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talilt)rnia gional Water Quality Con l Board <br /> Central Valley Region <br /> Karl E. Longley,ScU, P.E.,Chair <br /> .Ar <br /> Linda S.Adana <br /> II(RO.AmL'cnter Drive H200.12ancho Cordovu_Calilixnia 91670-6I LI rzen Schwaenegger <br /> Secrelor)•jor Phone(916)464-3291 •FAX(916)464-4645 <br /> !intiironnenlot Gorrrnm <br /> hllp.;hv�nv.watcrboardcca.govlcentralvallc� \ l <br /> Proleclion REV . <br /> 20 October 2008 OCT 2 1 2008 <br /> ENVIRON('dIE(J t NL? LTH <br /> PERMITF,cgViTE , <br /> Mr. Ed Ralston <br /> ConocoPhillips <br /> 76 Broadway <br /> Sacramento, CA 95818 <br /> CLOSURE ASSESSMENT WORK PLAN, FORMER UNION OIL BULK PLANT <br /> NO. 788, 8203 EAST 11TH STREET, TRACY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff reviewed the 6 October 2008 Closure Assessment Activities Work Plan (Work <br /> Plan) prepared by Stantec Consulting Corporation (Stantec) on behalf of ConocoPhillips for <br /> the former Union Oil Bulk Plant at 8203 East 11th Street in Tracy (Site). <br /> The Site is a former bulk fuel storage facility in the City of Tracy. In 1993, Site operations <br /> ceased, and all the tanks and associated piping and structures were removed. The Site is <br /> currently vacant and no longer in use. Since 1989, Union Oil (now ConocoPhillips) has <br /> installed 13 soil borings, sampled 13 test pits, collected <br /> 55 soil samples, and installed and sampled 10 monitoring wells. <br /> The Work Plan was prepared in response to the Regional Water Board staff's 13 August 2008 <br /> letter requesting ConocoPhillips to'evaluate the leachability of the remaining petroleum in the <br /> soil, address the concern about potential exposure to contaminated soil, and examine the soil <br /> vapor concentrations. On 1 October 2008, Regional Water Board staff and ConocoPhillips <br /> met and agreed that ConocoPhillips would excavate contaminated soil instead of conducting <br /> leachability modeling. <br /> ConocoPhillips proposes conducting the work in the tollowing three phases: <br /> 1 . Abandon all monitoring wells, <br /> 2. Excavate contaminated soil from the three areas that exceed the gross contamination <br /> screening levels, and <br /> 3. Conduct a soil gas survey <br /> Our comments are presented below: <br /> 1 . Regional Water Board staff concurs with the Work Plan with the exceptions listed below. <br /> By 13 March 2009, ConocoPhillips needs to destroy the monitoring wells, excavate <br /> contaminated soil, collect confirmation soil samples, analyze soil gas samples, and <br /> submit a report of findings. <br /> California Environmental Protection Agency <br /> `G� Reveled Pnl,rr <br />