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' Atlantic Richfield Company 8 ARCO 4932,16 E Harding Way,Stockton,CA June 7 2002 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 • Fuel oxygenates were detected in soil samples collected between 15 feet and ' 69 5 feet bgs in the boring for well DMW-1, and in all samples collected from the boring for EW-1 MtBE was detected 1n soil samples collected between 30 feet and 69 5 feet bgs in the boring for well DMW-1, and in all samples rcollected from the boring for well EW-1, at concentrations ranging from 0 24 mg/kg (EW-1, 47 5') to 290 mg/kg (EW-1, 27 5') A concentration of TBA was detected 1n the 15-foot sample from DMW-1 at 4 1 mg/kg All other fuel oxygenates were not reported above laboratory detection limits • Concentrations of BTEX constituents were reported in groundwater samples collected from wells EW-1 and DMW-1 Elevated concentrations of BTEX constituents were detected 1n well EW-1 at 9,900 ug/i, 40,000 ug/l,4,700 ug/l, and 24,000 ug/l, respectively A minor concentration of benzene was reported in samples collected from DMW-1 at 9 6 ug/l Due to raised detection limits as a result of elevated detections of MtBE,TPHg and/or other BTEX constituents ' were not detected 1n the wells • MtBE was detected 1n groundwater samples collected from wells DMW-1 and '. EW-1 at concentrations of 230 ug/1 and 520,000, respectively A concentration of TBA was reported 1n well DMW-1 at 93 ug/1 All other fuel oxygenates were not detected above laboratory reporting limits ' • Approximately 6,300 gallons of purge water and groundwater generated during aquifer testing, and approximately 4 32 tons of soil were transported by Dillard ' to 1nStrat for disposal VARIANCES TO THE JANUARY 15, 2002 AND MARCH 11, 2002 WORK ' PLAN SUBMITTALS, AND FEBRUARY 14, 2002 SJCEHD LETTER—SITE ASSESSMENT • Well Construction. According to SECOR's January 15, 2002 work plan and subsequent SJCEHD letter dated February 14, 2002, the proposed extraction well (EW-1) and deep monitoring well (DMW-1) were to be )Installed and ' completed at approximately 50 feet and 77 feet bgs, with screen intervals of approximately 25 feet to 50 feet bgs and approximately 72 feet to 77 feet bgs, ' respectively However, based on soil stratigraphy beneath the site, wells were completed at depths of approximately 44 feet and 81 feet bgs, with screen intervals of approximately 21 feet to 44 feet bgs, and approximately 75 feet to ' 80 feet bgs, respectively I1ARCO149321ReportslAsmt&AgfrTstRpt doc