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04 December 1997 <br /> AGE-NC Project No 95-0128 <br /> Page 3 of 5 <br /> The upper most ground water gradient and flow direction calculations were prepared from data <br /> collected from monitoring wells MW-4 through MW-7 and vapor well VW-1 The ground water <br /> gradient was calculated to be approximately 0 0043 ftlft directed northeast The ground water <br /> elevation contours for these wells on the site are illustrated in Figure 4 - G1 ound Water Elevation <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> 3 2 1 Chemical Analysis <br /> The highest concentrations of TPH were detected In the water sample collected from vapor ,ell <br /> I VW-1 TPH-g and TPH-d were detected at 89,000 parts per billion(ppb, reported as micrograms per <br /> liter)and 17 200 ppb,respectively The sample also contained BTE&X compounds at concentrations <br /> as high as 16,000 ppb (toluene), with benzene at 6,100 ppb <br /> TPH-g and TPH-d were detected in monitoring wells MW-4 through MW-7 at concentrations as <br /> great as 77,000 ppb (TPH-g in MW-5, located at the northeast boundaiy of the site) BTE&X <br /> constituents were also detected In each of these samples wells at concentrations as high as 18,000 <br /> ppb (toluene, MW-5) <br /> The only fuel additive detected in the ground water samples was MTBE, which was confirmed and <br /> quantified at concentrations as high as 5,900 (VW-1) by EPA Method 8260-In <br /> TPH-g was not detected in monitoring wells MW-1 through MW-3 However, TPH-d was detected <br /> in monitoring wells MW-2 and MW-3 and BTE&X compounds were detected in the sample <br /> collected from well MW-2 MTBE was detected in the sample collected frons monitored well MW-2 <br /> at a concentration of 6 2 ppb EPA Method 8260, with a detection limit of 1 ppb, did not confirm the <br /> presence of MTBE or benzene in MW2, but did confirm total xylenes at 1 2 ppb <br />' Analytical results for EPA Methods 8015 and 8020 for the ground water samples are summarized <br /> on Table 2 The analytical results for EPA Methods 8260 are summanzed on Table 3 The analytical <br /> results for EPA Method 8260 modified for oxygenated volatile compounds are sununarized on Table <br /> 4 The laboratory report (MAI Laboratory Sample TDs 82465 through 82472), QA/QC report and <br /> chain-of-custody are included as Appendix B <br /> 3 2 2 Iron and Manganese Analyses <br />' Two - <br /> ground water samples, MVV4/10-30-97 and V W 1110 30-97, were analyzed by EPA Methods <br /> 6010 and 200 7 for dissolved manganese and iron Manganese was detected at concentrations of 3 2 <br /> Advanced GcoEm ironmental Inc <br />