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4 Environmental Analysis 4.7 Geology, Soils, and Paleontological Resources on-site would adhere to the specifications, procedures, and site conditions contained in the final design plans. Any plans must incorporate seismic recommendations provided by a California- registered, professional geotechnical engineer in accordance with the CBC. The final structural design would be subject to approval and follow-up inspection by the San Joaquin County Building Division. Final design requirements would be provided to the on-site construction supervisor and the County Building Inspector to ensure compliance. Adherence to the applicable CBC requirements and local agency enforcement would ensure that the Project would not directly or indirectly cause substantial adverse effects, including the risk of loss, injury, or death involving strong seismic ground shaking. A corollary concern for moderate to strong seismic ground shaking, caused by an earthquake close enough to the area, is the risk of liquefaction. However, because on-site soils and conditions are not susceptible to liquefaction, this risk is considered low to moderate. Nevertheless, the Project owner is required to design proposed improvements in accordance with applicable CBC seismic design standards and any recommendations provided by a California- registered, professional geotechnical engineer in a site-specific, geotechnical report. As part of the geotechnical report, consistent with building code seismic design standards, the licensed geotechnical engineer would be required to consider potential liquefaction in the design plans. Compliance with CBC requirements, including implementation of recommendations provided in the geotechnical report and local agency enforcement, would reduce or avoid impacts related to ground failure, including liquefaction. Although the Project site has moderate topographic relief, no evidence of landslides has been mapped on an adjacent site (Janky 2022). The State provides landslide mapping (DOC 2021), but it does not cover the Midway Quad. This could be due to a lack of development in the area or the more subdued nature of local topography moving east from the Diablo Range. In addition, the proposed extent and amount of cut and fill required to prepare the site to install the battery energy storage system is significant. The proposed Project design options will require a significant amount of earthwork to create a single terrace on which the batteries would be installed. A relatively balanced cut and fill volume of just over 400,000 cubic yards of material will be handled, and result in several large 2:1 (horizontal to vertical) cut and fill slopes. The maximum depth of cut will be approximately 70 feet and the maximum depth of fill will be about 40 feet.A site-specific geotechnical investigation will provide specifications for treating the cut surfaces to address bedding plane configurations, handle surface drainage, or otherwise stabilize the new surface. Additional specifications will be provided for fill operations to address lift thickness, compaction requirements, and effective drainage given the nature of the soil and bedrock materials to be moved on-site. However, performing the planned, detailed, site-specific geotechnical investigation will provide the necessary background information to prepare an appropriate design to effectively minimize risks from landslides or potential landslides for the new surface configuration. With appropriate engineering design considerations for stabilizing new cut surfaces and fill volumes on the Project site and in the gen-tie corridor, the risk of landslides on cut and fill surfaces will be minimized. Griffith Energy Storage Project 4.7-16 Tetra Tech/SCH 2022120675 Draft Environmental Impact Report August 2023