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California Regional Water Quality Control Board <br /> Central Valley Region <br /> '\ Katherine Hart, Chair <br /> 11020 Sun Center Drive,#200, Rancho Cordova, California 95670-6114 <br /> Linda S.Adams (916)464-3291 • FAX(916)464-4645 Edmund G.Brown Jr. <br /> Acting Secretary for http://www.waterboards.ca.gov/centralvalley Governor <br /> Environmental Protection <br /> 14 March 2011 RECEIVED <br /> Mr. Nam Baek APR 14 2011 <br /> Glenn Springs Holdings, Inc. y. <br /> 5005 LBJ Freeway, Suite 1350 <br /> Dallas, TX 75244-6119 ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> SULFOLANE REMEDIAL INVESTIGATION WORK PLAN, FORMER OCCIDENTAL <br /> CHEMICAL COMPANY LATHROP FACILITY, 16777 HOWLAND ROAD, LATHROP, SAN <br /> JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Central Valley <br /> Water Board) staff received the Sulfolane Remedial Investigation Work Plan (Work Plan), <br /> dated 2 March 2011, and prepared on your behalf by ARCADIS US, Inc. (ARCADIS). <br /> ARCADIS proposes to evaluate the lateral and vertical extent of sulfolane impacts in the <br /> upper 90 feet of soil and groundwater at the Lathrop site. The proposed scope of work <br /> includes installing up to 19 soil borings in the vicinity of monitoring well PW26, where the <br /> highest groundwater concentrations of sulfolane have been found. These direct-push <br /> borings will be sampled in order to characterize impacts in the vadose zone. Depth-discrete <br /> groundwater sampling in up to 20 borings more distant from PW26 will provide information <br /> on the vertical and lateral extent of impacts in groundwater. <br /> I have reviewed the Work Plan and have the following specific comments. Provided we <br /> resolve these comments prior to the commencement of field work, we concur with the <br /> approach and methodologies presented in this Work Plan. <br /> 1. Section 4.2.1 states that CPT borings will be co-located with as many as four proposed <br /> direct-push borings advanced to approximately 90 feet bgs. Figure 4 shows one of these <br /> boring locations (SB-38). Figure 5 appears to show four, but it is not clear whether HP-7, <br /> HP-11, HP-12, and HP-16 are the same kind of sampling points as SB-38. HP-12 is <br /> apparently in the same location as SB-38. The text and figures need to be reconciled so <br /> that both are correct. <br /> 2. Text in the first paragraph of Section 4.2.3 does not explain why the four locations <br /> described above in Figure 5 were selected for lithologic profiling. Please provide this <br /> information. <br /> 3. Please provide the rationale for the grid spacing and distribution of the step-out borings <br /> HP-1 through HP-20. <br /> California Environmental Protection Agency <br /> ��Recycled Paper <br />