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I18 February 2003 AGE-NC Project No 98-0448 Page 6 of 8 ' 4 5 MASS CALCULATION OF RECOVERED PRODUCT The hydrocarbon mass removed during the SVE operating period was calculated using the following equation M= C•Q•t where M= cumulative mass recovered (kg) IC =vapor concentration (kg/m') ' Q = extraction flow rate (m3/hr) t= operational period, in hours Between 11 September 2002 and 17 December 2002, the SVE unit continuously operated approximately 2,328 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 Ithe approximate volume and mass of extracted gasoline during these periods Between the 11 September,30 October, 11 November and 17 December 2002 air morutoring events, Ithe mass of hydrocarbons extracted from the SVE system was calculated to be approximately ie 78 44 pounds, or equivalent to an approximate volume of 12 54 gallons of gasoline extracted A plot of the cumulative volume (gallons) of hydrocarbons extracted to date is in Appendix E Added to I the estimated 213 gallons of hydrocarbons extracted from the SVE system since 16 April 2001,the total volume of hydrocarbons extracted to date is estimated at 2.:6 22 gallons The mass/volume calculations for extracted hydrocarbons are included with Appendix F 5 0 DISCUSSION AND CONCLUSIONS I The implications from the December 2002 ground water monitoring event are as follows p �' g ' • Ground water elevations ranged between 10 68 and 12 97 feet below MSL, the decrease in ground water elevation of approximately 1 06 feet between August 2002 and December 2002 may be due to seasonal fluctuation The ground water elevation at the site was within the screened intervals ofwells MW-1 through MW-8 should be representative of shallow ground water conditions,however well MW-4B is"drowned"with water approximately 22 feet over the screen and yields a sample more representative of deeper ground water conditions • Ground water flow direction at the site was generally toward the southwest at a gradient of 0 01 ft/ft, or approximately 53 feet per mile • Due t o a n a nomalous h igh d epth t o ground w ater a t M W-4A, c oupled w ith o my 5 7% . recharge after purging for a well that normally recharges near 100%,AGE concluded that the IAdvanced GeoEnvironmental,Inc I