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08 June 2003 lie AGE-NC Project No 98-0448 IPage 7 of 9 5.0. DISCUSSION AND CONCLUSIONS The implications from the March 2003 ground water monitoring event are as follows IGround water elevations ranged between 5 56 and 1192 feet below MSL The Increase in ground water elevation of approximately 1 06 feet between December 2002 and March 2003 may be due to seasonal fluctuation The ground water elevation at the site was within the screened Intervals of wells MW-1 through MW-8 should be representative of shallow ground water conditions,however well MW-4B is"drowned"with water approximately 24 feet over the screen and yields a sample more representative of deeper ground water conditions • Ground water elevation recorded at well MW-4A was not utilized to contour ground water elevations at the site due to the possibility that the apparent formation of a sediment plug in Ithe well between 11 and 20 feet bsg Well MW-4A was redeveloped in April 2003 to remove the sediment accumulated at the bottom of the well • Ground water elevation data collected on 20 March 2003 does not suggest ground water mounding is occurring due to air sparging at the site Ground water flow direction at the site was generally toward the southwest at a gradient of 0 02 feet/feet,or approximately 106 feet lieper mile • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells MW-2 and MW-4A indicate that these wells are within the dissolved petroleum hydrocarbon "core area" of the plume (Figure 4) • Laboratory results of the water sample collected from well MW-4B (screened 45 to 50 feet Ebsg) suggest that only residual BTE&X constituents and residual MTBE remain in the dissolved petroleum hydrocarbon plume at deeper depth A decreasing trend of BTE&X constituents and MTBE in well MW-4B has been evident for eight consecutive quarters • Dissolved petroleum hydrocarbons continued to decline significantly in ground water samples MW-1 and MW-2 which may be attributed to the air sparging activity at MW-4B Downgradient well MW-6 has not detected any petroleum hydrocarbon constituents of _ concern for three successive quarters Based on S VEDAS remediation data collected between 17 December 2002 and 20 March 2003,AGE concludes • The volume of hydrocarbons extracted by the SVE system was calculated to be approximately 33 29 pounds, or equivalent to an approximate volume of 5 33 gallons of ' gasoline extracted (Appendix F) IAdvanced GeoEnvironmental,Inc