Arab Water Treatment Plant - Executive Summary
Arab Water Treatment Plant |
EPA ID: AL0001600766
The Arab Water Works facility (Arab Filter Plant (AFP)) treats an average of 3.5 million gallons per day of water from nearby Guntersville Lake, located approximately 3 miles west of the city of Guntersville, Alabama. The AFP consists of several water purification treatment processes, including Chlorination, Filtration, Flocculation and Sedimentation.
Chlorine gas has been in use for nearly a century as the choice disinfectant in the treatment of both sewage for discharge and surface and ground water for drinking. Currently the AFP maintains a maximum inventory or 8,000 pounds of Chlorine gas. Under EPA's Risk Management Program, Clean Air Act 112(r), any industry utilizing a regulated gas above the its threshold level, here 2,500 pounds for Chlorine, must develop a Risk Management Plan and implement a Risk Management Program.
The AFP, in implementing their Risk Management Program (RMP), is currently undergoing
changes in both process design and operations, as well as improving on their emergency response preparedness plans. In the spirit and law of the RMP, the AFP recognizes and is pursuing optimal public involvement in response to regulated substance emergencies. The AFP acknowledges that as a result of being in compliance with the RMP Rule, the safety of the surrounding community as well as that of on-site workers will be significantly enhanced. From improved record-keeping, training, operating procedures to better engineering design, the AFP is dedicated to minimizing the risk of using Chlorine gas while at the same time improving the quality of local services.
Chlorine gas is required at the AFP for disinfecting surface water pumped in from nearby Lake Guntersville, as well to add a "polish of residual Chlorine" to finished drinking water leaving the facility. The AFP recognizes that Chlorine gas, if accidentally released into the environment, may cause severe injury and ev
en death for a significant distance from the source. The AFP has recently adopted new policies under its RMP to prevent and prepare for the uncontrolled release of a regulated (toxic) gas from the AFP.
The AFP is currently owned by Arab Water Works Inc., Guntersville, AL. The Arab Water Works General Operations Manager is Mr. David Campbell ((256) 586-3159). Primary responsibility for the implementation of the RMP is under the direction of the Chief Operator of the AFP, Mr. Mike C. Kirkland. Mr. Kirkland's primary responsibility under the RMP will be to oversee the training and execution of the facility's health, safety and environmental programs. Additional individuals may be assigned responsibility for implementing individual requirements and will report to Mr. Kirkland on delegated matters. Responsible individuals will communicate information to other employees involved in operation and maintenance of the regulated process involving Chlorine gas, as required. All resp
onsible individuals so involved will be listed by name, title and duties, in the RMP located on site at this facility.
Any material changes in the design or maintenance [except for "replacements in kind"] of the current regulated process will be introduced into the RMP by those delegated that authority under the guidelines of the RMP. The public may contact the AFP by calling (256) 582-3633 or the Arab Water Works office at (256) 586-3159 for information regarding more details about the Risk Management Plan.
The AFP currently maintains up-to-date safety information related to the regulated substance, process, and equipment, including Material Safety Data Sheets for Chlorine, maximum intended inventories, and safe upper and lower temperatures, pressures and process flows for the regulated substance. Equipment specifications and process design Codes and Standards are also maintained in the RMP document on site.
In the case of an uncontrolled release of Chlorine gas fr
om the AFP, an integrated Emergency Response Plan has been adopted involving the coordinated effort of several organizations, including the local Fire Department, Emergency Management Agency, local Police, Sheriff's office and local Medical Emergency services and Hospitals. The AFP is prepared to assess and repair incidental or controlled leaks of the regulated materials but is currently not authorized to respond to uncontrolled releases of Chlorine from their facility. Instead, the AFP has coordinated first response assistance from federally regulated Hazardous Materials (HazMat) specialists. Currently the Arab, Guntersville and Albertville Fire Departments have joined together for first response action should an uncontrolled release of Chlorine gas occur on the AFP site. In coordination with local and nearby Police and Sheriffs, residents will be evacuated systematically, and as soon as decisions are made by the Emergency Coordinator (Fire Department) and others in the Emergency
EPA requires each regulated facility to analyze a Worst-Case Scenario release (the release of the entire contents of a regulated substance container) as well as an Alternative-Case Scenario in which the released regulated gas is brought under control at some point following uncontrolled release events.
