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California Regional Water Quality Control Board <br /> 'T ,; <br /> Central Valle Region " <br /> Robert Schneider,Chair �"'`�'�` <br /> Terry Tamminen Fresno Branch Office Arnold Schwarzenegger <br /> Secretary for Internet Address: http://www.swrcb.ca.gov/—rwgcb5 Governor <br /> Environmental 1685 E Street,Fresno,California 93706-2020 <br /> Protection Phone(559)445-5116•FAX(559)445-5910 <br /> Ro-,E�C�E�W F[0 <br /> 22 March 2004 <br /> MAR 2 3 2004 <br /> ENVIRONMENT HEALTH <br /> PERMIT/SERVICES <br /> Mr. M. Scott Mansholt <br /> ChevronTexaco <br /> Chevron Environmental Management Company <br /> P.O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW OF OFFSITE GROUNDWATER INVESTIGATION WORKPLAN, U.S. CAN/WELTY <br /> ROAD PROPERTY, VERNALIS, SAN JOAQUIN COUNTY <br /> We have reviewed the Off-Site Soil and Groundwater Investigation Workplan, U.S. Can/Welty Road, <br /> 35275 Welty Road report, dated 10 March 2004 submitted by Science Applications International <br /> Corporation (SAIC) on behalf of ChevronTexaco. <br /> The Workplan proposes to: a) collect additional offsite data regarding the crude oil pollution <br /> downgradient and adjacent to the site; b) initiate a quarterly groundwater sampling program for the four <br /> onsite wells and one Western Farm Services monitoring well; and, c) conduct a well search of <br /> Department of Water Resources files to identify water wells within 2,000 feet of the property. <br /> The Workplan proposes five offsite borings and one contingency boring to collect soil and groundwater <br /> samples for delineating the extent of petroleum hydrocarbons generally downgradient and/or lateral to <br /> offsite borings GMX-10, 11, and 12. Impacted soil and groundwater have been identified at those <br /> locations, which are downgradient of the onsite wells. <br /> We have the following comments to the Workplan: <br /> • Once the extent of impacted soil and groundwater has been determined, at least two of the <br /> offsite locations should be selected for installation of downgradient sentinel monitoring <br /> wells. <br /> • Sampling of the additional wells should be included with the proposed quarterly <br /> monitoring program for the onsite wells and the Western Farm Services well. <br /> • During fieldwork, the findings should be discussed with Regional Board staff to determine <br /> which of the borings may be converted to monitoring wells. <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />