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3.0 CWC 135: Unspecified Aqueous Solution Site 2010 guanti (lb) SLAC 14,878 SNL/CA 7,590 LBNL 4,712 3.1 Cleanout of Cooling Tower Sludge Site 2010 quantity (lb) SLAC 14,878 Input Materials: TopWeter Lmineral Cooling Chemical Additives to - Tower Sludge Off-site keep minerals in solution (CWC 135) disposal FIGURE 11I.3.L FLOW DIAGRAM FOR CLEANOUT OF COOLING TOWER SLUDGE Hazardous Wastes and Process Description Most of the hazardous waste in the CWC 135 category was from the removal of sludge from the basin of an old cooling tower that was being renovated (14,303 out of 14,878 pounds of the CWC 135 generated). This waste is close to being considered non -routine: however, SLAC conservatively assumed that this waste stream could happen again in the future when these cooling towers age and require cleaning. The balance of the waste in this category was generated from over eight other operational activities that are relatively small in waste quantity relative to the cooling tower cleaning operation. Continuous improvements in operational procedures and preventive maintenance are important measures that help reduce the generation of these wastes over time. The discussion below addresses more information on cooling tower operations. Chemicals are added to the cooling tower to condition the water for pH, biological growth and for reducing corrosion and mineral deposit during the evaporation process so that more water is re -circulated and in turn, less makeup water required. The sludge contains high levels of various non -Resource Conservation and Recovery Act (RCRA) metals such as iron and molybdenum, in part from chemical additives used to condition the water, and in part from the continuous evaporation of water that occurs in the cooling tower. The evaporation process increases the concentrations of ions that were originally at low concentrations in the potable water. The more concentrated water is eventually discharged to the POTW under the Mandatory Wastewater Discharge permit when total dissolved solids reach levels that impede cooling tower performance. SLAC uses cooling towers to remove heat from a primary closed-loop cooling system that is used to cool the two-mile accelerator and associated equipment. SLAC Facilities engineers try to maximize cooling tower water reuse to conserve water and reduce feed water usage and water discharge to the sanitary sewer. Over time, sludge will accumulate in the cooling towers and needs to be removed to reduce scaling in piping and cooling tower surfaces. The quantity of sludge will vary depending on cooling tower usage, cooling tower age, and frequency of cleaning. The cooling tower that was cleaned was old, and so it generated a significant accumulation of sludge relative to more routine cleaning activities for the other cooling towers on-site. The cooling tower structure (excluding the basin) was demolished and replaced by a new cooling tower. Hazardous Waste Management Approaches No hazardous waste management approaches are readily available except for providing optimal operation and maintenance of the cooling towers in regard to minimizing corrosion and mineral deposits while maximizing water usage. SLAC has seven major cooling towers that can impact on this waste stream: CT 101, 1200, 1201, 1202, 1701, 1801 and 404 to service large cooling requirements on the site and some minor cooling towers not listed here that are used for smaller cooling requirements. Since the last reporting period, the two-mile linear accelerator has not operated at full load to conduct the new types of experiments that SLAC is taking on as a multi-purpose laboratory. This results in conducting experiments with less energy loading on the accelerator, thus reducing cooling tower loading. As a result, this sludge waste stream is expected to be reduced in the future from this new operating scenario. ALUATION No recommended source reduction measure. The quantity of waste generated as CWC 135 or 181 from the cooling towers is expected to decrease over time between the upgrades and maintenance currently used for the cooling towers. For the temperature range involved for cooling requirements and the heat duty requirements, cooling tower technology is widely used, and SLAC Facilities engineers are optimizing cooling tower performance on an ongoing basis to reduce water usage and prevent scaling. There are always tradeoffs on the number of cycles that the water undergoes in the tower to meet cooling requirements and sanitary sewer discharge requirements. No other source reduction measures are being considered or recommended. September 1, 2011 SR 14 Plan 20 September 1, 2011 SB14 Plan