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' 15 February 2002 . AGE-NC Project No 96-0263 ' Page 3 of 4 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES TPH-g was detected in the water samples collected from monitoring wells MW1, MW2, MW4, MW5,MW7 and MW 11 at concentrations ranging from 82 micrograms per liter(µg/1) in MW 1 to 17,000 µg/1 in MW7 Benzene was detected in the water samples collected from monitoring wells MW2, MW4, MW5, and MW7 at concentrations ranging from 15 µg/l in MW4 to 570 µg/l in MW7 Toluene, ethylbenzene and total xylenes were also detected in the same samples at concentrations ranging from 14 µg/l of toluene in MW4 to 330 µg/1 of toluene in MW7 MTBE was detected by EPA method 8020 in monitoring well samples MW2, MW4, MW5, MW7 and MW8 at concentrations ranging from 14 µg/1 in the sample from MW8 to 7,600 µg/1 in MW7 MTBE was confirmed by EPA method 8260m in the same samples at concentrations ranging from 31 µg/1 in MW8 to 6,900 µg/1 in MW7 TAME was detected in the water samples collected from I wells MW2,MWS and MW7 at concentrations as high as 25 µg/l and ETBE and TBA were detected in the sample collected from MW7 at concentrations of 1 8 µg/1 and 1,200 µg/l, respectively No . other fuel oxygenates were detected in the ground water samples collected from the site The current and ast ground water sample analytical results are summarized on Table 2 Copies of p the laboratory report(CTEL Sample ID Nos 0112-105-1 through 0112-105-11),QA/QC report and Ichain-of-custody form are in Appendix B 4.0. SUMMARY AND CONCLUSIONS Based on the results of this investigation, AGE concludes that • Depth to ground water ranged from 6 93 feet to 7 88 feet below the well casing tops The prevailing ground water flow direction in December 2001 was inferred to be towards the north-northwest at an average hydraulic gradient of 0 005 feet/feet • The dissolved hydrocarbon plume extends northward from the former UST and dispenser areas, but not beyond the two down-gradient monitoring wells (MW9 and MW 10) The dissolved phase plume has been defined in all directions Isocontour maps illustrating the approximate extent of TPH-g-,benzene-and MTBE-impacted ground water are depicted on Figures 4, 5 and 6 •