Catoma Water Pollution Control Plant (WPCP) - Executive Summary |
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Policy Statement It is the policy of the Catoma Water Pollution Control Plant (WPCP) and the Montgomery Water Works and Sanitary Sewer Board (MWWSSB) to operate the WPCP safely, reducing to the greatest extent possible any hazards associated with the processes and reducing any subsequent risk to the surrounding community, personnel, and the environment. The policy includes working with the surrounding community and local emergency response agencies to promote a spirit of cooperation and teamwork, to orchestrate an effective contingency plan in the unlikely event that a process incident occurs at the Catoma WPCP. Stationary Sources and Regulated Substance Handled Primary Activities: Municipal wastewater treatment. Use of Regulated Substances Chlorine is used primarily as a disinfectant. Other possible uses of chlorine are odor control and to assist in the settling of biosolids in the clarification process. Digester Gas is a byproduct of anaerobic digestion, which is a process used to reduce the volume of excess biosolids produced during wastewater treatment. The digester gas is flammable because it contains 65 percent by volume of methane, a flammable gas. The quantity of digester gas stored is 9,630 pounds, which is below the threshold quantity for regulation under the RMP rule. Therefore, it is not included in the Data Elements. Quantities of Chlorine Handled or Stored Amount Handled: 2 one-ton containers, equivalent to 4,600 pounds; Total Amount Stored: 12 one-ton containers, equivalent to 27,600 pounds. Chlorine Worst-case Release Scenarios Failure of two liquid chlorine cylinders, resulting in a release of 4,600 pounds of chlorine in 10 minutes. There are no administrative controls in place. The 12 containers are stored in an enclosed building with a concrete roof. The building is 48 feet long and 23 feet wide. The actual release rate is 55 percent of the total chlorine released in the enclosed building because of passive mitigation. The release rate of 1.91 kg/s is modeled using DEGADIS 2.1. Distance to Endpoint: Under the worst-case weather conditions prescribed by the RMP rule, the distance to a toxic endpoint of 3 ppm is 1.97 miles, beyond which there will be enough dispersion that the release no longer poses a hazard to the public. Chlorine Alternative Release Scenarios Release of chlorine from a pipe 3/8-inch in diameter connecting the chlorine container to the evaporator. For a release duration of 15 minutes, the release rate is 0.1 kg/s. Chlorine sensors at the Catoma WPCP detect concentrations of chlorine greater than 5 ppm and activate the chlorine scrubber. The chlorine scrubber can remove chlorine with an efficiency rate of 99 percent. The release rate from the scrubber of 0.001 kg/s is modeled using DEGADIS 2.1. Distance to Endpoint: Under realistic weather conditions of 3.0 m/s wind speed and a wind stability class of "D," chlorine would travel 0.07 miles or 0.11 kilometers before dispersing enough that it no longer poses a hazard to the public. Accidental Release Prevention Program and Chemical-specific Prevention Steps Catoma WPCP is in compliance with the RMP Rule, 40 CFR Part 68. The facility has conducted a comprehensive review of all systems, as well as administrative, technical, operating, and maintenance procedures, in addition to the other required program elements of the RMP rule. A hazard review was conducted at this facility using a checklist extracted from the Guidelines for Hazard Evaluation Procedures. Five-year Accident History Catoma WPCP has not had a release of chlorine since 1991. Emergency Response Program The MWWSSB has an Emergency Response Program, which applies to Catoma WPCP, that coordinates response efforts with the local fire department's HAZMAT team, the police department, and the hospital. Response activities also have been discussed with the Alabama Emergency Management Office. Planned Changes to Improve Safety During the hazard review, it was ob served that the Catoma WPCP has the equipment and the operating and training procedures required for the safe operation of the chlorination system. Therefore, no changes were recommended for the chlorination system. |