4.6 GEOLOGY AND SOILS


City of Ceres Mitchell Ranch Center May 2010 Draft Environmental Impact Report

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This section of the Draft Environmental Impact Report (Draft EIR or DEIR) for the proposed Mitchell Ranch Center project describes the geology of the project site and surrounding vicinity and analyzes potential exposure of people and future improvements to geologic hazards, soil instability, and erosion. It also discusses the types of soil that have been identified on the site and their properties as they relate to the proposed project. The analysis contained in this section is based primarily on the Preliminary Geotechnical Engineering Analysis prepared for the project site by Consolidated Engineering Laboratories in June 2006 (see Appendix 4.6-1). The site plan has changed since this report was prepared; however, Consolidated Engineering Laboratories has subsequently reviewed the revised site plan and has prepared a letter certifying that the changes have no effect on their findings or recommendations (see summary memorandum of August 20, 2008 in Appendix 4.6-1). This section of the Draft EIR was also based on a review of other relevant data, including the City of Ceres General Plan, the Stanislaus County General Plan, and the Natural Resource Conservation Service’s Web Soil Survey and Official Soil Series Descriptions.

Following publication of the Notice of Preparation/Initial Study (NOP/IS), a comment letter was received from Sherri Jacobson that included a comment about the loss of topsoil.

4.6.1 ENVIRONMENTAL SETTING

REGIONAL GEOLOGIC SETTING

The project site is located in the Great Valley Geomorphic Province of California, which is an alluvial plain about 50 miles wide and 400 miles long. The Great Valley comprises the Sacramento Valley in the north and the San Joaquin Valley in the south. The alluvial plain is composed of thousands of feet of sedimentary deposits that have undergone periods of subsidence and uplifting over millions of years. Most of the surface of the Great Valley is covered with Recent (Holocene, i.e., 10,000 years before present to present day) and Pleistocene (i.e., 10,000 to 1,800,000 years before present) alluvium. This alluvium is composed of sediments from the Sierra Nevada to the west and the Coast Range to the east that were carried by water and deposited on the valley floor. Siltstone, claystone, and sandstone are the primary types of sedimentary deposits. Surface elevations within the Great Valley generally range from several feet below mean sea level (msl) to more than 1,000 feet above msl (CGS, 2002).

SITE GEOLOGIC SETTING

The project site is relatively flat with no significant topographical features. The elevation of the site ranges from 90 to 95 feet above msl.

FAULTING AND SEISMIC HAZARDS

There are no faults known to exist within the valley portion of Stanislaus County where the City of Ceres lies; however, faults do exist in the extreme eastern part of the county and in the Diablo Range west of Interstate 5. In the east, the Bear Mountain and Melones faults are found, though they are believed to have been inactive for the past 150 million years. Within the Diablo Range, the most recent movements were along the Tesla-Ortigalita fault approximately five million years ago, although minor earthquake activity without surface fracturing or faulting has occurred in recent time (City of Ceres, 2003). A portion of this fault is designated as an Alquist-Priolo Earthquake Fault Zone. The City of Ceres is not identified as a city affected by this or any other Alquist-Priolo Earthquake Fault Zone (DOC, 1997). The city is in California Building Code Seismic


Mitchell Ranch Center City of Ceres Draft Environmental Impact Report May 2010

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Zone 3, indicating moderate potential for ground shaking; however, the city has experienced no recorded seismic activity (City of Ceres, 1997).

Liquefaction and Seismic-Related Ground Failure

Liquefaction occurs when loose granular and silty soils that are saturated with water behave like a liquid when shaken by an earthquake. Three factors are required for liquefaction to occur: (1) loose, granular sediment; (2) saturation of the sediment by groundwater; and (3) strong ground shaking. Liquefaction can result in the following types of seismic-related ground failure:

• Loss of bearing strength – soils liquefy and lose the ability to support structures

• Lateral spreading – soils slide down gentle slopes or toward stream banks

• Flow failures – soils move down steep slopes with large displacement

• Ground oscillation – surface soils, riding on a buried liquefied layer, are thrown back and forth by shaking

• Flotation – floating of light buried structures to the surface

• Settlement – settling or subsidence of ground surface as soils reconsolidate (USGS, 2006)

The project site is not considered to be prone to liquefaction or liquefaction-induced phenomena. The granular soils located about 15 feet below the project site are generally medium-dense and the levels of expected ground shaking from large, distant earthquakes are relatively low (Consolidated Engineering Laboratories, 2006).