In the Worst-Case Scenario, detailed within the facility's RMP, a scenario is considered in which the uncontrolled release of the entire contents of a ton container of Chlorine gas occurs. There are no mitigation features included in this Worst-Case analysis, such as enclosed buildings or other structures, for the uncontrolled release of the regulated substance. The endpoint radius for such a release, in which injury to those exposed is potentially possible, was calculated using parameters which are facility specific as well as criteria provided by EPA. The endpoint radius was calculated to be 3.0 miles for the loss of a one ton containers of Chlorine
gas. Close to the source of such a release the potential for serious injury is high.
The safety mechanisms in place at the AFP designed to prevent this scenario from occurring include vacuum regulator valves on the ton containers themselves. These valves release Chlorine gas only when a vacuum is applied, hence, if a line should break in the Chlorine process manifold system the valves on the source will automatically shut off when the vacuum is lost.
Although the potential for an entire ton container of the gas to escape the Plant's boundaries is unlikely, it can happen. The EPA requires all responders to such a release to coordinate with the local Emergency Management Agency, the Fire Department, HazMat specialists and other local authorities such as the Police Department and Sheriff's office, in order to effectuate the best plan for evacuation efforts, if needed, and other requirements to assure the greatest protection for those who may be exposed to the gas. As descr
ibed below, recommendations have been submitted regarding improved maintenance and safety, the introduction of a community siren system, as well as improving on initial response activities coordinated through the efforts of the participating agencies and rescue organizations. In the analysis of the Worst-Case scenario release the AFP did not include mitigation features such as enclosed buildings or other physical parameters which might otherwise reduce the endpoint radius calculated.
As part of the Worst-Case scenario Emergency Response Action the cooperating agencies considered, and is currently implementing, procedures for responding to sensitive receptors within the endpoint distance of the regulated gas. For example, local Schools, Hospitals and other sensitive receptor sites are currently being integrated into the community's Emergency Response Plan through the efforts of the Fire Department, LEPC, Police Department and others. Cooperative interaction between the various
rescue organizations is enhanced under the RMP Program. An evaluation of the potential impact of released gas on the surrounding environment is also included in the RMP. USGS maps showing the effected areas within the endpoint distance are filed within the facility's RMP. The estimated population within the 3.0 mile endpoint radius is 2,400 persons.
In the Alternative Release Scenario the AFP adopted conditions of uncontrolled release in which the failure of a check valve results in the release of the regulated gas for a period of approximately 30 minutes. At this time the gas is assumed to be arrested and brought under control by emergency response personnel. The endpoint radius for Chlorine was calculated to be 1.2 miles (AFP choose a scenario provided by the AWWA's Compliance Guidance and Model Risk Management Program for Water Treatment Plants). Mitigation features which impede the dispersal of the released gases, such as an enclosed building, were integrated into the Alt
ernative Release Scenario calculations. The population of Guntersville affected within the 1.2 radius is estimated at 420 persons.
Currently the regulated gas, Chlorine, is connected to the Chlorine process within the "Chlorine Room", a fire proof enclosed room located approximately 50 feet from the Main Office at the AFP. The AFP maintains a modern Chlorine detector which is set to activate an alarm system at 1 parts per million concentration. This detector is tested everyday for responsiveness. The Chlorine building is equipped with automatic closure of all doors and relatively tight containment of the internal atmosphere (which is environmentally controlled). In the event of a partial release of Chlorine gas it is anticipated that the bulk of the gas will be contained within the immediate vicinity of the Chlorine room. A substantial portion of the released gas should be captured and treated within the immediate area of the Chlorine room. In addition, there is a substanti
al tree line with thick under-story in which considerable dispersion and quenching of the released gas is anticipated.
There has been no accidental release of Chlorine gas beyond incidental events, such as minor leaks, in the last five years.
During the development of the AFP's RMP Program several recommendations were made which are currently being addressed. Recommendations were introduced for windsocks, sirens, upgrading engineering process materials and instruments, and further upgrading of AFP's standard operating procedures for all process activities which are material to the Chlorine process. In addition, training will be improved upon and documented assuring that all Operators at the Arab Filter Plant are competently trained in the design and everyday handling of Chlorine gas.