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' 22 June 2004 <br /> AGE-NC Project No. 98-0520 <br /> ' Page 3 of 4 <br /> Toluene and xylenes were detected in samples MW-4 and MW-5, at maximum concentrations of <br /> 4.2 pg/l toluene and 3.3 µg/l xyleries in sample MW-5. In addition, ethylbenzene was detected in <br /> sample MW-5 at a concentration of 2.2 µg/l. Benzene was not detected at or above laboratory . <br /> ' reporting limits in any of the ground water samples. <br /> No other analytes were detected at or above laboratory reporting limits in the ground water samples . <br /> 1 collected. Analytical results of ground water samples are summarized on Table 2. The laboratory <br /> report (CTEL'Lab 'Project: No. CT214-0312095) and chain-of-custody forms are included in <br /> Appendix C. <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site, AGE concludes: <br /> • On 11 December 2003 the ground water elevation at the site averaged approximately <br /> 12.91 feet above MSL, which represents an elevation increase of approximately 0.70 feet <br /> since the last monitoring event. Net ground water flow was toward the northwest at an <br /> 10 ; average gradient of 0.004 foot/foot. <br /> • The ground water flow direction has been consistently northwest since the initiation of <br /> ground water monitoring in December 1999; however, the ground water gradient•is,very, <br /> '. shallow and seasonal changes can greatly influence the direction and pattern of g'round'water <br /> flow. <br /> ' TPH-g concentrations decreased in samples collected from wells MW-1 through MW-3 and <br /> MW-5; TPH-g concentrations decreased to non-detect in MW-1 for the first time since. <br /> sampling began in 1999.However,TPH-g was detected in MW-4 for the first time in the last <br /> ' five quarters, though only at 100 pg/l. <br /> • Toluene and xylenes were detected in MW-4 and MW-5, and ethylbenzene was detected in <br /> MW-5;all the concentrations were below•the DHS Maximum Contaminant Levels(MCLs) <br /> for drinking water. <br /> • The vertical extent of impacted ground water has been defined;TPH-g has not been detected <br /> ' in deep-screened well MW-6 since the well was installed in December 2001. Impacted <br /> ground water apparently does not extend beyond 45 feet bsg. <br /> ' Advanced GeoEnvironmental,Inc. <br /> i <br />