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{ C;eo[og e,ate,ch,aICS In C. <br /> I 1 101 7"Street <br /> Modesto,California 95354 <br /> (209)522-41.19/Fax(209)522-4227 <br /> G <br /> Feasibility Study Work Plan <br /> Dual Phase Soil Vapor and Groundwater Extraction Pilot Test <br /> Site of Investigation <br /> Valentine (Castle Motors) <br /> 2315 N. El Dorado Street <br /> Stockton, CA <br /> Project No. 723.2 <br /> September 8, 2003 <br /> 1.0 INTRODUCTION <br /> In April 1987 the site's two 3,000-gallon.gasoline underground storage tanks (UST) and one <br /> 150-gallon waste oil UST were removed (see Figure 1: Vicinity Map & Figure 2: Site Map). <br /> Analyses of soil samples from the UST excavations revealed that a petroleum hydrocarbon <br /> release had occurred. The San Joaquin County Environmental Health Division (SJC/EHD) <br /> subsequently directed Mr. Valentine to begin an investigation to determine the extent of the <br /> petroleum release. <br /> The following is a summary of work performed at the site to date: <br /> • In October 1993 four boreholes (SB-1 thru SB-4) were placed around the location of <br /> the fonner.waste oil tank. Results showed that all soil samples, except for the 36- <br /> foot sample from SB-2, were below detection limits for BTEX and TPH-G. <br /> • In September 1994 .monitoring well MW-1 was installed at the site. Soil sample <br /> analytical results indicated the presence of BTEX and TPH-G in the soil to a depth <br /> of 56 feet bgs. Waste oil was detected in the shallow soil samples. <br /> In June 1995 two additional monitoring wells, MW-2 & MW-3, were installed at the <br /> site. Results showed the presence of high levels of BTEX and TPH-G in the soil and <br /> groundwater. . <br /> • In June 1996 three additional monitoring wells (MW74, MW-5 & MW-6) and soil <br /> boring `B" were installed at the site. Soil sample analytical results indicated the <br /> presence of significant levels of BTEX, MTBE and TPH-G. . The results also <br /> indicated that the pump,-island was a;major source of contamination. <br /> • In September and October 1997 five Strataprobe soil borings (SP-1, SP-4 SP-5, SP- <br /> 5A & SP-6) were installed at the site. Groundwater samples collected from these <br /> borings indicated the presence of low to moderate levels of TPH-G to a depth of 60 <br /> feet bgs. <br /> - <br /> i <br />