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INFORMATION SHEET • • 2 WASTE DISCHARGE REQUIRMENTS ORDER NO. R5-2003-XXXX SPX CORPORATION MARLEY COOLING TOWER COMPANY STOCKTON, SAN JOAQUIN COUNTY conditioned for additional water treatment in a process called regeneration. During regeneration, which occurs approximately every 2.5 days, 15,000 gallons of solution containing the stripped chemicals is.removed from the ion exchange system and processed through the electrochemical unit. The electrochemical unit consists of an electrochemical reduction(Andco) and precipitation process which uses iron as the reducing agent for the hexavalent chromium followed by iron co-precipitation using pH adjustments. The addition of polymers and further pH adjustments are used to optimize settling. The effluent is then filtered prior to discharge. The solids from the clarifier are pumped and accumulated in a filter press. The filter press filtrate and mixed media filter backwash are returned to the treatment plant for further treatment. Filter press cake has been characterized as a California hazardous waste, and is collected in roll off bins for off-site disposal. The site is divided into two areas, the North Yard and the South Yard. All past wood treatment activities were conducted on the North Yard. Rain falling on the North Yard becomes contaminated after contact with treated cooling tower components. This contaminated rainwater is collected in a storm drain system and is passed through the treatment plant in the northeast portion of the site. Due to the past practice of storing treated wood products on the MCTC South Yard, some wood treating chemicals had been detected in the storm water runoff from the South Yard. The South Yard surface has been cleaned and residual contamination in pipes and ditches removed as part of the remedial actions undertaken by the Discharger. The groundwater treatment facility is designed to treat a maximum flow up to 0.94 mgd. Groundwater is extracted from approximately 17 extraction wells on and off-site. The groundwater extraction system can operate in a cyclical fashion with each of the two cycles lasting 56 hours or on a continuous basis with all extraction wells pumping at rates varying from 10-90 gallons per minute depending on effective capture of the groundwater contamination plume. When cycling, primary groundwater extraction is alternated between the north zone and the area south of the site. Water extracted from the north zone has higher contaminant concentrations. During south zone pumping, the capacity of the treatment plant is not fully utilized unless supplemental waste sources are added. Flushing water may be added to supplement the groundwater contaminant concentrations. Additionally, when sufficient storm water is accumulated on the North Yard to justify treatment, the operator will manually initiate storm water treatment through the Andco system. Groundwater from selected wells will simultaneously be delivered to the ion exchange treatment system. On 16/17 September 2002, a system malfunction resulted in discharge of a high pH water and fish- kill in the Stockton Diverting Canal. This Order includes a provision that the Discharger submit and implement a release preventive plan and a contingency plan to minimize the potential for future accidental discharges.