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6 <br /> California Regional Water Quality Control Board Lh <br /> Central Valley Region <br /> Robert Schneider Chair <br /> Terry Tamminen e <br /> Secretary for Sacramento Main Office ��E V�® Arnold Schwaaenegger <br /> Environmental Internet Address: hup://www.swrcb.ca.gov/rwgc Governor <br /> Protection 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 <br /> Phone(916)464-3291 OCT 0 6 2004 <br /> 4 October 2004 ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr.Bob Hopkins Mr. Jay Allen <br /> Union Oil Company of California Stone Brothers Management Company <br /> 276 Tank Farm Road. 1024 W. Robinhood Dr. <br /> P.O. Box 1069 ' Stockton,CA 95207 <br /> San Luis Obispo, CA 93406 <br /> LETTER REQUEST, CLEANUP AND ABATEMENT ORDER (CAO)NO. 5-00-707,-FORMER UNOCAL <br /> STATION#5098 AT 5606 PACIFIC AVENUE,AND FORMER MONTGOMERY WARDS AUTO SERVICE <br /> AT 5400 PACIFIC AVENUE,STOC%TON,SAN JOAQUIN COUNTY, <br /> Regional Board staff reviewed the 15 September 2004 Request for Extension to Restart SVE System and <br /> Evaluation of Potential Enhancement to SVE System (Letter), submitted by Unocal. The Letter proposes a date <br /> of 15 January 2005 for submitting a report recommending a proposal for enhancement to the existing SVE/AS <br /> system,to help cease plume movement. <br /> Background: My letter dated 15 May 2004 requested a Workplan by 15 June 2004, to comply with <br /> CAO No. 5-00-707, Order No. 15, which states: "If groundwater monitoring indicates that the groundwater <br /> plume has migrated beyond laterally or vertically defined limits during the quarter, the quarterly report shall <br /> include a workplan and schedule, with work to begin within 30 days of a report submittal, to define the new <br /> plume limits and cease plume movement. The Workplan,received 15 June 2004, did not include a schedule to <br /> begin work to redefining the limits of the groundwater plume within 30 days. A Notice of Violation(NOV) for <br /> CAO No. 5-00-707 was issued on 18 June 2004. The NOV required implementation of the approved Workplan <br /> by 15 July 2004, and also required submittal of a Report by 1 August 2004, showing the steps taken to cease <br /> plume movement. You did comply with both NOV deadlines by installing the monitoring wells and providing <br /> the Report,which redefined the limits of the groundwater plume and began the process for restarting the SVE/Air <br /> Sparging system. On 14 June 2004,the Air Sparging(AS) system was overhauled and restarted. The SVE <br /> system required a new air permit, and was scheduled to start by 15 September 2004. The Soil Vapor Extraction <br /> (SVE) system was restarted on 28 September 2004,per email notification received from your consultant ENSR <br /> International Inc. (ENSR). Additionally, in a phone discussion on 3 September 2004,ENSR proposed enhancing <br /> the SVE/AS remediation by In-Situ Chemical Oxidation, specifically Ozone Injection. Since additional time <br /> would be required to evaluate an injection of an In-Situ Chemical Oxidation substance, I suggested that ENSR <br /> begin the process by providing a baseline analysis using site soil and groundwater,prior to submitting a <br /> Workplan for a bench scale testing for ozone injection. A pilot study for ozone injection into the aquifer would <br /> also be necessary. ENSR provided email copies of the preliminary baseline analyses on 28 September 2004. <br /> I concur to the proposed 15 January 2005 deadline to provide a Report of the assessment of SVE/AS <br /> enhancement,provided the following due dates are met: <br /> • By 15 October 2004, submit a Workplan outlining the entire process for enhancement to the existing <br /> SVE/AS system, to help cease plume movement. Also,I have reviewed existing data and request <br /> inclusion of additional monitoring wells needed to enhance the vertical and lateral extent of <br /> contaminants. Specifically, adequate characterization is needed to show groundwater flow direction and <br /> California Environmental Protection:Agency <br /> 0 Recycled Paper <br />