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21 May 2003 <br />' AGE-NC Project No 95-0111 <br /> Page 3 of 4 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br />' TPH- was not detected reporting limits n les TPH-d <br /> g c ed at or above laboratory epo g im is� the ground water camp <br />' was detected in the ground water samples collected from wells MW-4 and MW-5 at concentrations <br /> of 690µg/1 and 270 gg/l,respectively BTEX compounds were not detected in the samples analyzed <br />' MTBE was detected utilizing EPA method 8260 in the ground water samples collected from MW-1 <br /> and MW-5 through MW-8 at concentrations ofbetween 13 gg/l(MW-7)and 360 pg/1(MW-8) No <br /> other fuel additives were detected at or above laboratory reporting limits in the ground water samples <br />' analyzed <br /> Analytical results of the ground water samples are summarized in Tables 2 and 3 The laboratory <br />' report(MAI Lab IDs 00303189-001 through 00303189-008),quality assurance and quality control <br /> report and chain-of-custody forms are included in Appendix B <br />' 4.0. SUMMARY AND CONCLUSIONS <br /> Based on the findings from this investigation, AGE concludes <br /> • The northerly ground water flow direction Inferred from data collected during this <br />' monitoring event is consistent with ground water flow directions determined during past <br /> monitoring events at the site Ground water data from well MW-2 was not used to determine <br /> the ground water flow direction and gradient, the ground water elevation data does not <br />' correlate with data collected from the other seven wells,the depth to water measurement was <br /> recorded incorrectly <br />' • TPH-d was detected in the ground water samples collected from wells MW-4 and MW-5 at <br /> concentrations of 690 gg/l and 270 µg/1, respectively TPH-g was not detected at or above <br /> laboratory reporting limits in the ground water samples <br /> • BTEX compounds were not detected above laboratory reporting limits in the ground water <br /> samples collected during the first quarter 2003 monitoring event <br />' • MTBE was detected by EPA Method 8260 in the samples collected from MW-1 and MW-5 <br /> through MW-8 The reported MTBE concentrations in off-site samples MW-6 and MW-8 <br /> exceeded the DHS' Primary MCL in drinking water <br /> • MTBE concentrations m off-site well MW-6 had been below 3 0 µg/l since ground water <br /> monitoring was initiated in January 1998, and had decreased to non-detectable levels by <br />' September 1999(Table 3), MTBE had not been detected in well MW-8 prior to September <br /> 2001 However, since September 2001, MTBE was detected in well MW-8 in six of seven <br /> monitoring events, with the highest concentrations detected in the more recent monitoring <br /> events of September 2002 and March 2003 (Figure 4) In addition,MTBE has been detected <br /> Advanced GeoEnvironmental Inc <br /> I <br />