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