3.5 Geology, Soils, and Paleontology

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1 3.5 Geology, Soils, and Paleontology Overview of Impacts The analytical approach taken by this Subsequent EIR is described in Section 3.0 (Introduction to Environmental Analysis). The following section provides a description of existing geological, soil, and paleontological conditions in the SSJID area, identifies plans and regulations applicable to the project, and assesses the potential impacts on geology, soils, and paleontology. An analysis of cumulative impacts from other past, present and reasonably foreseeable projects is included in Section 5 (Cumulative Impacts) of this Subsequent EIR. This table summarizes the geology, soils, and paleontology impacts for each of the four actions evaluated in this EIR. Geology, Soils, and Paleontology Impact 3.5-1: Expose people or structures to potential substantial adverse effects as a result of seismically induced groundshaking and/or ground failure Impact 3.5-2: Result in substantial soil erosion or the loss of topsoil Impact 3.5-3: Damage project facilities as a result of expansive (shrink swell) soils Impact Directly or indirectly destroy a unique paleontological resource Municipal Services Review Expanded Sphere of Influence Proposed 80-acre Annexation No Impact No Impact Less than Significant No Impact No Impact Less than Significant No Impact No Impact Less than Significant Updated Plan to Provide Retail Electric Service Less than Significant with Mitigation Less than Significant with Mitigation Less than Significant No Impact No Impact No Impact Less than Significant with Mitigation Existing Setting The Sphere Plan and MSR describe existing and planned services provided by SSJID, and these services are considered preexisting or previously approved for the purposes of this EIR. Section 2.0 describes the activities outlined in the Sphere Plan and MSR that are considered preexisting or previously approved activities rather than part of the proposed project. Activities supporting SSJID s existing services are either considered part of the baseline, to the extent that they have already been undertaken, or included in the cumulative impacts analysis as reasonably foreseeable projects, to the extent that they have yet to be implemented. SSJID is obligated to extend its services to anyone who requests service within the SSJID boundary, subject to standard terms and conditions. Infrastructure supporting SSJID s existing services protect against exposure to risks from geologic hazards by being built to the applicable design specifications of local jurisdictions and building codes Geology and Soils The SSJID territory is within the San Joaquin Valley, which is a deep structural basin of Cretaceous and Tertiary age marine and continental sediments shed from the Sierra Nevada Range to the east. More November Draft Subsequent EIR

2 recent tectonic forces including regional uplift and the associated folding and faulting of these basin deposits formed the Coast Ranges. The Cretaceous deposits comprise the Franciscan Complex and the Great Valley Sequence. The Tertiary sediments deposited on the Cretaceous sequence are composed predominantly of sandstone and shale with minor conglomerate beds, and typically dip toward the San Joaquin Valley. Deep, well drained agricultural soils created by sediments washed out of the region s major rivers characterize the San Joaquin Valley floor. Beneath the recent (Holocene) wind driven deposits and alluvium, Late Quaternary sediments of the project area are chiefly of fluvial origin. The young alluvial deposits characterize the valley floor and the soils long used for agriculture in the SSJID territory. Soil textures range from fine in lower and less well drained basin areas to medium in the low alluvial fan and terrace areas, with deposits of coarse grained sands and gravels. The SSJID territory does not have expansive soils and the erosion hazard rating is slight, indicating that erosion is unlikely under ordinary climatic conditions (San Joaquin County, 1999; and NRCS, 2011) Seismic Hazards There are several seismic faults in San Joaquin County, including the Patterson Pass Fault, Tesla Fault, Midway Fault, Black Butte Fault, and the Tracy Stockton Fault. However, none of the faults in the County have been identified as active by the State Geologist (San Joaquin County, 1992), so there is low potential for fault surface rupture to occur in the project area. Ground shaking and liquefaction would most likely occur in the project area as a result of an earthquake along one of the northern California s active faults, such as the San Andreas Fault or the Hayward Fault, which are located approximately 65 and 45 miles west southwest of the project area, respectively (San Joaquin County, 1992). The effects of a major earthquake in the region could result in maximum ground shaking in the project area of intensity VII+ on the Modified Mercalli Scale (San Joaquin County, 1992), which could cause significant damage to old unreinforced masonry buildings. Earthquake induced liquefaction would most likely occur where soils are saturated less than 50 feet below the ground surface. Depending on the time of year, shallow groundwater conditions above 50 feet below the ground surface exist in the southwest portion of the proposed project area Geologic Hazards The majority of the project area is relatively flat and is not identified by the County as an area that may be subject to downslope movement of earth materials, also known as landslides, creep, mudflows, rockfalls, etc. (San Joaquin County, 1992). In addition, soils in the proposed project area have a low potential to exhibit shrink swell behavior that could result in damage to infrastructure (San Joaquin County, 1999) Mineral Resources Within San Joaquin County, the primary mineral resource is aggregate, consisting of sand and gravel deposits that are used for construction purposes, such as the production of Portland cement. Additionally, San Joaquin County contains significant natural gas resources (an estimated billion cubic feet) contained between layers of subsurface sedimentary rock. Aggregate mining and natural gas extraction are actively ongoing within the county (San Joaquin County, 1992). Most of the project area is classified by the California Geological Survey (CGS) as MRZ 1 (areas where adequate information indicates no significant mineral deposits are present). No areas within the project area have been classified MRZ 2 (areas containing mineral deposits); however, much of the City of Manteca and area south and west of Manteca is classified as MRZ 3 (areas containing mineral deposits, the significances of which could not be Draft Subsequent EIR November 2011

3 determined) or areas that have not been evaluated by the CGS for potential mineral resources (San Joaquin County, 1992). According to a 1986 figure in the San Joaquin County General Plan, the southwestern portion of the SSJID territory, along West Ripon Road generally west of South Manteca Road, is located on an active or abandoned natural gas field, the McMullin Ranch (San Joaquin County, 1992) Paleontological Resources Quaternary (Pliocene or Pleistocene ) alluvium, lake, playa and terrace deposits underlie the project area (USGS, 2010). The soils of sediment transported from elsewhere or fill that is a mix of materials, and Quaternary age sediments, which make up the near surface formation are unlikely to host scientifically significant fossils. Throughout the project area, the overburden of disturbed soils and artificial fill relates to the long history of agricultural development in the area. These disturbed soils and fill extend to varying depths, but normally undisturbed sediment is not encountered above a depth of approximately 4 feet Rules and Regulations Federal Requirements The Institute of Electrical and Electronics Engineers (IEEE) 693 Recommended Practices for Seismic Design of Substations was developed by the Substations Committee of the IEEE Power Engineering Society, and approved by the American National Standards Institute and the IEEE SA Standards Board. This document provides seismic design recommendations for substations and equipment consisting of seismic criteria, qualification methods and levels, structural capacities, performance requirements for equipment operation, installation methods, and documentation. It provides detailed test and analysis methods for each type of major equipment or component found in electrical substations. This recommended practice is intended to assist the substation user or operator in providing substation equipment that will have a high probability of withstanding seismic events to predefined ground acceleration levels. It establishes standard methods of verifying seismic withstand capability, which gives the substation designer the ability to select equipment from various manufacturers, knowing that the seismic withstand rating of each manufacturer's equipment is equivalent. Although most damaging seismic activity occurs in limited areas, many additional areas could experience an earthquake with forces capable of causing great damage. This recommended practice should be used in all areas that may experience earthquakes. Clean Water Act. Soil erosion is regulated primarily by rules protecting water quality from unnecessary sedimentation. The Clean Water Act (CWA) (33 U.S.C. Section 1251 et seq.), formerly the Federal Water Pollution Control Act of 1972, regulates discharges through the National Pollutant Discharge Elimination System (NPDES) permit process (CWA Section 402). Pursuant to NPDES permit requirements for sites of one or more acres, SSJID would be required to prepare and adhere to a Storm Water Pollution Prevention Plan (SWPPP) that would minimize construction erosion. State Level Requirements The Alquist Priolo Earthquake Fault Zoning Act of 1972 (formerly the Special Studies Zoning Act) regulates development and construction of buildings intended for human occupancy to avoid the hazard of surface fault rupture. While the Act does not specifically regulate distribution lines or substations, it does help to define areas where fault rupture is most likely to occur. The Act groups faults into categories of active, potentially active, and inactive. Historic and Holocene age faults are considered active, Late Quater November Draft Subsequent EIR

