significant if the project would not be inundated during a 100 -year coastal flood within the life of the
project, or if the project would conform to flood - resistant building standards and be capable of adapting to
future flood hazard conditions. The analysis presented here is based on the best available science -based
projections for sea level rise, which are described above in "Sea Level Rise" on pp. 4.6.4 - 4.6.7.
201 Haskins Way Project Draft EIR 4.6.12 October 12, 2018
4.6 Hvdrolopv and Water
IMPACT EVALUATION
Water Quality Standards or Waste Discharge Requirements
Potential sources of pollutants include groundwater that is in contact with landfill waste material
(leachate) and traditional non -point source pollutants. Non -point source pollutants are washed by
rainwater from roofs, landscape areas, and streets and parking areas into the drainage network.
Anticipated and potential non -point source pollutants for development and redevelopment activities are
listed in Table 4.6.1: Anticipated and Potential Pollutants Generated by Land Use Type. Parking
lots /structures and commercial /industrial development at the site may generate some of these classes of
pollutants.
Impact HY -1: Construction activities and operation of the proposed project would not violate any
water quality standards or waste discharge requirements or otherwise substantially degrade water
quality. (Less than Significant)
Phase 1 and Project Buildout
WATER QUALITY EFFECTS OF CONSTRUCTION ACTIVITIES
Grading and earthmoving for the installation of utilities and infrastructure, demolition of existing
buildings, and construction of new buildings and structures would expose soil during construction.
Without proper controls, these activities could result in erosion, with potential chemicals and sediments
carried in stormwater runoff. Stormwater runoff from temporary on -site use and storage of vehicles, fuels,
wastes, and building materials could also carry pollutants if these materials were improperly handled.
These sediments and pollutants, if discharged to the Bay, would degrade water quality.
However, the CWA effectively prohibits discharges of stormwater from construction projects unless the
discharge is in compliance with an NPDES permit. During construction, stormwater from the project site
would drain to the existing storm drains on East Jamie Court and Haskins Way and into an existing catch
basin to an outfall pipe that discharges into the Bay. Stormwater would not be directed to the unnamed
riverine wetland to the east of the project site. Construction- related stormwater discharges to the
stormwater conveyance system would occur in accordance with the NPDES Construction General
Stormwater Permit.
Under the Construction General Stormwater Permit, construction activities that would drain to the storm
drain system would be characterized by the level of risk to water quality, as determined by using a
combination of the sediment risk of the project and the receiving water quality risk. Projects can be
characterized as Risk Level 1, Level 2, or Level 3, and the minimum BMPs and monitoring that must be
implemented during construction are based on the risk level. The BMPs are designed to prevent pollutants
from coming into contact with stormwater and to keep all products of erosion and stormwater pollutants
from moving off site into receiving waters. The BMPs are specified in a SWPPP that must be prepared by
a Qualified SWPPP Developer (QSD) and submitted to the San Francisco RWQCB before construction
begins. Construction activities under the project would not be characterized as Risk Level 3, because the
201 Haskins Way Project Draft EIR 4.6.13 October 12, 2018
4.6 Hydrology and Water Quality
Table 4.6.1. Anticipated and Potential Pollutants Generated by Land Use Type
Priority Project Heavy Organic
Pathogens Nutrients Pesticides Sediments
Trash and
Oxygen
Demanding
Oil and
Categories Metals Compounds
Debris
Substances
Grease
Commercial /Industrial
Development P(1) P(2) P(3) P(4) P(2)
X
P(3)
X
>100,000 square feet
Parking Lots X P(2) P(4) P(2)
X
P(3)
X
Notes:
X = anticipated
P = potential
(1) A potential pollutant if land use involves food or animal waste products.
(2) A potential pollutant if landscaping exists on site.
(3) Including solvents.
(4) A potential pollutant if the project includes uncovered parking areas.
Source: California Stormwater Quality Association; Stormwater Best Management Practice Handbook, New Development and Redevelopment; 2003;
p. 2 -7. Available online at:
htti)s: / /www.casoa.oro/ sites /default/files /BMPHandbooks /BMP NewDevRedev Complete.pdf.
