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24 June 2005 <br /> . AGE-NC Project No 95-0103 <br /> 1 Page 7 of 12 <br /> 3 2 1 Ground Water Elevations and Gradient <br /> Depth to ground water at the site ranged from 10 94 to 13 05 feet below the top of the well casings <br /> ' (Table 1) The ground water elevations ranged from 6 06 (MW-6) to 6 18 feet (MW-3,4,5)below <br /> sea level The ground water flow direction was generally southeast from the location of well MW-6 <br /> and well MW-3, and south inward toward the area of the extraction wells EW-2 and EW-3 <br /> The ground water gradient was approximately 0 001 ft/ft at the western portion of the site and <br /> approximately 0 0007 ft/ft at the eastern portion of the site Ground water elevation contours are ` <br /> 1 depicted in Figure 3 <br /> I3 2 2 Field Monitoring for Low-Flow Ground Water Sampling <br /> The geochemlcal parameters of purged ground water observed during low-flow sampling techniques <br /> were consider stable or generally representative of the shallow aquifer at the site, once the reading <br /> were detected within a low percentage of the previous two reading or within one minute the <br /> measurements were reading stable Generally the OPR stabilized, while the DO concentration <br /> ,. increased slightly prior to the stabilized reading The pH, conductivity and water temperature were <br /> also within a low percentage of prior readings and apparently stabilized quickly after the start of the <br /> ' 500-m1 flow rate The field measurements are included in Appendix B <br /> 3 2 3 Analytical Results of Low-flow Ground Water Sampling <br /> • A total of ten sample (MW-1 through MW-6, vapor wells VE-1, VE-6 and ground water <br /> ' extraction wells EW-1,EW-2 and EW-3)were collected for hydrocarbon analysis during the <br /> low-flow sampling event,with TPH-g detected in the seven sample and BTEX detected in <br /> seven ground water samples TPH-g was detected a concentrations as great as 14,000 µg11 <br /> and as low as 1,100 pg/l, extraction well EW-3 and EW-1, EW-2,respectively ' <br /> • TPH-g was not detected in the ground water samples 'from monitoring wells MW-2 and, <br /> r <br /> MW-5 <br /> • Generally, BTEX was only detected near the extraction wells and well MW-4, however <br /> significant benzene was detected the ground water sample from well VE-1 at 4,700 µg/1 <br /> Benzene was the only compound detected in well MW-1 at 21 µg11 <br /> • MTBE was detected in one ground water sample, collected from well VE-1 at a <br /> ' concentration of 34 gg/l <br /> � Advanced GeoEovironmentai,Inc <br /> 1 <br />