4 nary and Quaternary age faults are considered potentially active, and pre Quaternary age faults are considered inactive. These classifications are qualified by the conditions that a fault must be shown to be "sufficiently active" and "well defined" by detailed site specific geologic explorations. The California Building Code (CBC, 2010) is based on the 2009 International Building Code (IBC), with the addition of more extensive structural seismic provisions. Chapter 16 of the CBC contains definitions of seismic sources and the procedure used to calculate seismic forces on structures. Because the SSJID territory lies within Uniform Building Code (UBC) Seismic Zone 3, provisions for design of new distribution facilities should follow the requirements of Chapter 16. California Code of Regulations Title 24, Section and et seq. contain the provisions requiring protection of adjacent properties during excavations and requires 10 days written notice and access to the excavation be given to the adjacent property owners Environmental Impacts and Mitigation Measures Significance Criteria The following significance criteria for air quality were derived from Appendix G of the State CEQA Guidelines. The project would result in potentially significant impacts on the geologic environment if it would: Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving: (i) 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 (Refer to Division of Mines and Geology Special Publication 42); (ii) Strong seismic ground shaking; (iii) Seismic related ground failure, including liquefaction; (iv) Landslides; 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 project, and potentially result in on or offsite landslide, lateral spreading, subsidence, liquefaction, or collapse; Be located on expansive soil, as defined in Table 18 1 B of the Uniform Building Code (1994), creating substantial risks to life or property; Result in the loss of availability of a known mineral resource that would be of value to the region and the residents of the State; or Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature. No portions of the proposed project fall within a known active fault zone or are within any areas vulnerable to landslides (San Joaquin County, 1992). In addition, the proposed project would occupy established public utility easements, rights of way, or private agricultural lands in which mineral resource activity presently does not occur. Therefore, there would be no project impacts related to the rupture of a known earthquake fault, unstable soils affected by the occurrence of a landslide, or loss of mineral resources. These issues are not addressed further in this EIR Impacts and Mitigation The following section analyzes the impacts to geology, soils, and paleontological resources of the four separate actions Draft Subsequent EIR November 2011

5 Sphere Plan and Municipal Services Review, Proposed Expanded Sphere of Influence, Proposed 80 acre annexation, and Updated Plan to Provide Retail Electric Service. Sphere Plan and Municipal Services Review This analysis discusses the potential impacts associated with the Sphere Plan and MSR that can be identified during this programmatic review, and separate discussions follow disclosing the impacts related to the other adoption and approval actions: the proposed SOI expansion, proposed 80 acre annexation, and plan to provide retail electric service. Projects that would occur with or without the adoption and approval of the Sphere Plan and MSR, such as the Water Transfer Renewal Project, Phase II of the South County Water Supply Program (SCWSP), the supply of drinking water to Escalon and Ripon, and the Division 9 Project were subject to or will in the future be subject to separate environmental review. These infrastructure improvements are analyzed as part of this EIR as foreseeable projects for potential cumulative impacts (Section 5, Cumulative Impacts). Improvements associated with the proposed retail electric service plan that appear in the Sphere Plan and MSR are analyzed below as part of the Updated Plan to Provide Retail Electric Service. The Sphere Plan and MSR identify a variety of infrastructure investments necessary to provide an adequate level of service within the SOI. The analysis of the Sphere Plan and MSR discusses the general types of site specific impacts that could occur. However, no construction activities are proposed for approval with the potential adoption of the Sphere Plan and MSR. Any construction