SOIL CONDITIONS AND HAZARDS

Site Soil Conditions

Project site soils are of the Hanford sandy loam series as illustrated by Figure 4.6-1 and described in Table 4.6-1 below.

TABLE 4.6-1 PROJECT SITE SOILS

Soil Type Map Symbol Acres Percent of Site

Hanford sandy loam, 0 to 3 percent slopes HdA 0.1 0.004

Hanford sandy loam, moderately deep over silt, 0 to 1 percent slopes HdpA 26.3 99.996

Source: NRCS Web Soil Survey, 2007b

The project site soils are fairly similar having a soil erodibility factor (K-factor) of 0.32, a rainfall/runoff erosivity factor of 22, and a pH of 7.0. The K-factor represents both susceptibility of soil to erosion and the rate of runoff. A K-factor of 0.32 indicates that the soils are moderately susceptible to erosion due to their medium texture and moderate runoff. The R-factor is a measure of the erosion force of an area’s rainfall based on the amount of rainfall and peak intensity of rainfall sustained over an extended period. An R-factor of 22 indicates that the site has a relatively low rainfall/runoff erosivity potential (Michigan State University, n.d.).

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In addition, both soils contain approximately 12.5 percent clay and are assigned a Hydrologic Group rating of B, soils with a moderate infiltration rate when thoroughly wet (Consolidated Engineering Laboratories, 2006).

Consolidation

Consolidation is the densification of soil into a more dense arrangement from additional loading, such as new fills or foundations. Consolidation of sandy soils is usually a short-term process whereby the water is squeezed out of the soil matrix relatively rapidly with the introduction of a load. Consolidation of loose soil layers and lenses can cause settlement of the ground surface or buildings.

The density/consistency of the soils encountered in the borings and the results of the consolidation test performed by Consolidated Engineering Laboratories (2006) indicated that the near-surface soil has a moderate potential to consolidate and the subsurface soil below a depth of 5 feet has a low potential to consolidate under the proposed building loads. Special grading considerations for settlement of the surficial soils will be required.

Dynamic Compaction

Dynamic compaction is the densification of predominantly sandy soil above the water table caused by vibration, such as an earthquake or vibrating machinery. Forklift traffic in warehouses has been documented to cause dynamic compaction of loose, sandy trench backfill, causing floor slabs to crack and settle. Loose shading material above utility pipes could also be prone to this phenomenon. The loose sand densifies under the vibratory loading, possibly causing settlement of the ground surface. According to the geotechnical study prepared for the proposed project, the potential for settlement from dynamic compaction is low at the project site (Consolidated Engineering Laboratories, 2006).

Expansive Soils

A potential geotechnical concern at any site is the expansion potential of near-surface soils. Over time, expansive soils will experience cyclical drying and wetting throughout the year. As the moisture content of clay soils fluctuates with the dry and wet seasons, the soil will alternatively shrink and swell. These volumetric changes can affect buildings and foundations if not properly designed to absorb the shrinking and swelling (USGS, 2006).

Based on the sandy nature of the project site soils, the subsurface soils are considered to be nonexpansive (Consolidated Engineering Laboratories, 2006).

Subsidence

Land subsidence occurs when groundwater levels decline, typically due to excessive groundwater pumping, resulting in soil compaction. The Sacramento and San Joaquin valleys have experienced significant subsidence from excessive groundwater pumping for irrigation (Consolidated Engineering Laboratories, 2006). This condition was slowed or stopped in most affected areas of the valley in the 1970s through a reduction of groundwater withdrawals and importation of surface water (USGS, n.d.).

Since then, groundwater levels in the valley have largely rebounded including the Turlock Subbasin which has rebounded to just below 1970-levels (DWR, 2006). Regardless, subsidence continues to be a potential risk throughout the valley. According to the Stanislaus County



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General Plan, groundwater levels in the Modesto area appear to be good except in the extreme eastern portion where a cone of depression has developed due to extensive groundwater pumping and insufficient recharge caused by continuing development (Stanislaus County, 1994). The City of Ceres is not located within a cone of depression, and is within a separate groundwater basin than Modesto. The City of Ceres and surrounding communities rely almost entirely on groundwater as their municipal water supply (City of Ceres, 1997).

