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28 May 2003 <br /> AGE-NC Project No 95-0173 <br /> Page 6of8 <br /> 45 MASS CALCULATION OF RECOVERED PRODUCT <br /> The hydrocarbon mass removed during the SVE operating period was calculated using the equation <br /> M = C•Q•t <br /> where M = cumulative mass recovered (kg) <br />' C =vapor concentration (kg/m') <br /> Q = extraction flow rate (M3/hr) <br /> t =operational period, in hours <br /> Between 26 September 2002 and 17 December 2002, the SVE unit operated a total of 2,102 hours <br /> (Table 6) The average analytical results (approximately 1,620 µg/1) of the influent SVE air flow <br /> samples (Table 5), average flow rates (approximately 98 cfm, Table 6) and the operational period <br /> (2,102 hours)were used to calculate the approximate mass of extracted gasoline during this period <br /> During the September, October, November and December 2002 period, the mass of hydrocarbons <br /> extracted by the SVE system was calculated to be approximately 1,250 pounds, or equivalent to a <br /> . volume of 200 gallons of gasoline Added to the estimated 1,348 gallons of hydrocarbons extracted <br /> from the SVE system since 11 April 2000(start-up), the total volume of hydrocarbons extracted to <br /> date is estimated at 1,548 gallons (Table 7) A plot of the cumulative volume (gallons) of <br /> hydrocarbons extracted to date is included with Appendix E The mass/volume calculations for <br /> extracted hydrocarbons are included with Appendix F <br /> 5.0. CONCLUSIONS <br /> The implications from the December 2002 ground water monitoring event are as follows <br /> • Ground water flow direction at the site was generally toward the northeast at a gradient of <br /> 0 004 ft/ft or less Due to the low gradient at the site, slight variations in ground water <br /> measurements or changes of recharge/discharge of the local ground water could greatly <br /> modify ground water flow direction <br /> • The decrease of ground water elevation of approximately 10 1 feet between September 2002 <br /> and December 2002 is probably due to seasonal fluctuation <br /> • Ground water at the site was approximately between 10 feet and 30 feet above the screen <br /> intervals (drowned) of wells AW-lA, AW-1B, AW-2A and AW-213 and may not yield <br /> samples fully representative of shallowest ground water conditions, ground water was <br /> between 63 and 113 feet above the screen intervals of multi-level well MW-13 (A-C),which <br /> was designed to collect ground water representative of deep ground water conditions The <br /> Advanced CeoEnvironmental,Inc <br />