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Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA Fourth Quarter Groundwater Monitoring Report,October 2005 Page 6 of 4 Aqueous Phase Mass Removal -Ile groundwater treatment system has removed petroleum hydrocarbons from 354,033 gallons of ' groundwater during the- fourth quarter of 2005 Groundwater treatment system samples and associated data were collected to comply with the Self-Morutoring Sample Program of the MUD Groundwater Discharge Permit, as well as to monitor the operational efficiency of the system and the consumption of ' carbon(Attachment D) Groundwater is pumped from the subsurface via extraction wells MW-1 and MW-11 MW-1 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-1 have been increasing as anticipated and discussed above A total of 1,059,346 gallons have been treated by the ' system as of October 31, 2005 Calculations indicate that approximately 66 63 pounds of gasoline were removed from the groundwater at the site during the fourth quarter of 2005 Furthermore, an approximate total of 221 3 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-ioruzation 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 ' - 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 fourth quarter of 2005 the average flow was ' approximately 223 2 CPM 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 stark-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 This is confirmed by weekly PID measurements ' Vapor Phase Concentration Measurements, Calculations, and Quantification During the fourth quarter 2005, vapor samples were collected from the catalytic oxidizer influent and effluent for laboratory analyses on August 10, 2005, September 9, 2005 and October 12, 2005 PID measurements of the influent and effluent were also collected at the same time that the laboratory samples were collected For the August 10, 2005 laboratory analyses, TPH-G was detected at 24 ppmv and 1 8 ppmv for the influent and effluent, respectively The TPH-G for the September 9, 2005 laboratory analyses from the influent and effluent was detected at 45 ppmv and 1 3 ppmv respectively The TPH-G . for the October 12, 2005 laboratory analyses from the influent and effluent was detected at 16 ppmv and 1 ' tJ CONDOR