201 Haskins Way Project Draft EIR 4.6.14 October 12, 2018
4.6 Hvdrolociv and Water
Lower San Francisco Bay is not considered a sediment - sensitive water body under the Construction
General Stormwater Permit.38
For construction activities characterized as Risk Level 1, the Construction General Stormwater Permit
specifies minimum BMPs to be implemented that address good housekeeping practices (including those
for managing hazardous materials used during construction), non - stormwater management, erosion and
sediment control, and run -on and runoff control. A qualified professional must inspect the required BMPs
weekly when there is no rain and daily during a qualifying rainstorm. For construction activities
characterized as Risk Level 2, the minimum requirements identified for Risk Level 1 apply in addition to
more stringent requirements. For instance, erosion controls must be implemented in conjunction with
sediment controls in active construction areas, and linear sediment controls such as silt fences, gravel bag
berms, or fiber rolls must be used along slopes. In addition, a QSD must prepare a rain event action plan
for Risk Level 2 construction activities. This plan would identify the designated site stormwater manager,
the provider of erosion and sediment controls, and the stormwater sampling agent, as well as the types of
construction workers active at the site during all construction phases. The plan would include suggested
actions for each construction phase.
Compliance with the Construction General Stormwater Permit would ensure that water quality impacts
related to violation of water quality standards or degradation of water quality due to discharge of
construction- related stormwater runoff to the Bay, either directly or via the storm drain system, would be
less than significant. No mitigation is necessary.
WATER QUALITY EFFECTS OF GROUNDWATER DEWATERING
Groundwater was measured at nearby sites at depths varying from approximately 8 to 15 feet bgs.39 The
project site is underlain by approximately 20 to 25 feet of fill in addition to approximately 0 to 20 feet of
Bay Mud. Bedrock on the project site is estimated at depths between 20 and 78 feet. Therefore,
foundations may also require auguring or drilling to a maximum depth of approximately 78 feet bgs. In
addition, excavation on the site up to 13 feet would be required for the potential removal of the former
underground storage tank hot spot area. Based on the depth of these ground- disturbing activities,
construction - related groundwater dewatering may be required.
In the event that groundwater is encountered during construction, the discharge of groundwater produced
during dewatering would be either directly discharged to the sewer system or treated on site and
discharged to the storm drain system that leads to the Bay. If discharged to the sewer system, groundwater
discharges would be subject to Title 14 Water and Sewage, Chapter 14.08.2 10 Water Quality Control,
which regulates the quantity and quality of discharges to the sewer system. In accordance with Section
14.08.100, the discharger would be required to obtain a permit for the discharges and the permit would
contain appropriate discharge standards. The permit may also require installation of meters to measure the
38 California Department of Transportation, 2018. Water Quality Planning Tool. Available online at:
http:// svctenvims .dot.ca.gov /wgpt /wgpt.aslx. Accessed April 17, 2018.
39 Langan, 2017. Preliminary Geotechnical Evaluation: 201 Haskins Way, South San Francisco, California, Langan Project No.:
750645101,p.3.
201 Haskins Way Project Draft EIR 4.6.15 October 12, 2018
4.6 Hvdrolopv and Water
volume of the discharge. The groundwater could contain contaminants related to past site activities, as
well as sediment and suspended solids, but would be required to be treated as necessary to meet the
discharge limitations. Treatment could include methods such as using settling tanks to remove sediments,
filters to remove suspended solids, and other methods to meet chemical- specific discharge limitations.
The chemical - specific treatment method used would depend on the chemicals that exceed the specified
discharge limitation, but could include methods such as filtration or activated carbon treatment to reduce
chemical concentrations as necessary to meet permit requirements prior to discharge.
