Lake Mary WTP - Executive Summary |
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EXECUTIVE SUMMARY CITY OF LAKE MARY WTP Introduction The intent of the Executive Summary of the U.S. Environmental Protection Agency (EPA) Risk Management Program (RMP) is to provide complete and accurate information concerning the City of Lake Mary Water Treatment Plant (WTP) to the community. This document will be available to the public and shall include information pertaining to the following: * Water Treatment Facilities * Hazard Assessment * Prevention Program * Emergency Response Action Plan Water Treatment Facilities The City of Lake Mary WTP utilizes chlorine gas to provide disinfection of the potable water being supplied to customers within the Lake Mary area. The chlorine gas is stored in one ton-cylinders of chlorine, which are fabricated to FDOT standards (106A500X). The average container has a capacity of one short ton (2000 pounds), an outer diameter of 30 inches and an overall length of 82 inches. The heads on each end of the cylinders are convex inward and for ge welded to the barrel of the cylinder. The sides are crimped inward at each end to provide a grip point for lifting beams. All one ton-cylinders are equipped with six fusible metal plugs, three on each end. The fusible plugs serve as overpressure relief devices. The fusible metal is designed to melt between 158 (F and 165 (F to relieve pressure and prevent rupture of the container in case of fire or overheating. The ton-container is designed around a maximum hydrostatic pressure of 500 psig. The cylinders are stored outdoors in a three-sided building that provides ventilation and keeps the cylinders above the natural grade of the site. Two chlorine ton-cylinders are stored on a ton-cylinder scale and are operational, in the chlorination process, via an automatic switchover system. The remaining back-up cylinder is supported and spaced using trunnions. This allows the cylinders to correctly position the outlet valves. Also, in case of a leak, the ton-cylinder can be rotated so tha t the chlorine escapes as a gas rather than a liquid. The Chlorination system at the Lake Mary WTP converts liquid chlorine to chlorine gas and injects the gas into a water solution that is used for disinfection purposes. Chlorine is fed from the ton-cylinders through a device called a "chlorinator". The chlorinator system includes a vacuum regulator check unit that mounts directly to the upper gas valve of the ton-cylinder by means of a lead gasketed positive yoke assembly, and an ejector. The feed system from the container to chlorination and the ejector is operated under a vacuum, so any small leaks pull in air instead of releasing chlorine. Five chlorinators are housed in the chlorination room. The chlorinators are 200 and 500 lb/day units that meter chlorine gas flow. The chlorinator is equipped with a small 25 watt heating element. Therefore, as chlorine is drawn into the chlorinator from the ton-cylinder, it is deflected down into a drip-leg where any liquid chlorine is vapo rized, permitting only gas to enter the regulating portion of the chlorinator. A vent/relief valve is provided with the chlorination unit to vent chlorine gas to the atmosphere at a remote location. Hazard Assessment The Hazard Assessment was performed in compliance with the requirements of the EPA standards. The Off-Site Consequence Analysis (OCA) of worst-case and alternate-case releases of chlorine were estimated, and a five year accident history was evaluated. The OCA assessment includes dispersion models, identification of the area that is above the toxic end point criteria, and the estimated affected population or environmental receptors. The Off-Site Consequence Analysis (OCA) was performed using the RMP*Comp( model. The RMP*Comp( model was supplied by the EPA, and it takes into account variances in wind speed, temperature, humidity, surface roughness (urban or rural setting), and release rate. Worst-Case Release Scenario Analysis of the worst-case release scenario of ch lorine was performed utilizing the parameters provided in 40 CFR 68.22. The worst-case release scenario selected for the Lake Mary WTP's off-site consequence analysis is the release of the contents of an entire one-ton chlorine cylinder from the chlorination process in a period of 10 minutes. This yields a release rate of 200 lbs/min. The radius of influence in this worst-case scenario was determined by the RMP*Comp( model to be 1.3 miles. In accordance with 40 CFR 68.22, the population within the area of influence was determined, and other public and environmental receptors were identified. The population was based on census track data obtained using the LANDVIEW III program, which is available on the Internet at www.rtk.net. The information regarding public receptors was gathered using a combination of street maps and USGS maps. The information gathered is presented in Table 1. Table 1. Worst-Case Area of Influence Receptors FACILITY POPULATION PUBLIC RECEPTORS ENVIRONMENTAL RECEP TORS Lake Mary WTP 4380 Residents Commercial Parks 3-Small Lakes Alternate-Case Release Scenario Analysis of the alternate-case release scenario of chlorine was performed in accordance with 40 CFR 68.22 as well, but the scenario is modeled in a more realistic setting. This model assumed a release rate of 10.5 lbs/min for a duration of 60 minutes. The distance to the chlorine toxic end point was determined by the RMP*Comp( model to be approximately 0.1 mile. Within this area of influence, there are 18 residents and no other receptors, according to the census track data in the LANDVIEW III program. Accident History The Lake Mary WTP has had no accidental releases of chlorine reported in the last five years. Prevention Program 3 The City of Lake Mary stresses the importance of safety to all their employees. Programs have been developed for standard operating procedures, process safety training, and process technology for employees at all levels. The programs are in accordance wit h both OSHA PSM and EPA RMP Prevention Program 3. The City Lake Mary developed and implemented a training program that is in compliance with 29 CFR 1910.119. Within the first week, all new employees, who work with or are exposed to chlorine are given orientation safety training. The Director of Public Works will review with each employee, upon initial assignment, parts of the Emergency Action Plan (EAP) that he or she must know to protect him/herself in an emergency. Contractors and visitors will be briefed on the EAP and actions they must take in an emergency as well. In addition to the EAP orientation, each employee is trained in the standard operating procedures for the smooth operation of the Facility. This program is developed to train the employee in basic operation procedures such as initial startup, normal operation, temporary operations, emergency shutdown, emergency operations, and normal shutdowns. It is also intended to prepare employees for minor troubleshooting. As a policy, employees are tested to ensure they have retained the training and process safety information. Refresher courses are periodically required to maintain the smooth operation at the City of Lake Mary Water Treatment Facilities. A copy of the Process Safety Management Program is located at each Treatment Facility for easy access and quick reference by all employees. Emergency Response Plan The City of Lake Mary is committed to the safety of their employees as well as the surrounding community. The City coordinates with the local emergency responders such as the Fire and Police Departments to implement an Emergency Response Program. The Program is set up in accordance with the provisions of 29 CFR 1910.38(a) and includes procedures for handling small releases. The Lake Mary WTP is included in the community emergency response plan. In the event of a major chlorine release, the facility operating procedure is to evacuate the site upwind of the release and call 911 to report the i ncident. The local Fire Department and Police Department will coordinate to contain the release and handle any first aid and evacuation/sheltering-in-place as necessary. In the event of a minor leak, the operators will wear a self-contained breathing apparatus (SCBA) and attempt to seal the leak. Standard procedure is for one operator to fix the leak while a second operator observes from a distance to provide back up. Both operators will be wearing SCBA's. If the leak cannot be sealed, the major chlorine release procedures will be followed. This information is included in the City of Lake Mary Standard Operating Procedures and is kept at the water treatment facility for quick reference. The City of Lake Mary strictly adheres to the OSHA and EPA standards, relating to the Emergency Planning and Response. Each water treatment facility employee will be trained in an overview of the emergency action and response plan to assure that he/she knows what action to take in an emergency and ca n perform the tasks safely and in accordance with the outlined plans. City of Lake Mary WTP Executive Summary 5 3 |