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i 1 REMEDIATION SYSTEM EVALUATION ' Vapor Extraction System Evaluation From June 28 to September 27, 2004, the vapor extraction system was operational for approximately 1,451 hours The average extracted vapor flow rate was approximately 97 cubic feet per minute (cfm) and the average influent vacuum achieved by the thermal oxidizer was approximately 16 inches of mercury, based on the information contained on the field monitoring data sheets contained in Attachment 3 Based on the measured influent flow rate of 97 cfm, average influent concentration of TPHg of 43 ppmv, and using the values supplied by SunStar Labs of 24 5 liters of vapor per mole of TPHg and a molecular ' weight of 86 27 grams per mole of TPHg yields = 43 l TPHg x 97 ft3 x 60 min x 28 32 1 air x 1 mole TPHg x 86� 27 a x l lb ' 1,000,000 1 air min 1 hour 1 ft, 24 5 1 vapor mole TPHg 454 g 0 055 lb TPH x 1,451 hours = 80 lbs of TPHg during third quarter 2004 ' hour Total TPHg removed via vapor extraction since system startup on December 19,2002 8,488 lbs of TPHg total as of second quarter 2004 + 80 pounds of TPHg third quarter 2004 = 8,568 pounds of TPHg removed since the startup of the system No measurable concentrations of benzene were detected in the influent vapor samples collected during the third quarter ' Total benzene removed via vapor extraction since system startup on December 19, 2002 20 75 lbs benzene removed total as of second quarter 2004+0 Ib benzene third quarter 2004 = 20 75 pounds of benzene removed since the startup of the system ' Water Treatment System Evaluation From June 28 to September 27, 2004, the average groundwater extraction rate from the vapor extraction system knockout tank was approximately 26 gallons per hour and the total groundwater discharged to the ' City of Stockton sewer system was approximately 38,339 gallons Approximately 38,339 gallons of groundwater were extracted from VW1 through VW4 and well MW1 and the average influent concentrations of TPHg and total BTEX between June 26 and September 27, 2004, were less than 50 ug/l and approximately 1 0 ug/l, respectively The petroleum hydrocarbons in the extracted groundwater appear to be volatilizing and are being remediated by the thermal oxidizer Based ' on the lack of concentrations of TPHg and low BTEX concentrations detected in the groundwater samples collected from the influent sample port, the total mass of TPHg and BTEX treated and removed from the system was not calculated s lenviro1625961quartlyl3gr-2004 doe 7 ATC Associates Inc