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' 19 June 2003 <br /> • AGE-NC Project No 99-0637 <br />' Page 3 of 4 <br /> MTBE <br /> was detected In the ground water samples collected from wells MW1, MW4, MWS, MW6 <br /> and MW9 at concentrations ranging from 0 51 µg/l in well MW1 to 1,200 gg/l in well MW4 No <br /> other analytes were detected at or above laboratory reporting limits In the ground water samples <br />' The analytical results of ground water samples are summarized on Tables 2 and 3 The laboratory <br /> report(MAI Lab Work Order No 0305313),QA/QC report and chain-of-custody form are included <br /> in Appendix B <br /> I <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this Investigation <br /> E • The ground water elevations ranged from 15 83 feet to 17 53 feet above MSL Ground water <br /> flow was inferred to be ranging between a northwesterly flow direction on the east side of <br /> the site to a northeasterly direction on the west side of the site The average ground water <br /> liegradient was 0 004 feet/feet <br /> • TPH-g,TPH-d,BTE&X and fuel additives excluding MTBE,were not detected in any of the <br /> ground water samples collected from the site <br /> • MTBE was detected In the ground water samples collected from wells MW1, MW4, MW5 <br /> MW6 and MW9 at concentrations ranging from 0 51 µg/1 in well MW 1 to 1,200 gg/1 in well <br /> MW4 Overall, concentrations of MTBE decreased to non detectable levels In wells MW2 <br /> and MW 10, decreased in wells MWI, MW4, MW5 and MW6 and increased in well MW9 <br /> since the last monitoring event 1_n February 2003 <br /> r • The lateral extent of impacted ground water has been defined in all directions, except <br /> towards the northwest beyond well MW9 An Iso-concentration map depicting the <br /> approximate distribution of dissolved MTBE is presented in Figure 4 <br /> 5.0. RECOMMENDATIONS <br /> Based on the findings of this investigation, AGE recommends <br /> • Continuation of the Quarterly ground water monitoring program The next monitoring event <br /> should be performed in August 2003 <br /> • Since the extent of the MTBE impact to soil and ground water have generally been defined, <br /> . AGE believes that a Corrective Action Plan(CAP)should be prepared to determine and test <br /> Ithe best methods of remediation <br /> Advanced GeoEnvironmental,Inc <br /> I <br />