If discharged directly to the storm drain system, the groundwater discharges could be subject to
permitting requirements of the RWQCB under the Volatile Organic Compound (VOC) and Fuel General
Permit if the groundwater is polluted by VOC, fuel, or fuel additives.40 These permits specify water
quality criteria and monitoring requirements for discharges of extracted groundwater. Accordingly, under
this option, the project sponsors would be required to submit an NOI to the RWQCB describing the
proposed discharge and treatment system. The RWQCB must issue an Authorization to Discharge once it
is determined that the discharger is eligible to discharge under the permit. The contractors would install
an on -site treatment system, as needed, to comply with the effluent limitations of the applicable discharge
permit. The treated water would likely be discharged through a temporary discharge structure, and regular
influent and effluent water quality monitoring would be conducted to demonstrate permit compliance.
Alternatively, an individual NPDES permit from the RWQCB would be required and would impose
similar requirements.
With discharge to the sewer system or the Bay in accordance with the regulatory requirements, water
quality impacts related to a violation of water quality standards or degradation of water quality due to
discharge of groundwater produced during construction- related dewatering would be less than significant,
and no mitigation is necessary.
Operation
During operation of the proposed project, no ground- disturbing activities would occur and no activities
would cause polluted discharges to surface waters. Under both phases of development (including the
conceptual Phase 2 development plan), the proposed project would be designed to protect water quality
through the management of stormwater runoff as part of green infrastructure through low- impact
development (LID). This approach implements engineered controls to allow stormwater, filtering, and
storage and flood control. Controlled stormwater would flow through paved areas into designated
bioretention areas or storm drains. Portions of roof areas would also be designed as green roofs that would
provide filtration. Stormwater received through all proposed roof areas would be routed to the ground
level through downspouts and conveyed to bioretention areas. The bioretention areas would be designed
to allow water to evaporate, and provide pre - treatment of pollutants such as trash, debris, and larger
sediments, as well as filtration of other pollutants. After collection, filtered stormwater would be allowed
to infiltrate into groundwater or to storm drainage conveyances. Because of the presence of shallow
40 San Francisco Bay Regional Water Quality Control Board, 2018. VOC and Fuel General Permits. Available online at:
https:// www. waterboards .ca.gov /sanfranciscobay/board decisions /adopted_ orders /2012/R2- 2012- 0012.12df. Accessed May 8,
2018.
201 Haskins Way Project Draft EIR 4.6.16 October 12, 2018
4.6 Hvdrolopv and Water
bedrock and the influence of Bay waters and subsurface Bay Mud, it is unlikely that the existing project
site provides substantial groundwater infiltration from stormwater. Nonetheless, the BMPs specified in a
SWPPP would balance the rate of stormwater flows and impervious surfaces against the existing site
conditions.
For these reasons, operation of the proposed project would have a less- than - significant impact related to
water quality, and no mitigation is necessary.
Groundwater Depletion and Recharge
Impact HY -2: The proposed project would not substantially deplete groundwater supplies or
interfere substantially with groundwater recharge such that there would be a net deficit in aquifer
volume or a lowering of the local groundwater table level. (Less than Significant)
The project site is located within the Westside Groundwater Basin. Implementation of the project would
not result in depletion of groundwater resources in the Westside Groundwater Basin because, other than
possible pumping of groundwater during construction dewatering, the project would not involve the use
or extraction of groundwater. Rather, potable water for the project would be provided via pipe by the
California Water Service Company, which purchases most of its water from the San Francisco Water
Department. In addition, non - potable supplies from on -site sources (e.g., captured rainwater) would
supplement the municipal water used for on -site landscaping. The effects of construction dewatering on
the groundwater basin supplies would be minimal.
As stated in Impact HY -1, above, it is unlikely that the existing project site provides substantial
groundwater infiltration from surface stormwater due to the presence of shallow bedrock and the
influence of Bay waters and subsurface Bay Mud. Furthermore, the existing site consists of primarily
impervious surfaces. The existing 201 Haskins site includes an area of compacted gravel that was used for
truck storage. Due to the compacted nature of this gravel, significant infiltration likely does not occur.
However, as a conservative approach, this area is considered partially pervious for the purpose of
stormwater analysis. When this existing area is considered pervious, there may be a net increase in
impervious area with the proposed project.
