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R603 UPDATE-34 11/16/94 time, therefore no corrections to the measurements were necessary to compensate for reducing the atmospheric pressure at the well head Figure 4 , represents the measurements obtained on October 26, 1994 Ground water gradient shows a flow to the east and relatively flat . MW-8 SOURCE TEST On October 28 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 having 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 while limiting hydrocarbon removal to less than 0 1 pound per week We are proposing to utilize LTT vacuum trucks to pull an . estimated 11 feet of water vacuum on MW8, for two hours once a week and exhaust directly to atmosphere This vacuum will generate a flow rate of approximately 20 cfm, see Appendix A SUMMARY 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 . TTS ing benzene as an indi4cdtor, monitoriIlg wells IVIWl, MW4 , Mw!:), MW6, MW7 and MW9 have been reduced to below detection limits while the wells being utilized for vapor extraction (MW2 , MW3 , and MW10) have been reduced by better than 97a, 99°s and 990 respectively MW8 has been reduced by approximately 56% Of the newly installed wells MW11 and MW12 , MW12 has shown a significant (920) reduction in benzene concentration since the December 22, 1993 sampling MW11 has always tested below detection limits On October 26, 1993 , 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 Also at this time a two hour source test performed on MW-8 , indicated that a once a week two plus hour evacuation of this well will provide oxygen transfer to the PAGE 2