City of Lawrenceburg Wastewater Plant - Executive Summary |
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LAWRENCEBURG WASTEWATER PLANT EXECUTIVE SUMMARY A. The Lawrenceburg Wastewater Treatment plant(LWW) 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 LWW emergency response policy involves the preparation of response plans which are tailored to the facility and to the emergency response services available in the community, and is in compliance with the compliance with the EPA Emergency Response Program requirements. B. The LWW treatment system has been installed to disinfect the flow into the Lawrenceburg Wastewater System Plant located at 108 Ezell Drive. The wastewater comes into LWW Plant, is treated and flows out into Shoal Creek. The treatment process includes the use of chlorine and sulfur dioxide. Both chlorine and sulfur dioxide are housed together in an enclosed building. The building contains two (2) ton cylinders of chlorine, and two(2) tone cylinders of sulfur dioxide. Various types of safety equipment, monitoring devices, and control devices are housed within the building, as well as access to safety equipment inside and outside the building. The facility is monitored 10 hours daily by on site personnel, and call alarm 24 hours, 7 days a week. C.1 The offsite consequence analysis includes consideration of two(2) chlorine scenarios indentified as "worst case release" and "alternative release". The first scenario as deined by EPA, which states the "owner or operator shall assume that the...maximum qualilty in the largest vessel...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 scenario." Atmospheric dispersion modeling has to be preformed to determine the distance traveled by the chlorine released before its concentration decreases to the "toxic endpoint" selected by EPA of 3ppm, which is the emergency Repsonse 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 healthe 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." The worst case scenario at the Lawrenceburg Wastewater Plant involves total loss of ton cylinder during delivery of chlorine, dropping a one ton cylinder onto concrete from 5 feet during unloading , shearing valve. The offsite worst consequence analysis for this scenario was performed by EPA's RMP Comp Program including worst case scenarios for chlorine. The conditions pre-defined by EPA, namely release of the entire amount as a gas in 10 minutes, use the one hour average as the toxic endpoint, and consideration of the population residing within a full circle radius corresponding ot the toxic endpoint distance. EPA mandated meteorological conditions, namely Stability F, wind speed of 1.5m/sec, and 77F. C1.1 When atmospheric dispersion modeling for the worst case scenario was performed on chlorine using the EPA assumptions, a distance to toxic endpoint of 0.9 miles (1.4km) and a estimate of residential population potentially affected of 500 was obtained. C1.2 The alternative release scenario involves a leaking valve on a one(1) ton chlorine cylinder. The alternative release scenario involves a leaking valve on a one (1) ton chlorine cylinder. The chlorine released is 1800 pounds, at an average rate of one hour, if 30 pounds/minute. Toxic endpoints were obtained using EPA RMP COMP Program> The EPA mandated meterorological conditions used were Stability Class D, wind speed 3 meters/second, average air temperature of 77 F. The estimated distances traveled to toxic endpoint 0.1 miles (0.2km). Activation of the one chlorine detectors is an active mitigation measure that should be considered. A fixed chlorine monitor is located in the chlorine cylinder storage room and the feeding room, connecting to the call alarm box. An additional active mitigation system installed is the conversion of the existing chlorinators to a remote vacuum type with all pressurized chlorine piping replaved with vacuum piping. This will almost eliminate a release of chlorine (5lbs) in case of pigtail rupture. The vacuum regulator on chlorine cylinders is designed by the manufacturer to automatically shut off flow of gas upon detection of a vacuum leak within the process feed system. D. The general LWW accid ental release prevention program is based on the following key elements: High level of training of the operators Preventative maintenance programs Use of state of the art process and safety equipment Use of accurate and effective operating procedures, written with the participation of the operators. Performance of a hazard review of equipment and procedures Implementation of an auditing and inspection program. Chemical specific prevention steps include availability of self-sontained breathing apparatus (SCBA), awareness of the hazardous and toxic properties of chlorine and sulfur dioxide, as well as proper training of on site personnel in case of release. E. No accidental releases of chlorine or sulfur dioxide have occurred at this facility in the past 5 years. F. The facility has an emergency response program coordinated with Lawrenceburg Fire Department, and Police Department depending upon the size of the leak, weather conditions , wind speeds and direction. If advanced level of technical assistance is deemed necessary to control leak, Chemtrec may be called to give advice and assistance via 24 hour emergency number. PB & S emergency repsonse drill for chlorine loss has been conducted on site, where current reponse and emergency operations were utilized. G. We have in place a chlorine and sulfur dioxide emergency action and process safety management plan dated January16,1997. No revisions have been found necessary at this time. Mock emergency drills proved the plan in place was efficient and thorough. |