City of Mabank - Water Treatment Plant - Executive Summary |
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Mabank's water treatment plant lies inside the city limits of Gun Barrel City, Texas with boundaries delineated by a chain link fence. The facility has been in operation since the 1960's. The water treatment plant remains an essential facility for the City of Mabank, Texas. The plant treats and pumps approximately 2.6 million gallons per day of the city's potable water. This treatment plant is the primary source of drinking water for the City of Mabank's residents. Water treatment is the regulated process at this facility. Chlorine gas disinfects the water making it safe for public consumption. The use of chlorine gas for disinfection in water treatment results in a cost-effective method for meeting state and federal disinfecting rules and regulations. The plant safely stores 4800 pounds of chlorine on site. However, only one ton container is connected and in service at any one time. The chief operator drafted the written operating procedures in accordance wi th guidelines established by the TNRCC and the Chlorine Institute. In addition, all operators must have an operator's license from the Texas Natural Resource and Conservation Commission. The dangers of chlorine gas and how to safely handle it are heavily stressed to all employees. The size of the facility also aids in chemical safety. The storage and process areas are adjacent to each other. This allows for close monitoring of the chlorination system and a quick response in the event of a malfunction. The chief operator continually cross trains the men in all aspects of the chlorination system. Finally, the chief operator lives within ten minutes of the plant site and keeps a fully functional SCBA at the house. This prepares the chief operator to respond quickly to any chemical safety problems that may arise. The worst case release scenario models the complete release of a one ton container in ten minutes. An urban environment best describes the surrounding area. The EPA's RMP Comp Ver. 1.06 models the distance to toxic endpoint. The release has offsite impacts. They include schools, residences, public recreational areas, and commercial areas. However, such a release is unlikely due to several reasons. One is that the containers will in the future be protected from vehicle impact. Second, the chief operator has years of experience in the handling of chlorine. Third, the one ton containers all have relief valves that open when the temperature exceeds a set level. This prevents any chance of rupture of the containers. The alternative release scenario models a situation that is most likely to occur. The model represents a puncture in the lower portion of the tank while filled with liquid chlorine. The EPA's RMP Comp Ver. 1.06 models the distance to toxic endpoint. This particular scenario most closely corresponds to the actual chlorine container setup. The offsite impacts are schools, residences and public recreational areas. The Ci ty of Mabank's water treatment plant applies preventative maintenance and daily inspections to replace any deficient tubing, connections, or equipment parts. In addition, the tanks are located out of the path of vehicles and are not in danger of falling objects. The City of Mabank's water treatment plant complies with the rules and regulations of the EPA RMP. The most important preventative measure for avoiding accidental release involves the chlorine gas feed system. The chlorine gas feeds via a gas vacuum created by running water through an injector. The gas will cease to flow when any section of chlorine gas supply tubing breaks and vacuum is lost. This ensures that any failure in the process equipment cease gas flow which helps to eliminate chlorine releases. Since the vacuum regulator is mounted directly on the one ton container, the only potential for gas escaping results from a puncture in the container or a yoke valve failure. A building with proper ventilation enc loses the process area. All operators are trained in the written operating procedures. Preventative maintenance procedures meet or exceed manufacturer's recommendations. They aid in changing out wearable parts before they fail. For example, tubing is changed out annually or at any sign of deterioration. Gaskets are replaced after any type of servicing. Inspections of the storage area and process area help to ensure that all valves and components are quite capable of proper shut down to isolate and stop leaks. In addition the SCBA's are tested on a routine basis for proper functioning. The plant size itself allows for close monitoring and detection of any potential signs of chlorine gas. All maintenance and inspections and test are logged. Finally, this plant is competently staffed 24 hours a day and seven days a week. The Mabank's water treatment plant has not had any accidental releases within the last five years that resulted in personal injury or property damag e offsite or onsite. This facility coordinates emergency response with the local community emergency response. Any incidence of a chlorine chemical leak or spill subject to off-site contamination will result in a 911 call by plant personnel. The caller will state the nature of the emergency and whether or not to contact the police and volunteer fire department and implement the community emergency evacuation plan. The city of Mabank complies with EPCRA reporting requirements, thus all chemical quantities and storage locations are on file with the and Local Emergency Preparedness Committee (LEPC). The Henderson County LEPC's has CAMEO software, which helps to clearly define an evacuation area. The community emergency response personnel will implement evacuation procedures in accordance with the Emergency Management Plan. The Mabank water treatment plant is planning to improve safety by installing a barrier around the one ton containers to protect them from vehicle impa ct. In addition, the facility will receive an emergency repair kit for one ton cylinders. The chief operator plans on attending a HAZCOM / HAZMAT training class to aid in improved communicating and safe chemical handling with such materials as chlorine around the plant. |