Under NPDES permitting requirements, both Phase 1 and buildout of the proposed project would be
required to replicate the pre - project stormwater water balance for the smallest storms up to the 85th
percentile storm event, or the smallest storm event that generates runoff, whichever is larger .41 As
discussed in Impact HY -1, above, Phase 1 and project buildout would direct stormwater flows to
designated bioretention areas or storm drains. After collection, filtered stormwater would be allowed to
infiltrate into groundwater or to storm drainage conveyances. Because infiltration of stormwater may not
be feasible due the presence of shallow bedrock and Bay Mud, the BMPs specified in a SWPPP would
balance the rate of stormwater flows and impervious surfaces against the existing site conditions.
41 California State Water Resources Control Board, 2012. Order 2009 - 0009 -DWQ Construction General Stormwater Permit as
amended by 2010 - 0014 -DWQ and 2012 - 0006 -DWQ, Fact Sheet p. 41. Available online at:
https: / /www.waterboards.ca.aov /water_ issues / programs /stormwater /constpennits.shtml. Accessed August 27, 2018.
201 Haskins Way Project Draft EIR 4.6.17 October 12, 2018
4.6 Hvdrolopv and Water
For these reasons, the project would not interfere substantially with groundwater recharge as a result of
increased impervious surfaces and would not decrease the amount of rainwater recharged to the
groundwater at the project site.
For the reasons stated above, impacts related to depletion of groundwater resources and interference with
groundwater recharge would be less than significant, and no mitigation is necessary.
Alteration of Drainage
Impact HY -3: Construction of the proposed project would not substantially alter the existing
drainage pattern of the site or area in a manner which would result in substantial erosion or
siltation on or off site, or substantially increase the rate or amount of surface runoff in a manner
which would result in flooding on or off site. (Less than Significant)
The project site does not include any existing streams or watercourses that could be altered or diverted.
Therefore, the proposed project would have no impact related to alteration of drainage patterns by altering
the course of a stream in a manner that would cause erosion or flooding on- or off -site.
The proposed project would not involve construction of new unprotected drainage areas that could
produce erosion or siltation during a storm. As discussed in Impact HY -1, above, Phase 1 and project
buildout would be designed to control stormwater flows to designated engineered bioretention areas or
storm drains. The proposed bioretention areas would also provide pre- treatment and filtration of
sediments. Therefore, the proposed project would not alter the site drainage in a manner which would
result in substantial erosion or siltation off site.
Under the project, stormwater would continue to be routed to groundwater or the existing storm drains on
East Jamie Street and Haskins Way. As stated in Impact HY -2, above, both Phase 1 and buildout of the
proposed project would be required to replicate the pre - project stormwater water balance under NPDES
permitting requirements. The project would comply with all applicable BMPs and Conditions of
Approval regarding stormwater drainage and surface runoff detention measures, and therefore the amount
of surface runoff would not increase.
Therefore, neither alteration of existing drainage patterns at the project site nor changes in stormwater
runoff rates or volumes would result in substantial erosion, siltation, or flooding on- or off -site, and this
impact would be less than significant. No mitigation is necessary.
Changes in Stormwater Runoff
Impact HY -4: The proposed project would not create or contribute runoff water which would
exceed the capacity of existing or planned stormwater drainage systems or provide substantial
additional sources of polluted runoff. (Less than Significant)
As stated in Impact HY -1, above, both Phase 1 and buildout of the proposed project would be required to
replicate the pre - project stormwater water balance for the smallest storms up to the 85th percentile storm
event, or the smallest storm event that generates runoff, whichever is larger. Therefore, the project would
not create or contribute new runoff water that would exceed the capacity of the existing stormwater
201 Haskins Way Project Draft EIR 4.6.18 October 12, 2018
4.6 Hvdrolopv and Water
drainage systems because neither Phase 1 nor buildout of the proposed project (including the conceptual
Phase 2 development plan) would substantially increase stormwater runoff discharged from the site.
Therefore, water quality effects related to exceeding the capacity of the storm drain system would be less
than significant, and no mitigation is necessary.
