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I I' 15 October 2002 AGE-NC Project No 97-0333 tPage 7 of 8 ' feet bsg); MW-6 (screened 20 to 45 feet bsg) and EW-1 (screened 20 to 45 feet bsg) and is pnmanly impacted by TPH-g, BTEX, and MTBE • Substantial concentrations of dissolved TAME have been detected in water samples collected ' from wells MW-1,MW-2,MW-3 and MW-6 and a grab ground water sample collected from P-3, indicating that there is a limited area impacted with TAME in the area assessed 1 • Substantial concentrations of PCE have been detected in water samples collected from wells MW-3 and MW-4, low concentrations of TCE have been detected at wells MW-4 and MW-5 PCE and TCE are chlorinated solvents often associated with dry cleaning operations ' • Substantial concentrations of 1,3,5-tnmethylbenzene and 1,2,4-tnmethylbenzene were detected at well MW-5, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene and ' 1,2,4-dichlorobenzene were detected in previous water samples collected from MW-5 • The lateral and vertical extent of dissolved petroleum hydrocarbons is not known in any direction at the site (Figures 4 and 5) • Free-floating petroleum product has been encountered at wells MW-2, MW-6 and EW-1 during the December 2001 ground water monitoring event Free-floating petroleum product ' • has not been encountered in any wells during the February and May 2002 monitoring events I ' The results of interim ground water pump-and-treat remediation between 01 April and 06 June 2002 are as follows • Between 01 Apnl 2002 and 06 June 2002, the pump-and-treat system was in operation for approximately 67 days and processed approximately 123,453 gallons of water AGE estimates that an average 1,842 gallons of water was discharged per day during this time ' Dissolved MTBE was detected from grab samples collected at the influent end of the treatment system'at 6oncentrations between 13,000 pgll and 90,000 µg/l (Table 2) ' Laboratory analysis,Iof four grab water samples collected at the effluent end of the pump- and-treat system id not, detect any constituents of concern above state maximum contaminant levels (MCL's),however, TBA was detected in the 17 April 2002 sample at a ' cbncentration of 7 6 µg/1 (Table 2) f • Between 01 April 2002 and 06 June 2002, approximately-33 85 pounds of MTBE was removed from extracted ground water(Table 1), since system initiation, the estimated total ' mass removed is approximately 146 77 pounds of MTBE II I I I 1 1 4 , I •L I I I t I I I 1 I I I 1 I ' 1 1 I ! I I{ I II ` I Advanced GcGEavirpnmental,Inc e III 7 I i I Ir 6 1