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Groundwater Sampling an�'Analysis Plan <br /> Former Texaco Service Station <br /> jj Chevron Site ID 309075 <br /> L January 14, 2011 <br /> C <br /> 2.0 BACKGROUND INFORMATION <br /> 2.1 SITE HISTORY <br /> A summary of the site history and previous investigations is included in Attachment A. Historical <br /> groundwater monitoring and analytical data tables are included in Attachment B. Historical <br /> analytical soil data is included in Table 1. Soil boring and well construction details are included <br /> in Table 2. Groundwater gradient and flow direction data are included in Table 3. <br /> 2.2 SITE GEOLOGY <br /> Boring and well logs from previous investigations are included in Attachment C. Boring logs for <br /> MW-1, P1, P2, P3, and P4 are unavailable in historical record. A groundwater flow direction <br /> rose diagram is included in Attachment D. <br /> 2.3 ''REGIONAL GEOLOGY/HYDROGEOLOGY <br /> The Stockton area is underlain to a depth of approximately 150 feet below grade by Holocene <br /> age alluvium and the Victor Formation, whichis comprised of unconsolidated Quaternary age <br /> deposits. These formations are heterogeneous consisting of laterally discontinuous lenses of <br /> sand and gravel with varying amounts of sand and silt interstratified with units of clay and silt. <br /> Surface water bodies present in the vicinity of the site include 'Morman Slough, located <br /> approximately 3,000 feet to the north, and Walker Slough located approximately 6,000 feet to <br /> Cthe south. <br /> C \\CA5FP\Data\Aproject\ENV\CHEVRON\309075\6 Deliverables\Work Plan\SAP\309075_SAP_6671110950.doc 2 <br /> i.i <br />