Ponca City Water Treatment Plant - Executive Summary |
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Executive Summary Ponca City Water Treatment Plant Risk Management Plan The Ponca City Water Treatment Plant (PCWTP) stores chlorine on-site to provide a means of disinfecting treated water. The maximum quantity on-hand exceeds the threshold limit as defined by the Environmental Protection Agency (EPA), 40 CFR, Part 68, under Section 112 ( r ) of the Clean Air Act. The City of Ponca City and its facilities are devoted to the prevention of accidental releases of hazardous chemicals. This is evident by the long established training procedures utilized by the City coupled with the recent plant improvements. The PCWTP supplies drinking water to its customers and rural water districts. The process itself is capable of treating up to 12 mgd. Chlorine is used to inactivate pathogenic organisms in the treated water before distribution and to maintain a chlorine residual to protect the water quality. The chlorine supply is pulled from the ton container under a vacuum. The presence o f the vacuum prevents gas from escaping into the atmosphere because of piping failure. This vacuum feed begins at the regulators, which are mounted directly to the ton containers, which eliminates all pressure piping in the system. At the chlorinator, the gas is converted to a solution, thereby minimizing any potential hazards. The impact areas for both the worst case and alternate release scenarios were based on the results from RMP*Comp. The worst case release scenario considered a one-ton release within a 10-minute period. This resulted in a 1.3 mile radius impact area, with an estimated population of 8,100 persons. No active or inactive mitigation was considered in this scenario. The alternate release scenario was based on a gas release created by a valve breaking from the one-ton container since the rest of the system operates either under a vacuum or in a solution. A valve break at the container resulted in a release rate of 15 lbs/min of Cl2. The impact area of this r elease was determined by RMP*Comp to have a radius of 0.1 miles. Based on the Ponca City population density, an estimated 48 persons may be effected by a release. The chlorine system components at the plant comply with one or more of the following standards: NFPA 58, ASTM Standards, ANSI Standards, and ASME Standards. However, consistent maintenance and regular training sessions will minimize the potential for a toxic release. The PCWTP has not had any accidental chemical releases within the last five years. If a release were to occur, then the chlorine gas detectors would notify plant personnel of the presence of chlorine gas. Plant personnel would then call 9-1-1 to notify the fire department. Next, personnel would contact the Ponca City Emergency Management at (580)767-0380. Other regulatory agencies would be contacted as required. The fire department and emergency management would work with plant personnel to minimize the impact of the release as drilled in accordance with the county emergency response procedures manual. The chemical feed system in place at the plant was installed in 1997 and is in good working condition. At this time, no improvements are planned. |