Columbus Water Treatment Plant Number 1 - Executive Summary |
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Accidental Release and Emergency Response Policy The City of Columbus's Process Safety Management Plan (PSM) was prepared for the use of chlorine handling at the Columbus Water Treatment Plant Number 1 (WTP No. 1). Chlorine has never before been stored onsite at or above the threshold quantity of 2,500 pounds. However, the plant operations will be storing chlorine at volumes in excess of the threshold quantities in the near future for better economy and efficiency in water treatment processes. The PSM plan is designed and enforced to ensure the safety of city employees who work with chemicals in the event of an accidental release. The Risk Management (RMP) builds on the PSM and is designed to minimize hazards to the community and the environment in the event an accidental from releases of hazardous chemicals. The individual facility managers are responsible for the maintenance and enforcement of the RMP. Columbus Water Treatment Plant Number 1 and Regulated Substances Handling The Columbus WTP No. 1 treats drinking water for the City of Columbus, Indiana. The processes at the plant include mixing, filtration, sedimentation, digestion and chlorination disinfection. Drinking water disinfection is provided by chlorination. The only regulated substance used at the WTP No. 1 covered by this RMP is chlorine gas. Historically, this hazardous substance has always been stored on site at the Columbus WTP No. 1 in quantities less than the threshold quantity. Since the WTP No. 1 facility in the near future plans to take advantage of the economy and efficiencies presented by increased quantities onsite of this substance above the threshold quantiities of 2,500 pounds for chlorine gas, this RMP is now submitted under Predictive Filing. The facility will be purchasing cylinders of chlorine that are filled with 2,000 pounds of these pressurized gases. A total of 10,000 pounds or more of this substance could be stored onsite at any one time in the future. Worst Case Release Scenario and Alternative Release Scenario for Chlorine Gas The worst case scenario for chlorine involves the release of 2,000 pounds of this substance from a cylinder that has been damaged while transferring from the delivery truck to the loading dock in the storage building. It is assumed that all 2,000 pounds are the substances are released in 10 minutes at a rate of 200 pounds per minute with no mitigation. Assuming a wind speed of 1.5 meters per second and an atmospheric class F, the end point for Chlorine is 1.3 miles from the WTP No 1. facility. The potential population affected within this urban area is approximately 17,200. The alternative scenario involves the same factors except that chlorine is released from a valve failure inside of the processing room at the storage building. The building is enclosed except for small exhaust vents at the floor level. The building provides a mitigation factor of 55% and the release rate is 110 pounds per minute. The end p oint distance from the facility is 0.2 miles. The potential population affected within this urban area is approximately 200. Accidental Release Prevention Program and Chemical Specific Prevention Steps The Columbus WTP No. 1 is covered by the Emergency Planning and Community Right-to-Know (EPCRA) program and the OSHA Process Management Plan requirements. The identified hazards from controlled chemicals at the facility are represented by potential releases of chlorine gas from storage cylinders during unloading, overpressurization of process equipment, and failure of piping, valves, and other process equipment. The facility has the following process controls in use: relief valves, manual shutoff valves, alarms, procedures and rupture disks. When the outer doors are closed, the chlorine storage building provides some passive mitigation. Pursuant to U.S. EPA RMP guidance, this is assumed to reduce the rate of chlorine gas to the environment by 55%. Chlorine leaks can be detect ed through the use of chlorine detectors in the storage building. Five-Year Accident History The Columbus WTP No. 1 has no record of any accidental releases of hazardous chemicals during the past 5 years. Emergency Response Program The Columbus WTP No. 1 has developed an Emergency Action Plan (EAP) to cover procedures in the event of a release of hazardous chemicals from its facility. The EAP is included in the Bartholemew County Local Emergency Planning Commission emergency response and contingency plan. The WTP No. 1 employees are trained on-the-job by senior staff at hiring with periodic updated training on a regular basis. Employees receive training on responding to emergency releases of hazardous chemicals . Planned Changes to Safety The Columbus WTP No. 1 maintenance and operational staff will be trained by senior staff members in the contents of the Risk Management Plan. There are no organizational changes planned at this time. The increased storage of chlorine at t he facility will not affect any signicant changes in the established safety and training program. |