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1 <br /> 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 /> 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 /> rThe 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 /> rThe 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 scope of work described below is to assess the lateral and vertical extent of <br /> petroleum hydrocarbons in the location of soil sample D8-2. <br /> r5.0 SCOPE OF WORK <br /> ' 5.1 Pre-field Activities <br /> FREY will mark the proposed soil boring locations and obtain an underground service alert number <br /> prior to the conduct of any drilling operations.FREY will notify the SJCEHD at least 72 hours prior <br /> to the conduct of field activities. All field work will be conducted under the general guidelines set <br /> forth in the health and safety plan attached in Appendix B. <br /> 5.2 Drilling and Sampling of Four Soil Borings <br /> ' Four soil borings,designated as B 1 through B4,will be drilled as part of the investigation(Figure 2). <br /> Boring B 1 is proposed to be drilled through the location of previously collected soil sample D8-2. <br /> Borings B2,B3 and B4 are proposed to be located at approximate distances of 20 feet to the north, <br /> southeast and west of boring B L <br /> r <br />