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•� s Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA Second Quarter Groundwater Monitoring Report,April 2005 Page 7 of 10 measurements so they more accurately represent projected laboratory results on a weekly basis The corrected values are averaged, then the units of measurement are converted from parts per million of volume to milligrams per cubic meter The average contaminant concentration for the period is then multiplied by the total volume processed through the treatment system to yield total mass Vapor Phase Volume Measurements The airflow though the treatment system thermal oxidizer during the second quarter of 2005 was approximately 280 cubic feet per minute (CFM) During system start-up, approximately 50% of the air flow was coming from the groundwater air-stripper and approximately 50% was corning from the array of nine soil vapor extraction wells Laboratory analysis of a vapor sample collected from the effluent of the air-stripper and another vapor sample collected from the effluent of the soil vapor extraction wells, both collected at the time of start-up, indicated TPH-G concentrations of 2 9 and 690 parts per million (ppm), respectively The TPH-G input to the thermal oxidizer, therefore, is primarily from the soil vapor extraction wells (as anticipated) Vapor Phase Concentration Measurements, Calculations, and Quantification The PID was serviced and recalibrated on April 6, 2005 Vapor samples were also collected from the thermal oxidizer influent and effluent for laboratory analyses on May 5, 2005 PID measurements of the influent and effluent were also collected at the same time that the laboratory samples were collected TPH-G was detected at 13 and 0 86 ppm in the laboratory samples of the influent and effluent, respectively Corresponding PID measurements were 52 and 0 ppm Correlation of the TPH-G concentration in the laboratory sample from the system influent (13 ppm) and the PID measurement of the system influent (52 ppm) provides an empirical correction factor for future PID measurements of 0 25 for the system influent Correlation of the TPH-G concentration in the laboratory sample from the system effluent (0 86 ppm) and the PID measurement of the system effluent (0 ppm) could not be used to calculate an empirical correction factor for future PID measurements for the system effluent This is caused by effluent concentrations that were below the detection limit of the PID Monthly samples for laboratory analyses will be collected from the system influent and effluent to adjust the correction factors for the PID on an on-going basis Four PID measurements of the system influent were collected between Apnl 1, 2005 and June 1, 2005 The average PID measurement was 51 ppm The average PID reading multiplied by the correction factor of 0 25 results in an average corrected PID measurement of 13 ppm The average corrected PID value was multiplied by the laboratory-supplied conversion factor of 4 mg/m3, resulting in an average concentration of 52 mg/m3 An average airflow of 280 CFM was then used to calculate the mass of TPH-G removed by the system totaling I pound per day or 40 pounds during the period Five PID measurements of the system effluent were collected between April 1, 2005 and June 1, 2005 The average PID measurement was 0 ppm The average FID reading multiplied by the influent correction factor of 0 25 results in a corrected average PID measurement of 0 ppm The average corrected PID value did not correlate to the laboratory data, consequently, the laboratory analytical result of 3 5 mg/m3 was used for effluent calculations An average airflow of 280 CFM was then used to calculate the mass of TPH-G released by the system to the atmosphere, totaling 0 08 pound per day or 2 5 pounds during the period Vapor Phase Destructive Efficiency Calculations show that 9,613 5-pounds-were-destroyed-by the thermal oxidizer and 146 5 pounds were • released to the atmosphere, of the 9,760 pounds of TPH-G removed by the soil vapor extraction system CONDOR