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EnviroTech Consultants, Inc. Page 5 <br /> Site Investigation: Sampling Report <br /> Louise Avenue Water Treatment Facility <br /> 2.4 GEOLOGY, AND HYDROGEOLOGY <br /> 2.1 Area Geology <br /> The Site is located in the Great Valley Geomorphic Province(California Geological Survey 2002).The Great <br /> Valley generally trends north-south and is bordered by the Coast Ranges to the west and by the Sierra <br /> Nevada to the east. The Great Valley is an asymmetrical synclinal trough about 50 miles wide and 400 <br /> miles long with its axis off center to the west. Sediments have been deposited in this trough almost <br /> continuously since the Jurassic Period (about 160 million years ago). <br /> Lithology of the Great Valley consists of alluvial sediments known as the Great Valley Sequence, which is <br /> comprised of interbedded sedimentary units. The thickness of the Great Valley Sequence exceeds 25,000 <br /> feet in some areas. These sediments rest on a basement complex of metamorphic and igneous rocks. The <br /> surficial deposits are primarily eroded rock from the Sierra Nevada to the east and the Coast Range to the <br /> west. Because the synclinal trough was previously underwater, some of the sediments are of marine origin. <br /> A variety of unconsolidated Quaternary alluvial deposits are mapped in the site area;these represent active <br /> and inactive river and stream channel deposits, flood plain deposits, and alluvial outwash deposits. <br /> 2.2 Hydrogeology <br /> The Site is located within the Eastern San Joaquin Sub-basin of the San Joaquin River Valley Groundwater <br /> Basin as recognized by the California Department of Water Resources (DWR 2006). Groundwater-bearing <br /> formations in the vicinity of the Site consist of the Alluvium and Modesto/Riverbank Formations, Flood Basin <br /> Deposits, Laguna Formation, and Mehrten Formation. <br /> 5400 Rosedale Highway 0 Bakersfield, CA 93308 Tel 661.377.0073 Fax 661.377.0074 <br />