related to these infrastructure investments would occur with or without the adoption and approval of the Sphere Plan and MSR. The MSR, technically, is not a plan that commits SSJID to any particular course of action; rather, it is a review of services provided within a particular area, with the idea that it will provide information useful to LAFCo as it makes decisions. The following presents a general discussion of whether the service requirements under the Sphere Plan and MSR would create an adverse effect on geology, soils, and paleontology. The analysis of the Sphere Plan and MSR is a programmatic environmental assessment. Impact 3.5 1: Expose people or structures to potential substantial adverse effects as a result of seismically induced groundshaking and/or ground failure Earthquake generated ground shaking and ground failure, including liquefaction, lateral spreading, and differential settlement, could result in damage to any infrastructure, including existing water supply pipelines. The infrastructure improvements that SSJID would undertake to provide an adequate level of service within the SOI during the life of the SOI would be susceptible to groundshaking in the event of a significant earthquake on any of the regional active faults. Ground shaking as a result of a major earthquake in the region could result in damage to water supply facilities, damage to nearby roads or structures, and injury to people. Because infrastructure maintenance and improvements under the Sphere Plan and MSR are built to the applicable specifications of San Joaquin County, CBC, and UBC, and because the activities would be the same as currently undertaken by SSJID, adoption of the Sphere Plan and MSR would not increase the potential for impacts associated with ground shaking or ground failure. As the Sphere Plan and MSR would not increase the potential for impacts, no impacts would occur. Mitigation for Impact November Draft Subsequent EIR

6 Impact 3.5 2: Result in substantial soil erosion or the loss of topsoil Ground disturbance could result in soil erosion during infrastructure maintenance and improvements. Soil disturbance and stockpiling of earth during construction could potentially accelerate soil erosion. SSJID would be required to prepare and adhere to Regional Water Quality Control Board storm water quality requirements in order to minimize erosion caused during construction where one acre or more of land is disturbed during construction. SSJID adheres to the County, Manteca s, Ripon s, and Escalon s Storm Drain Master Plan requirements, where applicable. Because the infrastructure maintenance and improvements necessary to provide adequate level of service under the Sphere Plan and MSR are subject to applicable San Joaquin County, State, and City of Escalon and Manteca requirements, and because the activities would be the same as currently undertaken by SSJID, adoption of the Sphere Plan and MSR would not increase the potential for substantial soil erosion or loss of topsoil. As such no impacts would occur. Mitigation for Impact Impact 3.5 3: Damage project facilities as a result of expansive (shrink swell) soils Moderate to high shrink swell potential in soils can cause damage to buildings, roads, and underground facilities, such as water supply, through repeated and progressive heaving of the soils as they expand when wet and shrink when dry. However, soils in the proposed project area have a low potential to exhibit shrink swell behavior (San Joaquin County, 1999). Additionally, as no new infrastructure construction or change in action would occur with adoption of the Sphere Plan and MSR, adoption of the Sphere Plan and MSR would not increase exposure of water supply pipelines or other existing infrastructure to damage due to expansive soils. No impacts would occur. Mitigation for Impact Impact 3.5 4: Directly or indirectly destroy a unique paleontological resource Native, near surface deposits in the SSJID territory are alluvial and relatively young with little potential to yield paleontological resources. Additionally, the infrastructure improvements that SSJID would undertake to provide an adequate level of service within the SOI during the life of the SOI, described in Section would occur in previously disturbed road rights of way, on already existing substation yards, or on previously disturbed agricultural land. None of these regions would be expected to contain fossils. Because of this, the infrastructure improvements are not expected to result in impacts to paleontological resources. As no new infrastructure construction or change in action would occur, adoption of the Sphere Plan and MSR would not increase the potential to destroy paleontological resources. Consequently, no impacts would occur. Proposed Expanded Sphere of Influence The following presents a general discussion of whether the proposed expanded sphere of influence (SOI) would create an adverse effect to the geology, soils, and paleontological resources of the SOI. This analysis is a programmatic assessment of the proposed SOI described in Section Draft Subsequent EIR November 2011

