Plattsburg Water Treatment Plant - Executive Summary

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Plattsburg, Missouri 
The water treatment plant provides potable water to the City of Plattsburg and a significant portion of the surrounding area. The treatment plant uses chlorine to disinfect the water to meet federal and state requirements for microbial protection. Previously, the City has used an informal safety program to minimize risk associated with the chlorine disinfection system. The City now has in place a formal Risk Management Program (RMP) for the chlorine system. This program was developed to comply with new federal requirements. The RMP includes provisions for training, safe-operating procedures, periodic maintenance, hazard assessments, compliance audits, incident investigations and emergency response plans. Responsibility for implementation of the plan is also included in the RMP. The RMP was developed to provide a safe working environment for treatment plant personnel and minimize r 
isk to the surrounding community. 
The treatment plant uses chlorine supplied in one ton cylinders. A maximum of 2 one ton cylinders can be stored at the plant. Chlorine supplied in 150 lbs. cylinders are also stored at the treatment plant for use at the City's wastewater treatment plant.  A maximum of 6 of the 150 lbs. cylinders can be stored at the plant. All chlorine storage and feed equipment is located in enclosed rooms at the main plant building. The main plant building is constructed of masonry and concrete and is thus fire resistant and capable of resisting high wind forces. The chlorine rooms remain closed at all times except when deliveries are being made or plant personnel are required to complete work in them. The storage facilities are equipped with chlorine leak detectors, which activate an audible alarm in the event of a chlorine leak. The chlorine feed equipment is a vacuum type system. A vacuum type system requires a vacuum to draw chlorine from the cylinders. This typ 
e of feed system greatly reduces the potential for chlorine leaks. 
Chlorine is a toxic gas that at high enough concentrations can be a serious health hazard. The City is very conscious of this and makes safety a priority for operation of the chlorine system. All plant personnel receive basic safety training and operators of the system receive further instruction in the safe operation of the chlorine system. By following industry recognized safety procedures and facility design, risk to the community from a chlorine release is minimized. The plant has not had a significant accidental chlorine release of any kind for over 5 years. 
As part of the federal requirements for submitting a risk management plan, the City was required to model a "worst-case scenario" chlorine release from the plant. As required this "worst-case" event requires the release of a full cylinder of chlorine in 10 minutes. Since the plant uses one ton cylinders, the total release of chlorine is 2000 lbs. at a rate of 
200 lbs. per minute. Using a model developed by EPA, the toxic endpoint of a release of this type was calculated at 2.2 miles. This is a substantial distance from the plant, however a release of this magnitude is very unlikely. Chlorine is delivered in heavy steel cylinders, which are conservatively designed and not prone to failure. To cause a release of this magnitude would require an event that causes a puncture of the cylinder or a fire, which results in over-pressuring the cylinder. Neither of these events is very likely considering the design of the facilities. 
An alternate release scenario was also modeled to determine the effect of a more realistic and typical chlorine release event. A leak at the connection of the chlorine cylinder and the feed equipment was modeled at a release rate of 1lb. per minute for a period of 60 minutes. For this condition the EPA model calculated a toxic endpoint of 0.1 miles. As can be seen releases of this magnitude do not pose a significant risk 
to the surrounding community. 
In the event of chlorine accident at the treatment plant, operators have been instructed to notify the Plattsburg Fire Department. The City has met with the Fire Department and coordinated accident response procedures with the city and county emergency management office. Members of the Fire Department have toured the plant and are familiar with the facilities. Periodic review and updating of response procedures are undertaken to assure effective responses in the event of an accident.
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