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MWMC FACILITIES PLAN 2.2.4 Public Health Hazards Four types of potential public health hazards were evaluated for the WPCF: · Air pollution resulting from chlorine or sulfur dioxide releases at the facility · Air pollution from other facility sources (e.g., wind-blown dust or combustion engine exhaust) · Worker or public exposure to chlorine or sulfur dioxide, or physical collapse of onsite buildings due to seismic instability · Potential biohazard from spill of biosolids during offsite transport The first potential public health hazard (chlorine or sulfur dioxide release) is addressed under EPA's Risk Management Program (RMP) Rule. This rule, developed in 1996 following guidance under the Clean Air Act Amendments of 1990, requires companies using more than threshold quantities of certain flammable and toxic substances to develop a Risk Management Plan (RMP). Risk Management Plans include the following features (EPA, 2002): · Hazard assessment detailing potential effects of an accidental release, an accident history over the last 5 years, and an evaluation of worst-case and alternative accidental releases · Prevention program describing safety precautions and maintenance, monitoring, and employee training measures · Emergency response program detailing emergency health care, employee training measures, and procedures for informing the public and response agencies if an accident Occurs Chlorine and Sulfur Dioxide Usage at Existing Facilities Currently, the WPCF uses chlorine gas for disinfection of effluent prior to wastewater discharge into the Willamette River. Chlorine has been an effective disinfectant at the WPCF. No chemical release accidents resulting in injury to facility workers or the public have occurred in facility history. Disinfected wastewater has met permit requirements consistently since plant startup in 1984. Sulfur dioxide gas is used to dechlorinate WPCF effluent prior to discharge into the Willamette River. Sulfur dioxide is transported to the WPCF in pressurized 1-ton containers. It is metered hy one to two sulfonators to the effluent channel just upstream of the outfall pipe. The sulfur dioxide system has proven effective in controlling chlorine residual to meet effluent requirements. A 2-ton capacity emergency scrubber is located in the chemical building. The neutralizing chemical in the scrubber used during a chlorine or sulfur dioxide leak is sodium hydroxide. The scrubber has been operational since plant startup. 2-12 MWMC_2.0_REV23.DOC