ARCHIVED REPORTS_XR0008259 CASE 2

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12/02 02 TUE 09 16 FAX 19259469968 ERMWEST WC Z009 Mr Harm Knoll 15 June 1999 Page 8 pattern and distribution of benzene displayed on this figure TPH-g concentrations d=rush by one order of magnitude moving laterally away from B-5 to B-6 Fuel oxygenates were detected in the sample collected from boring B-6 only CONCLUSIONS Based on the results of investigations conducted to date, ERM makes the following conclusions regarding site conditions The release source causing soil contamination has been removed The surface of the site is now entirely sealed with asphalt pavement, and is used as a parking lot All soil contarrunation was identified at depth within the property boundary and beneath the asphalt cover The lateral extent of soil contarrunation has been adequately defined within an approximately 20-foot radius of the former release location . The vertical extent of soil contamination is adequately defined at approximately 20 feet bgs This highest level of TPH-g in soil was found at a depth of 16 5 feet (13-2) bgs at a concentration of 17,000 mg/kg A PRG does not exist for TPH-g contaminants of concern (COC) in soil are those compounds detected in soil at concentrations greater than the PRG CDCs in the soil are summarized in the following table- Compound Location(depth) Concentration PRG Toluene B-2(16 51) 570 mg/kg 520 mg/kg Xylenes 5-2(165') 1,700 mg/kg 860 mg/kg Ground water was encountered at a depth of 34 feet bgs and flows towards the northeast Ground water impacts were detected in the uppermost unconfined aquifer No identified uses for this aquifer were identified in the immediate area affected by the release CDCs in ground water were identified as those compounds detected in 0 ground water at concentrations exceeding the MCL for drinking water COCl in ground water are summarized in the following table