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' 25 November 2002 AGE-NC Protect No 98-0448 ' Page 6 of 8 ' Between 11 June 2002 and 11 September 2002, the SVE unit continuously operated approximately 2,208 hours The average of analytical results between SVE air flow sampling events (Table 5), average SVE air flow rates, (Table 6) and the operational period were used to calculate the tapproximate volume and mass of extracted gasoline during these periods ' Between the 11 June, 17 July, 20 August and 11 September 2002 air monitoring events, the mass of hydrocarbons extracted from the SVE system was calculated to be approximately 182 pounds,or equivalent to an approximate volume of 29 19 gallons of gasoline extracted A plot of the cumulative ' volume (gallons) of hydrocarbons extracted to date is in Appendix E Added to the estimated 173 gallons of hydrocarbons extracted from the SVE system since 16 April 2001, the total volume j of hydrocarbons extracted to date is estimated at 213 68 gallons The mass/volume calculations for ' extracted hydrocarbons are included with Appendix F ' S.O. DISCUSSION AND CONCLUSIONS The implications from the August 2002 ground water monitoring event are as follows '• e Ground water flow direction at the site was generally toward the southwest at a gradient of 0 006 ft/ft north of well MW-4, but steepens to 0 02 ft/ft south of MW-4 ' c The decrease of ground water elevation of approximately 123 feet between May 2002 and September 2002 may be due to seasonal fluctuation ' • The ground water elevation at the site was within the screened intervals of wells MW-4A, MW 5,MW-6,MW-7,MW-8 and slightly above the screened intervals of wells MW-1 and MW-2 and should be representative of shallow ground water conditions, however well ' MW-4B is"drowned"with water approximately 23 feet over the screen and yields a sample more representative of deeper ground water conditions Ground water elevation data collected on 30 August 2002 indicated ground water mounding Idue to air sparging at the site,however,the ground water elevation difference between nested wells MW-4A and MW-4B was greater than 4 feet, and no mounding of significance had I occurred at the site since air sparging was initiated in April 2001 The anomalously high ground water elevation at MW-4A may be due to a depth measurement error • The elevated concentrations of petroleum hydrocarbons detected in samples collected from Iwells MW-2 and MW-4A indicate that these wells are within the dissolved petroleum hydrocarbon "core area"of the plume (Figures 4) I Advanced GeoE nvi ronmental,Inc