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1 <br /> SATE OF CALIFOkAIA C, ( Q W AIF Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— <br /> CENTRAL VALLEY REGION MAY 1 4 1990 -. <br /> 3443 ROUTIER ROAD <br /> SACRAMENTO,CA 95827-3098 ENVIRONMENTAL HEAL <br /> s May 1990404%I,TiSER`diCES <br /> Mr. Ken Smith MAY , 1 1990 <br /> Delta Truck Sales <br /> P.O. Box 8068 <br /> Stockton, CA 95208 <br /> HAR WORKPLAN APPROVAL AND MEETING SUMMARY, DELTA TRUCK SALES INC. , SAN JOAQUIN <br /> COUNTY, Tr-CA 1105-i33 <br /> We have reviewed the 30 April 1990 work plan for the Delta Truck Sales site <br /> investigation submitted by Environmental Science and Engineering (ESE) . Although <br /> not indicated in the title of the submittal , this office considers that it <br /> constitutes a workplan for the Hydrogeological Assessment Report (HAR) in <br /> accordance with the Toxic Pits Cleanup Act (TPCA) . <br /> A complete HAR must address all items listed in Section 25208.8 of the Health and <br /> Safety Code, and in general must determine the lateral and vertical extent of <br /> soils and ground water contamination. The workplan as submitted is hereby <br /> approved, however, the following comments should also be addressed: <br /> 1 . Three monitoring wells screened across the first shallow water surface <br /> only provides a planar gradient and flow direction. The locations chosen <br /> by ESE for the proposed monitoring wells may not be directly downgradient <br /> from the surface impoundment and thus may not intersect a stream tube of <br /> potential contaminant flow. If the monitoring wells do not yield <br /> representative water quality data directly down gradient of the surface <br /> impoundment, then the installation of additional monitoring wells may be <br /> required. <br /> 2. In addition to the proposed 5 foot intervals of subsurf,;ce soil samples, <br /> samples are also to be taken at major lithologic changes, i .e. organic <br /> clays or sandy layers. <br /> 3. The State Department of Health Services takes the position that hazardous <br /> waste intermixed with non-hazardous wastes must be considered hazardous. <br /> The likelihood is high that "hot" spots of soluble lead are present in the <br /> existing waste piles. A random grid of sampling may miss the hot spots <br /> and indicate that the waste piles are non-hazardous and possibly inert. <br /> ESE needs to characterize the hazardous waste and differentiate the waste <br /> from intermixed native soils and construction debris. <br /> At the 3 May 1990 meeting between RWQCB and Delta Truck Sales we discussed at <br /> length waste piles characterization, surface impoundment excavation and <br /> characterization, monitoring well location, and scenarios for disposal , <br /> remediation and closure alternatives. ESE indicated that a time schedule for <br /> completion of the phases of the HAR would be submitted to the RWQCB. ESE <br /> indicated that chemical analysis of the waste piles and surface impoundment <br />