Heart of Fairfield Plan. February 2, 2017 Page 8-1

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1 February 2, 2017 Page GEOLOGY AND SOILS This EIR chapter describes geology and soils implications of the proposed Heart of Fairfield Plan. The chapter addresses the specific geology and soils impact concerns identified by the CEQA Guidelines--i.e., would development under the proposed Plan expose people and structures to geological hazards (e.g., earthquakes, landslides, expansive soils). 1 The California Supreme Court decision (December 2015) in California Building Industry Association v. Bay Area Air Quality Management District concluded, [W]e hold that CEQA does not generally require an agency to consider the effects of existing environmental conditions on a proposed project s future users or residents. What CEQA does mandate is an analysis of how a project might exacerbate existing environmental hazards. The environmental impact analysis in this section (and throughout the EIR) takes into consideration this Court decision. 8.1 SETTING Regional Geologic Setting The approximately 513-acre Plan Area is located within the Coast Range, which encompasses the greater San Francisco Bay region. The Coast Range geomorphic province features northwest trending mountain ranges, broad basins, and narrow valleys that roughly parallel major geologic structures and the coastline of central California. The Suisun-Fairfield area consists of low-lying alluvial plains covering the merger of the Franciscan Formation with the Great Valley Sequence (where the Pacific and North American tectonic plates collide), and forming a mixture of rock types that reaches throughout the northern California Coast Ranges. 2 Over the past five to eight million years, alluvial deposits from as far east as the Sierra Nevada accumulated, and more recent alluvial fan deposits (within the past 15,000 years) have resulted from the Sacramento and San Joaquin Rivers flowing to the sea prior to formation of Suisun and San Francisco Bays. 3 This process of sediment deposited by streams continues to this day Topography and Surface Soils The Plan Area is generally flat, with surface elevations ranging from 5 to 35 feet above sea level. The Plan Area gently slopes from southeast to northwest. 1 CEQA Guidelines, appendix G, item VI (a through e). 2 Blake, M. C., Jr., and David L. Jones, The Franciscan Assemblage and Related Rocks in Northern California: A Reinterpretation, in Ernst, W.G. (Ed.), The Geotectonic Development of California, Thomasson, H.G., Jr., F.H. Olmsted, and E.F. LeRoux, "Geology, Water Resources and Usable Ground-Water Storage Capacity of Part of Solano County, California," Geological Survey Water-Supply Paper 1464, 1960, pp

2 February 2, 2017 Page 8-2 Soil types in the Plan Area are primarily Capay clay, with some Sycamore silty clay loam and a little Alviso silty clay loam making up most of the rest. 1 The Capay clay series consists of very deep, moderately well-drained soils. Permeability is slow. The Sycamore series consists of nearly level, somewhat poorly drained soils formed in alluvium washed from mixed sources. Permeability is moderately slow, and erosion is a slight hazard. The Alviso series consists of nearly level, poorly drained soils formed in mixed alluvium. Permeability is slow, and erosion is a slight hazard. 2 Three creeks pass through the Plan Area. Ledgewood Creek crosses underneath I-80 at Auto Mall Parkway and runs southeast across Woolner Avenue, then past Beck Avenue to SR 12. Pennsylvania Avenue Creek is contained in a culvert alongside Pennsylvania Avenue until it exits to a concrete-lined ditch near Illinois Street and then crosses SR 12. Union Avenue Creek passes in an open ditch underneath the railroad tracks east of Union Avenue and then runs north near Delaware and Clay Street before going into a culvert at Texas Street Seismicity (a) Earthquake Risk. The Plan Area is not located in an Alquist-Priolo Special Study Zone, and no faults run through the Plan Area. The only known active fault passing within the borders of Solano County is the Concord/Green Valley fault. According to the Association of Bay Area Governments (ABAG), Solano County could experience strong seismic ground shaking in the event of an earthquake on one of several identified active or potentially active faults in the region, including the Hayward, Rodgers Creek, Green Valley, West Napa, San Andreas, Huntington Creek-Berryessa, and Great Valley faults. Given the close proximity to the Hayward fault (approximately 25 miles) and its likelihood of rupturing in the next 30 years, ABAG has determined that Solano County is at risk in the next major earthquake. 3 The Working Group on California Earthquake Probabilities provides estimates of earthquake probabilities over a 30-year period. In 2013, the Working Group updated its 2007 estimates. The likelihood of moderate-sized earthquakes (magnitude 6.5 to 7.5) is lower than previously estimated in 2007, whereas the likelihood of larger events (greater than magnitude 7.5) is higher. 4 Table 8-1 shows the 30-year earthquake probabilities for 18 nearby faults (or fault segments), along with the ABAG assessment of seismic hazard for Solano County. 1 U.S. Department of Agriculture. Natural Resources Conservation Service, Web Soil Survey. accessed 3/2/16. 2 U.S. Department of Agriculture, Natural Resources Conservation Service, Official Soil Series Descriptions, accessed 3/2/16; U.S. Department of Agriculture, Soil Conservation Service, Soil Survey of Solano County, California, ABAG Resilience Program, accessed 3/3/16. 4 Working Group on California Earthquake Possibilities, Third Uniform California Earthquake Rupture Forecast (UCERF3), accessed 3/2/16,

