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WASTE DISCHARGE REQUOMENTS • 2 MARLEY COOLING TOWER COMPANY SAN JOAQUIN COUNTY TENTATIVE back into the facility treatment system. The treated water flow from the injection system beneath the retort pit is primarily vertical. 6. Approximately 5%of the treated water (effluent from the treatment system), defined as flushing water, is reinjected into shallow soils in the area of a closed retort pit at 37 degrees, 58 minutes, 11 seconds latitude and 121 degrees, 14 minutes, 00 seconds longitude, as shown on Attachment B, a part of this Order. The process flushes the wood-treating chemicals from the soil into the chromium and copper plume being captured by the above mentioned groundwater extraction system. 7. 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. 8. The ion exchange unit consists of two anion exchange vessels and a cation exchange vessel. In the anion exchange vessels,hexavalent chromium in the water is adsorbed onto the ion exchange resins. ht the cation exchange vessel, trivalent chromium and copper are adsorbed. The exchange process continues until the resin's exchange sites are filled and exchange capacity is exhausted. The adsorbed chromium and copper are stripped from the ion exchange resins and the resins are 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 unit. 9. The electrochemical unit of the treatment plant is supported by processes consisting of electrochemical reduction(Andco) and precipitation 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 electrochemical unit side of the treatment plant for further treatment. 10. 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 polluted after contact with treated cooling tower components. This polluted rainwater is collected in a storm drain system and is passed through the treatment plant in the northeast portion of the site. Due to storage of treated wood products on the MCTC South Yard, some wood treating chemicals were once detected in the storm water runoff from the South Yard. The South Yard surface has been cleaned. The residual contamination in pipes and ditches has been removed as part of the remedial actions undertaken by the Discharger. MCTC is in the process of obtaining a general discharge permit for the South Yard. 11. The treatment facility is designed to treat flows to 0.94 mgd. Groundwater is extracted from a minimum of 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 08/22/02 2:02 PM Marley Cooling