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MIG 7.A. - Page 213 City of Redwood City Lin r�uuciiuuni October 8, 2012 Page 3-50 differential settlement and ground failure/liquefaction. Because the current Pete's Harbor project proposes fewer residences than the previous Pete's Harbor project component (411 vs. 633), the potential extent of this impact would be reduced; however, the impact is still considered potentially significant. Similar to the mitigation for Impacts 11-1 and 11-2 above, mitigation details for this impact would be included in the detailed, design-level geotechnical investigations required for both the previous project and the current project, including analyses of the site's seismic stability, liquefaction potential, and soil response characteristics. All project construction would be required to comply with the City's most recently adopted version of the International Building Code with California Amendments. Conclusion. Modified mitigation. The 2003 EIR mitigation for this impact refers to the 1997 UBC; the modified mitigation refers to "the City's most recently adopted International Building Code with California Amendments," which would be applied to the current project; otherwise, the mitigation identified in the 2003 EIR for Impact 11-3 remains applicable to the current Pete's Harbor project and remains sufficient to reduce this impact to a less-than-significant level. Since the 2003 EIR was certified, the majority of Redwood City, including the project site, has been identified as in a Seismic Hazard Zone prone to liquefaction.' Therefore, the geotechnical report will also have to address liquefaction, per State Department of Mines and Geology (DMG) Special Publication 117, "Guidelines for Evaluating and Mitigating Seismic Hazards in California." Impact 11-4 Analysis: Encountering Groundwater in Bay Mud During Excavation. The 2003 EIR concluded that excavation for the proposed project's below-grade installations, such as utilities, could encounter groundwater. This condition continues to apply to the current Pete's Harbor project. Similar to the mitigation for Impacts 11-1 through 11-3 above, mitigation details for this impact would be included in the detailed, design-level geotechnical investigations required for both the previous project and the current project, including analyses of the project's proposed dewatering techniques, slope and shoring requirements for excavations, buffer zones for construction equipment near slope edges, the potential for requiring light grading equipment, subgrade remediation techniques, and the use of excavated fill. Conclusion. No change. The mitigation identified in the 2003 EIR for Impact 11-4 remains applicable to the current Pete's Harbor project and remains sufficient to reduce this impact to a less-than-significant level. Impact 11-5 Analysis: Corrosive Soils. In the 2003 EIR, the on-site soil was classified as "severely corrosive," with potential to result in long-term damage to project building foundations and underground utility systems. This condition continues to apply to the current Pete's Harbor p roj ect. Similar to the 2003 EIR mitigation for Impacts 11-1 through 11-4 above, mitigation details for Impact 11-5 would be included in the detailed, design-level geotechnical investigations required 'State of California Seismic Hazards Zones map, Palo Alto Quadrangle; Department of Conservation, October 18, 2006. T:1106951Addenduml3(10695-01).doc