FIELD DOCUMENTS_1992-1999 - Laserfiche WebLink

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WASTE DISCHARGE REQUIREMENTS -3- MARLEY COOLING TOWER COMPANY SAN JOAQUIN COUNTY 11. The Discharger has constructed a treatment plant which includes a new electrochemical reduction and precipitation unit operating in parallel to the previously existing ion exchange treatment system to remove contaminants from the water, see Attachment C, incorporated herein and made part of this Order. The ion exchange system 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. In the cation exchange vessel , trivalent chromium and copper are adsorbed. The exchange process continues until the resins' exchange sites are filled and exchange capacity is exhausted. The adsorbed wood treating chemicals 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 gals. of solution containing the stripped chemicals is removed from the ion exchange system and processed through the new electrochemical unit. 12. The new treatment plant 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. The new system was placed in operation in January 1992. 13. The ground water 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 ground water contamination plume. When cycling, water will be extracted primarily from the north zone near the site for a period and then, ground water extraction will be from the area south of the site. Water extracted from the north zone will have higher contaminant concentrations. During south zone pumping, the capacity of the treatment plant will not be utilized fully unless supplemental waste sources are added. Flushing water may be added to supplement the ground water concentrations. In either mode, 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. Ground water from selected wells will simultaneously be delivered to the ion exchange treatment system. 14. The Report of Waste Discharge describes the combined storm water and ground water characteristics prior to treatment as follows: Average Flow: Existing Plant - 0.59 million gallons per day (mgd) Expanded Plant Treatment Capacity: 0.94 mgd