3 February 2, 2017 Page 8-3 Table YEAR EARTHQUAKE PROBABILITIES Fault Great Valley - Gordon Valley Great Valley - Pittsburg/ Kirby Hills Distance from Plan Area (miles) 1 Probability of Event (Modified Mercalli Intensity MMI) MMI 6.7 MMI 7.0 MMI 7.5 MMI 8.0 ABAG Hazard < Violent Strong-Very Strong Green Valley Concord Huntington Creek Strong Berryessa West Napa <0.01 Strong Hayward (North) Moderate- Strong 4 Rodgers Creek - Healdsburg San Andreas (North Coast) <0.01 Moderate/ Strong Moderate/ Strong Hayward (South) Moderate Maacama Moderate San Andreas (Peninsula) Moderate Greenville Moderate Mount Diablo Moderate San Gregorio Moderate Calaveras (Central) Light Cordelia 5 ~ SOURCE: UCERF3 & Google Earth, 3/1/16; ABAG Resilience Program, 2/29/16. Notes: 1 Distances measured using Google Earth. 2 ABAG uses the following range for estimating hazards from earthquake events, based on the Modified Mercalli Intensity (MMI) scale (see upcoming Table 8-2 for more detail): MMI Risk 5 Light 6 Moderate 7 Strong 8 Very Strong 9 Violent 10 Very Violent 3 ABAG lists the Concord-Southern Green Valley hazard as Strong-Very Strong, but the UCERF3/Google Earth map data show separate Concord and Green Valley faults.

4 February 2, 2017 Page ABAG lists Hayward (North & South) hazard as Moderate-Strong, but the UCERF3/Google Earth map data show separate Hayward North and Hayward South faults. 5 The Cordelia Fault was not evaluated by either ABAG or the UCERCF3, but some estimates of seismic hazard show this fault capable of producing an earthquake with a magnitude between 7.35 and 8.1 (Richter scale), which would translate to 7 and 8 MMI. (From: Perkins, Jeanne B., "Maps Showing Cumulative Damage Potential from Earthquake Ground Shaking, San Mateo County, California," USGS, 1987, p. 3.) -- = information not available (b) Earthquake Hazards. Hazards that can result from an earthquake include surface rupture, ground shaking, landsliding, differential settlement, liquefaction, and lateral spreading. (1) Surface rupture occurs along active fault traces, or where compressed and distorted soils break open to relieve earthquake-induced stress. When this occurs on a fault, everything built across the trace or line of the fracture is generally destroyed, but if it occurs in the course of stress relief, the damage is usually less catastrophic. As noted above, no active or potentially active fault traces have been identified in the Plan Area. (2) Ground shaking is caused by the seismic waves that radiate out from an earthquake's epicenter. The severity of ground shaking at a particular location is primarily determined by distance from the epicenter of the earthquake and by the local soil profile. Loose or unconsolidated sedimentary deposits (such as alluvial soils) can transform the relatively high frequency (back and forth) motion of underlying bedrock into lower frequency but higher amplitude motion at the surface. The most commonly used intensity scale for measuring earthquakes is the Modified Mercalli Intensity (MMI) scale. The intensity of ground shaking at a site varies for any particular earthquake based on several factors, including the size (magnitude) of the earthquake (which is related to the length of the fault that ruptures); the distance from the site to the fault source for the earthquake; the directivity (focusing of earthquake energy along the fault axis rather than perpendicular to the fault); and the type of geologic material underlying the site, with stronger shaking occurring on softer soils. 1 Table 8-2 shows the Mercalli intensity and moment magnitude scales with a description of effects typically experienced during earthquakes. (3) Landsliding entails sudden slope failure. Due to the generally flat topography of the Plan Area, landsliding does not pose a significant concern. (4) Differential settlement normally occurs within unconsolidated soils subjected to unequal surface loading. Movement of the ground causes an additional compaction of the soil that is proportional to the soil's pre-existing density and to the magnitude of imposed loads. These 1 Association of Bay Area Governments, Earthquake and Hazards Program, The San Francisco Bay Area: On Shaky Ground--Documentation for 2003 Mapping Updated in 2010.