7 The expanded SOI would make the SOI boundaries consistent with the Manteca city limits. Adoption of the expanded SOI requires no construction or operation activities. Because there would be no construction or operation activities, the expanded SOI would not be subject to seismically induced ground shaking or ground failure or impacts from expansive soils. There would be no new facilities or modifications to existing facilities and no potential impact to soil erosion or impacts to paleontological resources. Proposed 80 Acre Annexation The following presents a discussion of whether the 80 acre annexation would create an adverse effect to the geology, soils, and paleontological resources. This analysis is a project level assessment of the annexation. This annexation has been proposed as a separate action wholly independent of and for distinctly different reasons than SSJID s proposed plan to provide retail electric services, and it is not dependent in any way upon SSJID s separate proposal to provide such electric services. The proposed 80 acre annexation is described in Section and would be located west of the intersection of French Camp Road and Austin Road, near Castle Road. Minor construction would be required to install a sprinkler sump from the existing SSJID irrigation facilities to the 80 acre property. This construction would be limited in nature and is expected to take one month or less to complete. Construction would occur only at the existing SSJID District Lateral Q or existing Lateral Qk. Because construction would be minor and would occur near the surface where deposits are alluvial and relatively young there would be little potential to yield paleontological resources and no impacts to paleontological resources would occur. Impact 3.5 1: Expose people or structures to potential substantial adverse effects as a result of seismically induced groundshaking and/or ground failure Installation of a sprinkler sump would require minor construction at the existing SSJID District Lateral Q or Lateral Qk. The sprinkler sump would be susceptible to groundshaking in the event of a significant earthquake, and this could damage the sprinkler sump. However, the new sump system would be required to comply with seismic standards pursuant to the California and Uniform Building Code standards, which account for seismic hazards. Installation of a sprinkler sump would not impact the existing SSJID irrigation system which is in compliance with the California Building Code standards. Therefore, any impacts due to groundshaking would be a less than significant impact regarding seismically induced ground shaking or ground failure. Mitigation for Impact Impact 3.5 2: Result in substantial soil erosion or the loss of topsoil Due to the relatively small size of the construction area required for installation of the sprinkler sump minimal ground disturbance is expected and a SWPPP would not be required. The potential for causing substantial soil erosion is low. Because the construction to install the sprinkler sump would be minor, would occur on less than one acre, and would occur during a short time frame, impacts related to soil erosion from installing the sprinkler sump would be adverse but less than significant. Mitigation for Impact November Draft Subsequent EIR

8 Impact 3.5 3: Damage project facilities as a result of expansive (shrink swell) soils Moderate to high shrink swell potential in soils can cause damage to buildings, roads, and underground structures such as cables and pipelines through repeated and progressive heaving of the soils as they expand when wet and shrink when dry. However, soils in the proposed project area have a low potential to exhibit shrink swell behavior (San Joaquin County, 1992). Therefore, potential impacts to the proposed project facilities related to expansive soils are considered to be less than significant. Mitigation for Impact Updated Plan to Provide Retail Electric Service The following presents a discussion of whether the updated plan to provide retail electric service would create an adverse effect to the geology, soils, and paleontology within the SSJID territory. This analysis is a project level assessment of the updated plan. This impact analysis discusses the potential project specific impacts associated with the plan to provide retail electric services and identifies mitigation measures for potentially significant impacts. This represents a project level assessment of the updated plan and also a programmatic level assessment of foreseeable consequences of the retail electric service plan such as the expansion of SSJID s retail electric service to Area D or Area E (see Figure 2 2 in Chapter 2, Project Description), which are outside SSJID s existing territory, but within its current and proposed SOI. However, SSJID has no