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Mr George Takemon Project OF90-002 04 August 21, 1995 ' Page 5 Percentage Uptime ' The system has been operational an average of 40 percent of the time during the second quarter of 1995 (see Table 2) The unit was not operational while the extraction blower ' was retrofitted with a new pulley The new pulley reduced the blower's speed and thereby the extraction flow rate In addition, the system was shut down during the installation of the air sparge system Soil Vapor Concentrations and Flow The average flow rate through the system has been 225 cfm during the second quarter (see Table 3) The flow rate was reduced from 250 cfm to 200 cfm during the second half of ' the quarter to extract soil vapors from the impacted vadose zone and reduce the radius of influence (ROI) within the clean area Induced vacuums were measured at surrounding monitonng wells to estimate the ROI of the extraction system (see Table 4) The ROI was observed to have been reduced from about 85 to approximately 65 feet, due to the reduction of extraction flow rates During the quarter, the concentration of TPHG in the soil vapors decreased from 1,800 milligrams per cubic meter (mg1m3) to 1,570 mg/m3, while benzene concentrations increased from 3 7 mg/m3 to 114 mg/m3 (see Table 3) A total of 1,168 pounds (lbs), or approximately 188 gallons, of T PFIG were removed dunng ' the second quarter 1995 Destruction Efficiency ' During the second quarter 1995, the destruction efficiency of the system has been over 99 percent for TPHG and over 95 percent for benzene, based on the soil vapor analytical ' results (see Table 5) The average emission rate during the second quarter is calculated to be 0 007 lbs/day and 0 0003 lbs/day for TPHG and benzene, respectively The operation of the remediation system is in compliance with the requirements set forth by the San Joaquin Valley Unified Air Pollution Control District's Permit to Operate CONCLUSIONS The system was operational for an average of 40% and removed approximately 1,168 lbs during the second quarter of 1995 Analytical results of soil vapor samples collect during the first quarter of 1995, indicate the remediation system extracted approximately 2,000 lbs Therefore, the cumulative mass of TPHG removed to date is approximately 3,168 lbs The concentrations of TPHG and benzene were dropping towards the end of the first quarter due to a large ROI Reduction in the extraction flow rates increased the TPHG and benzene concentrations and, hence, the mass extraction rates ' SAC\N 1PJMOF9010F900020 4cs-95 PAS 2