Lebanon WaterTreatment Plant - Executive Summary |
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Process Description The Lebanon Water Treatment Plant provides safe drinking water to the City of Lebanon and surrounding communities. The water treatment process at the plant includes the use of chlorine as a disinfectant to destroy harmful organisms. In this process, gaseous chlorine from a 1-ton container is mixed with water to form a chlorine solution. This chlorine solution is then added to the water for disinfection. Chlorine is listed by the Environmental Protection Agency (EPA) as a regulated toxic substance. Facilities that handle amounts of chlorine over 2,500 pounds are required by the EPA to develop a Risk Management Program (RMP) to reduce the risk to employees and the public of injury from an accidental release of chlorine. The Lebanon Water Treatment Plant stores 8,000 pounds (four 1-ton containers) of chlorine and is therefore required to submit an RMP. Accidental Release Prevention and Emergency Response Policies It is the policy of the City of Lebanon that all ope rators at the water plant who are involved in the chlorine process have been thoroughly trained in the handling of chlorine and its potential health hazards, the operation of chlorine equipment and emergency awareness. Employees are required to obtained refresher training at least once a year. In addition, cooperation with local emergency responders is an important part of the plant's emergency response policy. Off-Site Consequence Analysis RMP regulations require the analysis of a worst-case release scenario and an alternative release scenario to determine the area that could potentially be affected by a chemical release. The EPA defines the worst-case release scenario as "the greatest amount held in a single vessel ... released as a gas over 10 minutes". This scenario is highly unlikely, but is used as the basis for the analysis of potential risk involved with the use of regulated chemicals and in the development of the risk management program. The alternative release scenario inv olves a release that is more likely to occur than the worst-case release scenario. A computer model provided by the EPA was used to estimate the distance the regulated chemical could travel and have an impact on the public and the environment. This model utilizes the parameters required by the regulations, such as specific atmospheric conditions. In addition, the model was run with scenarios using a "release in an enclosed space, in direct contact with outside air" since the chlorine is stored in a vented room. This parameter decreases the rate of release to 55% of the rate of a release happening outdoors. The worst-case scenario for chlorine analyzed the release of a 1-ton chlorine container over a duration of 10 minutes. The model calculated the distance that the chlorine could travel in a rural area and have significant impact to be 2.2 miles. This indicates that a worst-case release could potentially affect the residential population and the environment within a 2.2 mile radius of the water treatment plant. For the alternative release scenario, a review of the chlorination process determined that a leak was most likely to occur when connecting a full container. Specific operating procedures have been implemented and include opening the chlorine container valve slightly, re-closing it immediately and testing for chlorine leaks. Therefore, any leak will be detected and the problem corrected before placing the container in service. Using the model for this scenario, a consequence distance of 0.10 mile was determined. This is the minimum distance the model will provide. Accidental Release Prevention Program The Lebanon Water Treatment Plant has developed an accidental release prevention program which meets the requirements of the EPA Risk Management Program and OSHA Process Safety Management and includes the following elements: -Analysis of hazards involved with the chlorine process to prevent or minimize the effects of an accidental chemical release -Use of written operating procedures to ensure safe operation of the chlorine equipment and prevention of accidental chemical releases -Annual operator training in chemical hazards, operating procedures, emergency response to accidental chemical releases and use of self-contained breathing apparatus (SCBA) -Prestartup safety review and contractor safety program for any modifications made to the existing process -Preventive maintenance program to ensure the continued integrity of process equipment and prevent accidental chemical releases resulting from mechanical failure -Investigation of incidents that resulted in or could have resulted in a chemical release -Audit of prevention program every three years to verify compliance with the regulations -Use of control measures such as a leak detector to minimize the effects of an accidental chemical release Five-Year Accident History The Lebanon Water Treatment Plant has not had any accidental chlorine releases in the past five years. Emergency Re sponse Program The Lebanon Water Treatment Plant has emergency response procedures in place should an accidental release of chlorine occur and is included in the community emergency response plan developed by the Wilson County Emergency Management Agency (WEMA). Changes to Improve Safety The chlorine process evaluation determined that adequate safety mechanisms are currently in place to prevent an accidental chlorine release. However, the installation of automatic shut-off devices on the chlorine containers would provide an even greater degree of safety. It is anticipated that these devices will be installed by the end of this year. |