Asbestos and Asbestiform Materials

Asbestos is the generic term for the naturally-occurring fibrous (asbestiform) varieties of six silicate minerals. These minerals are chrysotile, fibrous tremolite, fibrous actinolite, crocidolite (fibrous riebeckite), fibrous anthophyllite, and amosite (fibrous cummingonite-grunerite). Chrysotile is the most common asbestos mineral in California and belongs to the serpentine mineral group. The remaining asbestos minerals belong to the amphibole mineral group (EPA, 2007).

Asbestiform minerals occur naturally in rock and soil as the result of geologic processes, often in veins near earthquake faults in the coastal ranges and the foothills of the Sierra Nevada. Naturally-occurring asbestos (NOA) can take the form of long, thin, separable fibers. Natural weathering or human disturbance can break NOA down to microscopic fibers easily suspended in air. There is no health risk if asbestos fibers in soil remain undisturbed and do not become airborne. When inhaled, these thin fibers irritate tissues and resist the body’s natural defenses. Asbestos, a known carcinogen, causes cancers of the lung and the lining of internal organs, as well as asbestosis and other diseases that inhibit lung function (EPA, 2007).

According to maps prepared by the California Division of Mines and Geology, a small area in far western Stanislaus County is likely to contain NOA. However, no areas in central Stanislaus County, near the project site, were identified as being likely to contain NOA (CDMG, 2000).

Asbestos also refers to an industrial product obtained by mining and processing deposits of the asbestiform minerals listed above. Asbestos products are discussed in Section 4.2, Air Quality, of this Draft EIR.

Erosion

Erosion is the displacement of solids (soil, mud, rock, and other particles), usually by the agents of currents such as wind, water, or ice by downward or down-slope movement in response to gravity. Construction activities such as grading, excavation, and soil hauling can cause soil disturbance and exposure to wind and water, resulting in accelerated erosion. Soil loss can be evaluated using the Universal Soil Loss Equation, which utilizes site-specific factors, including the soil erodibility factor (K-factor) and the rainfall/runoff erosivity factor (R-factor) of the soils. The K-factor for the site is 0.32, indicating a slight erosion hazard. The R-factor for the site is approximately 22, also indicating a relatively low potential for erosion (Consolidated Engineering Laboratories, 2006; Michigan State University, n.d.).

4.6.2 REGULATORY FRAMEWORK

STATE

Alquist-Priolo Earthquake Faulting Zone Act

The Alquist-Priolo Earthquake Fault Zoning Act of 1972 (prior to January 1, 1994, called the Alquist-Priolo Special Studies Zones Act – CCR, Title 14, Section 3600) sets forth the policies and



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criteria of the State Mining and Geology Board, which governs the exercise of governments’ responsibilities to prohibit the location of developments and structures for human occupancy across the trace of active faults. The policies and criteria are limited to potential hazards resulting from surface faulting or fault creep within Earthquake Fault Zones, as delineated on maps officially issued by the State Geologist. Working definitions include:

Fault – A fracture or zone of closely associated fractures along which rocks on one side have been displaced with respect to those on the other side.

Fault Zone – A zone of related faults, which commonly are braided and sub-parallel, but may be branching and divergent. A fault zone has a significant width (with respect to the scale at which the fault is being considered, portrayed, or investigated), ranging from a few feet to several miles.

Sufficiently Active Fault – A fault that has evidence of Holocene surface displacement along one or more of its segments or branches (last 11,000 years).

Well-Defined Fault – A fault whose trace is clearly detectable by a trained geologist as a physical feature at or just below the ground surface. The geologist should be able to locate the fault in the field with sufficient precision and confidence to indicate that the required site-specific investigations would meet with some success.

“Sufficiently active” and “well defined” are the two criteria used by the State of California to determine if a fault should be zoned under the Alquist-Priolo Act.

