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MWMC FACILITIES PLAN The existing WPCF disinfection system uses liquid chlorine for disinfection and sulfur dioxide for de.chlorination of the disinfected effluent. Chlorine solution is delivered to secondary effluent or blended primary and secondary effluent flow streams through a diffuser at the influent box to each chlorine contact basin. Following chlorine addition, flow passes through a chlorine contact basin to gain the desired detention time. The current disinfection capacity is estimated at 175 mgd, although higher peak wet weather flows in excess of 200 mgd have been disinfected effectively because of their dilute nature. The addition of sulfur dioxide for dechlorination takes place before the final effluent flows to the outfall box. Sulfur dioxide is delivered to the plant in 1-ton cylinders. Sulfonators dispense the sulfur dioxide in the desired quantities. Sulfur dioxide injectors operate in a manner similar to the chlorine injectors. The sulfur dioxide solution is added to the effluent downstream of the chlorine contact basins as the effluent flows through a mixing orifice. Table 3.2.2-4 presents a summary of the existing equipment associated with the disinfection system. The existing chlorine and sulfur dioxide systems have a sodium hydroxide wet scrubber system that is automatically started if a chemical leak is detected in the chlorine building. The wet scrubber has a 2-ton capacity, contains a 4,100-gallon tank of 12 percent NaOH, and is rated at 10,000 cfm. TABLE 3.2.2-4 WPCF Disinfection Facility Equipment MWMC Facilities Plan, Eugene-Springfield Capacity, (each/total Equipment Type Quantity firma/totalb) Chlorine Contact Four contact basins each 585 ftx 15 fl x 4 58/185/230 MGD Basins 13 ft, volume: 0.85 MG, 6.8 MG total volume, capacity at 20 minutes for instantaneous peak Evaporators (chlorine) Wallace and Tiernan, Series 50-202 2 8,000/8,000/16,000 lb/day Chlorinators Portacel, AVP2, 2000 lb/day units 5 1,000/4,000/5,000 lb/day running with 1000 lb/day rotometers Evaporators (sulfur Wallace and Tiernan, Series 50-202 2 8,000/8,000/16,000 lb/day dioxide) Sulfonator Wallace and Tieman, V2020 1 450/450/450 lb/day Sulfonator Podacel, AVP2, 2000 lb/day units I 1,000/1,000/1,000 lb/day running with a 1000 lb/day rotometer Chlorine Scrubber I 10,000 cfm -airflow 12% NaOH solution Chlorine Scrubber Currently under construction 1 5,000 cfm - airflow 20% NaOH solution Notes: ~ Total firm capacity is with largest unit out of service. b Total capacity is with all units in service. 3-42 MWMC_3.0_REV11.DOC