Discharges of stormwater to the stormwater system during construction would not provide an additional
source of polluted runoff because all discharges would be in accordance with the NPDES Construction
General Stormwater Permit. Implementation of source control BMPs would reduce potential pollutant
loads in the stormwater runoff and would improve the quality of the runoff to the sewer system or
separate stormwater system. Source control measures would include covering and hydraulically isolating
pollutant - generating activities, implementing maintenance activities such as regular sweeping of exposed
areas, and using non - polluting building and maintenance materials. Treatment BMPs would further
reduce pollutant loads in stormwater via infiltration (e.g., permeable pavement or infiltration basins or
trenches), bioretention (e.g., flow through planter or rain garden), or biofiltration (e.g., vegetated areas;
media, sand, or vegetated rock filters; use of swirl separators, water quality inlets, or drain inserts). One or
more treatment BMPs may be required to address each of the potential stormwater pollutants of concern.
As stated in Impact HY -1, above, both Phase 1 and buildout of the proposed project would be required to
protect water quality through the LID stormwater management with engineered controls to allow
stormwater filtering. The proposed bioretention areas are designed to provide pre- treatment of pollutants
prior to infiltration into groundwater or to conveyance to storm drainages. The proposed new office /R &D
uses constructed under Phase 1 and project buildout would also adhere to Leadership in Energy and
Environmental Design, City, and NPDES conservation measures applicable to LID and landscaping
requirements.42 Although infiltration of stormwater is also an allowable method of stormwater
management, it is unlikely that infiltration is a feasible approach for the project site because of the
presence of shallow bedrock and Bay Mud. However, selection of the appropriate BMPs would be guided
by existing site conditions, design and development goals, and the pollutants of concern at the site.
With implementation of the source control and treatment BMPs in accordance with the Construction
General Stormwater Permit, both Phase 1 and project buildout of the proposed project would not provide
an additional source of stormwater pollutants, and this impact would be less than significant. No
mitigation is necessary.
Flooding
Impact HY -5: Operation of the proposed project would not place structures within a future 100 -
year flood zone that would impede or redirect flood flows, nor would it expose of people or
structures to a significant risk or loss, injury, or death involving flooding. (Less than Significant)
The project site is located in a low -lying area adjacent to the Bay shoreline. There are no dammed surface
waters (rivers or lakes) or levees in the East of 101 Area. The project site is not located downstream of a
42 Phase 2 development is conceptual at this time and is subject to future site - specific site plan review. Phase 2 office/R &D uses
are assumed to be developed according to the same LID standards as Phase l design, if not better, as future technologies improve
and regulations are developed.
201 Haskins Way Project Draft EIR 4.6.19 October 12, 2018
4.6 Hvdrolopv and Water
dammed surface water, nor is it located in a potential floodway of any levee or dam. Therefore, there
would be no impact associated with the exposure of people or structures to a significant risk or loss,
injury, or death involving flooding as a result of failure of a levee or dam.
The project site is located outside of the 100 -year flood hazard zone as determined by FEMA, and the
proposed project would not expose people or structures to a significant risk or loss, injury, or death
involving coastal flooding due to the existing 100 -year flood hazard zone. However, the City recognizes
that sea level rise is a local issue of concern. The effects of sea level rise on the proposed project are not
subject to CEQA review.43 However, for informational purposes, the EIR provides information on sea
level rise that may be used for planning purposes. As described above in "Existing Conditions" on
pp. 4.6.4 to 4.6.7, when the effects of a 100 -year storm surge are combined with sea level rises of 24
inches (anticipated by 2050) or 66 inches (anticipated by 2100), the southwestern corner of the project
site would be partially inundated by 0 to 2 feet and 0 to 6 feet, respectively, as shown in Figure 4.6.1 and
Figure 4.6.2.44
The areas that would be inundated under the 24 -inch projection in 2050 include landscaping and parking
areas on the 400 -450 East Jamie Court parcel.45 No Phase 1 development is planned in this area. Further,
it is unlikely that project buildout associated with Phase 2 would occur in the inundation areas, since the
majority of that anticipated flooded area either lies within the 10 -foot street- facing setback or is located
within the access way into the existing building garage. The areas that would be inundated under the 66-
inch projection in 2100 include landscaping, parking areas, and the southwestern portion of the existing
building at 400 East Jamie Court .46 The proposed Phase 1 office /R &D uses at the 25,000- square -foot
building addition at 400 East Jamie Court would be outside the effects of a 100 -year storm surge in
combination with projected sea level rise. Similarly, it is unlikely that project buildout associated with
Phase 2 would occur in the inundation areas, since the majority of that anticipated flooded area either lies
within the 10 -foot street- facing setback or is located within the access way into the existing building
garage. Since no new buildings are anticipated to be placed in areas subject to flooding, construction of
the project would not impede or redirect flood flows.