California Building Code

California Code of Regulations, Title 24, also known as the California Building Standard Code or the California Building Code (CBC), establishes guidance for foundation design, shear wall strength, and other structurally related concerns. The CBC includes common engineering practices requiring special design and construction methods that reduce or eliminate potential expansive soil-related impacts. The CBC requires structures to be built to withstand ground shaking in areas of high earthquake hazards and the placement of strong motion instruments in larger buildings to monitor and record the response of the structure and the site of seismic activity. Compliance with CBC regulations ensures the adequate design and construction of building foundations to resist soil movement. In addition, the CBC also contains drainage requirements in order to control surface drainage and to reduce seasonal fluctuations in soil moisture content.

LOCAL

City of Ceres General Plan

The City of Ceres General Plan was adopted in February 1997 and serves as the overall guiding policy document for land use, development, and environmental quality for the City. The Health and Safety Element identifies policies associated with geology and soils. Table 4.6-2 analyzes the proposed project’s consistency with applicable City of Ceres General Plan Health and Safety Element policies. While this Draft EIR analyzes the consistency of the proposed Mitchell Ranch Center project with the City of Ceres General Plan pursuant to California Environmental Quality Act (CEQA) Guidelines Section 15125(d), the City of Ceres will ultimately make the determination of the proposed project’s consistency with the General Plan. Environmental impacts associated



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with inconsistency with General Plan goals and policies are addressed under the appropriate impact discussion sections of this Draft EIR.

TABLE 4.6-2

PROJECT CONSISTENCY WITH CITY OF CERES GENERAL PLAN POLICIES: GEOLOGY AND SOILS

General Plan Policy Consistency

with General Plan

Analysis

Policy 4.E.5. The City shall require appropriate mitigation for grading activities during the rainy season to avoid sedimentation of storm drainage facilities.

Yes The project applicant will be required to prepare and implement an approved Stormwater Pollution Prevention Plan (SWPPP) for all construction activities including grading. The SWPPP will include best management practices (BMPs) to minimize the potential for soil erosion and sedimentation and to protect downstream waterways and drainage facilities. See Impact 4.6.2 and Section 4.8, Hydrology, Drainage, and Water Quality.

Policy 6.B.4. The City shall continue to require the use of feasible and practical best management practices (BMPs) to protect receiving waters from the adverse effects of construction activities and urban runoff.

Yes The project applicant will be required to prepare and implement an approved Stormwater Pollution Prevention Plan (SWPPP) for all construction activities including grading. The SWPPP will include best management practices (BMPs) to minimize the potential for soil erosion and sedimentation and to protect downstream waterways and drainage facilities. See Impact 4.6.2 and Section 4.8, Hydrology, Drainage, and Water Quality.

Policy 7.A.3. The City shall require that new structures and alterations to existing structures comply with the current edition of the Uniform Building Code.

Yes All new structures constructed as part of the proposed project will be designed and built in compliance with the most recent version of the California Building Code, which has replaced the Uniform Building Code for foundation design, shear wall strength, and other structurally related concerns. Additionally, the City of Ceres Development Services Department, Building Division, will review all project plans and will perform inspections of the project site to ensure compliance with the California Building Code and any other applicable City construction standards.

Policy 7.A.6: The City shall avoid siting of structures across soil materials of substantially different expansive properties.

Yes Project site soils are of the Hanford soil series. Soil series are identified and classified based on groupings of soils with very similar characteristics. Therefore, it is reasonable to assume that the expansive properties of the project site soils are similar throughout. Mitigation measure MM 4.6.1 requires the preparation of a geotechnical study of the project site to determine, among other things, the expansive potential of project site soils.



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Mitchell Road Corridor Specific Plan

The proposed Mitchell Ranch Center project is located within the Mitchell Road Corridor Specific Plan, which establishes guidelines and regulations for the development of approximately 450 acres located along a 2.5-mile stretch of Mitchell Road. The Specific Plan, however, has no policies pertaining to geology and soils that are applicable to the proposed project.

Ceres Municipal Code Chapter 17.24

Chapter 17.24 of the City’s Municipal Code requires the preparation of a preliminary soils report for any proposed subdivision prior to approval of a final subdivision map. If such a report indicates the presence of critically expansive soils or other soil problems which, if not corrected, would lead to structural defects, a soil investigation is required for the site including recommendations for corrective action to prevent structural damage to proposed buildings prior to issuance of building permits.

