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24 December 2001 t AGE-NC Project No. 97-0327 Page 3 of 4 i 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES A total of three ground water samples were submitted to a DHS-certified laboratory for analysis of TPH-g, TPH-d, BTEX and fuel oxygenated compounds. TPH-g was not detected in water samples collected from MW-1, MW-2 or MW-3• however, TPH-d was detected in water sample MW-3 collected from MW-3 at a concentration of 160µg/1. BTEX compounds were not detected in ground water samples collected from MW-1, MW-2 or MW-3. ' MTBE was detected (EPA Method 8260)In ground water samples collected from wells MW-1 and MW-2 at concentrations of 2.3 µg/1 and 16 µg/1 respectively; TBA was detected in a sample collected from well MW-2 at a concentration of 48 µg/1; 1,2-DCA was detected in samples from wells MW-1 and MW-2 at concentrations of 6.2 ug/l and 3.2 yg/l. No other fuel oxygenated compounds were detected by laboratory analysis. Analytical results of the ground water samples are ' summarized in Tables 2 and 3. The laboratory reports (Castle Analytical Laboratory Reference No. 3848) and chain-of-custody forms are presented in Appendix B. 4.0. DISCUSSION AND CONCLUSIONS The implications of the findings from the June 2001 ground water monitoring event are as follows: ' • Ground water flow direction at the site was inferred to be toward the south-southwest at a gradient of 0.0005 fl/fl or less. • Due to the low gradient at the site, slight variations in ground water measurements or ' changes of recharge/discharge of the local ground water could greatly modify ground water flow direction. ' Ground water elevation decreased approximately 1.11 feet between February 2001 June 2001; decreasing ground water elevations have been observed at the site since May 2000. ' Dissolved TPH-d was detected in.a sample collected from well MW-3; previously, the greatest TPH-d concentrations have been detected from wells MW-2 and MW-3 while low concentrations have been detected from well MW-1. ' Low concentrations of dissolved.MTBE and.1.,2-DCA were detected in samples from wells. MW-1 and MW-2 indicating a minor impact to ground water in the area assessed. ' Minor concentrations of dissolved TBA were detected in the sample collected from well �I MW-2; TBA had previously been detected in wells MW-1, MW-2 and MW-3 indicating a minor impact to ground water in the area assessed. The elevated petroleum hydrocarbon concentrations previously detected in the grab ground water Advanced Geo Environmental,Inc.