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03/27/2007 Mitigation 15-1. At the City Building Official's discretion, future discretionary development projects proposed within the Precise Plan area shall be required to undertake detailed, design-level geotechnical investigations that include analysis of project site seismic stability, liquefaction potential, and soil response characteristics with respect to ground acceleration, in accordance with Special Publication 112, "Guidelines for Analyzing and Mitigating Liquefaction in California," published by the California Division of Mines and Geology. The detailed, design-level geotechnical investigations should include the following: • Seismic stability analysis of the existing on-site soil; • Evaluation of liquefaction potential throught he performance of additional cone penetration tests, borings, and/or equivalent methods; and • Determination of site-specific soil response characteristics and maximum credible ground acceleration for an earthquake recurrence interval specified by the City. Recommendations from the investigations, including appropriate soil stabilization and foundation construction techniques, minimum setbacks around potentially unstable areas, and criteria for the compaction and treatment of on-site fills, shall be incorporated into the final project grading and foundation plans. In general, these recommendations are expected to include the following requirements: • that all construction comply with the most current edition of the Uniform Building Code) for Seismic Zone 4, or with the most recently adopted building codes. • that all project structural designs be based on proper estimates by the project geotechnical engineer of peak and maximum repeatable earthquake-induced ground surface accelerations expected to occur on the project site; and • that excavations will be adequately sloped or shored in order to minimize ground movements. Finding: Implementation of these measures set forth in mitigation measure 15-1, combined with conformance with standard Uniform Building Code, City of Redwood City, and other applicable regulations, would reduce the potential effects of ground shaking to aless-than-significant level. B. Soil Erosion and Sedimentation Impacts Impact 15-2: Soil Erosion and Sedimentation. Under either the Maximum or Moderate Intensity Precise Plan alternative, grading for future development in accordance with the proposed Precise Plan would temporarily disturb the site's existing topography and vegetative cover, leaving soils exposed to wind and water erosion during the construction period. Eroded soils could be washed into on-site or off-site drainage facilities. Resulting sedimentation could affect the flows in these drainage facilities, increasing flooding potential and maintenance problems and degrading water Atty/Reso/Reso.1683 33 14769 030707 Muff #613