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18 February 1997 <br /> AGE-NC Project No 95-0104 <br />' Page 4 of 22 <br />' well VW-1 The vacuum applied to the extraction well causes hydrocarbons in the soil to volatilize <br /> and flow through the vacuum pump to the IC engine The induced vacuum was measured at <br /> surrounding monitoring points using Magnehelic vacuum gauges <br />' The extracted hydrocarbon vapor is destroyed as part of the normal internal combustion process <br /> Emissions from the engine are routed through two catalytic converters to maximize the destruction <br />' rate of the hydrocarbon vapor <br />' 3 2 PILOT TEST PROCEDURES <br /> Air-tight well caps, pre-connected with Magnehehc vacuum gauges, were attached to SVE well VW- <br />' 1 and ground water monitoring wells MW-1 through MW-4 The air stream from VW-1 was <br /> monitored for the presence of organic vapor using a photo-ionization detector (PID Thermo <br /> En,,ironmental 580A, 10 0 eV, calibrated to isobutylene) Measurements were recorded at regular <br />' intervals throughout the test and are included in Table 4 - Vopor Ertiaclion Pilot lest Field Data <br /> Field sheets are included in Appendix A <br /> 3 3 COLLECTION AND ANALYSIS OF VAPOR SAMPLES <br /> IA total of four vapor samples were collected at two-hour intervals from the inlet of the extraction <br /> well to measure concentrations of extracted hydrocarbon vapor The samples were collected in Tedlar <br />' bags using a PID as an air pump <br /> Following sample collection, the samples were placed in a covered container and transported under <br /> I chain-of-custody to McCampbell Analytical Inc (MAI) in Pacheco, California Each sample was <br /> analyzed within 72 hours for TPH-g and BTE&X in accordance with EPA Methods 8015m and 8020, <br /> respectively <br /> 3 4 RESULTS OF VAPOR EXTRACTION PILOT TEST <br /> IThe induced vacuum was measured in MW-1 through MW-4 The greatest vacuum was measured <br /> in MW-1, approximately twelve-feet from VW-1 Vacuum measurements ranged from 1 90 inches <br /> to 2 15 inches of water in M`kV-I during the duration of the pilot test <br /> Low to negative vacuum measurements were reported at MW-3 and MW-4 during the pilot test, <br /> Ilocated approximately 35 feet northeast and southeast, respectively, from VW-I However, the top <br /> of the screen intervals from MW-3 and MW-4 are located at 80 feet bsg, and groundwater depth was <br /> measured at approximately 75 feet bsg Therefore, low and negative vacuum measurements reported <br />