immediate plans to annex areas within Area D or Area E or to provide retail electric service in these areas. If the current proposal for retail electric service is approved and the areas are annexed in the future, SSJID would likely expand this service to Area E within 10 years and to Area D within 30 years. Mitigation measures that apply to the proposal for retail electric service would likely also apply to the future expansion of electric service within the SOI. Approval of the proposed project, however, would not commit SSJID to exactly these mitigation measures for possible future annexations because considerations may arise within 30 years that would make the near term measures obsolete or outdated. Specific proposals for annexations or service beyond SSJID s existing territory may need to undergo the project level environmental review process and other required approvals should SSJID decide to pursue such an annexation or service expansion in the future. Impact 3.5 1: Expose people or structures to potential substantial adverse effects as a result of seismically induced groundshaking and/or ground failure Earthquake generated ground shaking and ground failure, including liquefaction, lateral spreading, and differential settlement, could result in damage to the proposed overhead and underground electric distribution system modifications as well as to the proposed Jack Tone Substation and modified substations. Damage to distributions line, or substations could result in power outages, damage to nearby roads or structures, and injury to people. However, implementation of Mitigation Measure 3.5 1a would ensure that SSJID designs and builds the distribution system modifications to withstand geologically induced stresses, in compliance with existing utility design standards and practices set by the California Public Utilities Commission (CPUC General Order 95), IEEE, CBC, and San Joaquin County. The proposed Jack Tone Substation and the proposed substation modifications would be constructed pursuant to the IEEE, CBC, and UBC standards, which account for seismic hazards. Because the proposed distribution facilities would be built to the established specifications and would comply with the requirements described in Draft Subsequent EIR November 2011

9 Mitigation Measure 3.5 1a, potential impacts associated with ground shaking or ground failure are considered to be less than significant. The impacts of the possible future expansion of SSJID s retail electric service to Area D or Area E (Figure 2 2 in Chapter 2, Project Description), if the areas are annexed in the future, would be similar to these impacts described for the proposed project; however, there are no plans for this possible expansion currently under consideration. Mitigation measures that apply to the current proposed project would likely also apply to these future, programmatic impacts. However, approval of the proposed project would not commit SSJID to exactly these mitigation measures for possible future annexations because considerations may arise within 30 years that would make the near term measures obsolete or outdated. Specific proposals for annexations or service beyond SSJID s existing territory may need to undergo the project level environmental review process and other required approvals should SSJID decide to pursue such an annexation or service expansion in the future. Mitigation for Impact a Engineer electric facilities in accordance with standards and practices. New electric facilities would be engineered to withstand potential ground shaking in accordance with existing utility design standards and practices and would meet or exceed the relevant seismic requirements. Standards and practices are defined in California Public Utilities Commission (CPUC) General Order 95, Institute of Electrical and Electronics Engineers (IEEE) Standard 693, California Building Code (CBC) requirements for Uniform Building Code (UBC) Seismic Zone 3, and San Joaquin County specifications. [New Mitigation Measure] Impact 3.5 2: Result in substantial soil erosion or the loss of topsoil Ground disturbance during construction related to the retail electric service plan could result in soil erosion in the project area. Construction of the project would require some subsurface excavation for concrete pad development at the existing and proposed substation sites. Although construction and modification of the overhead distribution lines would require limited excavation for pole installation, several miles of trenching at various locations in the project area would be required to install the underground conductor cable. Soil disturbance and stockpiling of earth during construction could potentially accelerate soil erosion. Pursuant to NPDES permit requirements, SSJID would prepare and adhere to a SWPPP in order to minimize erosion caused during construction, where one acre or more of land is disturbed during construction. The SWPPP for the electric distribution