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5ep-23-02 04:35P SIEW PACIFIC GROUP 916 33 3197 P.02 April 23, 1997 Ms. Wendy Wyels,Agricultural Regulatory Unit Central Valley -Regional Water Quality Control Board 3443 Routier Road, Suite A Sacramento, Califoniia 05827-3098 Subject: Request For Conditional Site Closure at Cargill'..Former Molasses Feed Product Facility, Port Roar!No. 8, Stockton, California: Sierra-Pacific Project No. 96-128.06 Dear Ms. Wyels: on behalf of Cargill, Inc. (Cargill), Sierra-Pacific Groundwater Consultants, Inc. (Sierra-Pacific) is herein requesting that the Regional Water Quality Control Board (RWQCB) issue a conditional closure letter for a former molasses Iced product facility located at Port Road No.8, Stockton, California. Based on soil and ground-water sampling, laboratory test results, and information from the scientific literature, ,sierra-Pacific believes that the former Cargill feed product facility no longer poses a significant threat to the waters of California (Table 1). Sierra-Pacific's argument is based can the following: • Soils Test Results - Three limited soil sampling programs were conducted at the site, Test results indicate that feed product concentrations in the soil are much lower than originally anticipated. The first. report of results was submitted to RWQCB on 29 May 1996 (Table 1). The second soil sampling event took place during the installation of three shallow monitoring;' wellsthe installation report was submitted to RWQCB on 15 November T996. Finally, a composite soil sample was collected in February 1097 to characterize unexcavated soils for possible disposal at Forward Landfill; Manteca. The composite sample work plan was prepared for Cargill on i t February 1997_ Partial demolition of the Port Thad No.8 facility in April 1997 revealed that about 80 percent of the facility had been paved with Portland cement and asphaltic concrete. Excavation showed that soils beneath paved areas were usually clean and dry. The ten-point, composite soil sample was collected in nun-paved (potentially contaminated) areas of the site in February 1997. Laboratory test results from the composite soil sampling event indicated that soils in these areas contained an average of about 680 mg/kg 'Total Kjeldahl Nitrogen (TKN) and 14 mg/kg nitrates (Appendix A). Nitrate (NO) at a coneentration or 14. mg/kg is cquivatent to 3.1 mg/kg; nitrogen-as-nitrate (N-NQ,). in other words, 99.6 percent of the nitrogen present in shallow soils at the site is present as organic and ammoniacal nitrogen, earlier testing further supports that finding(Table 1). 0 Ground Water Test Results - Laboratory test results indicate that shallow ground water at the