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5.ENVIRONMENTAL CHECKLIST MOUNTAIN HOUSE NEIGHBORHOODS K AND L INITIAL STUDY 6. GEOLOGY AND SOILS The project would be required to comply with all California laws designed to minimize the potential adverse effects of an earthquake.These laws include the Essential Services Buildings Seismic Safety Act of 1986,the Hospital Seismic Safety Act of 1972,the Field Act of 1933, and the requirements of the latest California Building Code(CBC). Mountain House Community Services District (MHCSD)standards and the Uniform Building Code(UBC)would also apply. The 1994 MEIR identified Mitigation M4.6-1 (preparation of a Community Earthquake Preparedness Plan)to promote public awareness and education on earthquake hazards.This plan has been completed and is currently being implemented by the MHCSD. Existing mitigation measures and policies related to strong seismic ground shaking can be found in the 1994 MEIR(Mitigation M4.6-1) and the Master Plan (Policies 6.5.1(b)[Emergency Preparedness]and 6.8.3[Soils, Geologic,and Seismic Hazards]). Despite project compliance with California laws related to earthquake hazards ' and the implementation of mitigation measures called for in the Master Plan and 1994 MEIR,the impact on Neighborhoods K and L related to ground shaking would be significant and unavoidable and could not be mitigated to a less-than- significant level. No additional mitigation measures are available. This impact was addressed in the 1994 MEIR, and no new impacts related to ground shaking have been identified for the Neighborhoods K and L development. iii) Seismic-related ground failure,including liquefaction? Laboratory soil testing conducted and summarized in geotechnical engineering studies for Neighborhoods K and L indicates that thin, discontinuous, potentially liquefiable deposits are present in the project area. These deposits create the potential for hazards to people or structures, such as damage to structural foundations, lateral spreading, and/or localized settlement of ground surfaces. Although the studies also suggest that overlying non-liquefiable soils make liquefaction in the area unlikely,they provide recommendations to mitigate potential liquefaction hazards in the project area. �3 Liquefaction hazards at Neighborhoods K and L were evaluated using Standard Penetration Test(SPT) blow counts or Cone Penetration Test(CPT)data, a peak ground acceleration (PGA)of 0.4g,and a mean moment magnitude of 6.4. The results of the analysis indicate that potentially thin,discontinuous deposits of liquefiable materials(e.g., isolated layers of sands and low-plasticity silts)exist in Neighborhood K and L(as discussed earlier). With respect to seismic-related ground failure,the proposed project would result in less-khan-significant impacts with mitigation incorporated. The geotechnical engineering studies for these neighborhoods identified a number of ways to minimize such impacts. These measures would be integrated into the design of i structures for Neighborhoods K and L to mitigate impacts to less-than-significant G� levels. (917111) 5-78