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source test as it pertains to air quality conditions in the Stockton area and has allowed Wickland to perform the weekly two hour venting of this well The weekly venting of MW8 commenced on Janaury 25, 1995 and each lasts a duration of two hours The average flow rate calculated during during these venting events is 64 cfm with an average vapor stream containing 0 111 mg/L as gasoline and 2 1% carbon dioxide, see Table 3 The above results show that the weekly two hour venting of MW8 , is removing excess carbon dioxide and allowing oxygen transfer to occur A calculated 2 71 pounds of gasoline range hydrocarbons has been removed from MW8 as of June 27, 1996, see Table 3 and Appendix B - Field Notes and Appendix D for methods and proceedures SMRMRY There has been no evidence of floating product or product sheen on the ground water in MW1 since April 14 , 1992 and MW3 and MW10 since November 11, 1992 The last evidence of product, as a sheen in the condensate recovery system, was on March 1, 1993 . Vapor recovery has reduced the hydrocarbons in ground water significantly since the May 25, 1990 sampling, see Table 1 . On January 31, 1996 a sample of the water being treated by air stripping inside the "ConVault" was obtained for certified laboratory analysis This was accomplished to prove the suitability for dumping this cleaned water to the City of Stockton' s sanitary sewer This water (800 gallons) was discharged to sewer on February 20, 1996 . Since that time there has been no additional discharge to sewer Bio-venting of MW8 was initiated on October 26, 1994 . Sample results obtained of the ground water at and near MW8 suggests that this weekly venting is beneficial in controlling the migration of the gasoline hyrocarbon plume As of June 27, 1996 an estimated 12080 gallons of gasoline range hydrocarbons have been removed from the soil and ground water beneath this site The 12080 gallons consists of previously removed floating product (40 25 gallons) , condensation from vapor extraction (48 75 gallons) , pro3ected petroleum hydrocarbon vapor extraction--destruction using Thermal Oxidation (74849 pounds/6 25 = 1.1975 8 gallons) , projected petroleum hydrocarbon vapor extraction-adsorbtion using Activated Carbon (92 pounds/6 25 = 14 72 gallons) and venting of MW8 (2 71 pounds/6 25 = 0 43 gallons) No chlorinated solvents were detected in chromatogram Ili of the vapor samples, � e it 1, 2, Dzchloroethene (DCE) - retention time 2 . 079 minutes, Trichloroethylene (TCE) - retention time 3 023 minutes and Tetrachloroethylene (PCE) - retention time 3 75 minutes . PAGE 3 R603 UPDATE-44 7/19/96