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.� F1 <br /> S E C O R ----- - - <br /> Mr. Michael Infurna <br /> San Joaquin County Environmental Health Department <br /> March 27, 2007 <br /> Page 5of8 <br /> SECOR proposes collecting grab groundwater samples from the initial four soil borings <br /> and possibly from one of the step-out soil borings, depending on observed groundwater <br /> conditions. <br /> Soil and Groundwater Sampling and Analysis <br /> Soil samples will be collected approximately every 5 feet in the initial four soil borings. <br /> Soil samples will be collected based on evidence of chemical impact, such as visual <br /> discoloration, olfactory evidence, or elevated PID readings. If no such evidence is <br /> observed, soil samples will be collected at a frequency which demonstrates the vertical <br /> gradient of target constituents in soil. SECOR proposes collecting up to seven soil <br /> samples per soil boring, corresponding to one sample every 5 feet assuming a total <br /> depth of 35 feet bgs. <br /> Soil samples will be collected from additional step-out soil borings using similar criteria. <br /> In addition, specific zones may be targeted based on observations made during <br /> advancement of the previous soil borings. SECOR proposes collection and analysis of <br /> up to eight additional soil samples from the step-out soil borings. <br /> Grab groundwater samples will be collected from each of the initial four soil borings and <br /> possibly from one of the step-out soil borings, if conditions warrant. Grab groundwater <br /> samples will be collected using dedicated, disposable bailers inserted through temporary <br /> polyvinyl chloride (PVC) well casings with approximately 5 feet of screen. Based on <br /> SECOR's review of local hydrologic conditions, first-encountered groundwater is <br /> anticipated in the upper 35 feet. If groundwater is not encountered in the upper 35 feet <br /> bgs, SECOR may elect to extend one or more soil borings to greater depth as conditions <br /> allow. Conversely, if it can be demonstrated that a significant zone of separation exists <br /> between the deepest petroleum hydrocarbon impacts attributable to the Site and first- <br /> encountered groundwater (on the order of 20 feet), the soil borings may be terminated <br /> before reaching groundwater. <br /> Soil and grab groundwater samples will be shipped to Calscience Environmental <br /> Laboratory, Inc. (Calscience), a state-certified analytical laboratory in Garden Grove, <br /> California. <br /> I:\PG&E\French Camp\additional 2007 investigation\work plan\2007 Investigation Work Plan—Final.doc March 27,2007 <br /> Project No.050T.50351.01 <br />