4.6.3 PROJECT IMPACT ANALYSIS

STANDARDS OF SIGNIFICANCE

Based on the CEQA Guidelines Appendix G thresholds of significance, the proposed project would create a significant impact if it would:

• Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving seismic-related ground failure, including liquefaction.

• Result in substantial soil erosion or the loss of topsoil.

• Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the proposed project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction, or collapse.

• Be located on expansive soil, as defined in the California Building Code, creating substantial risks to life or property.

The Initial Study prepared for the proposed project (see Appendix 1.0-1) determined that implementation of the proposed project would have no impact or a less than significant impact related to rupture of a known earthquake fault, landslides, mineral resources, and soil stability associated with septic tanks. Therefore, these issues will not be addressed further in this Draft EIR.

METHODOLOGY

The following analysis is based primarily on the Preliminary Geotechnical Engineering Analysis prepared for the project site by Consolidated Engineering Laboratories in 2006. The Stanislaus County General Plan and the California Probabilistic Seismic Hazard Maps prepared by the California Geologic Survey were reviewed to determine the location of faults in the region as well as to estimate the likelihood of earthquake ground motion in the vicinity of the project site. The Stanislaus County Soil Survey and the Natural Resources Conservation Service (NRCS) Official Soil Series Descriptions were also reviewed to determine the general characteristics of the project site soils and the associated potential for liquefaction, ground failure, and expansive soils. In addition, the proposed project designs were evaluated to determine the potential for construction activities to disturb soils or otherwise result in erosion.



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IMPACTS AND MITIGATION MEASURES

Ground Failure

Impact 4.6.1 Implementation of the proposed project may expose people, structures, and development to ground failure from seismic activity or unstable soils. This is a potentially significant impact.

According to the Preliminary Geotechnical Engineering Analysis prepared for the project site, the site is not considered to be prone to liquefaction or liquefaction-induced phenomena. The granular soils below about 15 feet are generally medium-dense and the levels of expected ground shaking from large, distant earthquakes are relatively low. The geotechnical analysis also indicates that the potential for settlement from dynamic compaction at the site is low.

The density/consistency of the soils encountered in the borings and the results of the consolidation test performed by Consolidated Engineering Laboratories (2006) indicate that the near-surface soil has a moderate potential to consolidate and the subsurface soil below a depth of 5 feet has a low potential to consolidate under the proposed building loads. Special grading considerations are necessary to address settlement of soils from ground level to a depth of approximately 5 feet.

As described above, the project site is located in the San Joaquin Valley, which has experienced significant historical and, in some areas, recent subsidence due primarily to groundwater pumping. Although the project site is not likely susceptible to seismic activity due to the distance to active faults, the potential for seismic activity does exist. Significant subsidence in an area can affect building foundations and roadways if they are not properly designed. As noted, this is a potentially significant impact and warrants mitigation.

Mitigation Measures

MM 4.6.1 The project shall comply with the recommendations of the Preliminary Geotechnical Engineering Analysis prepared by Consolidated Engineering Laboratories in June 2006 (see Appendix 4.6-1). These recommendations include the following:

• Existing Structures and Trees – All existing structures to be abandoned shall be demolished and foundations entirely removed or cut off. Any existing trees that are to be abandoned shall have their major root systems removed. Additionally, buried objects from past land use activities that are encountered during construction shall be removed.

• Loose Near-Surface Soil – The presence of loose near-surface soil will require over-excavation and compaction in the building pad areas.

• Underground Utility/Trench Excavation – Due to the sandy soils at the project site, trench walls may not stand vertical during and after excavation. All project contractors shall be notified of the potential for sloughing of utility trench and foundation excavation sidewalls.

• Winter Grading – If grading occurs during the rainy season, unstable subgrade conditions may be encountered. Project site soils shall be



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treated/stabilized prior to grading or other soil-disturbing activities during the winter months.

• Seismic Considerations – The site is located proximal to a seismically active region. At a minimum, the building designs shall comply with the latest edition of the California Building Code.

Timing/Implementation: Ongoing during project construction and mitigation shall be noted on the improvement plans.

