W. R. Wise Water Treatment Facility - Executive Summary |
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Greenwood Commissioners of Public Works (CPW) owns and operates a water treatment plant located in Greenwood County, South Carolina. The facility provides potable drinking water to the city of Greenwood and surrounding areas within the County. In order to provide water that is free of harmful bacteria and pathogens, chlorine, considered potentially toxic by the US EPA, is used to disinfect the water. It is the facility's policy to adhere to all applicable Federal and state rules and regulations associated with the safe handling of this chemical. A maximum of 32,000 lb of chlorine could be stored at the facility at any given time. This is larger than the threshold quantity for this chemical as listed in 40 CFR Part 68. Ammonia, also regulated by 40 CFR Part 68, is stored at this facility in an amount less than the threshold quantity. As a result, only chlorine is discussed in the facility's Risk Management Program. The W.R. Wise Water Treatment Plant has had no major chlorine spills or accidents in the past five years. Small chlorine leaks are common at water treatment facilities and do occur at this facility. The leaks are typically caused by improper tank connections and are easily detected with a simple test performed by operators or by chlorine sensors located in and around the chlorine storage building. Once detected, operators are able to stop these leaks quickly. The chlorine cylinders, when in use, are stored inside a building. The building's walls help to contain any harmful chlorine gas that may leak from the cylinders. Additionally, CPW has established a program to prevent the accidental release of chlorine gas. The prevention program, presented in the Risk Management Plan, consists of procedures and training designed to prevent accidents including: 7 Standard Operating Procedures 7 Employee Training 7 Mechanical Integrity (Preventative Maintenance) Program 7 Investigating/ Documenting Accidents 7 Compliance Audits 7 Process Safety Infor mation 7 Process Hazard Analysis 7 Management of Change 7 Pre-Startup Safety Review 7 Employee and Employer Responsibilities When Hiring Contractors to Work On-Site 7 Employee Participation 7 Hot Work Permits CPW believes that the prevention program is effective, and no major release are expected at the water treatment plant. Because of the lack of chlorine accidents in the past, CPW sees no need and has no plans to improve safety at this time. However, CPW has developed an emergency response program to be used in case of an accidental release. The Emergency Response Program includes procedures for notification of the local fire department and any potentially affected neighbors as well as first aid for victims. As a part of this Risk Management Program, CPW has modeled a worst case and three alternative release scenarios in an attempt to predict the effect of certain potential accidents. Results show that the worst case scenario would result in potentially toxic concentrations of chlorine in a 5.4 mile radius from the water plant, affecting approximately 10,000 residents of Greenwood and Laurens Counties. The worst case scenario would be the result of a tank failure where the entire contents of a 2,000 lb chlorine cylinder are released in 10 minutes. Mitigation is not considered in this case. The alternative scenarios are situations that are considered more likely to occur including small leaks from flanges, joints, valves, and pipes. The most serious of the alternative scenarios would cover a radius of 1.4 miles, affecting 700 citizens. The remaining two scenarios cover 1.2 miles and 0.74 miles and could affect 500 and 135 people, respectively. |