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01 May 2000 <br /> AGE-NC Project No 95-0121 <br />' Page 5 of 7 <br /> as high as 490µg/1 and from the outlet at concentrations as high as 220 µg/1 <br /> BTEX compounds were detected in soil-gas vapor samples collected from the SVE inlet at <br /> concentrations as high as 4 µgA BTEX compounds were detected in soil-gas vapor samples <br /> collected from the SVE outlet at concentrations as high as 2 7 µg/1 Analytical results of soil-gas <br /> vapor samples are summarized in Table 3 The laboratory report (Precision Enviro-Tech Analytical <br /> Laboratory Sample I D 's AD0228,AG308 and PE7626) and chain-of-custody forms are presented <br /> in Appendix D <br /> 4 5 - MASS CALCULATION OF RECOVERED PRODUCT ' <br /> ' s <br />' The hydrocarbon mass removed during the SVE operating penod was calculated using the following <br /> equation M = C•Q•t <br />' where M = cumulative mass recovered (kg) <br /> C =vapor concentration (kg/m3) <br /> Q = extraction flow rate (m3/hr) <br /> t W operational period, in hours <br />' Between 15 February 2000 and 31 March 2000, the extraction unit operated a total of 1,056 hours <br /> The analytical results of the vapor samples combined with average flow rates(approximately 25 cfin) <br /> and the operational period were used to calculate the approximate mass of extracted gasoline during <br />' these periods <br /> The mass of hydrocarbons extracted from the SVE system was calculated to be approximately 5 7 <br />' gallons The mass calculations for the pilot test are in Appendix E <br />' 5.0. DISCUSSION AND CONCLUSIONS <br /> The Implications from the findings of the January 2000 ground water monitoring event are <br /> • Ground water mon tonng data collected in the area of wells MW_,1 through MW-7 Indicated <br /> a ground water flow direction generally toward the northeast-north at an average gradient of <br /> 0 01 ft/ft The flow direction is close to the norm for the area Due to the low gradient at the <br /> site, slight variations in ground water measurements or changes of recharge/discharge of the <br /> local ground water could greatly modify ground water flow direction ` <br /> • From October 1999 to January 2000, a general decrease in dissolved petroleum hydrocarbon <br /> concentrations was quantified in samples collected from wells MW-1, MW-4 and MW-7 <br /> Advanced GeoEnvironmental,Inc <br /> t <br />