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1 u ' 19 July 2002 • AGE-NC Project No 95-0173 ' Page 6 of 8 ' C =vapor concentration (kg/m3) Q = extraction flow rate (m3/hr) t = operational period, In hours Between 31 December 2001 and 29 March 2002 (first quarter), the SVE unit operated a total of 1,975 hours (Table 7) The average analytical results (approximately 627 µg/1) of the SVE air flow ' samples (Table 5), average flow rates (approximately 95 cfin, Table 6) and the operational period (1,975 hours)were used to calculate the approximate mass of extracted gasoline during this period ' During the first quarter, the mass of hydrocarbons extracted by the SVE system was calculated to be approximately 441 pounds, or equivalent to a volume of 70 gallons of gasoline Added to the estimated 1,155 gallons of hydrocarb ons extracted from the SVE system since 11 Apn12000 (start- up),the total volume of hydrocarbons extracted to date is estimated at 1,225 gallons (Table 7) A plot of the cumulative volume (gallons) of hydrocarbons extracted to date is Included with Appendix E The mass/volume calculations for extracted hydrocarbons are Included with Appendix F . 5.0. CONCLUSIONS ' The implications from the March 2002 ground water monitoring event are as follows p €n' g ' • Ground water flow direction at the site was generally toward the northeast at a gradient of 0 002 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 ground water flow direction • The Increase of ground water elevation of approximately 1 31 feet between December 2001 ' and March 2002 Is probably due to seasonal fluctuation • Ground water elevation data collected on 08 March 2002 does not suggest ground water mounding Is occurring due to air sparging at the site • Ground water at the site Is between 3 feet and 70 feet above the screen intervals (drowned) of wells MW-1 through MW-4, AW-lA through AW-2B and MW-13 and may not yield samples fully representative of shallowest ground water conditions The ground water elevation appeared to be within or near the screen Intervals of wells MW-5 through MW-12 and should be representative of shallowest ground water conditions 1 • The elevated concentrations of petroleum hydrocarbons detected in samples collected from wells MW-3, MW-4, AW-1 and AW-2 Indicate that these wells are within the dissolved petroleum hydrocarbon "core area" of the plume (Figures 4 and 5) • ' Advanced Geo Environmental,Inc