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Results of the sod sampling from under the former USTs and dispenser islands indicated that significant concentrations of gasoline hydrocarbons were detected beneath the north end of the former middle UST and in shallow subsurface soil in the vicinity of the west dispenser island The soil sample results are summarized in Table 1 The sod sample collected from 14 feet below ground surface (bgs) under the north end of the middle former UST (Tank 2) contained 7,000 milligrams per kilogram (mg/kg) of TPH-as-gasoline, 3 5 mg/kg of benzene, 90 mg/kg of ethylbenzene 590 mg/kg of xylenes and 0 024 mg/kg of MTBE Neither TPH-as-gasoline nor BTEX compounds were detected in the other five soil samples collected from beneath the former USTs MTBE was detected in one other soil sample at a concentration of 0 021 mg/kg TBA was detected in four of the six soil samples at a maximum concentration of 0 067 mg/kg The maximum concentration of lead detected beneath the former USTs was 11 mglkg The soil sample collected from approximately 3 5 feet bgs from beneath the east dispenser did not contain detectable concentrations of TPH-as-gasoline, BTEX or the five oxygenate compounds Total lead was detected in this soil sample at 6 1 mg/kg The soil sample collected at approximately 4 5 feet bgs from beneath the west dispenser contained 190 mg/kg of TPH-as- gasoline, 0 6 mg/kg of benzene, 10 mg/kg of toluene, 3 mg/kg of ethylbenzene, 14 mg/kg of xylenes and 130 mg/kg of MTBE The other oxygenate compounds DIPS, ETBE, TAME and TBA were not detected Total lead was detected in this soil sample at 30 mg/kg These soil sample results are also summarized in Table 1 Approximately 200 cubic yards of excavated overburden soil was stockpiled in the southeast corner of the site A total of eight discrete soil samples were collected for laboratory analysis from the soil stockpile The soil stockpile was uncovered and allowed to passively aerate On February 5, 1998, based on the detection of elevated concentrations of gasoline hydrocarbons beneath the west dispenser island, PHSIEHD completed and filed an Unauthorized Release Form and directed that further site characterization be completed to determine the full nature and extent of contamination The concentrations of gasoline hydrocarbons beneath the north end of former middle UST were not further investigated On February 6, 1998, under PHSIEHD observation, West Hazmat Drilling Corporation drilled two soil borings in the vicinity of the south end of the west dispenser island (Figure 3) The first soil boring (D-1) was positioned approximately 20 feet west of the former UST excavation and drilled vertically to a total depth of 20 feet bgs From D-1, soil samples were collected for laboratory analysis from 15 and 20 feet bgs The second soil boring (D-2) was located to the south and west of the former west dispenser and drilled at an angle of 30 degrees off-vertical The boring was 4