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4 <br /> ' The Site lies in the Eastern San Joaquin Subbasin of the San Joaquin Valley Groundwater Basin <br /> (Groundwater Basin Number 5-22.01). The Eastern San Joaquin Subbasin is defined by the areal <br /> extent of unconsolidated to semiconsolidated sedimentary deposits that are bounded by the <br /> t Mokelumne River on the north and northwest, the San Joaquin River on the west, the Stanislaus <br /> River on the south, and consolidated bedrock on the east (DWR, 2003). <br /> ' The Eastern San Joaquin Subbasin is drained by the San Joaquin River and several of its major <br /> tributaries namely,the Stanislaus,Calaveras,and Mokelumne Rivers. The San Joaquin River flows <br /> northward into the San Francisco Bay. The average rainfall in the Eastern San Joaquin Subbasin <br /> ranges from 11-inches in the southwest to about 25-inches in the northeast(DWR, 2003). <br /> Water bearing units in the basin in descending order consist of the Recent to late Pleistocene age <br /> Alluvium and Modesto/Riverbank Formations,the Plio-Pleistocene age Laguna Formation,and the <br /> late Miocene to Pliocene age Mehrten Formation (DWR;2003). <br /> ' 3.4 Depth to Groundwater <br /> ' The depth to groundwater in the Site vicinity varies between 55 feet below the ground surface(bgs) <br /> and 65 feet bgs according to the San Joaquin County Department of Environmental Health(Lagorio, <br /> 2003). <br /> ' 4.0 OBJECTIVE <br /> ' The objective of the investigation was to assess the.lateral and vertical extent of petroleum <br /> hydrocarbons in soil in the location of soil sample D8-2c <br /> 5.0 FIELD INVESTIGATION <br /> All activities related to this subsurface investigation were conducted under the supervision of a State <br /> of California Certified Engineering Geologist in accordance with accepted engineering practice and <br /> protocol. <br /> ' 5.1 Pre-field Activities <br /> ' FREY personnel visited the Site on April 15, 2004 and marked the proposed boring locations. <br /> FREY obtained underground service alert number. 180385 and soil boring permit number <br /> SR0037896 prior to the conduct of drilling activities: A copy of the soil boring permit has been <br /> attached in Appendix A. <br /> ' FREY <br /> 1 <br />