2025-041 - Certifing Final Supplemental Enviromental Impact for The Village

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Explanation of the Rationale: The rationale and facts supporting the above finding are fully developed in Section 4.4, Geology and Soils, pages 4.4-15 through 4.4-17 of the Draft Supplemental EIR. The following presents a summary of that rationale: The Project site is underlain by moderately compressible soils as well as soil with low to moderate potential for seismically induced settlements. Model analysis resulted in 1 to 2 inches of total settlement below a mat slab foundation. Implementation of Project-Specific MM G-1 and MM G- 2 to prepare a detailed geotechnical investigation in support of the final design plans and apply the recommendations which include measures related to foundation specifications for heavier, intermediate, and lighter structures, such as use of pile or pier foundations, mat/raft foundations, stone columns, injection grouting, or deep soil mixing,to reduce impacts related to settlement and collapse, would result in less than significant impacts related to settlement and collapse. In addition, the Project site has relatively shallow groundwater conditions. Direct groundwater extraction would not occur as part of the Project; however, excavations deeper than approximately 10 to 15 feet are likely to encounter groundwater seepage, and excavations deeper than 15 feet may encounter artesian conditions. Project-Specific MM G-1 and MM G-2 to prepare a detailed geotechnical investigation in support of the final design plans would include local dewatering and inflow control for excavations deeper than approximately 15 to 20 feet for construction activities. Therefore, impacts to subsidence would be less than significant with mitigation incorporated. Further, slope failure and landslides are not a major hazard in Santa Ana because the entire city is nearly flat. Lateral spreading is a type of liquefaction-induced ground failure on mildly sloping ground. Impacts related to landslides or lateral spreading are less than significant. Refer to Threshold G-1(iii)for the discussion on liquefaction. Threshold G-4: The Project would not be located on expansive soil, as defined in Table 18- 1-B of the Uniform Building Code (1994), creating substantial direct or indirect risks to life or property, with the implementation of mitigation. Findings: The City finds that changes or alterations have been required in, or incorporated into, the Project, which avoid or substantially lessen the significant environmental effect as identified in the Final Supplemental EIR. Specifically, the City finds that Project-Specific MM G-1 and MM G-2 (listed previously)shall be implemented to reduce potentially significant soil impacts resulting from the Project. Additionally, the City finds that the Project will implement regulatory requirements RR G-1 through RR G-3 (listed above). (Draft Supplemental EIR, p. 4.4-11.) Explanation of the Rationale: The rationale and facts supporting the above finding are fully developed in Section 4.4, Geology and Soils, pages 4.4-17 through 4.4-18 of the Draft Supplemental EIR. The following presents a summary of that rationale: The Project site contains alluvium which consists primarily of clay and silt in the upper 15 to 20 feet, with local thin lenses of sandy alluvium. Below 20 feet, there is considerably more sand and sandy silt layers, with local thin layers of clay. Clay-based soils are susceptible to expansion; therefore, implementation of Project-Specific MM G-1 and MM G-2 would include recommendations or measures for preventing expansive soils as part of the detailed geotechnical Resolution No. 2025-041 Page 76 of 140