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Val2or System During the fourth quarter of 2004, the vapor extraction system consisted of a 150-standard cubic feet per minute (SCFM) Frontier thermal oxidizer, a 500-gallon propane above ground storage tank (AST) for supplemental fuel supply, necessary hoses, pipes, gauges to transfer the propane, subsurface piping and wellhead connections between the SVE remediation wells, the AS remediation wells and the fenced remediation equipment compound. There were originally four SVE remediation system wells (V W 1 through VW4). VW 1 is screened between 10 and 30 feet bgs. VW2 is screened between 20 and 35 feet bgs. VW3 and VW4 were screened between 15 feet bgs and 25 feet bgs. Each SVE wellhead connection includes a gate valve, vacuum gauge, sampling port, and flow rate measurement port. ATC started the SVE system continuously on December 19, 2002. After the initial start-up operations, VW3 was taken off line to reduce water production and VW4 was partially closed off but remains on line. In July of 2004, the completions of VW1 and VW2 were altered to further reduce produced water. These wells now include stingers set at approximately 32 feet bgs and 28 feet bgs, respectively. MW 1 was converted to a vapor extraction well on February 10, 2004. The well completion of MW 1 was • altered with a stinger, set at approximately 32 feet bgs. The SVE system was inoperational during the fourth quarter 2004 and was subsequently removed by the vendor without notice during the month of November. Water Treatment System Components of the water treatment system which are located within the remediation compound include the knockout tank on the thermal oxidizer; one 1,000-gallon drop tank; three transfer pumps; two two thousand pound canisters connected in series containing aqueous-phase granular activated carbon; associated piping, control valves, pressure gauges, flow meters, instrumentation and controls. From the effluent end of the lag canister, fluid is pumped into a 100-gallon tank where it is discharged to the sanitary sewer system located on the south side of the on site building. The vapor extraction system as well as the groundwater treatment and discharge system were started up on December 20, 2003. During initial start up of the vapor extraction system, approximately 25 gallons of groundwater per hour were extracted from the four vapor wells (VWl — VW4). ATC closed the valves on vapor extraction wells V W 1 and VW2 and only extracted from vapor wells VW3 and VW4, which are screened approximately two feet above the current water level. Seven gallons of groundwater per hour were extracted from vapor wells VW3 and VW4. To operate the vapor extraction system more efficiently, ATC modified the vapor extraction system to include groundwater treatment and discharge to the City of Stockton sewer system. (This is the groundwater that accumulates during operation of the vapor extraction system.) ATC submitted the • necessary permit application information for the discharge of treated groundwater and on November 6, 2002 the DMU issued the Groundwater Discharge Permit (GDP). Following the issuing of the GDP, s:lenvirolb25961quartlyl4gr-2004.doc 4