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26 September 2000 AGE-NC Project No 96-0263 Page 2 of 10 22 PREVIOUS INVESTIGATIONS On 24 June 1998, a total of nine soil probe borings (B 1 through B9) were advanced at the site Grab ground water samples were collected and analyzed from probe borings B 1, B3, B5,B6, B7, B8 and B9 TPH-g was detected in nine of fifteen soil samples analyzed from seven of the soil probe borings TPH-g was detected at concentrations as high as 670 mg/kg(sample B4-5') TPH-g was detected in soil from depths greater than 10 feet bsg at concentrations up to 240 mg/kg (B5-12') TPH-g was not detected in soil samples collected at depths of 20 feet and 25 feet bsg BTEX compounds were detected in eleven of the fifteen soil samples analyzed The greatest concentrations of BTEX compounds detected were generally in soil samples collected at depths of five and ten feet bsg, however, in the former dispenser area BTEX compounds were detected in a soil sample collected from a depth of twelve feet bsg at a considerable concentration MTBE was detected in 12 of the fifteen soil samples analyzed MTBE concentrations detected in soil from depths less than 10 feet bsg were as lugh as 43,000 micrograms per kilogram (mg/kg) (Sample B5-10') MTBE was detected in the soil sample collected at 25 feet bsg at a concentration of 58 mg/kg Laboratory results of soil samples analyzed for petroleum hydrocarbons area summarized in Table 3 TPH-g was detected in four of the seven grab ground water samples collected from the site at concentrations ranging from 3,200 to 27,000 micrograms per liter(J.cg/l) BTEX compounds were detected in four of the water samples at significant concentrations ranging from 30 mg/l benzene in boring B3 to 5,400 µg/1 of xylene in boring B 1 MTBE was the only oxygenated fuel additive detected in the water samples, and was detected in five of the seven samples analyzed at concentrations ranging from 65 4g/1 to 11,000 mg/l Only the grab ground water samples collected from borings B7 and B9 did not contain detectable concentrations of MTBE Laboratory results of grab ground water samples analyzed for petroleum hydrocarbons area summarized in Tables 4 and 5 In November 1999 eight soil borings were advance at the site and completed as ground water monitoring wells A total of 21 soil samples were analyzed for TPH-g, BTEX and MTBE and the suite of five fuel additives by EPA Method 8260 Modified TPH-g was detected in soil samples analyzed from borings MW2, MW4, MWS, and MW6 at concentrations as high as 150 milligrams per kilogram(mg/kg) The BTEX compounds were detected at concentrations as high as 0 82 mg/kg, 1 7 mg/kg,4 8 mg/kg and 14 mg/kg,respectively Petroleum hydrocarbons were not detected in soil bonngs MW1 and MW3 MTBE was detected in samples collected from monitoring wells MW2, MW4, MWS, MW6 and Advanced GeoEnhronmental,Inc