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Californi Regional Water Quality Control Board ,. <br /> \- Central Valley Region <br /> Karl E. Longley,Sell),P.E.,Chair <br /> Linda S.Adams Sacramento Main Office Arnold <br /> Seri emq for H020 Son Center Drive 4200,Rancho Cordova,California 95670-6114 Schwarxenegger <br /> lbrvapnmemal Phone(916)4643291 -FAX(916)464-4645 Governor <br /> Proleelion hnpJ/%"vw,waterhoards.ca.govlcentralvalley <br /> Mr. Ed Ralston 29 April 2008 <br /> ConocoPhillips <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> WORK PLAN FOR CONFIRMATION SOIL BORINGS, FORMER UNION OIL BULK PLANT NO. <br /> 788, 8203 EAST 11TH STREET, TRACY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water Board) staff <br /> reviewed the 17 April 2008 Work Plan for Confirmation Soil Borings (Report) prepared by SECOR <br /> International, Inc, (SECOR) on behalf of ConocoPhillips for the former Union Oil Bulk Plant at 8203 <br /> East 11'i' Street in Tracy (Site). <br /> The Site is a former bulk fuel storage facility in the City of Tracy. In 1993, Site operations ceased, <br /> and ConocoPhillips removed all the tanks and associated piping and structures. The Site is currently <br /> vacant and no longer in use. Since 1989, Union Oil (now ConocoPhillips) has installed 13 soil <br /> borings, sampled 13 test pits, collected 55 soil samples, and installed and sampled10 monitoring <br /> wells. <br /> ConocoPhillips proposes to drill five soil borings at the Site to evaluate current soil concentrations. <br /> The boring locations are adjacent to the five locations with the historical maximum soil <br /> concentrations. ConocoPhillips will collect two soil samples from each boring; one at five feet below <br /> ground surface and one just above the water table, which is assumed to be about eight feet bgs. <br /> Our comments are presented below: <br /> 1. Regional Water Board staff concur with the proposed scope of work, but ConocoPhillips <br /> needs to add one more soil boring adjacent to previous sample location TP-8. By <br /> 1 July 2008, please drill the six soil borings, collect the soil samples, and submit a report of <br /> findings. The report of findings needs to include a comparison of historical soil concentrations <br /> to current data and an estimate of the mass of petroleum hydrocarbons remaining in soil. <br /> 2. ConocoPhillips needs to collect a minimum of two soil samples per boring (both unsaturated) <br /> and the samples need to be collected at the depths of the maximum historical concentration. <br /> If you have any questions, you may contact me at (916) 464-4819 or by email at <br /> kshelton(a).waterboards,ca.gov. ( o U <br /> APR 3 0 2008 <br /> KRISTI SHELTON <br /> Water Resources Control Engineer By <br /> cc: Ms. Margaret Lagorio, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Mark Bare, SECOR, Rancho Cordova <br /> California Environmental Protection Agency <br /> Ofecycled Paper <br />