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i ' 10 December 2001 • AGE-NC Project No 98-0448 ' Page 6of8 ' Between 01 July 2001 and 30 September 2001 (third quarter 2001), the SVE unit operated a total of 1,584 hours (Table 6) The average of analytical results between SVE air flow sampling events (Table 4), average SVE air flow rates, (Table 5) and the operational period were used to calculate ' the approximate volume and mass of extracted gasoline during these periods During the third quarter 2001, the mass of hydrocarbons extracted from the SVE system was calculated to be approximately 222 28 pounds, or equivalent to a volume of 35 56 gallons of gasoline extracted A plot of the cumulative volume (gallons) of hydrocarbons extracted to date is in Appendix E Added to the estimated 108 5 gallons of hydrocarbons extracted from the SVE system ' since 16 April 2001, the total volume of hydrocarbons extracted to date is estimated at 144 gallons The mass/volume calculations for extracted hydrocarbons are included with Appendix F ' 4.0. DISCUSSION AND CONCLUSIONS ' The implications from the July 2001 ground water monitoring event are as follows lie • Ground water flow direction at the site was generally toward the south-southwest at a gradient of 0 016 ft/ft or less, due to the low gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction • The decrease of ground water elevation of approximately 0 34 feet between April 2001 and July 2001 is probably due to seasonal fluctuation • The ground water elevation at the site was generally within the screened intervals of wells MW-1, MW-2, MW-3, MW-4A, MW-5, MW-6, MW-7 and MW-8 and should be representative of shallow ground water conditions,however well MW-4B is"drowned"with water approximately 25 feet over the screen and yields a sample more representative of deeper ground water conditions • Ground water elevation data collected on 24 July 2001 was inconclusive regarding potential -water-mounding due to air sparging at-the site _ __ _—_ _- �L _ _ — —__ _ — _ _ _ • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells MW-1,MW-2, MW-4A and MW-4B indicate that these wells are within the dissolved petroleum hydrocarbon "core area" of the plume (Figures 4) ' { • Previous and current analytical results from ground water samples suggest that there is a minor MTBE, DIPE and TBA-impact to ground water in the areas of wells MW-3 and MW-4 (Table 2) IAdvanced GeoEnvironmental,Inc