City of Gardner, Hillsdale Water Treatment Plant - Executive Summary

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Gardner, Kansas 
The water treatment plant provides potable water to the City of Gardner and part 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 risk to the surround 
ing community. 
The treatment plant uses chlorine supplied in 1-ton cylinders. A maximum of three 1-ton cylinders can be stored at the plant. All chlorine storage and feed equipment is located in an enclosed room 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 room remains closed at all times, except when deliveries are being made or plant personnel are required to complete work on the equipment. The storage facilities are equipped with a chlorine leak detector, which activates 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 type 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 mak 
es 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. This "worst-case" event requires the release of a full cylinder of chlorine in 10 minutes. Since the plant uses 1-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 v 
ery unlikely. Chlorine is delivered in heavy steel cylinders, which are conservatively designed and not prone to failure. 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 1 pound 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 a chlorine accident at the treatment plant, operators have been instructed to notify the South Johnson County Fire District. The City has met with the Fire District and co 
ordinated accident response procedures with the Miami 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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