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California Rd%onal Water Quality ntrol Board <br /> Central Valley Region <br /> Terry Tamminen <br /> Robert Schneider Chair <br /> Secretary for Sacramento Main Office Arnold Schwarzenegger <br /> Environmental Internet Address: http://w .sw b.ca.gov/mgcb5 Governor <br /> Protection 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 <br /> Phone(916)464-3291 Fax(916)4644797 <br /> 10 September 2004SEP 13 <br /> 2004 <br /> ENVIR NM <br /> Mr. Kyle Rutherford PEIRMIr ENI If <br /> Union Oil Company of California �SERViCES <br /> P.O. Box 1069 <br /> San Luis Obispo, CA 93406 <br /> REVIEW OF REPORTS, SOUTH SHORE PARCELS, UNOCAL OPERABLE UNIT, <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> Staff of the Central Valley Regional Water Quality Control Board (Regional Board) reviewed the <br /> following reports submitted by Clayton Group Services on behalf of Union Oil Company of California, <br /> responsible party for the South Shore Parcel Parcel 2A Unocal Operable Unit (OU): <br /> • 29 July 2004 Quarterly Monitoring Report, Second Quarter 2004(QMR); <br /> • 11 August 2004 Subsurface Investigation Report(Report); and <br /> • 17 August 2004 Update to Interim Remedial Action Workplan (Work Plan). <br /> The QMR discusses the groundwater monitoring activities conducted in June. The Report describes the <br /> !soil and groundwater sampling results from 2S borings across the site. The Work Plan proposes to <br /> 'expand the dimensions of the areas proposed for excavation in the 3 December 2003 Interim Remedial <br /> Action Workplan and revised in the 16 January 2004 Response to Comments/Investigation Workplan. <br /> We have the following comments on the Report: <br /> 1. The Report does not discuss the qualifiers applied by the analytical laboratory. The Unocal OU <br /> must discuss this information and how it affects the validity of the sampling results. <br /> 2. In Section 3.4 of the Report, Quality Assurance/Quality Control, there is no discussion of <br /> equipment blanks. Based on the order of borings and detections in the samples from the first <br /> advanced borings, the Unocal OU should have collected equipment blanks. Future field <br /> investigative activities need to include collection of equipment blank samples. <br /> 3. Based on the results from some of the borings, the vertical extent of petroleum pollution is not <br /> defined. <br /> Regional Board staff concurs with the Work Plan proposal to expand the areas of excavation. The <br /> Uncal OU needs to provide sample results for the fill material for Regional Board staff concurrence <br /> California Environmental Protection Agency <br /> ed Recycled Paper <br />