Choccolocco Creek Wastewater Treatment Plant - Executive Summary |
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Regulated substances handled at the Choccolocco Creek Wastewater Treatment Plant are liquid chlorine and liquid sulfur dioxide, which are used in effluent disinfection and dechlorination. There have been no accidents in the last five years which resulted in personal injury or property damage either on-site or off-site. Inventories are kept to the minimum amounts needed to provide a dependable supply for necessary plant functions. Plant operators have been trained with regards to the nature of the chemicals and in the proper handling of the chemical containers and use of connectors and feed equipment. Process equipment inspections are performed and operational procedures are reviewed for the purpose of prevention of accidental releases of chlorine and sulfur dioxide. Leak repair kits and self-contained breathing apparatus are kept onsite for rapid response to leaks if they occur. Leak detection equipment is in use in appropriate areas. Operations personnel have been trained in the use of the repair kits and breathing apparatus. Operators are instructed to call 911 to report any significant incident. The EMA Local Emergency Response Planning Committee has been notified in writing concerning the chemicals used at the plant. Chemical storage containers are stored inside buildings to assist in the protection of the containers and to limit the release rate of chemicals to the surroundings. In accordance with the Clean Air Act, a worse-case release scenario and alternative release scenarios have been developed for the regulated processes. Off-site consequence analyses were performed using EPA guidance document EPA-550-B-98-010. The worse-case scenario is by definition not a situation which is likely to occur but describes the total release of a full container of chlorine or sulfur dioxide while the container is outside the building and on a very hot day under stabile atmospheric conditions which would discourage dispersal. The worse-case scenario envisions a di stance to toxic endpoint of 1.3 miles from the plant. Alternative-case release scenarios are by definition situations which are more likely to occur that the worse-case. The alternative-release scenario chosen for this plant is a leaking valve on a container inside a building which discharges approximately two-thirds of a container of chlorine or sulfur dioxide on an average day with typical atmospheric conditions. The alternative release scenario envisions a distance to toxic endpoint of 0.2 miles from the plant. Improvements and additions are currently under design for this plant which would include a chlorine gas/ sulfur dioxide gas scrubber. This scrubber is expected to be constructed within the next two years and will effectively prevent the escape of toxic gas from the plant site. |