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17 January 2005 <br /> AGE-NC Project No 95-0103 <br /> Page 6 of 9 <br /> ' additive MTBE was detected by EPA Method 8020 in sample EW-3 at a concentration of <br /> 27 µg/1 <br /> • October 2004 A water sample was collected from the Influent port of the ground water <br /> extraction system TPH-g and BTEX compounds were detected in the influent sample at <br /> concentrations of 1,900 µg/1 TPH-g, 5 0 gg/l benzene, 40 µg/1 ethylbenzene and 65 µg/1 <br /> xylenes <br /> ' • December 2004 Grab ground water samples were collected from the four extraction wells <br /> during pumping Each ground water extraction sample had detectable TPH and BTEX <br /> ' compounds, the highest TPH and BTEX concentrations were detected in sample EW-3 at <br /> 8,400 µg/1 TPH-g, 170 µg/1 benzene, 22 µg/1 toluene, 230 µg/1 ethylbenzene and 490 µg/1 <br /> xylenes In addition, the fuel additive MTBE was detected in sample EW-3 at 44 µg/1 <br /> TPH-g/d, BTEX compounds and fuel additives were not detected in the effluent ground water <br /> treatment samples analyzed The analytical results are summarized in Table 4,laboratory reports are <br /> provided in Appendix C Trend analysis of the extraction well concentrations is depicted in <br /> Appendix D <br /> 3 1 2 Volume-Mass Removal Calculations <br /> During remediation in 2004 an estimated 0 57 lbs of benzene and 32 lbs of TPH-g were extracted <br /> from ground water The total years (2004) volume-mass calculations from the ground water <br /> treatment system are presented in Appendix D <br /> 3 2 GROUND WATER MONITORING RESULTS <br /> Ground water elevation and flow direction were determined from field data Hydrocarbon-impact <br /> to ground water was quantified from laboratory analysis of the ground water samples <br /> 3 2 1 Ground Water Elevations and Gradient <br /> Depth to ground water at the site ranged from 14 12 to 16 20 feet below the top of the well casings <br /> (Table 1) The ground water elevations ranged from 9 19 (MW-6) to 9 55 feet (MW-3)below sea <br /> level The ground water flow direction was radially inward toward the area of the extraction wells <br /> ' The ground water gradient was approximately 0 005 ft/fl at the eastern portion of the site and <br /> approximately 0 003 ft/ft at the western portion of the site Ground water elevation contours are <br /> �• depicted In Figure 3 <br /> Advanced CeoEnvironmenta!,Inc <br /> S <br />