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' 08 August 2000 <br /> AGE-NC Project No 99-0657 <br />' Page 3 of 4 <br />' MTBE was detected in ground water samples from wells MW1 through MW4 at concentrations of <br /> 560,ug/l, 950,ug/l, 13 ,ug/l and 1,000,ug/l, respectively TAME was only detected in sample MW2 <br /> at a concentration of 2 5 µg/1 TBA was detected in the ground water samples collected from MW 1 <br />' through MW3 at concentrations of 61 µg/1, 21 ,ug/l, and 11 /,zg/l, respectively <br /> The analytical results of water samples collected in July 2000 are summarized on Table 2 The <br />' laboratory report (AAL Order No A00071102), QA/QC report and chain-of-custody form are <br /> included in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this investigation <br /> • The ground water elevations ranged from 9 30 to 9 82 feet AMSL A possible ground water <br />' mound has developed west of the UST excavation with ground water flowing in a east- <br /> northeast to southeast direction The hydraulic gradient ranges from 0 008 feet/feet to 0 01 <br /> feet/feet The relative ground water elevation at the site increased an average of 2 72 feet <br /> lie between the April 2000 and July 2000 monitoring events <br /> • Concentrations of dissolved TPH-g, TPH-d, BTE&X compounds and fuel oxygenates have <br /> decreased significantly in monitoring wells MW I, MW2 and MW4 since the last monitoring <br /> event in April 2000 The hydrocarbon concentrations have increased slightly in MW3 The <br /> highest concentration of dissolved hydrocarbons is in monitoring well MW4 which is south- <br /> southwest of the UST excavation <br /> • The lateral extent of petroleum hydrocarbon impacted ground water has not been defined <br /> I <br /> 5.0. RECOMMENDATIONS <br /> Based on the findings of this investigation, AGE recommends <br /> IContinued quarterly monitoring of the ground water monitoring wells The next monitoring <br /> event should be performed in October 2000 <br /> • Additional monitoring wells should be installed in all directions to further assess the extent <br /> of the dissolved phase hydrocarbons <br /> I <br /> • <br /> Advanced GeoEnvironmental,Inc <br />