system construction would be prepared once the project is approved, and an important component of the SWPPP would be specified Best Management Practices (BMPs) to minimize soil erosion. BMPs in the SWPPP may include, but not be limited to, Mitigation Measure 3.5 2a, which would schedule excavation and grading activities for the dry season when possible. If excavation were to occur during the rainy season, Mitigation Measure 3.5 2a would ensure that SSJID regulates storm runoff through a storm water management/erosion control plan to cover stockpiles of loose material, divert runoff away from exposed soil materials, and remove any trapped sediment from the basin or trap and place it in a suitable location. SSJID would also be required to adhere to the County and Manteca s SWPPP requirements, where applicable. Compliance with San Joaquin County, State, and City of Manteca NPDES requirements would ensure that impacts associated with soil erosion are reduced to less than significant levels. November Draft Subsequent EIR

10 The impacts of the possible future expansion of SSJID s retail electric service to Area D or Area E (Figure 2 2 in Chapter 2, Project Description), if the areas are annexed in the future, would be similar to these impacts described for the proposed project; however, there are no plans for this possible expansion currently under consideration. Mitigation measures that apply to the current proposed project would likely also apply to these future, programmatic impacts. However, approval of the proposed project would not commit SSJID to exactly these mitigation measures for possible future annexations because considerations may arise within 30 years that would make the near term measures obsolete or outdated. Specific proposals for annexations or service beyond SSJID s existing territory may need to undergo the project level environmental review process and other required approvals should SSJID decide to pursue such an annexation or service expansion in the future. Mitigation for Impact a Follow best management practices for soil erosion control. SSJID shall follow best management practices for soil erosion control, including but not limited to: Schedule excavation and grading activities for the dry season (April 15 to October 15). If excavation must occur during the rainy season, regulate storm runoff from the construction area through a storm water management/erosion control plan prepared prior to the construction period. The plan shall include, at a minimum, the following elements: sand bags, road bars, certified weed free mulch, etc. Stockpiles of loose material must be covered or stabilized and runoff diverted away from exposed soil material. Sediment basin/traps must be located and operated to minimize the amount of offsite sediment transport. Any trapped sediment must be removed from the basin or trap and placed at a suitable location onsite, away from concentrated flows, or removed to an approved disposal site. [New Mitigation Measure] Impact 3.5 3: Damage project facilities as a result of expansive (shrink swell) soils Moderate to high shrink swell potential in soils can cause damage to buildings, roads, and underground structures such as cables and pipelines through repeated and progressive heaving of the soils as they expand when wet and shrink when dry. However, soils in the proposed project area have a low potential to exhibit shrink swell behavior (San Joaquin County, 1992). Therefore, potential impacts to the proposed project facilities related to expansive soils are considered to be less than significant. The impacts of the possible future expansion of SSJID s retail electric service to Area D or Area E (Figure 2 2 in Chapter 2, Project Description) would be similar to these impacts described for the proposed project; however, there are no plans for this possible expansion currently under consideration. Mitigation for Impact Impact 3.5 4: Directly or indirectly destroy a unique paleontological resource Native, near surface deposits in the project area are alluvial and relatively young (Pliocene or Pleistocene) with little potential to yield paleontological resources. In addition, most of the proposed project would occur in previously disturbed road rights of way or agricultural land that would not contain fossils. However, Draft Subsequent EIR November 2011

