Okmulgee Water Treatment Plant - Executive Summary
The Okmulgee Water Treatment Plant is a conventional treatment facility. The Surface Water Treatment Rule (SWTR) as promulgated by the Environmental Protection Agency (EPA) requires that disinfection be included as part of the treatment of surface water for potable use. Chlorine has been used extensively since 1908 as the preferred method of disinfecting water supplies for potable use and is used for disinfection at the treatment plant, however, it is a small part of the physical plant. The chlorine is applied as a chlorine gas and is stored in one (1) ton containers. Four cylinders are attached to the gas chlorinators. There are spaces for two additional cylinders. These are usually empty cylinders, however, full cylinders could be stored in these spaces, therefore, the maximum chlorine gas in the chlorinator and chlorine solution is piped to the point of application. At the Okmulgee Water Treatment Plant there are four (4) points of application. Thses include prechlorina |
tion - raw water, post chlorination - filters 1 & 2, post chlorination - filters 3 & 4, and post chlorination - clearwell. The worst case release scenario considered is a dropped cylinder during delivery by the supplier. The chlorine cylinder could rupture and release the contents of the cylinder. This would occur outside the chlorine building and 2,000 lbs of chlorine could be released. EPA's RMP Guidance for Waste Water Treatment Plants Reference Tables were used for modeling. Based upon these tables, the distance to the toxic endpoint for urban conditions would be 1.3 miles. The off-site impact would include approximately 600 residential population, public receptors such as fishing in the nearby Deep Fork River, and a State Game Management Area is within the 1.3 mile radius.
The alternative scenario selected for the Okmulgee Water Treatment Plant is a "rust hole" in the chlorine cylinder. This would involve the release of liquid chlorine from a 1/4" hole. The liquid cylinder would flash immediately to vapor and fine liquid droplets, and carried downwind. EPA's RMP Guidance for Waste Water Treatment Plants was used to determine the release rates and distance to the endpoint for urban topography would be 0.2 mile. There are no residential populations within the 0.2 mile endpoint, however, fishing in the Deep Fork River does occur within the 0.2 mile radius. The only release of chlorine that has occurred during the past five years resulted in injury to one city employee. The a
ccident occurred on May 24, 1995 at 9:45 a.m. At 8:15 a.m. plant personnel changed out one empty chlorine cylinder and checked for leaks on both cylinders and both manifold connections. When no leaks were detected the plant operators returned to their duties. At 9:45 a.m. the City Electrician reported a chlorine leak and plant operators put on gas masks and repaired the leak. The cause of the leak was a used washer being left at the manifold connection. There were no off-site impacts. The overall approach to chemical safety at the Okmulgee Water Treatment Plant is to be well informed in regards to proper employee training, proper safety instructions, supervisors to train employees how to use personal protective and other safety equipment provided. Training classes for all employees are conducted periodically to mainta
in a high degree of competence in handling procedures. Employees are thoroughly informed of the hazards that may result from improper handling of chlorine. They are trained to prevent leaks and instructed regarding proper action to take in case leaks occur. Plant operators are to be instructed in what to do in an emergency and informed as to first aid measures. Only designated persons who have been trained an tested will use the specialized equipment for containing chlorine leaks. Even though the Okmulgee Water Treatment Plant is not subject to the OSHA PSM rule, this rule has been used to establish and put into practice an accidental release prevention program and a chemical - specific (chlorine) prevention steps. In addition, the City has contracted with a chlorine equipment supplier to provide an inspection of the
chlorine system quarterly. Training on the use of this equipment is also provided during these quarterly inspections. The Director of Plant Operations is the person responsible for overall emergency response coordination within the plant. The Director's responsibilities include the following: (1) Determine the need for a rescue team, (2) Determine the need for an emergency repair team, and (3) Determine if emergency extends outside the plant and if so, notify the City Manager and transfer the command of the overall emergency response plan to the City Manager. The Fire Department is a major factor of the rescue team and has been trained with water plant personnel. A new
chlorine feed system and building was put into operation a few years ago. This has greatly improved the chlorine safety at the Water Treatment Plant.