Papillion Creek Wastewater Treatment Plant - Executive Summary |
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The City of Omaha Public Works Department operates the Papillion Creek Wastewater Treatment Plant for the treatment of domestic and industrial wastewaters in the Bellevue and Omaha, Nebraska areas. As part of the wastewater treatment process, one 112(r) regulated chemical is stored and/or used on-site: chlorine. Chemical hazards are taken seriously by city officials and plant operations staff. These hazards are communicated on a yearly basis to employees during training sessions. Chlorine is used in the disinfection process. It is located in a completely enclosed building. Chlorine is used as a disinfectant for wastewater effluent prior to discharge. Disinfection of the wastewater is required by the NPDES permit between April 15 and September 30 of each calendar year. It controls bacteria levels when wastewater effluent enters rivers during public recreation periods. Chlorine is brought into the facility in one-ton steel cylinders. The cylinders are connected to a manifold where chlorine gas is drawn off by a vacuum and feed to the chlorine contact basin to be mixed with wastewater. Since chlorine was used above it's regulated quantity, a worst-case release scenario was considered. The worst-case release analysis indicated that the process has off-site impacts. The worst-case release involved a one-ton cylinder, the largest single vessel, and a building enclosure that encompasses the disinfection process reducing the release rate by 55%. The worst-case analysis is unlikely since they assume a complete failure of the storage cylinder and the entire contents being released in a period of ten minutes. This would approximately correspond to a 3 inch hole, which is not probable. The alternative-case release was also analyzed. It was determined that this analysis also has off-site impacts. Due to the mechanical nature of chlorine cylinders, one of the more probable failure points is the gas valve. This analysis did not indicate any off-site impacts, t herefore the alternative-case was analyzed using the manifold as a failure point. As with the worst-case, the alternatve-case analysis was completed using a building enclosure that reduces the release rate by 55%. A Prevention Program was developed in accordance with 112(r) for the chlorine disinfection process. Prior to the 112(r) rule implementation, plant operators maintained operation and maintenance procedures, and conducted yearly training sessions discussing chemical hazards and proper process operations. This information was compiled into a formal document for plant operation use. Preventing accidental releases begins at how the process is operated and maintained. Following recommended operations and maintenance checks, most potential releases will be avoided. Operating procedures, training programs and maintenance will be reviewed on a regular basis in order to continually improve prevention practices. No accidental releases of chlorine that qualify in a five-year acc ident history have occurred. This again is proof that preventative measures, when used correctly, will prevent most releases. Plant operators will not respond directly to accidental releases, therefore, the Bellevue Volunteer Fire Department (BVFD) will respond. Chlorine releases will be handled by BVFD and their hazardous materials team. Chlorine detection systems are installed to sense the presence of chlorine gas. During chlorine alarm activation, the BVFD will be notified to allow them to mobilize on-site in the case of a major release. Coordination with the BVFD has taken place and will continue in the future for response expectation discussions, develop familiarity of the site and conduct response training drills. No significant changes to the chlorine process, or prevention practices are expected at this time. Both regulated chemicals are common in municipal wastewater treatment. Chlorine is used for disinfecting wastewater. If disinfection does not take place, a signifi cant rise in diseases, infections and illnesses would probably occur to those who use the Missouri River for recreational activities and as a source of drinking water downstream of the Papillion Creek treatment plant. |