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a. <br /> �- Geofogica(Technics Inc. <br /> 2741 River Road <br /> Modesto,caCforma 95351 <br /> (209)538-64241Fax,#538-5852 <br /> Lr <br /> LW Work Plan <br /> Additional Site Characterization <br /> L. <br /> Site of Investigation <br /> Valentine <br /> 2315 N Eldorado St., <br /> Stockton, CA <br /> Project No.: 723.2 <br /> October 29, 1998 <br /> 4. <br /> 1.0 INTRODUCTION <br /> A telephone conference was held with Mr. Jeff Wong on October 19, 1998 regarding the <br /> investigation of the vertical extent of the soil and groundwater plume. During this phone <br /> conversation it was decided to drill a deep borehole near the primary source or point of <br /> 4. release of gasoline. This borehole would be logged by continuous soil coring. Soil and <br /> groundwater samples collected for testing purposes will be collected using SimulProbe <br /> technology. This information will be used to propose construction of nested wells. A water <br /> well/receptor survey of the surrounding area will also be performed. This work plan <br /> discusses the work to be completed. <br /> 2.0 SITE HISTORY <br /> The following is a summary of worked performed at the site to date: <br /> • In April 1987 the sites two 3,000-gallon gasoline fuel tanks and the one 150-gallon waste <br /> oil tank were removed. <br /> • In late October 1993 four borehole (SB-1 thru SB-4) were placed around the location of <br /> the former waste oil tank. Results showed that all soil samples, except for the 36-foot <br /> sample from SB-2, were below detection limits for BTEX and TPH-G. <br /> + In Late September 1994 monitoring well, MW-1, was installed at the site. Results <br /> showed the presence of BTEX and TPH-G in the soil to a depth of 56 feet bgs. Waste oil <br /> was detected in the shallow soil samples. <br /> • In early June 1995 two additional monitoring wells, MW-2 & MW-3, were installed at <br /> the site. Results showed the presence of high levels of BTEX and TPH-G in the soil and <br /> groundwater. <br /> In late June 1996 three additional monitoring wells (MW-4, MW-5 & MW-6) and soil <br /> boring `B" was installed at the site. Results showed the presence of significant levels of <br /> BTEX, MTBE and TPH-G. Results also indicate that the pump-island was a major <br /> source of contamination. <br /> �- + In late September and early October 1997 five Strataprobe soil borings (SP-1, SP-4 SP-5, <br /> SP-5A & SP-6) were installed at the site. Groundwater samples collected from these <br />