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Atlantic Richfield Company 7 ARCO 4932 16 E Harding Way Stockton,CA June 7,2002 ' MtBE TBA and 1,2-DCA PA Method 8260) were detected in the groundwater sample from deep well DMW-1, at concentrations of 9 6 ug/l, 140 ug/l, 93 ug/l, and 2 5 ug/l, respectively All other petroleum hydrocarbon constituents and fuel oxygenates were not detected in deep monitoring well DMW-1 Groundwater analytical data are ' presented in Tables 3 and 5, and on Figure 5 Certified laboratory analytical results and chain-of-custody documentation for the April 11, 2002 monitoring and sampling event are included in Attachment H Groundwater sampling field data sheets are included in ' Attachment I SECOR will submit the results of the second quarter 2002 groundwater monitoring and sampling event, including field and laboratory procedures, in a separate report Stockpiled Soil ' Approximately 4 32 tons of soil were generated from the installation of wells DMW-1 and EW-1, and stockpiled on-site One composite sample (4 parts to 1 sample) was collected from the stockpiled soil, which was analyzed for TPHg and BTEX by the DHS/LLTFT Method, and total lead by EPA Method 6010B Following waste profiling, the stockpiled soil was transported by Dillard on April 9, 2002 to InStrat in Rio Vista, California for disposal Stockpiled soil analytical data is presented in Table 6 Waste disposal confirmation sheets are included in Attachment E '• SUMMARY OF FINDINGS • One deep monitoring well and one extraction well were installed at the site to depths of 81 feet and 44 feet bgs Soil consisted predominantly of sandy silt ' from ground surface to approximately 25 feet to 30 feet bgs, with occasional interbedded layers of silty sand Below approximately 25 feet to 30 feet bgs, ' soils were comprised of interbedded layers of sandy silt, clayey silt, sand, and silty sand to the total depths explored(81 feet and 50 feet bgs, respectively) • Depth to groundwater in wells EW-1 and DMW-1 was measured at ' approximately 28 feet bgs During the second quarter 2002 groundwater monitoring event, groundwater flow direction within the shallow zone was to the ' northeast at a gradient of 0 002 foot/foot • Soils collected at 50 feet and 69 5 feet bgs from the boring for deep well DMW- 1, and ail samples collected from the boring for well EW-1 reported detectable concentrations of TPHg and BTEX TPHg was detected at concentrations ranging from 3 2 mg/kg (DMW-1, 50') to 780 mg/kg (EW-1, 27 5') Benzene was detected at concentrations ranging from 0 0081 mg/kg (DMW-1, 69 5') to 5 1 mg/kg (EW-1, 27 5') Toluene was detected in soil samples from the boring for EW-1 at concentrations ranging from 0 25 mg/kg (EW-1, 47 5') to 73 mg/kg ' (EW-1, 275') Ethylbenzene and xylenes were detected at concentrations of • ethylbenzene ranging from 0 017 mg/kg (EW-1, 15') to 23 mg/kg (EW-1, 27 5'), and concentrations of xylenes ranging from 0 0098 mg/kg (EW-1, 15') to 120 ' I 1ARCO149321Reports\Asmt&AgfrTstRpt doc