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Californigegional Water Quality Cogs of Board ✓°` � <br /> Central Valley Region <br /> Karl E.Longley,ScD,P.E.,Chair <br /> Linda S.Adams Arnold <br /> Secrem or Sacramento Main Office <br /> n'f <br /> Environmental 11020 Sun Center Drive H2O0,Rancho Cordova,California 956766114 Schwarzenegger <br /> - <br /> Prolenion Phone(916)464-3291 •FAX(916)464-4645 ^f� "E �t ED Governor <br /> htip://www.waterboards.ca.gov/centralval ley IUUUuUUU{IL'�`� "EV <br /> ED <br /> December 2007 DEC 2 6 2007 <br /> Ms. Stephanie Frugal Mr. Jay Allen ENVIRONMENT HEALTH <br /> Chevron Environmental Management Company Stone Brothers I��rientOE ompany <br /> 6001 Bollinger Canyon Road 1024 W. Robinhood Dr. <br /> San Ramon, CA 94583 Stockton, CA 95207 <br /> DOCUMENT REVIEW, CLEANUP AND ABATEMENT ORDER (CAO) NO. 5-00-0707, <br /> FORMER UNOCAL STATION #5098 AT 5606 PACIFIC AVENUE, AND FORMER <br /> MONTGOMERY WARDS AUTO SERVICE AT 5400 PACIFIC AVENUE, STOCKTON, <br /> SAN JOAQUIN COUNTY <br /> I reviewed the Remedial Design Plans (Attachment A) and Work Plan for Air Sparging/Soil <br /> Vapor Extraction Well Installation (Attachment B), submitted in the document titled <br /> RE.- 5400/5606 Pacific Avenue, Stockton (Workplan), and received on 6 December 2007 from <br /> ENSR, the consultant for Chevron Environmental Management Company (CEMC). The <br /> Workplan was submitted following a meeting with Regional Board and ENSR staffs on <br /> 14 May 2007, in which I questioned the efficiency of the existing air sparging/soil vapor <br /> extraction (AS/SVE) treatment system. At that time, ENSR responded that, prior to conducting <br /> optimization of the existing AS/SVE.treatment system, an evaluation would be conducted and <br /> recommendations would be submitted to the Regional Board. <br /> The Workplan states that redesign of the existing AS/SVE system is necessary, due to fact <br /> that "...operating pressures of the existing AS may not have been sufficient to achieve <br /> breakthrough for each of the operating wells." The Workplan adds that a Performance <br /> Monitoring Plan (PMP) will be submitted after construction of the new AS/SVE system. The <br /> PMP will propose that six months of data (field and analytical) "...be compiled and submitted <br /> as an evaluation separate from the quarterly monitoring data." <br /> Attachment A includes eighteen pages of professionally stamped specifications and drawings <br /> for the proposed construction activities. Attachment B proposes six tasks for the installation of <br /> six additional AS wells (AS-14 through AS-21) and three additional SVE wells (VEW-16, <br /> VEW-19, and VEW-22), includes the removal and relocation of the existing equipment in the <br /> treatment compound, and retrenching from the treatment compound to the wells for <br /> installation of new piping. <br /> California Environmental Protection Agency <br /> Zd Recycled Paper <br />