Enforcement/Monitoring: City of Ceres Development Services Department Engineering and Planning Divisions

Adherence to the recommendations made in the geotechnical analysis for the proposed project will ensure that the soils between ground level and a depth of five feet are free of debris, incursion by roots and capable of being compacted as needed to support construction. Implementation of mitigation measure MM 4.6.1 reduces this impact to a less than significant level.

Soil Erosion

Impact 4.6.2 The proposed project includes substantial construction and site preparation activities. These activities can increase soil erosion, especially from wind and water, and siltation of local drainages during construction, excavation, and grading activities. This impact is less than significant.

Construction activities during project site development, such as grading, excavation, and soil hauling, would disturb soils and potentially expose them to erosion from a variety of sources, including wind and water. In addition, construction activities generally involve the use of water, which may further erode topsoil as the water drains from the site. As discussed previously in this section, the Hanford sandy loam series has a relatively low potential for erosion.

The proposed development would involve paving and other site improvements, substantially increasing the area of impervious surface (incapable of being penetrated by water). These impervious surfaces generate higher levels of urban runoff, which have the potential to adversely affect surface and groundwater quality in the area. Projects that will disturb one or more acres, such as the proposed project, are subject to coverage under the National Pollutant Discharge Elimination System (NPDES) General Construction Storm Water Permit administered by the State Water Resources Control Board (SWRCB). The project applicant will be required to prepare and implement a Stormwater Pollution Prevention Plan (SWPPP) meeting the requirements of the General Permit. The SWPPP will specify best management practices (BMPs) to avoid soil erosion and associated pollution of waterways. These BMPs may include the scheduling of construction activities for periods of dry weather, the protection of slopes through hydroseeding, mulching, or the use of soil binders, or the protection of waterways through the use of silt fencing or sediment traps and basins. Implementation of the BMPs included in the approved SWPPP will minimize erosion and loss of topsoil on the project site to the greatest extent feasible and will reduce this impact to a less than significant level. The reader is referred to Section 4.8, Hydrology, Drainage, and Water Quality, for further discussion regarding erosion and water quality.



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Mitigation Measures

None required.

Expansive Soils

Impact 4.6.3 Expansion of soils on site could potentially result in damage to building foundations, structures, and paved areas on the site. This impact is considered less than significant.

Expansive or shrink-swell soils are soils that swell when subjected to moisture and shrink when dry. Expansive soils typically contain clay minerals that attract and absorb water, greatly increasing the volume of the soil. This increase in volume can cause damage to foundations, structures, and roadways. The project site contains soils of the Hanford sandy loam series. According to the Preliminary Geotechnical Engineering Analysis, project site soils are nonexpansive. In addition prior to approval of the final map, the City will require (Municipal Code Chapter 17.24) the preparation of a preliminary soil report including soil borings to determine the expansiveness of project site soils. Should expansive soils be identified on the site, the City will require the preparation of a soil investigation prior to issuance of building permits including recommended corrective action to prevent structural damage to the proposed buildings. This impact is less than significant.

Mitigation Measures

None required.

4.6.4 CUMULATIVE SETTING, IMPACTS, AND MITIGATION MEASURES

CUMULATIVE SETTING

Geological impacts tend to be site-specific, rather than cumulative in nature. However, the area of the cumulative setting considered for this analysis includes the City of Ceres, other nearby communities, and the surrounding unincorporated areas of Stanislaus County. Seismic events may damage or destroy a building on the project site, but the construction of a development project on one site will not cause any adjacent parcels to become more susceptible to seismic events, nor can a project affect local geology in such a manner as to increase risks regionally. However, a regional development project could increase the risk of exposure of people to earthquake hazards by attracting large groups of people to an area at significant risk of seismic activities. In addition, impacts regarding surficial deposits, namely erosion and sediment deposition, can be cumulative in nature within a watershed.

CUMULATIVE IMPACTS AND MITIGATION MEASURES

Cumulative Geologic Impacts

Impact 4.6.4 Implementation of the proposed project in combination with reasonably foreseeable development would not contribute to cumulative geologic and soils impacts. The proposed project’s incremental contribution would be less than cumulatively considerable.



