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California Ogional Water Quality Co"tl Board <br /> Central Valley Region 0 <br /> Karl E. Longley,SCD,P.E.,Chair <br /> Linda S.Adams 11020 Sun Center Drive 9200,Rancho Cordova,California 95670-6114 Arnold <br /> Secretaryjar Phone(916)464-3291 •FAX(916)464-4645 Schwarzenegg <br /> Environmental Protection http://www.waterboards.ca.gov/certralvalley Govemor <br /> G E D <br /> 11 March 2009 <br /> MAR 13 2009 <br /> Mr. Jeff Baker ENVIRONMENT HEALTH <br /> Tesoro Companies, Inc. PERMIT/SERVICES _ <br /> 3450 South 344th Way, Suite 100 <br /> Auburn, WA 98001-5931 <br /> PILOT STUDY WORK PLAN AND ANNUAL REPORT, STOCKTON TERMINALS <br /> TECHNICAL COMMITTEE FACILITIES, PORT OF STOCKTON, SAN JOAQUIN <br /> COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Regional Water Board) <br /> staff reviewed the 27 January 2009 Pilot Study Work Plan and Revised Contingency <br /> Plan (Work Plan) submitted on behalf of the Stockton Terminals Technical Committee <br /> (STTC) by Stantec Consulting Corporation (Stantec). STTC is comprised of three bulk <br /> fuel facilities at the Port of Stockton (Site) including British Petroleum (BP) (formerly <br /> ARCO), Tesoro Petroleum Company Inc. (Tesoro), and Time Oil Company. Appendix A <br /> of the Work Plan contains a revised contingency plan that includes revisions requested <br /> by Regional Water Board staff in July 2008. <br /> Between September and October 2008, STTC installed seven wells (PS/MW-20A <br /> through PS/MW-20D, OW-3CR, OW-3DR, and TS/MW-3D) to evaluate whether <br /> groundwater pollution observed in downgradient well OW-5D emanates from the STTC <br /> facilities. The 15 December 2008 Monitoring Well Destruction, Installation, and <br /> Additional Assessment Report (Assessment Report) describes the investigation. <br /> During the well installations, groundwater was encountered at about six feet below <br /> ground surface (bgs). Groundwater bearing units underlying the Site are subdivided into <br /> four progressively deeper hydrestratigraphic units designated by the STTC as the <br /> A Zone, B Zone, C Zone, and D Zone. The Assessment Report describes the D zone as <br /> isolated sand units interbedded with silts and clays and occurring below 80 feet bgs. <br /> Table 2 of the Assessment Report provides the results of soil sampling conducted in the <br /> monitoring well boreholes intermittently between 10 and 160 feet bgs. The maximum <br /> soil concentrations of total petroleum hydrocarbons as gasoline (TPHg) and TPH as <br /> diesel (TPHd) were encountered in the boring for TS/MW-3D at 10 feet bgs. The TPHg <br /> concentration was 2,400 milligrams per kilogram (mg/kg) and TPHd was 2,000 mg/kg. <br /> Grab groundwater sampling results obtained during the advancement of the TS/MW-3D <br /> borehole are tabulated in Table 2 of the Assessment Report. Maximum dissolved <br /> concentrations of TPHg and TPHd in groundwater were observed at 125 feet bgs at <br /> concentrations of 880 micrograms per liter (Ng/L) and 590 Ng/L, respectively. Benzene <br /> and tertiary butyl alcohol (TBA) were also detected at this depth at 350 Ng/L and <br /> California Environmental Protection Agency <br /> ed Recycled Paper <br />