South Walton Utility Company WWTP - Executive Summary |
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SUMMARY: The South Walton Utilities (SWU) Wastewater Treatment Plant (the Facility) is located at 71 Miramar Beach Drive, Destin, Walton County, Florida. South Walton Utilities is a member owned, non profit corporation organized to provide potable and wastewater services to its members located in southern Okaloosa County and southern Walton County. South Walton Utilities is committed to operating this facility in full compliance with all applicable OSAH, EPA and FDEP regulatory requirements. The Facility is operated in a safe manner and in compliance with applicable OSAH and EPA regulations. SWU has developed this Risk Management Plan PROCESS DESCRIPTION: The Facility is designed to the treatment of wastewater from the SWU sewer system. The Facility uses chlorine for wastewater disinfection. Chlorine is delivered to the Facility via truck and stored in silver-colored one-ton (2,000 pound) and 150-pound containers that are used onsite as storage vessels. These containers are stored and used on a chlorine dock located just east of the main office building at the Facility. The maximum intended inventory of chlorine at this location is 6,000 pounds in one-ton and 150-lb containers. To facilitate the chlorination process, two (2) one-ton containers are simultaneously connected to a split manifold. Only one (1) container is active at any given time. WORST CASE AND ALTERNATIVE CASE RELEASE SCENARIOS: The worst case release scenario is the sudden release of the contents of one (1) full one-ton container of chlorine, or 2,000 pounds, over a period of ten (10) minutes, as required by the applicable Risk Management Plan regulations. In addition to assuming the release of a full container of chlorine, the worst case scenario included other worst case assumptions, such as low wind speed (1.5 m/s), and a highly stable Class F atmosphere. These worst case assumptions contributed to a highly conservative, large distance to the toxic endpoint of 0.0087mg/l as define d by the regulations. Under this worst case scenario, the toxic endpoint was determined using RMP-COMP to be 1.3 miles from the point of release. This endpoint results in potential impacts to approximately 2,500 people. There were no environmental receptors, such as wildlife refuges, within the affected area. It is important to recognize that the regulations require the identification of the potentially impacted population within a circle with a radius that is 1.3 miles. In actuality, the released gas would impact a population within only a portion of the circle located in a downwind direction from the source. A more realistic, alternative release scenario was also examined. For this scenario, it was assumed that the one-ton containers were half full, resulting in a release of 1,000 pounds of chlorine. In addition, a more realistic release period of 30 minutes was used for the alternative case scenario. A realistic wind speed of 3.0 m/s, Class D atmosphere was used. The dis tance to the toxic endpoint was determined using RMP-COMP to be 0.1 miles. The potentially impacted population was estimated to be 500 people. Potential public receptors are located within the endpoint, but there were no identified environmental receptors. ACCIDENTAL RELEASE PREVENTION PROGRAM: The Facility has an aggressive accidental release program that is based upon a foundation of employee awareness and proactive system maintenance. FIVE YEAR ACCIDENT HISTORY: There have been no accidental releases at the Facility in the five (5) years prior to the date of this Plan. EMERGENCY RESPONSE PROGRAM: The Facility has an Emergency Response Plan that defines the sequence of actions taken by Facility employees in the event of an accidental release of chlorine. This plan has been communicated to the South Walton Fire District. It is the policy of SWU that its personnel are trained to the First Responder Awareness Level. These are individuals who are likely to witness or discover a c hlorine release. These individuals have been trained to initiate an emergency response by notifying the South Walton Fire District. They would take no further action beyond notifying the authorities of the release. Thus it is the policy of SWU that the Facility employees dial 911 in the event of a release emergency and allow the local Hazardous Materials Response Team to mitigate the release conditions. |