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MIG F 8.A. - Page 291 <br /> City of Redwood City Revised Elm Auaenaurn <br /> January 22, 2014 Page 3-50 <br /> 3.8 SOILS AND GEOLOGY <br /> The relationships of the current Pete's Harbor project to the previously certified 2003 EIR soils <br /> and geology impact and mitigation conclusions are described below. <br /> Impact 11-1 Analysis: Geotechnical Hazards Associated with Project Grading. The <br /> certified 2003 EIR concluded that, based on the applicant's preliminary geotechnical <br /> investigation, the interaction of existing geotechnical conditions with the project proposed <br /> grading, dredging, and surface modifications could result in significant geotechnical impacts <br /> associated with surface settlement, seismic hazards, and/or soil erosion. <br /> The associated 2003 EIR mitigation required the project applicant to have detailed, design-level <br /> geotechnical investigations professionally prepared for each project structure. Topics <br /> addressed in the investigations would include, among others, strength parameters for <br /> foundation design, perimeter slope stability, soil corrosivity potential, and characteristics of the <br /> underlying Bay mud. All geotechnical recommendations resulting from the investigations would <br /> be subject to review and approval by an independent engineering geologist or geotechnical <br /> engineer retained by the City Engineer at applicant expense. <br /> The current Pete's Harbor project, although smaller, would still result in similar potentially <br /> significant geotechnical hazards associated with project grading and surface modifications (the <br /> current project would not include dredging). <br /> Conclusion. Modified impact and mitigation. References to dredging have been removed from <br /> the impact and mitigation because the current project would not involve dredging. Otherwise, <br /> the mitigation identified in the 2003 EIR for Impact 11-1 remains applicable to the current Pete's <br /> Harbor project and remains sufficient to reduce this impact to a less-than-significant level. <br /> Impact 11-2 Analysis: Total and Differential Settlement. The project site is located atop <br /> weak, compressible Bay mud. Both the previous project and the current project would introduce <br /> structural loads too great to be supported on conventional shallow foundations over Bay mud, <br /> potentially resulting in excessive total and differential settlements. Associated mitigation details, <br /> involving common engineered solutions for such projects atop Bay mud, would be included in <br /> the detailed, design-level geotechnical investigations required for both the previous project and <br /> the current project (see Impact 11-1 above), including analyses of all fill material. <br /> The previous Marina Shores Village project would require building foundations supported on <br /> piles driven approximately 95 feet or greater in depth (based on the depth to bedrock). <br /> However, the applicant has concluded that any piles required for the current Pete's Harbor <br /> project would be auger cast and not driven. <br /> Conclusion. Modified impact and mitigation. References to dredging, pile driving (auger cast <br /> piles could be necessary), and reduced marinas (the inner marina would be reconfigured within <br /> its existing 3.18 acres) have been removed from the impact and mitigation because the current <br /> project would not involve these activities. Otherwise, the mitigation identified in the 2003 EIR for <br /> Impact 11-2 remains applicable to the current Pete's Harbor project and remains sufficient to <br /> reduce this impact to a less-than-significant level. <br /> Impact 11-3 Analysis: Ground Shaking/Liquefaction. Both the previous project and the <br /> current project would place new residences in a subregion that is expected to experience <br /> T.110695 Pete's Harbor EIR Addendumlrevised addendum no 213(10695-01).doc <br />