FIELD DOCUMENTS AND WORK PLANS 1988

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INFORMATION SHEET MARLEY COOLING TOWER COMPANY STOCKTON, SAN JOAQUIN COUNTY Facility Description and Discharges The Marley Cooling Tower Company (MCTC) owns a cooling tower fabrication plant in the east Stockton area. As part of the fabrication process, MCTC operates wood treatment facilities at the site. The primary chemicals used in the wood treat- ment process are copper and chromium. Arsenic was also used in the wood treatment solutions until 1982. The site is divided into two areas, the North and South Yards. All wood treating activities are performed and all treated products are stored in the North Yard. Rainfall contacting the North Yard becomes contaminated with wood treatment chemicals. MCTC has implemented controls to reduce rainfall contamination and contain all runoff in the North Yard. Previously, all contaminated stormwater from the North Yard was discharged to an on-site holding pond for evaporation and infiltration. Contaminated stormwater is now conveyed to an on-site treatment plant before discharge to the Stockton Diverting Canal . The South Yard is used for fabrication and storage of nontreated cooling tower components. Stormwater from the South Yard is discharged directly to the local drainage ditch system. Soil analysis results from stormwater ditches adjacent to the South Yard have shown the presence of relatively low levels of wood treat- ment chemicals, due to past temporary storage of treated components prior to shipment. MCTC has discontinued this practice and initiated cleanup of residual contamination in the South Yard. Past operational practices by MCTC have resulted in soil and ground water contami- nation by wood treatment chemicals. Soils beneath the wood treatment retort and the stormwater pond contain elevated levels of copper, chromium, and arsenic. Underlying ground water has been contaminated with chromium and copper. Ground water contamination exceeding the federal drinking water standard for chromium of 50 ug/l extends approximately 1000 feet off-site to the southwest. First ground water is approximately 40 feet below ground surface. The depth of ground water contamination extends to approximately 200 feet. To mitigate the ground water contamination, MCTC plans to extract and treat ground water. Contaminated ground water will be treated at the same on-site facilities for treating contaminated stormwater during times of no rainfall . Discharge of treated ground water will also be to the Stockton Diverting Canal . The on-site treatment facilities consist of flow equalization and settling, multi-level filtration, and both anion and cation exchange. The facilities have a design capacity of 0.37 million gallons per day (mgd) . Effluent from the treat- ment facility will be discharged to the Stockton Diverting Canal , at a point approximately one quarter mile east of the site.