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easibility Testing Work Plan Jimco Truck Plaza C A M B R I A 1022 Frontage Road Ripon, California May 18, 2005 laboratory for analysis. TPHg was detected in soil samples collected from boring MW-9 at 20,25 and 30 ft bgs at concentrations of 260, 0.36 and 0.24 mg/kg,respectively. No benzene was detected in any of the soil samples analyzed. MTBE was detected in samples collected from boring MW-9 at 15, 25, and 30 ft bgs at concentrations of 0.016, 0.54, and 0.27 mg/kg, respectively. TPHd was only detected in the 20 ft sample at a concentration of 800 mg/kg. June 2002: In June 2002, AGE conducted a 48-hr groundwater extraction pilot test to assess the . characteristics of the aquifer and its response to groundwater extraction. The test was performed on extraction well EW-1 screened from 16 to 36 ft bgs.-A maximum drawdown of 9.76 feet was measured in extraction well EW-1 while pumping at a constant rate of 6 gpm. A maximum drawdown of 0.40 feet was obseryed in observation MW-1, located 20 feet away from the extraction well. Additional details.are presented.in AGE's November 6, 2002 Well Installation and Groundwater Aquifer Pumping Test Report. May 2004: In May 2004,TEC Accutite removed one 1,000-gallon,steel waste oil tank. Soil samples collected by Cambria during the UST removal activities(TP1 and TP2)confirmed that soil beneath the UST was minimally impacted by TPHd. TPHd-was detected at concentrations of 4.0 and 160 mg/kg. 4.0 CONTAMINANT DISTRIBUTION 4.1 Lateral Extent of Contamination Vq � Soil Contamination: Soil data indicates that gasoline an diesel-impacted soil is present primarily between 15 to 25 ft bgs in the vicinity of the former USTs, and with shallower gasoline and diesel- impacted soil present beneath the eastern line of former dispensers. The lateral extent of hydrocarbon impacted soil appears to be adequately characterized. — d ' +- n' b T 1 lt s rn4p does 4" Groundwater Contamination:Based on the most recent groundwater uality data(Feb ru �2,2005),the lateral extent of im acted roundwater a ears to be de uatel defined all directi s except for �61 r h rP Y fine. / r southwest of the former USTs, towards monitoring wells MW-8 and MW-9 (Figure 3). Relatively high hydrocarbon concentrations (primarily diesel) are also present in well MW-6 which is located approximately 270 feet east of the former USTs and was originally installed in conjunction with the investigation of a fuel release at the adjacent Ripon Farm-Services goperty. The intervening distance, the anomalously high TPIId concentrations, and westerly groundwater flow direction suggest that hydrocarbon impact observed in well MW-6 is likely due to a source other than the former USTs at the 5 a