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09/09/2013 Impact: Impact 15-2: Excavation Instabilities Caused by High Groundwater. Groundwater encountered during construction of the proposed projecYs below- grade installations could destabilize excavation walls, reduce the bearing capacity of in-place soils that might otherwise be suitable for foundation support, and exert additional stresses on basement walls and floor slabs. Mitigation: Mitigation 15-2. The detailed, design-level geotechnical investigations recommended under Mitigation 15-1 for each project construction phase shall fully characterize groundwater conditions on the development site and make appropriate recommendations regarding dewatering techniques, slope and shoring requirements for excavations, stabilization or replacement of saturated foundation materials, and hydrostatic pressure implications for the design of below-grade structures. Finding: Implementation of Mitigation 15-2 would reduce these potential groundwater impacts to a less-than-significant level. Facts in Support of Finding: Implementation of Mitigation 15-2 would reduce potential high groundwater impacts to a less-than-significant level by requiring detailed, site- specific geotechnical investigations and solutions prepared by a registered engineering geologist or geotechnical engineer, with review and approval authority by the City Engineer. These facts are described in Draft EIR chapter 15 (Geology and Soils) on pages 15-1 through 15-15, which is hereby incorporated by reference. Impact: Impact 15-3: Soil Erosion. Project development would disturb the site's existing cover of buildings, pavements and landscaping, potentially leaving soils exposed to wind and water erosion during the construction period. Eroded soils would be washed into on-site drainage facilities that discharge to the Bayfront Canal and San Francisco Bay. Deposition of these soils through natural sedimentation could adversely affect the carrying capacity of drain lines, pumping equipment and open channels, increasing flooding potential and maintenance requirements. In addition, suspended sediment would degrade water quality in the canal and in the bay by increasing turbidity levels. Mitigation: Mitigation 15-3. The applicant shall develop an erosion control plan in accordance with the provisions of the project's City-approved Stormwater Pollution Prevention Plan (SWPPP). The erosion control plan would be implemented throughout project construction, and would include measures for the post-construction stabilization of all disturbed ground. Finding: Implementation of Mitigation 15-3 would reduce these potential soil erosion impacts to a less-than-significant level. Facts in Support of Finding: Implementation of Mitigation 15-3 would reduce potential soil erosion impacts to a less-than-significant level by requiring detailed, site-specific geotechnical investigations and solutions prepared by a registered engineering geologist or geotechnical engineer, with review and approval authority by the City Engineer. These facts are described in Draft EIR chapter 15 (Geology and Soils) on pages 15-1 through 15-15, which is hereby incorporated by reference. ATTY/RES0.2901/STANFORD EIR CERTIFICATION RESO.#15294 REV:09-10-13 VR MUFF#100 Page 18 of 55