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I27 April 2003 <br /> ' . AGE-NC Project No 96-0235 <br /> Page 7 of 8 1 <br /> concentrations have declined significantly from the previous quarters The BTEX <br />' concentrations in sample EW-l and the benzene concentration in sample MW-10 were above <br /> the DHS Maximum Contaminant Level (MCL) in drinking water <br /> I • MTBE was detected by EPA Method 8260 in the shallow-screened wells MW-10,MW-1 3A <br /> a and EW-1 and in the deep-screened wells MW-9, MW-11B, MW-12B, MW-13B and <br /> MW-14B at concentrations as high as 250 ptg/l (EW-1) With the exception ofMW-13A, <br />' the MTBE concentrations were above the DHS' Primary MCL of 13 µg/l in drinking water, <br /> the MTBE concentration in MW-13A exceeded the DHS' Secondary MCL of 5 gg/l in <br /> r <br />' drinking water <br /> • The concentrations of 1,2-DCA detected in ground water samples MW-11B, MW-12B, <br /> MW-13B, MW-14B and EW-2 exceeded the DHS' MCL <br />' • In the former UST cluster area, the most impacted ground water appears to be centered <br /> around EW-1 and'MW-10 The vertical extent of the contamination plume, as well as the <br />' lateral extent east and south of the former UST cluster, are not well defined <br /> 5 <br /> Based on the data collected from the former UST No 3 area, AGE finds <br />' • Ground water flow in the upper monitored interval was inferred to be towards the east- <br /> southeast Ground water flow in the lower interval was inferred to be toward the south- <br /> southwest <br /> • TPH-g and TPH-d were detected in the samples collected from MW-1,MW-2 and EW-2 at <br />' concentrations as high as 2,300 pg/l and 770 µg11, respectively <br /> • Various BTEX compounds were detected in water samples MW-2 and EW-2, the benzene <br /> concentrations in samples MW-2 and EW-2 were above the DHS's MCL in dnnkmg water <br />' • MTBE was not detected in any of the ground water samples collected from the former UST <br /> No 3 excavation area However,,1,2-DCA was detected in water samples MW-1, MW-2, <br />' MW-5, MW-6B, MW-7 and MW-8A at concentrations exceeding the MCL for drinking <br /> water <br /> • The vertical extent of the contamination plume, as well as the lateral extent to the south, are <br />' not well defined <br /> E <br /> 5.0. RECOMMENDATIONS <br /> Based on the findings of the environmental activities recounted in this report, AGE recommends <br /> iAdvanced GeoEnviron mental,Inc <br />