5 February 2, 2017 Page 8-5 Table 8-2 MODIFIED MERCALLI INTENSITY SCALE AND MOMENT MAGNITUDE SCALE Magnitude Intensity/Shaking Description/Damage 1.0 to 3.0 I. Not Felt Not felt except by a very few under especially favorable conditions. 3.0 to 3.9 II. Weak Felt only by a few persons at rest, especially on upper floors of buildings. 3.0 to 3.9 III. Weak Felt quite noticeably by people indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated. 4.0 to 4.9 IV. Light Felt indoors by many, outdoors by few people during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. 4.0 to 4.9 V. Moderate Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop. 5.0 to 5.9 VI. Strong Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight. 5.0 to to 6.9 VII. Very Strong Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. 6.0 to to VIII. Severe IX. Violent Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations X. Extreme Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent. SOURCE: USGS Earthquake Hazards Program, 2016.

6 February 2, 2017 Page 8-6 conditions often result in unequal settlement, which can cause the failure of poorly stabilized cut-and-fill embankments and of foundations that are not properly engineered to span areas of discontinuous support. (5) Liquefaction is a loss of foundation support that occurs in saturated granular soils, most notably loose, uniformly graded, fine-grained sand. Under liquefaction, these materials can experience a temporary loss of strength due to build-up of excess pore water pressure, especially during cyclic loadings such as those induced by earthquakes. When this occurs, significant total and differential settlement of structures built on the surface can result. According to ABAG, liquefaction susceptibility for alluvial fan deposits in virtually all of the Plan Area is moderate, but along Ledgewood Creek the liquefaction susceptibility is high. 1 Table 8-3 shows liquefaction hazards based on Modified Mercalli Intensity and liquefaction susceptibility. (6) Lateral spreading occurs when local ground shaking causes generally flat-lying alluvial deposits to be displaced horizontally toward an open cut or excavation (such as along the side of a drainage channel). As mentioned in subsection above, three creeks pass through the Plan Area: Ledgewood Creek, which crosses underneath I-80 at Auto Mall Parkway and runs southeast across Woolner Avenue, then past Beck Avenue to SR 12; Pennsylvania Avenue Creek, which is contained in a culvert alongside Pennsylvania Avenue until it exits to a concrete-lined ditch near Illinois Street before crossing SR 12; and Union Avenue Creek, which passes in an open ditch underneath the railroad tracks east of Union Avenue and then runs north near Delaware and Clay Street before going into a culvert at Texas Street. (7) Subsidence is the motion of the ground as it shifts downward, mainly from the removal of subsurface water. 8.2 REGULATORY SETTING Fairfield Municipal Code. Municipal Code chapter 6 (Disasters and Emergencies) pertains to City emergency organization and (1) creates a Disaster Council to develop a City emergency plan and mutual aid plans, agreements, ordinances, rules, and regulations to implement the plan; and (2) authorizes the City Manager to perform as Director of Emergency Services in the event of a local- or State-declared emergency. Fairfield Public Works Department General Development Conditions. The Public Works Department applies General Development Conditions to individual development proposals. Many of the conditions directly and proactively address environmental issues relevant to this CEQA EIR analysis. A General Development Condition related specifically to CEQA geology and soil issues is: An erosion and sedimentation control plan shall be included as part of the grading plan submittal, subject to review and approval by the City Engineer. Alquist-Priolo Earthquake Fault Zoning Act. The Alquist-Priolo Earthquake Fault Zoning Act was passed in 1972 to mitigate the potential hazard of surface faults to structures for human occupancy. The main purpose of the Act is to prevent the construction of human-occupied 1 ABAG Resilience Program, accessed 2/29/16.

