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Atlantic Richfield Company 5 ARCO 4932 16 E Harding Way Stockton CA June 7,2002 '• measured at 29 feet and 28 feet bgs, respectively During drilling, wet soils were consistently present within the silty sand and sand layers in both soil borings to the total depth explored Soil Sampling and Analysis Soil encountered during the advancement of the borings for deep well DMW-I and extraction well EW-1 were logged at 5-foot intervals to approximately 50 feet bgs and ' 20 feet bgs, respectively In order to evaluate stratigraphy of deeper zone soil, soils encountered beyond 50 feet bgs in the boring for deep well DMW-1 and beyond 20 feet bgs in the boring for extraction well EW-1 were continuously logged to the total depths ' explored of 81 feet bgs and 50 feet bgs, respectively Soil samples were collected at 5- foot intervals from each well using a California modified split spoon sampler Selected samples were submitted for analysis for TPHg and benzene, toluene, ethylbenzene, and xylenes (BTEX)by the California Department of Health Services/Leaking Underground Fuel Tank (DHS/LUFT) method, and fuel oxygenates(MtBE, TAME, di-isopropyl ether [DIPE],EtBE, TBA, ethylene dibromide [EDB], and 1,2-DCA) by EPA Method 8260B Soils collected between approximately 30 feet and 69 5 feet bgs from the boring for ' deep well DMW-I and all samples collected between 15 feet and 47 5 feet bgs from the boring for EW-1 reported detectable concentrations of TPHg and BTEX Of the 10 soil samples collected from the two borings, TPHg was detected in the 50-foot sample from the boring for well DMW-1 at 3 2 mg/kg, and in three samples collected between 27 5 feet and 47 5 feet bgs in the boring for well EW-1 at concentrations ranging from 7 2 mg/kg (EW-1, 40') to 780 mg/kg (EW-1, 27 5') Benzene was detected in the 50-foot ' and 69 5-foot samples from the boring for well DMW-1 and all four samples from the boring for well EW-1 at concentrations ranging from 0 0081 mg/kg (DMW-1, 69 5') to 5 1 mg/kg (EW-1, 27 5') Toluene was only detected in three samples collected between 27 5 feet and 47 5 feet bgs from the boring for well EW-I at concentrations ranging from 0 25 mg/kg (EW-1, 47 5') to 73 mg/kg (EW-1, 27 5') Ethylbenzene and ' xylenes were detected in the 50-foot sample from the boring for well DMW-1 and all four samples collected from the boring for well EW-1, at concentrations of ethylbenzene ranging from 0 017 mg/kg (EW-1, 15') to 23 mg/kg (EW-1, 27 5'), and concentrations rof xylenes ranging from 0 0098 mg/kg (EW-1, 15') to 120 mg/kg (EW-1, 27 5') Petroleum hydrocarbons were not detected above laboratory reporting limits in the ' deepest sample collected from the boring for well DMW-1 at 80 feet bgs Of the fuel oxygenates analyzed by EPA Method 8260B, MtBE was detected in eight of the ten samples collected from the two soil borings MtBE was detected in four samples ' collected between 30 feet and 69 5 feet bgs from the boring for well DMW-1 and in all four samples collected between 15 feet and 47 5 feet bgs from the bonng for well EW-1, at concentrations ranging from 0 24 mg/kg (EW-1, 47 5')to 290 mg/kg (EW-1, 27 5') One sample reported a concentration of TBA at 4 1 mg/kg (DMW-1, 15') All other fuel oxygenates were not detected above laboratory detection limits ' 11ARCOW9321Reports\Asmt&AgfrTstRpt doc