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<br />' 12 July 2006
<br /> AGE-NC Project No 95-0130
<br />' Page 11 of 14
<br /> (43-63 ft) which is consistent with previous monitoring results (Table 3) TPH-g, benzene,
<br />' ethylbenzene and xylene concentrations were detected as high as 260,000 gg/l, 46,000 µg/l,
<br /> 5,400 gg/l and 22,800 gg/l, respectively, from well MW-7B, toluene as detected as high as
<br />' 24,000 gg/l from well VW-I C(Table 4) TPH-g was not detected in well MW-5 for the third
<br /> consecutive quarterly monitoring event, likely representing a retraction of the dissolved
<br /> ground water plume Additionally,the deepest detection of dissolved TPH-g and BTEX was
<br />' in the sample collected from well MW-6E (137-142 feet) The approximate extent of
<br /> dissolved TPH-g is depicted in Figures 5 and 7
<br /> • Although an overall trend of decreasing MTBE concentrations has been evident at the site,
<br />' an MTBE increase was reported from wells MW-6 (B-E), MW-7 (B-C), VW-1C, VW-2A
<br /> and VW-3A during the February 2006 sampling event The increasing dissolved MTBE
<br />' concentrations could be attributed to the recent addition of wells of VW-I C, VW-2A and
<br /> VW-3A to the interim ground water pump-treat system in August 2005 The highest
<br /> concentrations of dissolved MTBE were detected from MW-6B at 13,000 µg/l, and was the
<br />' most intense concentration ever reported from MW-6B,the approximate extent of dissolved
<br /> MTBE is depicted in Figures 6 and 8
<br /> • The highest concentration of 1,2-DCA was detected in sample MW-6B at 190 µg/l,
<br />' • significant concentrations of 1,2-DCA were detected or have consistently been detected from
<br /> wells MW-3, MW-6(B-D), MW-7(B-D), MW-8, VW-I B, VW-I C, VW-2A, VW-2B and
<br /> VW-3A, indicating a significant 1,2-DCA-impact to ground water at the site
<br />' • Significant concentrations of TAME were detected or previously detected from wells MW-1
<br /> through MW-3, MW-6(B-E),MW-7(B-D),VW-I C,VW-2A and VW-3A at concentrations
<br />' as high as 750 µg/1(MW-6B), indicating a significant TAME-impact to ground water at the
<br /> site
<br /> • Low concentrations of DIPE were detected from wells MW-6B, MW-7B and VW-2A at
<br /> concentrations of 6 6 gg/l, 6 4 µg/l and 2 2 gg/l, respectively
<br /> • TBA and EDB were not detected in any of the analyzed water samples, however, they had
<br /> been detected previously TBA had been detected in wells MW-1, MW-2, MW-3, MW-5,
<br /> VW-1 C,VW-2A,VW-213 and VW-3A,suggesting a minor TBA-impact to ground water at
<br /> the site EDB had been detected from wells MW-7B, VW-lB, VW-1C and VW-2A at
<br /> concentrations significantly above the DHS's Maximum Contaminant Level (MCL) in
<br /> drinking water
<br /> • The high concentrations of petroleum hydrocarbons detected in samples collected from wells
<br /> MW-6(B and C),MW-7(A and B),VW-I C,VW-2A and VW-3A indicated that these wells
<br /> are within or near the dissolved petroleum hydrocarbon"core area"of the plume (Figures 5
<br /> through 8)
<br /> Advanced GcoEnvironmental,Inc
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