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' 07 May 2003 • AGE-NC Protect No 95-0143 ' Page 4 of 5 ' MTBE was not detected in the analyzed ground water samples collected during the December 2002 sampling event ' Analytical results of ground water samples collected during the December 2002 monitoring event are summarized on Table 2 Analytical results of historical ground water samples are summarized on Tables 3 and 4 The laboratory report(MAI Lab IDs 0212020-001 through 0212020-005)and chain- of-custody forms are included in Appendix B I4.0. SUMMARY/CONCLUSIONS Based upon data collected from the site, AGE concludes ' • The average ground water elevation was 8 19 feet below mean sea level(MSL), a decrease of 0 48 feet since the September 2002 monitoring event The inferred ground water flow Idirection was northeast at a gradient of approximately 0 001 foot/foot • Ground water was within the screened intervals of MW-10,MW-14,MW-15,MW-16,MW- 17, MW-22, MW-23 and MW-24,but ranged froml 77 feet to 5 16 feet above the screened interval in the other four monitoring wells • TPH-g and BTEX compounds were detected in MW-3, MW-6 and MW-9 at maximum concentrations of 170,000 µg/1 TPH-g and 4,600 gg/l benzene, 51,000 gg/l toluene, 4,500 gg/l ethylbenzene and 27,000 gg/1 xylenes, in sample MW-3 BTEX compounds are present at concentrations that are significantly above the DHS's Maximum Contaminant Levels for BTEX in drinking water However, the concentrations of TPH-g and BTEX detected in sample MW-9 were the lowest since monitoring began in June 1994 I • MTBE was not detected in samples collected from the site during the December 2002 sampling event 5.0. RECOMMENDATIONS rBased upon data collected during the December 2002 and previous sampling events, AGE recommends a Continued quarterly monitoring of the ground water monitoring well system on the site concurrent with monitoring at the Madison site • Initiation of the ozone sparge system • Advanced GeoEnvironmental,Inc