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7.1.A. - Page 30 <br /> of the Hayward fault. The project area itself is not within an Alquist-Priolo Zone, and there are <br /> no active faults known to exist in the project area. Therefore, the potential for surface rupture <br /> and ground displacements due to surface faulting is considered to be low. In addition, there are <br /> no known unique geologic or physical features present in the project vicinity. Although the <br /> project is located in a seismically active area, no elements of the project include buildings and <br /> other structures that will be occupied by people. Project facilities will be designed in accordance <br /> with seismic standards adopted by the City of Redwood and with Title 22 requirements. In <br /> addition, detailed geotechnical analyses will be prepared for all project facilities, and the <br /> recommendations of these analyses will be incorporated into project design. In particular, the <br /> storage reservoirs and pump stations would be designed and constructed to withstand the <br /> maximum expected ground accelerations, in accordance with recommendations contained in <br /> the geotechnical studies. Therefore, impacts to project facilities resulting from seismic ground <br /> shaking and other activities would be less than significant. <br /> Liquefaction— Liquefaction is a process whereby strong ground shaking causes loose, saturated, <br /> unconsolidated sediments to lose strength and behave as a fluid. Most of the project area that <br /> encompasses the Greater Bayfront areas is underlain by thick strata of fine-grained, highly <br /> plastic and compressible silty clay of lacustrine (marine) origin, commonly known as bay mud. At <br /> its base, the bay mud strata transitions into much firmer stony clays and silty gravel of alluvial <br /> origin. Bedrock, composed of sandstone and shale of the Franciscan Foundation, exists <br /> approximately 300 feet below the surface. By its nature, bay mud is fine-grained, highly saline, <br /> impervious, not subject to liquefaction in the absence of continuous layers of saturated silty <br /> sand, and does not support the lateral transmissibility of groundwater in the absence of inter- <br /> connected granular bedding. <br /> Bay mud has the propensity to laterally flow and close even very shallow, open and <br /> inadequately shored utility trenches. Potential impacts during construction would be minimized <br /> by adequate shoring of all open excavations that intrude into the underlying bay mud, <br /> particularly in open trenches where workers may be present. With implementation of this <br /> measure, construction-related impacts would be less than significant. <br /> Slope-Related Issues — The project area is relatively flat; therefore, landslides are not <br /> anticipated. The lack of slope in the project area would result in negligible soil erosion or loss. <br /> However, increases in erosion of exposed soils by wind or water could occur during excavation <br /> associated with pipeline construction. Contractors will be required to implement San Mateo <br /> County Stormwater Pollution Prevention Program (STOPPP) Best Management Practices to <br /> address erosion and construction run-off concerns. <br /> Expansive Soils — Shrink-swell, or expansive soil behavior, is a condition in which soil reacts to <br /> changes in moisture content by expanding or contracting. Soils in the project area may exhibit <br /> shrink-swell potential. As noted above, detailed geotechnical analyses will be prepared for all <br /> project facilities, and the recommendations of these analyses, including those related to <br /> expansive soils, will be incorporated into project design. <br /> 16 <br />