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a _ <br /> i <br /> i J <br /> '! 16 October 2003 <br /> 'AGE NC Project No 96-0235 <br /> I <br /> Page 4of5 <br /> 1 <br />' 4.0. _SUMMARY AND CONCLUSIONS <br /> I <br /> > Based on the data collected from the former UST cluster area, AGE finds <br /> • The shallow-screened data delineated a northeasterly water flow pattern at a gradient of <br /> 0 002 ft/ft,the deep-screened data delineated a radial ground water flow direction toward the <br />' west-nothwest at a gradient of 0 008 ft/ft <br /> • TPH-g was detected in ground water samples collected from MW-10 and EW-1 at <br /> concentrations of 2,700 µg/1 and 8,300 µg/, respectively TPH-d was detected in samples <br /> collected fromMW-9,MW-10,MW-11B,MW-i4B,MW-15B and EW-1 at concentrations <br /> as high as 7,100 µg/l (MW-10) <br />' BTEX compounds were detected in water samples collected from MW-10, MW-14B and <br /> EW-1 The maximum BTEX concentrations were detected in the sample from EW-1, <br /> t however the concentrations have declined significantly from the previous quarters The <br /> BTEX concentrations in sample EW-1 and the benzene concentration in sample MW-10 <br /> were above the DHS' Maximum Contaminant Level (MCL) in drinking water <br /> t • MTBE was detected by EPA Method 8260 in the shallow-screened wells MW-10,MW-13A <br /> 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 270 µg/1 (EW-1) With the exception of MW-13A, <br /> the MTBE concentrations were above the DHS's Primary MCL of 13 µg/1 in drinking water, <br /> the MTBE concentration in MW-13A was equal to the DHS' Secondary MCL of 5 µg/1 in <br /> drinking water <br /> • The concentrations of 1,2-DCA detected in ground water samples MW-11B, MW-12B, <br /> MW-13B and MW-14B exceeded the DHS's MCL <br /> II • 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 /> Based on the data collected from the former UST No 3 area, AGE finds <br /> Ground water flow direction at the shallow-screened level was inferred to,be towards the <br /> southeast at a gradient of 0 005 ft/ft, ground water flow direction at the deep-screened level <br /> 1 was inferred to be toward the south-southwest at a gradient of 0 018 ft/ft <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 21,000 µg/1 and 2,900 µg/1, respectively <br /> 1 <br /> 'Advanced CeuEnvironmental,Inc <br /> 1 <br />