11 infrastructure improvements on undisturbed land requiring ground disturbance beyond a depth of 24 inches, could damage or destroy previously unknown paleontological resources. Implementation of Mitigation Measure 3.5 4a ensures that a qualified vertebrate paleontologist would determine the paleontological sensitivity of the area and establish a monitoring and treatment plan to record and protect potential paleontological resources. As such this impact would be adverse but less than significant. The impacts of the possible future expansion of SSJID s retail electric service to Area D or Area E (Figure 2 2 in Chapter 2, Project Description), if the areas are annexed in the future, would be similar to these impacts described for the proposed project; however, there are no plans for this possible expansion currently under consideration. Mitigation measures that apply to the current proposed project would likely also apply to these future, programmatic impacts. However, approval of the proposed project would not commit SSJID to exactly these mitigation measures for possible future annexations because considerations may arise within 30 years that would make the near term measures obsolete or outdated. Specific proposals for annexations or service beyond SSJID s existing territory may need to undergo the project level environmental review process and other required approvals should SSJID decide to pursue such an annexation or service expansion in the future. Mitigation for Impact a Provide proper treatment of paleontological resources. Although no significant resources are anticipated due to the relatively young, alluvial character of the soils, prior to ground disturbance of a depth beyond 24 inches at sites that have not been previously disturbed, SSJID would hire a qualified vertebrate paleontologist, for example, as in Standard Guidelines established by the Society of Vertebrate Paleontology (SVP) (SVP, 1995), to further evaluate the paleontological sensitivity of the area underlying the ground disturbance. Should the paleontologist determine that materials with moderate, high, or unknown paleontological sensitivity could be impacted SSJID shall hire a qualified vertebrate paleontologist to design a worker education program and if deemed necessary to prepare a Paleontological Monitoring and Treatment Plan. [New Mitigation Measure] Conclusion With implementation of Mitigation Measures 3.5 1a, 3.5 2a, and 3.5 4a, all of the potential impacts related to geology, soils, and paleontology would be reduced to less than significant levels. Therefore, no significant and unavoidable impacts related to geology, soils, and paleontology would occur as a result of the proposed project. November Draft Subsequent EIR

12 3.5.4 Mitigation Monitoring Program Table shows the mitigation monitoring, compliance, and reporting program for Geology, Soils, and Paleontology. Table Mitigation Monitoring Program Geology, Soils, and Paleontology IMPACT MITIGATION MEASURE Location Monitoring / Reporting Action Effectiveness Criteria Responsible Agency Timing IMPACT MITIGATION MEASURE Location Monitoring / Reporting Action Effectiveness Criteria Responsible Agency Timing IMPACT MITIGATION MEASURE Location Monitoring / Reporting Action Effectiveness Criteria Responsible Agency Timing Expose people or structures to potential substantial adverse effects as a result of seismically induced groundshaking and/or ground failure 3.5-1a: Engineer electric facilities in accordance with standards and practices All areas of proposed electric distribution system construction A monitoring report shall be prepared upon completion of retail electric system construction Electric facilities would meet or exceed relevant seismic requirements.. South San Joaquin Irrigation District Prior to construction Result in substantial soil erosion or the loss of topsoil 3.5-2a: Follow best management practices for soil erosion control All areas of proposed electric distribution system construction A monitoring report shall be prepared upon completion of retail electric system construction Soil erosion best management practices would be properly implemented and managed subject to SWPPP requirements. South San Joaquin Irrigation District During construction Directly or indirectly destroy a unique paleontological resource 3.5-4a: Provide proper treatment of paleontological resources Previously undisturbed electric distribution system construction sites A monitoring report shall be prepared upon completion of retail electric system construction Paleontological materials with a moderate, high, or unknown paleontological sensitivity are properly managed. South San Joaquin Irrigation District Prior to and during construction References CBC (California Building Code) Uniform Building Codes (UBC) & California State Building Code Title 24 Amendments California Building Standards Commission (CBSC). NRCS (Natural Resource Conservation Service) Web Soil Survey Soil Data Version 6, June 25, Accessed September San Joaquin County San Joaquin County District Viewer. Viewer.asp. Accessed August Expansive Soils Accessed August Draft Subsequent EIR November 2011

13 San Joaquin County General Plan 2010: Volume II: Community Plans, and Volume III: Technical Appendices, Section IV. Adopted July SVP (Society of Vertebrate Paleontology) Assessment and Mitigation of Impacts to Nonrenewable Paleontologic Resources, Standard Guidelines. SVP News Bulletin No. 163, pp USGS (United States Geological Survey) Geologic Map of California. gov/gmaps/gmc/stategeologicmap.html. Accessed August. November Draft Subsequent EIR