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' 16 June 2004 AGE-NC Project No 95-0173 tPage 7 of 9 45 MASS CALCULATION OF RECOVERED PRODUCT The hydrocarbon mass removed during the SVE operating period was calculated using the equation ' M = C•Q•t where M=cumulative mass recovered (kg) ' C = vapor concentration (kg/ma) Q =extraction flow rate (m3/hr) t =operational period, in hours Between 09 September 2003 and 30 December 2003, the SVE unit operated a total of 1,745 hours (Table 6) The average analytical results (approximately 2,240 µg/1) of the influent SVE air flow ' samples (Table 5), average flow rates (approximately 86 scfm, Table 6) and the operational period (1,745 hours)were used to calculate the approximate mass of extracted gasoline during this period During the September 2003 through December 2003 operational period, the mass of hydrocarbons extracted by the SVE system was calculated to be approximately 1,259 pounds, or equivalent to a • volume of 201 gallons of gasoline Added to the estimated 1,698 gallons of hydrocarbons extracted ' from the SVE system since 11 April 2000 (start-up), the total volume of hydrocarbons extracted to date is estimated at 1,899 gallons (Table 7) A plot of the cumulative volume (gallons) of ' hydrocarbons extracted to date 1s included with Appendix E The volume/mass calculations for extracted hydrocarbons are included with Appendix F 5.0. CONCLUSIONS ' The implications from the December 2003 ground water monitoring event are as follows • Ground water flow direction at the site was generally oriented northeast across the site with a gradient was as great as 0 005 ft/ft Due to the generally low gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow direction • The decrease of ground water elevation of approximately 0 44 feet between September 2003 anti the December 2003 monitoring events is probably due to seasonal fluctuation • Ground water at the site was significantly above the screen intervals (drowned) of wells AW-1 (A and B), AW-2 A and B) and MW-13 (A, B and C) and yield samples more representative of deeper ground water conditions The ground water elevation appeared to be within or near the screen intervals of all other wells at the site and should be representative of shallowest ground water conditions Advanced GeoEnvironmental,Inc