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' Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA First Quarter Groundwater Morutonng Report,January 2006 _ Page 6 of 9 . Groundwater is pumped from the subsurface via extraction wells MW-I and MW-I1 MW-I 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 MW-I have been increasing as anticipated and discussed above A total of 1,535,498 gallons have been treated by the system as of January 31, 2006 Calculations indicate that approximately 92 2 pounds of gasoline were removed from the groundwater at the Site during the first quarter of 2006 Furthermore, an approximate total of 314 9 pounds of gasoline have been removed since the system was made operational A calculation worksheet is included in Attachment D Vapor Phase Quantification Methodology Soil vapor mass removal and destructive efficiency calculations are made using the following methodology - Field photo-ionization detectors (PID) measurements are collected weekly and laboratory samples are collected and analyzed monthly - The data is compiled and a correction factor is calculated between corresponding PID measurements and laboratory analytical results I - The correction factor is then applied to the PID 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 (ppmv)to milligrams per cubic meter(mg/m3) - 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 catalytic oxidizer has averaged approximately 270 cubic feet per minute (CFM) since system start-up During the first quarter of 2006 the average flow was approximately 276 6 CFM Approximately 50% of the airflow is from the groundwater air-stripper and approximately 50% 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 catalytic oxidizer, therefore, is primarily from the soil vapor extraction wells Tlus is confirmed by weekly PID measurements Vapor Phase Concentration Measurements, Calculations, and Quantification During the first quarter 2006, vapor samples were collected from the catalytic oxidizer influent and effluent for laboratory analyses on November 23, 2005, December 8, 2005, and January 11, 2006 PID measurements of the influent and effluent were also collected at the same time that the laboratory samples were collected For the November 23, 2005 Iaboratory analyses, TPH-G was detected at 12 ppmv and 10 ppmv for the influent and effluent, respectively The December 8, 2005 laboratory analyses of the influent and effluent samples indicated TPH-G concentrations of 8 6 ppmv and 0 35 ppmv, respectively The January 11, 2006 laboratory analyses of the influent and effluent samples indicated TPH-G concentrations of 40 ppmv and 12 ppmv, respectively Corresponding PID measurements for the November 23, 2005 influent and effluent analyses were 3 0 ppm and 0 1 ppm, respectively The PID measurements for the December 8, 2005 influent and effluent analyses were 3 1 ppm and 0 1 ppm, respectively The PID measurements for the January 11, 2006 influent and effluent analyses were 62 ppm and 0 1 ppm, respectively A correlation was created between the TPH-G concentrations obtained from the laboratory • sample analyses and the PID measurement to provide an empirical correction factor for the PID measurements This correlation was created for concentrations from the system influent as well as the �/a CONDOR