Northwest Water Reclamation Plant - Executive Summary |
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Executive Summary The Northwest Water Reclamation Plant (NWWRP) is one of the facilities owned and operated by the City of Mesa. The NWWRP has prepared a Risk Management Plan (RMP) in accordance with the EPA and OSHA regulatory requirements. A brief overview of the RMP and the associated policies at the facility is described below. Prevention and Response Policies The City takes an active role in preventing accidental releases by ensuring that its employees are properly trained in the safe operation of covered processes and the safe handling of treatment chemicals. The City has also established and maintains procedures for emergency notification and response. These are reviewed with employees on a periodic basis and revised to accommodate changes in staffing when they occur. To increase employee safety and awareness, the City: * maintains up-to-date safety information and operating procedures, * performs regular preventative maintenance, * provides per iodic refresher training on safe handling of chemicals, and * conducts periodic safety drills. Facility Description and Regulated Substances NWWRP treats wastewater from residential, commercial, and industrial sources to reuse standards through a series of physical, chemical, and biological treatment operations that include: * preliminary treatment, * primary sedimentation, * activated sludge for carbonaceous BOD removal, * nitrification and denitrification, * secondary sedimentation, * dual media filtration, * chlorination, and dechlorination. The regulated substance handled at NWWRP is chlorine. The chemical is stored in 1-ton (2,000 lbs) containers, with a maximum of 6 containers on site. Release Scenarios Worst-case and alternative release scenarios have been determined after careful review of the regulation and consideration of the storage vessel configuration at the faci lity. The EPA's software program RMP*Comp was used to model both release scenarios and determine the radius of impact. In the worst-case release scenario, the regulation clearly states the release quantity shall be the contents of the single largest vessel of the covered process chemical, at ground level and under very stable atmospheric conditions. These conditions are most likely to result in a cloud of the released chemical remaining intact as it slowly moves along the ground. As required by regulation, the worst-case scenario assumed a complete release of chlorine from a single container (2,000 lbs). In addition, no mitigation effects, such as a release inside the chlorine storage building, were considered. Planning for an accidental release under these unlikely conditions provides the City with additional safety margin in protecting the public. For the alternative release scenario, the assumptions were that (a) a failure occurred in the ton container safety devic e (fusible plug), and (b) 600 lbs of chlorine were released over a 60-minute period before the leak could be repaired. No mitigation effects, such as a release inside the chlorine storage building, were considered. Prevention Steps for Chlorine The prevention program fulfills the requirements of the OSHA Process Safety Management (PSM) rule and the EPA RMP rule, and includes: * formal and on-the-job training, * written operating procedures, and * a process equipment preventive maintenance program. Accident History There has been no release of the covered chemical in the past five years. Emergency Response Program The NWWRP has established and maintains an emergency response program that is coordinated with local response agencies. The goals of the program are to protect on-site employees from the hazardous effects of a release and to minimize the effects of releases on the general public. The program is routinely reviewed and updated to reflect personnel and regulatory changes. Planned Changes for Improved Safety Ideas for changes to improve safety are actively sought from employees. Employee meetings that focus on safety issues are held regularly at the facility. Employees are encouraged and trained to recognize hazards and present ideas to eliminate them or to minimize the potential consequences of those hazards. During the development of this RMP document, a process hazard analysis of the chlorine system was conducted with key employees to fulfill the prevention program requirements. During these sessions, recommendations were made for the purpose of improving safety and preventing accidental chemical releases. Each recommendation will be or has been considered for implementation. In addition, the exercise provided all affected employees with a heightened awareness of safety issues related to the covered process. |