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3.0 SOIL VAPOR EXTRACTION SYSTEM OPERATION <br /> On June 2, 1999, ENSR started the thermal oxidizer soil vapor extraction (SVE) system in the <br /> �. presence of an inspector from the San Joaquin Valley Unified Air Pollution Control District <br /> (SJVUAPCD). <br /> According to ENSR, five extraction wells (VW-1 D, VW-1 S, VW-2S, VW-3 and VW-4) were utilized <br /> by the system, during startup. The system parameters at startup included a flow rate of 214 <br /> standard cubic feet per minute (scfm), vacuum of 65 inches of water column, and a concentration <br /> of volatile organic compounds by Flame Ionization (FID) of 2,100 parts per million by volume <br /> +•• (ppmv). <br /> During startup, ENSR collected vapor samples for analysis to monitor the efficiency of the SVE <br /> system. The system influent soil vapor sample contained 4,960 milligrams per cubic meter(mg/m3) <br /> of purgeable hydrocarbons, 109 mg/m3 of benzene, 650 mg/m3 of toluene, 148 mg/m3 of <br /> ethylbenzene, and 560 mg/m3 of xylenes. This translated to an initial mass recovery rate of 123.5 <br /> pounds per day. Between startup on June 2, 1999 and the last monitoring of the fourth quarter of <br /> 1999 on December 2nd, a total mass of 7,878.2 pounds of hydrocarbons had been removed. <br /> During the first quarter of 2000, ENSR monitored the system on January 6, 2000. The system was <br /> operating at 111 scfm, with a vacuum of 55 inches of water column. ENSR extracted exclusively <br /> from VW-2S and VW-3, since these two wells have shown the highest concentrations of gasoline <br /> hydrocarbons. During the quarter, an air sparge pump operated daily from 11:00 am to 1:00 pm <br /> and 11:00 pm to 1.00am. Between December 2, 1999 and January 6, 2000, ENSR reported that <br /> the SVE system operated with an up-time of 100%. The mass recovery rates have declined to 7.68 <br /> +� pounds per day. <br /> Between December 2, 1999 and January 6, 2000, a total of 281.4 pounds of hydrocarbons were <br /> removed by the system. Since startup on June 2, 1999, a total of 8,159.6 pounds have been <br /> removed. Given the sharp decline in mass recovery rates, ENSR temporarily shut down the system <br /> .w to conserve fuel costs. Currently, the system remains down. <br /> V <br /> L„r 6 <br /> it <br /> V <br />