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1 <br /> 28 April 1998 <br /> v AGE-NC-95-0103 <br /> Page 7 of 9 <br /> 1 , <br /> ' rate of destruction <br /> 1 <br /> 3 61 ' , MASS OF RECOVERED HYDROCARBONS <br /> The hydrocarbon mass removed during the operating period was calculated using the following <br /> equation M= C•Q•t <br /> where M = cumulative mass rec6vered (kg) <br /> I' C = vapor concentration(kg/m3) <br /> Q = extraction flow rate (m3/hr) 4 <br /> t= operational penod, an hours <br /> The operational time over the last quarter was estimated to be 76 6 (days The mass of h)drocarbons <br /> removed was based on laboratory analysis of two soil gas samples collected and analyzed The mass <br /> of extracted hydrocalbons was calcu3lated for the period using the average hydrocarbon <br /> i concentrations determined from the influent vapor samples collected and the average air flow rate <br /> An estimated total of 65 gallons of hydrocarbons quantified as gasoline were removed from the site F <br /> The,mass calculations are attached in Appendix G ` <br /> I I <br /> 4 0. f DISCUSSION/CONCLUSIONS <br /> r r , <br /> ' Based upon data collected from the site and the on-going monitoring during site remediation, AGE <br /> concludes the following F <br /> w I I <br /> • The ground water flow has returned to'a westerly flow direction over the last quarter A <br /> portion of the ground water flow is directed toward the southwest and northeast, away from' <br /> f central portion of the`slte The hydraulic gradient was similarto that determined for previous ' <br /> quarterly monitoring events <br /> ' L The ground water monitoring'well slotted intervals have a reduced effectiveness to <br /> characterize the dissolved-phase hydrocarbon plume The screened interval of monatonng <br /> wells MW-1, MW-2, MW-3 and MW-5 had ground water approximately 5 feet above the <br /> ' top of the screened interval, however, local ground water`elevations were lowered intoE the " <br /> screened interval of the wells during purging *' <br /> • The greatest concentrations of,petroleum hydrocarbons were detected an samples collected <br /> l , <br /> ' I Advanced GeoEnvnronmental,Inc <br /> I £ ,fin II i I $ 1 "I '� <br /> ti <br />✓I ; ' ' 1 '' '� E ' I 5 i 14 L � i <br />