7 February 2, 2017 Page 8-7 Table 8-3 ESTIMATE OF LIQUEFACTION HAZARD BASED ON COMBINATIONS OF MODIFIED MERCALLI INTENSITY AND LIQUEFACTION SUSCEPTIBILITY MMI Description of Liquefaction Susceptibility Category Value Shaking Severity Very Low Low Moderate High Very High V Light VI Moderate VII Strong Moderately Moderately Moderate Low Low VIII Very Strong Moderate Moderate High IX Violent High High High X Very Violent High High High SOURCE: ABAG Earthquake and Hazards Program, Supplementary Information Used for the 2011 Update of ABAG's Liquefaction Hazard Maps, September buildings over active faults. The Act only addresses the hazard of fault rupture and is not directed toward other earthquake hazards. The Act requires the State Geologist to establish regulatory zones (known as Earthquake Fault Zones) around the surface traces of active faults and to issue maps to all affected cities, counties, and State agencies for their use in planning and controlling development. Local agencies must regulate most development projects within the zones, and generally there can be no construction for human occupancy within 50 feet of an active fault zone. Seismic Hazards Mapping Act. The Seismic Hazards Mapping Act addresses earthquake hazards other than fault rupture, including liquefaction and seismically induced landslides. Seismic Hazard Zones are mapped by the State Geologist to assist local governments in land use planning. Due to funding limitations, Seismic Hazard Zone maps have only been completed in selected portions of the Bay Area; Solano County (and Fairfield) have not been included at this time. As maps become available, though, affected cities and counties are required to condition project approval on the incorporation of necessary mitigation measures related to site remediation, structure and foundation design, and seismic hazards avoidance. California Building Standards Code. The California Building Standards Code (CBSC) is contained in the California Code of Regulations (CCR), Title 24. The purpose of the CBSC is to establish minimum standards to safeguard the public health, safety, and general welfare through structural strength, means of egress facilities, and general stability, by controlling the design, construction, quality of materials, use and occupancy, location, and maintenance of building and structures. The 2016 CBSC is based on the 2015 International Building Code (IBC) published by the International Code Council. The CBSC contains specific requirements

8 February 2, 2017 Page 8-8 for seismic safety, excavation, foundations, retaining walls, and site demolition. It also regulates grading activities, including drainage and erosion control. Association of Bay Area Governments (ABAG) Multi-Jurisdictional Local Hazard Mitigation Plan. The ABAG Multi-Jurisdictional Local Hazard Mitigation Plan ( Taming Natural Disasters ) involves local agencies throughout its nine-county Bay Area jurisdiction, with an overall strategy to maintain and enhance disaster response of the region. The plan focuses on mitigation before rather than after disasters by: (1) identifying natural hazards faced by the community and region (e.g., earthquakes, flooding, severe weather), (2) assessing the community s and region s vulnerability to these hazards, and (3) identifying specific preventive actions that can be taken to reduce the risk from the hazards. The plan, which has been approved by FEMA and adopted by ABAG, fulfills the requirements of the Federal Disaster Mitigation Act of The adopted its 2010 Local Hazard Mitigation Plan Annex, which was incorporated into the ABAG Plan and also approved by FEMA. Adoption of the Annex allows the to become eligible for State and federal disaster assistance. Federal Disaster Mitigation Act of The Disaster Mitigation Act of 2000 authorizes the Federal Emergency Management Agency (FEMA) to set mitigation planning requirements for state, local, and Indian Tribal governments as a condition of mitigation grant and disaster assistance, and requires close coordination of mitigation planning and implementation efforts between FEMA and jurisdictions. 8.3 IMPACTS AND MITIGATION MEASURES This section describes potential impacts related to geology (including seismicity) and soils that could result from the Heart of Fairfield Plan, and discusses components of the Plan that would avoid or reduce those potential impacts. The section also recommends mitigation as needed to reduce potentially significant impacts to less-than-significant levels Significance Criteria Based on the CEQA Guidelines, 1 implementation of the Heart of Fairfield Plan would have a significant impact related to geology and soils if it would: (a) Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: (1) Rupture of a known earthquake fault, as delineated on the most recent Alquist- Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault (Division of Mines and Geology Special Publication 42); (2) Strong seismic ground shaking; (3) Seismic-related ground failure, including liquefaction; or 1 CEQA Guidelines, appendix G, item VI (a through e).

