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' 16 August 1999 <br /> AGE-NC Project No 95-0111 <br />' Page 3 of 4 <br />' Benzene was detected in samples collected from wells MW-1, MW-2, MW-4 and MW-7 at <br /> concentrations of 29 µg/1, 3 2µg/l, 1 5 µg/1 and 1 1 µg/l, respectively Ethylbenzene was detected <br /> in MW-1, MW-2, MW-4 and MW-7 at concentrations as high as 21µg11 Xylenes were detected in <br />' samples from MW-1, MW-2, MW-4 and MW-7 at concentrations as high as 15 µg/l <br />' MTBE was detected by EPA Method 8260 Modified in samples collected from wells MW-1, MW- <br /> 4, MW-5, MW-6 and MW-7 at concentrations of 61µg11, 17 µg/1, 18 µg11, 1 7 µg/1 and 25 µg11, <br /> respectively Tert-butanol was detected in MW-4 at a concentration of 6 0 µg/l <br />' Analytical results of ground water samples are summarized in Table 2 and Table 3 The laboratory <br /> report(MAI Laboratory Sample Nos 14503 to 14510), quality assurance and quality control report <br />' and chain-of-custody form are included in Appendix B <br />' 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site during the current and preceding ground water monitoring <br />' events, AGE concludes <br /> Y The ground water flow direction inferred from data collected during this monitoring event <br /> is consistent with ground water flow directions determined during past events at the site <br /> • Except for TPH-g and TPH-d in sample from well MW-5, the concentrations of TPH-g and <br /> BTEX detected in the ground water samples remain at the low end of the range,of <br /> concentrations previously detected The TPH-d concentration in the sample from well MW-5 <br /> greatly exceeds the previous maximum detection <br />' • Relatively high concentrations of TPH-d in MW-4 and MW-5 demonstrates the presence of <br /> a persistent plume of dissolved diesel fuel in ground water along the north edge of the site <br /> I <br /> 5.0. RECOMMENDATIONS <br /> I <br /> Based on present site conditions, AGE recommends <br />' • Quarterly monitoring and sampling should continue at the site <br /> • The next quarterly monitoring should be scheduled for September 1999 On the collection <br /> of one-year of monitoring data, closure criteria for the site should be determined <br /> I <br /> Advanced GeoEnvironmental Inc <br />