Fairfield Water Treatment Plant - Executive Summary |
|
Chlorine is utilized at the Fairfield Water Treatment Plant (WTP) to purify water for drinking. Chlorine equipment and related procedures are designed to maintain the safe handling and use of chlorine. In the Fairfield WTP five-year accident history, no off-site accidental releases of chlorine have occurred. Chlorine is stored in quantities up to 8,300 pounds in a Program 3 process. Chlorine is only fed into the process as a gas. The Fairfield WTP operates with two chlorine ton containers connected to the chlorine manifold. Also, located in close proximity are two additional ton containers and two chlorine 150 pound cylinders. The chlorine process, as defined under RMP requirements, includes both vessels that are interconnected and co-located. The worst-case release scenario assumes that 2000 pounds of chlorine are released from a ton container as a gas in a ten minute period. However, the release rate of chlorine from the chlorine room is estimated to be 55% of the release ra te from the container due to the passive mitigation of the chlorine room. This release is estimated to travel 2.2 miles before no longer posing a hazard to the public. The alternative scenario assumes the release of chlorine from a ton container due to a valve failure, bad flexible tubing connection, or flexible tubing failure. Any of these events could release chlorine gas through the 5/16 inch diameter valve body opening. Over a 60 minute period, 318 pounds of chlorine are estimated to be released. This release is predicted to travel 0.38 miles before no longer posing a hazard to the public. The Fairfield WTP uses a variety of equipment and procedures to prevent accidental releases. Among this equipment are monitors to detect releases, vacuum regulators on the chlorine flow from the chlorine containers, the chlorine room with its fire prevention design, and chlorine containers in conformance with ASME code. Procedures include the safe storage of chlorine containers, periodic inspections and testing of the chlorine process equipment, maintenance that requires regular part replacement, operator training, the evaluation of contractor safety programs, the review of proposed chlorine process changes to preserve the safe operation of the chlorine process, the periodic review of process hazards, and steps to investigate releases that do occur in order to prevent reoccurrence. These procedures and more have been developed through the OSHA PSM and RMP Program 3 requirements. One change currently under evaluation for improved safety include the wiring of the local chlorine gas detector alarm back to the main plant control panel to alert more employees of a detected chlorine release. In the event of an accidental release, the Fairfield WTP has coordinated and pre-planned response activities with offsite responders. Fairfield WTP employees will evacuate the site and notify these responders according to the Fairfield WTP emergency action plan. |