9 February 2, 2017 Page 8-9 (4) Landslides; (b) Result in substantial soil erosion or the loss of topsoil; (c) Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landsliding, lateral spreading, subsidence, liquefaction, or collapse; (d) Be located on expansive soil, as defined by Table 18-1-B of the Uniform Building Code, creating substantial risks to life or property; or (e) Have soils incapable of adequately supporting the use of septic tanks or alternative wastewater disposal systems where sewers are not available for the disposal of wastewater; Regarding criterion (a)(1), there are no known active faults in the Plan Area (see Setting, above). No impact from fault rupture would result, and this issue is not discussed further. Regarding criterion (a)(4), the Plan Area and vicinity are relatively flat. Due to the absence of appreciable slopes in the vicinity, slope stability hazards are considered less-than-significant. No significant impact would result, and no mitigation is required. This issue is not discussed further. Regarding criterion (e), the Plan Area is served by a comprehensive, integrated wastewater collection, treatment, and disposal system. Neither septic tank systems nor alternative wastewater disposal systems are proposed as part of Plan implementation. No impact would result, and this issue is not discussed further. The California Supreme Court decision (December 2015) in California Building Industry Association v. Bay Area Air Quality Management District concluded, [W]e hold that CEQA does not generally require an agency to consider the effects of existing environmental conditions on a proposed project s future users or residents. What CEQA does mandate is an analysis of how a project might exacerbate existing environmental hazards. The environmental impact analysis in this section (and throughout the EIR) takes into consideration this Court decision Relevant Specific Plan Components The Regulatory Setting above applies to Heart of Fairfield Plan implementation. The Plan document itself does not include additional components directly related to geology and soils Impacts and Mitigations Effects of Strong Seismic Ground Shaking. Based on the information included in Table 8-1 above, the Plan Area could experience strong seismic ground shaking and related effects in the event of an earthquake on the fault or on one of the other identified active or potentially active faults in the region. Mandated project compliance with the stringent seismic design provisions of the latest California Building Standards Code (CBSC), as adopted by the City, would reduce the risk of property loss or hazards to occupants to a less-than-significant level (see criterion [a][2] in subsection 8.3.1, Significance Criteria, above). Mitigation. No significant impact has been identified; no mitigation is required.

10 February 2, 2017 Page 8-10 Potential Soil Erosion and Loss of Topsoil. Grading and construction activities may result in minor erosion or the minor loss of some topsoil. City-required standard grading- and construction-period erosion control techniques (e.g., for reducing surface water runoff over exposed soil) would mitigate this potential impact to a less-than-significant level (see criterion [b] in subsection 8.3.1, Significance Criteria, above). Mitigation. No significant impact has been identified; no mitigation is required. Also see chapter 5 (Air Quality) and chapter 11 (Hydrology and Water Quality) of this EIR for more detail. Impact 8-1: Potential Ground Instability Impacts. The potential for ground instability can depend on specific, highly localized underlying soil conditions. Determination of differential settlement, liquefaction, lateral spreading, and subsidence potential in the Plan Area would require site-specific geotechnical studies for future, discretionary, individual development proposals. Possible ground instability conditions, if not properly engineered for, could result in associated significant damage to project buildings and other improvements, representing a potentially significant impact (see criteria [a][3], [c], and [d] in subsection 8.3.1, Significance Criteria, above). Any potential for earthquake-induced on-site differential settlement, liquefaction, lateral spreading, and subsidence, and associated damage to proposed buildings or other improvements can be mitigated to a less-than-significant level through implementation of Cityrequired geotechnical investigations and associated engineering design standards, specifications, and measures. Geotechnical mitigation requirements identified here include completion of detailed studies to address specific concerns as future site-specific project designs are refined. The CEQA Guidelines and recent court decisions indicate that mitigation measures must be mandated that will alter the potentially significant soil and geologic impacts of the project. In particular, mitigation measures must ensure that a project would be implemented in a manner that renders insignificant or minimizes potentially significant soil and geologic impacts of the project. There is substantial, reasonable, historical information to support the conclusion that the specific subsequent geotechnical/geologic investigations, inspections, and specific formulations required to meet City-adopted standards would adequately mitigate related impacts to less-than-significant levels. The routinely requires such geotechnical/geologic investigations and specifications at phases of discretionary development review that follow CEQA compliance. Individual measures are typically, and most efficiently, specified at a later, more detailed level of design. A significant record exists demonstrating the effectiveness of such post-ceqa-certification design and engineering requirements in mitigating the potential soil and geology impacts of concern. Under the City's grading permit and building permit provisions, requirements, and regulations, an individual development project cannot be given final approval without project compliance with geotechnical/geologic requirements. These requirements and related City inspection and verification procedures prior to project operation provide reasonable, professional assurances that the project would incorporate the design and engineering refinements necessary to reduce the degree of impacts to less-than-significant levels by either avoiding identified soil and geologic impact areas altogether (i.e., basic project design

11 February 2, 2017 Page 8-11 changes), or by rectifying the impact through conventional engineering and construction procedures (e.g., suitable foundation design and construction) identified throughout the post- EIR investigation and monitoring process. Mitigation 8-1. Subject to City review and approval, complete and implement the geotechnical mitigation recommendations identified in the required individual projectand site-specific geotechnical investigations and engineering studies for discretionary proposals, in coordination with City grading permit and building permit performance standards. Incorporation of this mitigation requirement would reduce this impact to a less-than-significant level.

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