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1 - <br />' 03 April 2002 <br /> • AGE-NC Project No 98-0534 <br />' Page 3 of 4 <br />' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in the ground water samples collected from wells MW-3, MW-4, MW-6 and <br />' MW-7 at concentrations of 120 micrograms per liter (µg/1), 110 µg/l, 90 µg/1 and 800 µg/l, <br /> respectively Toluene was the only BTEX compound detected in the ground water samples, at a <br /> maximum concentration of 1 5 µg/1 in MW-4 TPH-d was not detected in any of the samples <br /> MTBE was detected by EPA Method 8020 in the ground water samples from wells MW-3,MW-4, <br /> MW-6, MW-7 and MW-8 at concentrations of 6 2 µg/l, 14 µg/1, 30 µg/1, 19 µg/1 and 2 4 µg/1, <br /> respectively, MTBE was detected by EPA Method 8260 in the samples from wells MW-3, MW-4, <br /> and MW-6 at concentrations of 7 0µg/l,20 and 43 µg/1,respectively No other fuel oxygenates were <br /> detected in any of the samples The lateral extent of dissolved MTBE is depicted on Figure 4 <br />' The current and historical ground water analytical results are summarized on Table 2 The laboratory <br /> report (Cal Tech laboratory ID No 0201-036-1 to 0201-036-7), chain-of-custody form and the <br /> laboratory QA/QC report are included in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based on the findings from this investigation, AGE concludes <br /> G Ground water on the site was flowing toward the north from the former UST area at a low <br /> hydraulic gradient of approximately 0 01 feet/feet <br /> • Dissolved benzene and MTBE in shallow ground water are delineated by the well network, <br /> except south of well MW-3 above a concentration of 7 0 µg/1 <br /> • MTBE was detected in three ground water samples collected by EPA 8260,with the highest <br /> dissolved concentration occurring within the former UST area at 43 µg/1 <br /> 50. RECOMMENDATIONS <br /> EAGE recommends <br /> a Continued quarterly ground water monitoring <br /> • One deep soil boring should be established within the former UST area for the collection of <br /> grab ground water samples to define the vertical extent of the hydrocarbon impact to ground <br /> water <br /> • <br /> Advanced GeoEnvtron mental,Inc <br /> I <br />