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15 July 1997 <br /> i AGE-NC Project No 95-0111 <br /> Page 2 of 4 ' <br /> I <br />' 3.0. FINDINGS <br /> 3 1 GROUND WATER FLOW DIRECTION AND GRADIENT <br />' The relative elevation of ground water in each well was calculated by subtracting the ground water <br /> depth from the surveyed casing elevation The depths to ground water and relative ground water <br /> elevations are tabulated in Table 1 - Relative Ground Water Elevations All wells were surveyed, <br /> relative to casing of monitoring well MWA, which had been assigned an arbitrary casing elevation <br /> of 20 feet <br /> The depth to ground water ranged from 9 85 feet in MW-1 to 6 63 feet in MW-4 The relative round <br /> g g <br /> water elevation at the site ranged from 10 62 feet in MW-3 to 9 29 feet in MW-6 The relative <br /> ground water elevation increased an average of 0 1 feet at the site between March and June 1997 <br /> Ground water flow direction at the site was toward the north-northeast Ground water gradient was f <br /> approximately 0 0049 ft/ft over the distance from the up gradient to the down gradient monitoring <br /> wells Ground water elevation isocontours are depicted in Figuf e 3 - Relative Gi ound Wates <br /> • Elevation <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in samples collected from monitoring wells MW-1 and MW-5 at concentrations <br /> of 290 micrograms per liter(ug/l, approximately equivalent to parts per billion ppb) and 140 ppb, <br /> respectively TPH-d was detected in samples from wells MWA,MW-4 and MW-5 at concentrations <br /> of 100 ppb, 340 ppb and 2,200 ppb, respectively Laboratory notations for samples collected from <br />' wells MW-5 indicated the presence of an immiscible sheen <br /> Benzene was detected in samples collected from wells MW-1, MW-2, MW-4 and MW-5, at <br /> concentrations as high as 82 ppb, ethyl benzene, toluene and xylenes were detected in samples from <br /> MW-1, MW-2 and MW-5 at concentrations as high as 20 ppb <br /> MTBE was detected by EPA method 8020/602 in samples collected from wells MW-1, MW-4 and <br /> MW-5 at concentrations of 84 ppb, 30 ppb and 13 ppb, respectively <br /> Analytical results of ground water samples are summarized in Table 2 -Analytical Results of Ground <br /> Water Samples The laboratory report (MAI Laboratory Nos 77636 to 77641), QA/QC Report and <br /> chain-of-custody are included in Appendix B j <br />