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s4 MW-8 BYO-VENTING/OXYGEN TRANSFER On October 26 , 1994 , a bio-venting source test was performed on MW-8 The purpose of this test was to evaluate the benefit of Performing a once a week evacuation of the well to enhance oxygen transfer and remove residual CO2 Presently the vapor extraction system at Former Regal Station 603 , PTO ## N-1090-1-0, is only having only limited effect on the leading edge of the dissolved gasoline range plume that has traveled east from the site, across Pacific Avenue Two sources tests, of two hours each, were conducted on MW8 The well is near the leading edge of the plume and results indicate that a two hour vacuum extraction once a week will help control the migration of the plume and will enhance biodegradation by removing CO2 and enhancing oxygen transfer whale limiting hydrocarbon removal to less than 0 1 pound per week Mr. Mark Schonhoff of San Joaquin Valley Unified Aar Pollution Control District, evaluating this 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 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 1.11 mg/L as gasoline and 2 111 carbon dioxide, see Table 4 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 1 23 pounds of gasoline range hydrocarbons has been removed from MW8 as of June 16 , 1995 , see Table 4 and Appendix E - Field Notes MW8 VENTING PROCEDURES We are using LTT vacuum trucks to pull an estimated 11 feet of water vacuum on MW8 , for 2 hours weekly and exhaust directly to atmosphere This vacuum generates a flow rate of approximately 64 cfm COLLECTING SAMPLES The sample is obtained from a sample port located, prior to the vacuum puma from s sampl e nn-rt- pn f-"h= fl L L L""� 441 V111i1..G U4Gl i1G poly tubing was used to attach a one liter tedlar bag, fitted with a special septum "valve" and tubing bib, to the sample port . The sample port is on the vaccum side of the pump and therefore a vacuum greater than the well vacuum must be exerted on the outside of the tedlar bag to fill" the bag with the vapor sample A special vacuum box, in which the tedlar bag is sealed inside, is used to exert a high vacuum to the exterior of the bag, thereby pulling a sample into the bag Once the tedlar bag is filled, its valve is closed and locked and the appropriate label is placed on the bag PAGE 3 R603 UPDATE-39 7/1.4/95