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Impacts associated with geology and soils are based on existing site-specific conditions that are situated within the subsurface materials that underlay the project site. These inherent conditions are an end result of natural historical events that have played out through vast periods of geologic time. For these reasons, geologic and soil-related impacts are generally site-specific and are determined by a particular site’s geologic and soil characteristics, topography, and proposed land uses. Development projects are analyzed on an individual basis and must comply with established requirements of the City, the Regional Water Quality Control Board and the CBC as they pertain to protection against known geologic hazards and potential geologic and soil-related impacts. There are no active faults in close proximity to the project site. Furthermore, implementation of mitigation measure MM 4.6.1 and CBC standards that address foundation design, shear wall strength, and other structural-related conditions will minimize effects from earthquakes and subsequent ground shaking. The proposed project itself does not significantly alter regional geologic conditions or increase geologic risks and hazards to surrounding lands. In addition, although the proposed project is regional in nature and could, along with other development projects in the vicinity, attract groups of people from outside the area, the low risk for significant ground shaking in the area and the proper design and construction of the proposed structures, in accordance with the above-referenced standards, would not increase the potential to expose such groups to risks associated with seismic activity.

However, the proposed project has the potential to result in erosion and the loss of topsoil due to construction activities such as grading, excavation, and soil hauling that could expose project site soils to wind and water erosion. This impact could contribute to cumulative soil erosion within the surrounding watershed when considered in combination with other development projects in the area (see Table 4.0-1). As described under Impact 4.6.2 above, all projects in California that will disturb one or more acres are subject to the requirements of the National Pollutant Discharge Elimination System (NPDES). This program requires the implementation of BMPs that minimize the potential for erosion and sedimentation of surrounding and downstream waters. Implementation of BMPs in accordance with the NPDES permit will ensure that the project’s contribution to cumulative geology and soil related impacts would be less than cumulatively considerable.

Mitigation Measures

None required.



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REFERENCES

California Department of Conservation (DOC), Division of Mines and Geology. 1997. Special Publication 42: Fault-Rupture Hazard Zones in California.

California Department of Mines and Geology (CDMG). 2000. A General Location Guide for Ultramafic Rocks in California – Areas More Likely To Contain Naturally Occurring Asbestos.

California Department of Water Resources (DWR). 2006. California Groundwater Bulleti118: San Joaquin Valley Groundwater Basin, Turlock Subbasin.

California Geological Survey (CGS). 2002. Note 36: California Geomorphic Provinces.

City of Ceres. 1997. City of Ceres General Plan Policy Document.

City of Ceres. 2003. Emergency Operations Plan.

Consolidated Engineering Laboratories. 2006. Preliminary Geotechnical Engineering Analysis: Ceres Shopping Center.

Environmental Data Resources Inc. 2007. The EDR Radius Map with GeoCheck: Mitchell Ranch Center Project Site.

Michigan State University, Institute of Water Research. n.d. Revised Universal Soil Loss Equation On-Line Soil Erosion Assessment Tool. http://www.iwr.msu.edu/rusle/ (accessed June 2008).

Stanislaus County. 1994. Stanislaus County General Plan.

United States Department of Agriculture, Natural Resources Conservation Service (NRCS). 2007a. Official Soil Series Descriptions. http://soils.usda.gov/technical/classification/osd/ index.html (accessed August 2007).

United States Department of Agriculture, Natural Resources Conservation Service (NRCS). 2007b. Web Soil Survey. http://websoilsurvey.nrcs.usda.gov/app/ (accessed September 2007).

United States Environmental Protection Agency (USEPAEPA). 2007. Naturally Occurring Asbestos in California. http://www.epa.gov/region09/toxic/noa/ (accessed October 2007).

United States Geological Survey (USGS). 2006. San Francisco Bay Region Geology and Geologic Hazards. http://geomaps.wr.usgs.gov/sfgeo/liquefaction/aboutliq.html (accessed September 2007).

United States Geological Survey (USGS). n.d. Ground Water Atlas of the United States – Segment 1 California Nevada: Land Subsidence. http://ca.water.usgs.gov/groundwater/gwatlas/ valley/landsub.html (accessed June 2008).

4.6 GEOLOGY AND SOILS

Documents

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