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1 GeoHydrologic Consultants, Inc The extraction well groundwater sample results indicated that elevated concentrations of ' TPHg, BTEX, and MTBE were detected Concentration for TPHg in groundwater at the beginning of the test was recorded to be 11,800 gg/L and at the end of the test it was 101,000 gg/L A slight decrease was observed for benzene (19,600 gg/L to 19,300 gg/L), toluene indicated a slight increase (8,600 gg/L to 10,700 p,g/L), a decreasing trend was observed for ethylbenzene (2,520 gg/L to 2,440 gg/L), and xylenes (14,700 gg/L to 12,600 gg/L) MTBE indicated an increase from the start(4,320 µg/L) to the finish (5,270 gg/L) of the test on EW-5S A total of approximately 180 gallons of hydrocarbon- affected groundwater were extracted during this test at an average extraction rate of 0 4 gallons per minute ' The data from the combined vapor/groundwater extraction pilot tests are tabulated in Table 4 and Table 5, and the field data sheets are included in Appendix D Laboratory ' analytical results of the air samples collected during the combined test are summarized in Table 6 The analytical results for the groundwater samples collected at beginning and at the end of the multi-phase extraction test from EW-5S are summarized in Table 7 ' Laboratory reports and chain-of-custody documentation are included in Appendix E 5.3 Hydrocarbon Mass Removal During the total eight-hour multi-phase extraction pilot testing (EW-5D), based on the average laboratory analytical results for TPHg vapor concentrations for the combined influent, and the average flow rate and duration of operation, the mass extracted during each pilot test and the average hydrocarbon extraction rate were as follows 03/17/05 (multi-phase extraction test, EW-5D)• • average TPHg concentration of 23 3 ppm, • average MTBE concentration of 0 093 ppm • average benzene concentration of 1 22 ppm, • average flow rate of 115 cfm, approximately 0 33 pounds of hydrocarbon ' removed—extraction rate 1 0 pound of hydrocarbon per day A total of 0 33 pounds of TPHg, 0 0139 pounds of benzene, and 0 0012 pounds of MTBE were removed and destroyed during the multi-phase extraction pilot test performed on well EW-5D (Table 8) These correspond to removal rates of 1 0 pound per day of TPHg, 0 042 pounds per day of benzene, and 0 0036 pounds per day of MTBE ' During the total eight-hour multi-phase ase extraction pilot testing (EW-5S), based on the ' average laboratory analytical results for TPHg vapor concentrations for the combined influent, and the average flow rate and duration of operation, the mass extracted during each pilot test and the average hydrocarbon extraction rate were as follows • I TOC 171 Piot study Page 14