Five Mile Creek Wastewater Treatment Plant - Executive Summary |
|
Policy Statement It is the Jefferson County Environmental Services Department's (JCESD) policy to operate safe wastewater treatment plants (WWTPs), reducing to the greatest extent practicable any hazards associated with the necessary treatment processes and reducing any subsequent risk to the surrounding community, personnel, and environment. This policy includes working with the surrounding community and local emergency response agencies to promote a spirit of cooperation and teamwork and to orchestrate an effective contingency plan in the unlikely event of a process incident occurring at the Five Mile Creek WWTP. It is the JCESD's policy to adhere to the applicable federal, state, and local laws applicable to the Five Mile Creek WWTP. Description of Facility and Regulated Substance Handled The Five Mile Creek WWTP is a municipal wastewater treatment plant. Chlorine is used primarily as a disinfectant. Other possible uses of chlorine are for odor control and to assist in the se ttling of biosolids in the clarification process. The maximum quantity of chlorine stored at the facility is four 1-ton containers, equivalent to 8,000 pounds. The chlorination system consists of vacuum regulators, V-notch chlorinators, chlorine leak detectors, alarms, associated piping, valves, and other miscellaneous equipment. Sulfur dioxide is used for dechlorinating the effluent before it is discharged into Five Mile Creek. However, the sulfur dioxide storage quantity is less than the RMP applicability threshold of 5,000 pounds. Engineered controls including vacuum regulators, sulfur dioxide leak detectors, alarms, associated piping, and valves are present on the sulfur dioxide system to minimize the risk of an accidental release. Chlorine Worst-case and Alternative Release Scenarios The EPA-defined worst-case scenario is the failure of one liquid chlorine container resulting in a release of 2,000 pounds of chlorine in 10 minutes. The chlorine container is stored outdoors. The estimated distance to the endpoint of the worst-case scenario is 2.06 miles, beyond which there will be enough dispersion to reduce the concentration below the toxic endpoint. The total population affected by this hypothetical worst-case release is estimated to be 13,200 people, based on 1990 Census data. Realistically, the JCESD does not anticipate that the worst-case scenario could actually happen. In the event of a total rupture of a 1-ton container of chlorine, most of the chlorine would remain in liquid form until the fire department's HAZMAT team could neutralize the release. JCESD has developed an alternative release scenario (ARS) for chlorine that is a more realistic "worst-case" scenario. The ARS is the release of chlorine gas from a <-inch-diameter pipe connecting the chlorine container to the feed manifold. This scenario was selected because it is the most likely failure scenario based on the experience of the plant operators who participated in the hazard review . It is estimated that the release will require approximately 20 minutes before a trained mechanic can repair the leak. The estimated distance to the endpoint for the alternative release scenario is 0.29 mile. The total population within the distance to the endpoint for the alternative release is estimated to be 150 people, based on 1990 Census data. General Accidental Release Prevention Program and Chemical-specific Prevention Steps The Five Mile Creek WWTP has complied with the requirements of the RMP Rule, 40 CFR 68. The facility has conducted a comprehensive review of all systems, as well as administrative, technical, and operating and maintenance procedures, in addition to the other required program elements of the RMP Rule. A detailed hazard review was conducted at this facility using a "What-If" analysis. Five-year Accident History The Five Mile Creek WWTP has never had a release of chlorine resulting in injuries, deaths, property or environmental damage, evacuations, or shelterings in place. The effectiveness of the facility's design, operating procedures, and training has resulted in an excellent safety record. Emergency Response Program The JCESD has an emergency response plan for the Five Mile Creek WWTP, which coordinates response efforts with the local fire department's HAZMAT team, the police department, and the hospital. Response activities also have been coordinated with the Jefferson County Local Emergency Planning Committee (LEPC). Planned Changes to Improve Safety It was observed during the hazard review that the Five Mile Creek WWTP has the necessary equipment and the operating and training procedures required for the safe operation of the chlorination system. However, the following recommendation for improving the safety of the chlorination process was made: 1. Install a wind sock or a flag to indicate the wind direction during a release event. |