Inundation
Impact HY -6: The proposed project would not expose people or structures to substantial risk of
loss, injury, or death due to inundation by seiche, tsunami, or mudflow. (Less than Significant)
A seiche is a tide -like rise and drop of the surface of a landlocked body of water (e.g., a lake); its period
can vary from a few minutes to several hours. The site is not located in close proximity to a landlocked
body of water that could cause inundation by seiche. The site is also nearly level and not bordered by hills
43 California Building Industry Association v. Bay Area Air Quality Management District (December 17, 2015, Case No.
S213478) and Ballona Wetlands Land Trust v. City of Los Angeles (2011) 201 Ca1.App.4th 455.
44 Adapting to Rising Tides, San Mateo County Sea Level Rise Inundation Scenarios, 2018. Available online at:
http:// smcmaps. maps.arcgis.com/apps/MapSeries/ index. html? appid= 51676b57ab5f4446a03adl3a9432986d. Accessed April 17,
2018.
45 Ibid.
46 Ibid.
201 Haskins Way Project Draft EIR 4.6.20 October 12, 2018
4.6 Hvdrolopv and Water
that could result in mudflow across the site. Consequently, there would be no impact related to seiche or
mudflow.
Tsunamis, or tidal waves, are huge sea waves that are caused by seismic activity or other disturbance of
the ocean floor. Portions of South San Francisco that are near the Bay and low -lying areas are considered
to be at risk for inundation by tsunami wave run -up. Wave run -up is estimated at 4.3 feet MSL for
tsunami with a 100 -year recurrence and 6.0 feet MSL for a 500 -year tsunami .4' The southern portion of
the project site immediately borders the Bay waters; however, the project site elevation ranges from 10 to
25 feet MSL, which is higher than tsunami wave run -up inundation areas. In addition, the shoreline of the
project area is protected by rip -rap to prevent damage to the shoreline by wave run -up. Consequently, this
impact would be less than significant with no mitigation required.
Cumulative
Impact C -HY -1: The proposed project would not make a cumulatively considerable contribution to
significant cumulative impacts related to hydrology and water quality. (Less than Significant)
Assuming concurrent implementation of the project with other reasonably foreseeable probable future
projects in the vicinity, adverse cumulative effects on hydrology and water quality could include
construction impacts related to increases in stormwater runoff and pollutant loading to the Bay. Each of
the cumulative projects listed in Section 4.1.5, Approach to Cumulative Analysis, pp. 4.1.7 -4.1.9, would
occur on similar paved, in -fill sites. The nearest cumulative project is greater than 0.25 mile away and
would not directly impact localized flood conditions. The project and other future projects in the City
would be required to comply with the Construction General Permit to control runoff and regulate water
quality at each development site. New projects would be required to demonstrate that stormwater volumes
could be managed by downstream conveyance features and would not induce flooding. Therefore, no
significant cumulative impact on hydrology and water quality would occur and the proposed project
would not contribute considerably to any significant cumulative impacts in combination with other
foreseeable projects. The impact would be less than significant. No mitigation is necessary.
47 General Plan: Health and Safety Element, p. 8 -6 to 78 -7. Available online at: hftp: / /www.ssf.net/home /showdocument ?id =472.
Accessed April 17, 2018.
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