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• f <br /> 5900 Hollis Street,Suite A, Emeryville,Calfornia 94608 <br /> Telephone: 510420,0700 Facsimile: 510.4209170 <br /> CONESTOGA-ROVERS w .CRAworldxom <br /> &ASSOCIATES <br /> November 30, 2011 RECEIVbh ae No. 241729 <br /> OE;; 0 2 2011 <br /> EN PlR0NMCM_'L HEALTH <br /> Ms. Kristin Shelton C19M11 SERVICES <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 11020 Sun Center Drive#200 <br /> Rancho Cordova,California 95670-6114 <br /> Re: Shell Stockton Terminal <br /> 3515 Navy Drive <br /> Stockton,California <br /> SAP Code 356164 <br /> Incident No. 300002 <br /> Dear Ms.Shelton: <br /> Conestoga-Rovers & Associates (CRA) prepared this letter on behalf of Equilon Enterprises LLC <br /> dba Shell Oil Products US (Shell) to provide an update on the remedial system installation in <br /> lieu of a system installation report due on December 1, 2011 and to recommend a revision to the <br /> remedial strategy for this site. <br /> As discussed in CRA's August 1, 2011 Groundwater Monitoring and Remediation Report- First and <br /> Second Quarters 2011, CRA completed the design of an air sparge and soil vapor extraction <br /> system and solicited bids from installation contractors and equipment vendors. In reviewing <br /> these bids,we note that the costs to install the remediation system are significantly higher than <br /> anticipated. Although a feasibility study (FS) was completed in 2007, no formal corrective <br /> action plan (CAP) has been prepared for the site,and soil and groundwater data have been <br /> collected since the FS submittal. Groundwater monitoring data indicate that constituents of <br /> concern(COCs) are defined in the down-gradient direction and that COC concentrations are <br /> decreasing in source area wells and stable to decreasing in cross-gradient wells. The subject site <br /> is an operating terminal on Rough and Ready Island near properties with historical heavy <br /> industrial use. These data suggest that there is limited risk to potential receptors. <br /> In light of these site conditions,CRA believes it is appropriate to reevaluate whether the <br /> potential risk to receptors warrants pursuing active remediation as planned at this time. This is <br /> consistent with the approach to petroleum cases described in the State Water Resources Control <br /> Board's Draft Low-Threat Underground Storage Tank Closure Policy. CRA recommends preparing <br /> a CAP that will reevaluate remedial alternatives and include the data we have obtained since <br /> the previous remedial action plan submittal,which will also evaluate the life-cycle costs and <br /> sustainability of the remedial alternatives. <br /> Equal <br /> Employmem <br /> Opportunity Employer <br /> Worldwide Engineering, Environmental,Construction,end IT Services <br />