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GROUNDWATER SAMPLE RESULTS These latest sample results showed that only monitor wells MW2 , MW3 , MW8, MW10 and MW12 contained above laboratory detection limits for gasoline range hydrocarbons and MW3 , MW8 and MW12 showing declines in levels, see Table 1, Figure 5 , and Appendix A VAPOR RECOVERY OPERATIONS AND RESULTS The original REMOX unit operated for 14452 hours out of a total of 21048 hours (69k) . From August 18 , 1992 to March 5, 1.996, the new replacement unit operated 18786 hours out of 31095 hours (60%;) During the site visit on June 7, 1995, excessive noise generating from the blower prompted the noon shut down of the REMOX unit The unit remained off until September 23 , 1995 . At that time the blower was replaced with 2 DR 505 Rotron blowers and the system was restarted As of March 5, 1996 an estimated 74849 pounds of gasoline range hydrocarbons had been destroyed by the TO (Thermal Oxidizer) . A request for Modification to the system was made, to remove the TO and replace it with activated carbon vapor scrubs This modification was approved, see Update #29-Appendix D On March 6, 1996, start-up of the Carbon Adsorbtion system occurred. Table 2 is a summary of the Carbon Adsorbtzon Vapor Recovery System and shows approximately 126 5 pounds of gasoline range hydrocarbons have been removed as of October 17, 1996 . MW-8 BIO-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 The vapor extraction system at Former Regal Station 603 , PTO # N- 1090-1-0, was 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 source 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 while limiting hydrocarbon removal to less than O . J. pound per week. Mr Mark Schonhoff of San Joaquin Valley Unified Air 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 each lasts a duration of two hours The average flow rate calculated during during these venting events is 51 cfm with the average PAGE 2 R603 UPDATE-45 11/07/96