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1 <br />' 29 January 2001 <br /> • AGE-NC Project No. 98-0450 <br /> Page 5 of 6 <br />' 3.4. MASS OF RECOVERED HYDROCARBONS <br /> The hydrocarbon mass (TPH-g) removed during the operating period was calculated using the <br />' following equation: M = C•Q•t <br /> where: M = cumulative mass recovered (kg) <br /> C = soil-vapor concentration (kg/m') <br /> Q = extraction flow rate (m'/hr) <br /> t=operational period, in hours <br />' The operational time was divided into three time periods. Mass of hydrocarbons removed was based <br /> on analysis of soil-vapor samples. The mass of extracted hydrocarbons was calculated for each time <br />' period using average hydrocarbon concentrations of influent soil-vapor sample data and average air <br /> flow rates. <br /> Approximately 500 gallons of hydrocarbons as gasoline were extracted and destroyed from SVE <br /> network at the site between 26 September and 27 November 2000. The volume/mass calculations <br /> are attached in Appendix D. <br /> lie <br />' 4.0. DISCUSSION AND CONCLUSIONS <br /> Based on the data collected during this monitoring period, AGE concludes: <br />' - Ground water on the site was flowing toward the south-southwest from the former UST area <br /> with an overall flow direction to the south. The ground water table is nearly flat with a <br /> 1 hydraulic gradient of 0.005 feet/feet. <br /> • The greatest concentration of dissolved hydrocarbons continues to,be in the area of well <br /> BMW-4 located in the area of the former UST location. A significant reduction of <br /> 'hydrocarbon concentrations has occurred in the area of the former USTs. <br /> • MTBE was detected in three of the six samples at concentrations as high as 280 ,ug/1 in <br /> sample BMW-2. <br /> • The'soil vapor extraction system has removed approximately 500 gallons of hydrocarbons <br /> as gasoline over two months of operation. <br /> IAdvanced GeoEn viron mental,Inc. <br />