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..e .� INFORMATION SHEET WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2003-0100 SPX CORPORATION,MARLEY COOLING TOWER COMPANY IN SITU GROUNDWATER REMEDIATION PILOT STUDY SAN JOAQUIN COUNTY The Marley Cooling Tower Company(MCTC), a wholly owned subsidiary of SPX Corporation (hereafter Discharger) owns and operates a groundwater extraction and treatment system in the East Stockton Area of San Joaquin County. The Discharger previously operated a cooling tower fabrication plant at the site which included a wood preservation process using solutions containing copper, chromium and arsenic. Wood preserving was discontinued at this facility in January 1991, _ however past operational practices have resulted in contamination of soils and groundwater underlying the site. Soils have been contaminated with copper, chromium, and arsenic; groundwater has been polluted primarily by chromium at concentrations up to 18,900 micrograms/liter(µg/1). The plume of polluted in groundwater extends approximately 2,500 feet south of the MCTC facility. Groundwater is currently extracted from 14 extraction wells on and off-site. The groundwater ` extraction system operates with extraction wells pumping at rates varying from 10-90 gallons per minute depending on effective capture of the groundwater contamination plume. The groundwater treatment system consists of a treatment plant with an electrochemical unit operating in parallel to an ion exchange unit that removes waste constituents from the extracted water. The Discharger is permitted to discharge up to a maximum of 0.94 million gallons per day(mgd)of treated groundwater and storm water runoff under National Pollution Discharge Elimination System (NPDES)Permit CA0081787, Order No. 115-2003-0030, to the Stockton Diverting Canal,a water of the United States and a tributary to the Calaveras River. The Discharger is evaluating alternatives to accelerate the cleanup of the polluted groundwater, including in-situ chemical reduction of chromium. The Discharger submitted a Report of Waste Discharge (RWD),dated 8 November 2001, for a pilot study to evaluate the potential for in-situ treatment of groundwater containing chromium. The Discharger also submitted a(a)Supplemental Pilot Study Work Plan for In Situ Chromium Reduction at The Marley Cooling Tower Facility, dated 21 January 2003 that proposed changes to the RWD dated 8 November 2001. Additional supporting information was submitted by the Discharger on 1 and 16 April, and 1 May 2003. The pilot study will target groundwater in the uppermost water-bearing zone. The objective of the in-situ groundwater pilot study is to evaluate the (a) ability of in-situ hexavalent chromium reduction using calcium polysulfide and ethanol injection, (b)assess the secondary impacts of in- situ chemical reduction on groundwater quality, (c) identify design and operational factors that influence the successful performance of the in-situ chemical reduction approach,and (c) generate performance, design and cost data that can be used for evaluation as a possible alternative to the current groundwater extraction and treatment system. The Discharger proposes to inject a chemical reducing agent(calcium polysulfide)and an organic carbon source(ethanol). The calcium polysulfide is intended to quickly alter the oxidation/reduction state of the groundwater and reduce hexavalent chromium to trivalent