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' 28 October 2005 . AGE-NC Project No 95-0130 ' Page 11 of 13 ' • The greatest concentrations of Top Filling Station dissolved MTBE were detected at concentrations as high as 3,200 µg11 in the samples collected from well MW-6B (screened 50 to 55 feet), the approximate extent of dissolved MTBE is depicted in Figures 6 and 8 ' • TBA was not detected in any of the analyzed water samples,however, TBA was previously detected in wells MW-I, MW-2, MW-3, MW-5, VW-IC, VW-2A, VW-2B and VW-3A, suggesting a minor TBA-impact to ground water at the site ' • Significant concentrations of 1,2-DCA were detected or have consistently been detected from wells MW-3, MW-8, MW-6B, MW-6C, VW-1B, VW-1C, VW-2A, VW-2B and VW-3A, ' indicating a significant 1,2-DCA-impact to ground water at the site • EDB has previously been detected from wells MW-7B, VW-1B, VW-1C and VW-2A at ' concentrations significantly above the DHS's Maximum Contaminant Level (MCL) in drinking water • TAME was detected in ground water samples collected from wells MW-6 (B-D), MW-7 ' (B-D),VW-1C, VW-2A and VW-3A at concentrations as high as 750 µg/l(MW-7B) This is the fifth consecutive occurrence that TAME has been detected in ground water samples collected from the site,with the exception of one detection of TAME in December 2003 and March 2003 in wells VW-2A and VW-3A, respectively • The high concentrations of petroleum hydrocarbons detected in samples collected from wells MW-6(B and C),MW-7(A and B),VW-1 C,VW-2A and VW-3A indicated that these wells are within or near the dissolved petroleum hydrocarbon"core area" of the plume (Figures 5 through 8) • The lateral and vertical extent of the dissolved petroleum hydrocarbon plume is not known toward the northwest,north, northeast, east and southeast of the area bound by wells MW-1 through MW-7 (Figures 5 through 8) Based on SVE remediation data collected between 08 March 2005 and 22 June 2005, AGE concludes • Due to a crack that developed in the heat exchanger, SVE operations were temporarily suspended between 12 April and 22 June 2005 to that the heat exchanger could be replaced by the manufacturer (Solleco) • SVE inlet vapor concentrations decreased from 5,000 Vg1l to 480 µg11,the average SVE inlet vapor concentration was approximately 3,493 µg/l • A significant decline in hydrocarbon vapor concentrations was evident between the first quarter 2005 and the second quarter 2005 monitoring events, a plot of the influent TPH-g concentrations versus time is included in Appendix F Advanced GeaEnvu onuzental,iuc