City of Tonawanda Water Treatment Plant - Executive Summary |
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A. The City of Tonawanda Water Department accidental release prevention policy involves a unified approach that integrates technologies, procedures, and management practices. All applicable procedures of the U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to. The Water Department emergency response policy involves the preparation of a response plan which is tailored to the facility and to the emergency response services available in the community, and is in compliance with the EPA Emergency Response Program requirements. B. The City of Tonawanda Water Treatment Plant was built to provide potable drinking water to the City of Tonawanda, which has a current population of 17,284. The chlorination station is located at the Filtration Plant at 111 Niagara Shore Drive. The Station includes a chlorination room, which contains liquid chlorine containers, two (2) chlorinators and various safety equipment; and an injector room where the gaseous chlorine is inject ed into water and piped to various stages of the water treatment process by schedule 80 CPVC piping. The amount of chlorine handled is three one-ton containers of liquid chlorine. Two containers are on a scale, with a chlorinator attached to each. The third container is on the floor for a stand-by. Teflon tubing connects the chlorinators to a switchover device. Chlorine is drawn off only one cylinder at a time. When that cylinder becomes empty, the switchover device closes the tube and opens the other, so that the second cylinder is drawn off of. Teflon tubing connects the switchover device to the two roto meters in the injector room and the roto meters to the two chlorine ejectors. C. The offsite consequence analysis includes consideration of two chlorine release scenarios, identified as "worst case release" and "alternative scenario." The first scenario is defined by EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest ve ssel ... is released as a gas over 10 minutes," due to an unspecified failure. The alternative scenario is defined as "more likely to occur than the worst case release scenario." Atmospheric dispersion modeling has to be performed to determine the distance traveled by the chlorine released before its concentration decreases to the "toxic endpoint" selected by EPA of 3 ppm, which is the Emergency Response Planning Guideline Level 2 (ERPG-2). This is defined by the American Industrial Hygiene Association (AIHA) as the "maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action." The residential population within a circle with a radius corresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected." D. The general City of Tonawanda Water Department accidental release prevention program is based on the following key elements: 1. High level of training of the operators. 2. Preventive maintenance program. 3. Use of state-of-the-art process and safety equipment. 4. Use of accurate and effective operating procedures, written with the participation of the operators. 5. Performance of a hazard review of equipment and procedures. 6. Implementation of an auditing and inspection program. Chemical-specific prevention steps include awareness of the hazardous and toxic properties of chlorine, and presence of chlorine detectors. E. No accidental releases of chlorine have occurred at this facility in the past five years. F. The facility has an emergency response program, which has been coordinated (reviewed) by the City of Tonawanda Fire Department, which is a member of the Local Emergency Response Planning Committee (LEPC). This program includes an emergency response decision t ree and a notification plan. Emergency response drills and drill evaluations are conducted every six months; emergency operation and response procedures are also reviewed at that time. |