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James PGdest 2 September 9, 1993 <br /> The filtered cooling water will be held in a 21,000 gallon tank, and will be analyzed <br /> daily for compliance with discharge limits before discharge. The treated cooling water <br /> is to be discharged to the sewer when the Destec facility is not operating. The sludge <br /> will be disposed of as a hazardous waste. <br /> The estimated treated cooling water characteristics are as follows: <br /> Total Chromium <0.5 mg/I <br /> Total Dissolved Solids 5,000 mg/1 <br /> pH 8.5-10 <br /> The acidic reduction of hexavalent chromium followed by alkaline precipitation is a <br /> common chromium treatment method and is capable of lowering the chromium con- <br /> centration to less than 0.5 mg/1 as estimated. The proposed system is acceptable for <br /> the treatment of the glass furnace cooling water. <br /> At 0.5 mg/1 total chromium concentration, approximately 0.08 pounds of chromium <br /> would be discharged per day, and is within the City of Manteca limits of 0.25 pounds <br /> of chromium per day. However, it is important to minimize the amount of chromium <br /> discharged due to sludge monitoring, and possible pretreatment program development <br /> monitoring at the City of Manteca wastewater treatment plant. Increased chromium <br /> levels could adversely affect development local chromium limits. For this reason it is <br /> recommended that operational parameters regarding pH during filtration be adopted. <br /> Published information on chromium hydroxide solubility indicates minimum solubility <br /> between the pH range of 8.5 to 9.0. Chromium solubility increases at pH values <br /> outside this range. To minimize effluent chromium, it is recommended that filtration <br /> of the cooling water be conducted in the range of 8.5 to 9.0 as an operational guide- <br /> line, and that filtration will be not be conducted at a pH less than 8.0 or above 9.5. <br /> Sampling is`bonducted on a daily basis. The sample will be split for on-site and off- <br /> site analysis of pH, total chromium, and total dissolved solids. The off-site sample <br /> will be analyzed by a California Department of Health Services approved laboratory. <br /> The Libby-Owens-Ford facility is subject to categorical pretreatment requirements for <br /> process wastewater. The glass furnace cooling water is not considered a process <br /> wastewater, and is not subject to categorical limits. <br />