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Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA First Quarter Groundwater Momtonng Report,January 2005 Page 6 of 8 . samples and associated data were collected to monitor the operational efficiency of the system and the consumption of carbon (Attachment D) The primary groundwater extraction well is MWA MWA has contributed approximately 95% of the total groundwater influent into the treatment system The concentrations of BTEX, TPH-G, and MTBE detected in samples collected from MWA have been increasing as anticipated and discussed above The TPH-G concentration detected in the sample collected from MW1 on January 21, 2005 was 30 mg/L and that concentration was used to calculate total TPH-G removed from groundwater A total of 299,216 gallons have been treated by the system as of March 1, 2005 The calculation indicates that approximately 75 pounds of gasoline have been removed from the groundwater at the site A calculation worksheet is included in Attachment D The air flow though the treatment system thermal oxidizer during system start up was approximately 240 cubic feet per minute (CFM) Approximately 120 CFM was coming from the groundwater air-stripper and approximately 120 CFM was coming 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 samples were also collected from the thermal oxidizer influent and effluent for laboratory analyses, shortly after system start up 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 460 and 3 ppm, respectively, in the laboratory samples of the influent and effluent, respectively Corresponding PID measurements were 163 and 2 1 ppm, respectively Correlation of the TPH-G concentration in the laboratory sample from the system influent (460 ppm) and the PID measurement of the system influent (163 ppm) provides an empirical correction factor for future PID measurements of 2 82 for the system influent Correlation of the TPH-G concentration in the laboratory sample from the system effluent (3 ppm) and the PID measurement of the system effluent (2 1 ppm) provides an empirical correction factor for future PID measurements of 143 for the system effluent 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 Eight PID measurements of the system influent were collected between November 1, 2004 and March 1, 2005 The average PID measurement was 619 ppm The average PID reading multiplied by the correction factor of 2 82 results in a corrected average PID measurement of 1745 ppm The average corrected PID value was multiplied by the laboratory supplied conversion factor of 4 mg/m3, resulting in an average concentration of 6,980 mg/m3 An average air flow of 258 CFM was then used to calculate the mass of TPH-G removed by the system totaling 162 pounds per day or 9,720 pounds during the period Eight PID measurements of the system effluent were collected between November 1, 2004 and March 1, 2005 The average PID measurement was 18 ppm The average PID reading multiplied by the correction factor of 143 results in a corrected average PTT] messiverriPnt of 26 ppm Thi- nvPragP onrrarte-d Pn-) value was multiplied by the laboratory supplied conversion factor of 4 mg/m', resulting in an average concentration of 104 mg/m3 An average air flow of 258 CFM was then used to calculate the mass of TPH-G released by the system to the atmosphere totaling 2 4 pounds per day or 144 pounds during the period Of the 9,720 pounds of TPH-G removed by the soil vapor extraction system and air-stripper, therefore, 9,576 pounds were destroyed by the thermal oxidizer and 144 pounds were released to the atmosphere, resulting in an overall destructive efficiency of approximately 98 5% A work sheet showing the calculations is included in Attachment D • 4 �� CONDOR