SITE INFORMATION AND CORRESPONDENCE_FILE 2

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OrHRIFTY OIL CCr. March 9, 2006 0.64825 Mr. Mike Infurria, Jr., Senior REHS RWQCB #390652 County of San Joaquin Global ID #T0607700504 LOP/Site Mitigation Unit IV Public Health Services/Environmental Health Division 304 East Weber Avenue, 3rd Floor Stockton, CA 95202 ''SIL_,; RE: Former Thrifty Oil Co. Station #172 MAd 1 4 2006 TOSCO Station #2705449 7647 Pacific Avenue ENVIRONMENT HEALTM Stockton, CA 95207 PERMIT/SERiACES Status of Groundwater Recovery System Dear Mr. Infurna: Currently, the groundwater portion of the remediation system at Thrifty#172 is kept off due to vandalism and necessary piping repair activities. Prior to repairing the existing system and restarting the groundwater portion of system, Thrifty has performed an overall system evaluation in response to the new Groundwater Discharge Permit issued by the City of Stockton, Department of Municipal Utilities effective November 1, 2005 (copy attached). New requirements in the permit call for the discharge to be non-detect for all oxygenate constituents including MTBE, DIPE, ETBE, and TAME at<0.5 ug/L and TBA at<5 ug/L. The configuration of the treatment portion of the system was not designed to remove all oxygenates to the levels now required by new discharge permit. Originally, the discharge permit conditions required only the analyses for TPH and BTEX compounds. MTBE was added in the discharge permit made effective August 1, 2002. The addition of MTBE required almost monthly change-out of the carbon to maintain compliance with the MTBE requirement. Since carbon has very little absorption capability for TBA, Thrifty believes that the rate of carbon change out will increase to a logistical and economically impractical frequency. Thrifty does not believe a re-design of the system is practical because: (1) the frequency of carbon change-outs will still be too high to be cost effective and(2) in order to prevent any oxygenates to be discharged to the sewer outlet, it would likely require two additional 1,000 pound carbon canisters added to the existing two canisters. The addition of the carbon canisters would in turn necessitate the re-sizing of the treatment compound due to the space constraints within the existing treatment compound. Given the current/existing groundwater remediation components that are no longer adequate to meet the newly established discharge limits, Thrifty believes that repairing the system will not be cost effective and restarting the groundwater remediation system the undercurrent configuration will not be practical. Therefore, Thrifty will continue to operate the vapor extraction portion of the system and keep the groundwater treatment system off. V 13116 Imperial Highway, Santa Fe Springs, CA 90670 9(562) 921-3581