Wright Patman Water Plant - Executive Summary |
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The Wright Patman Water Treatment Plant is a conventional coagulation, sedimentation, filtration, disinfection water treatment plant using chlorine as the primary disinfection chemical. The plant is a municipal facility, owned and operated by the City of Texarkana, Texas, located in the City of Texarkana, Bowie County, Texas with an approximate capacity of eighteen (18) million gallons per day. The facility's only activity is to treat surface water to drinking water standards for customers in the Texarkana area. Liquid chlorine is the only chemical used in sufficient quantity at the facility to be regulated under the RMP program. Up to fourteen (14) one ton cylindeers are stored on site at any one time with no more than two cylinders, piped independently, used in the process. Texarkana Water Utilities is dedicated to the safe and proper handling of chemicals necessary for the production of drinking water and treatment of wastewater for its citizens. Utility management has consistentl y budgetd and the elected bodies of the two Texarkana's have consistently approved funds to support personnel and citizen safety preventative maintenance training, chemical awareness and handling, emergency response and equipment related to chemicals used at the facility. The worst case scenario considers the release of 2000 lbs of chlorine from a one ton cylinder in ten (10) minutes. The dispersion model ALOHA (Area Locations of Hazardous Atmospheres), which is recognized by EPA's RMP Offsite Consequence Analysis (OCA) Guidance, was used to determine the distance to the toxic endpoint for chlorine. Using digital census block files in conjunction with digital area maps, offsite impacts on population, public receptors and environmental receptors were analyzed. The estimated residential population within the distance to endpoint is 29,000 and at least one of each of the six major public receptors is found within the distance to endpoint. None of the listed environmental receptors are kn own to be found within the distance to endpoint. Several training and procedural methods make a worst case release unlikely. The site is staffed twenty-four (24) hours a day with periodic inspections of the chlorination facilities made on each of the three daily shifts. Highly trained personnel and an extensive preventative maintenance program keep all chlorination equipment in like new condition. The chlorination room is monitored by a remote chlorine gas detector and alarm set at 1 ppm. Safety procedures, including those associated with chlorine are standardized through written Standard Operating Procedures (SOP's). Chlorine cylinder repair kits are kept at several locations in the system. The American Water Works Association publication Compliance Guidance and Model Risk Management Program for Water Treatment Plants, was used in the selection of an alternative release scenario. Scenario I.D. CLA-3 was chosen, as most closely approximating a possible release at this facility. Site specific data was substituted in the ALOHA model and analyzed. The alternative release scenario considers the release of 317 lbs., over a sixty (60) minute period due to the failure of a transfer hose. The same methods were used in the analysis of the alternative scenario as were used for the worst case. The estimated residential population within the distance to the endpoint is 692. There are schools, residences, recreational areas and major commercial areas located within the distance to endpoint. None of the listed environmental receptors are located within the distance to endpoint. For the same reasons listed for the worst case scenario, even this type of release is highly unlikely. The accidental release prevention program is predicated on well informed, well trained employees. The facility makes use of written, video and classroom training from the Texas Natural Resource Conservation Commission, Arkansas Department of Health, Chlorine Institute, The American Water Works Associat ion and the Water Environment Association. Facility management has developed written standard operational procedures for all chemical equipment and chemical handling. These SOP's set up and require extensive preventative maintenance programs that provide frequent checks and keep equipment in like new condition. Gas detection and alarm devices are used to provide early alert to any chlorine releases. There have been no reportable chlorine releases or accidents for a period exceeding five (5) years largely due to the previously described steps taken by Texarkana Water Utilities Management. The Utility is included in the written community emergency response plan and maintains a close working relationship with the local Emergency Management Office. The facility has its own written emergency response plan and participate in site-specific, multi-agency response drills. Boots and Coots, a company which maintains a Hazardous Waste Operations and Emergency Response (HAZWOPER) team, is availab le to back up and respond to any chemical release. The Utility is currently considering the possibility of the installation of a chlorine gas absorption unit to mitigate any release up to a one ton cylinder. The Utility has a geographic information system base map that is being developed to assist utility, fire, police and emergency management personnel in prevention and response planning for any chemical release. |