City of Pocatello POTW - Executive Summary |
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EXECUTIVE SUMMARY Pocatello's Wastewater Treatment Plant is located west of the city at 10733 Rio Vista Road. The plant treats all wastewater generated by the City of Pocatello and the City of Chubbuck. Treatment consists of primary and secondary treatment with disinfection using a final chlorination/dechlorination process prior to being discharged to the Portneuf River. Because the City of Pocatello exceeds the threshold quantity for the chemicals Chlorine and Sulfur Dioxide it must comply with the mandated EPA Risk Management Plan (RMP). The two major elements in the RMP for Pocatello are the Off Site Consequence Analysis' for chlorine and sulfur dioxide and a Prevention Program. The City of Pocatello's Waste Water Treatment Plant is also required to do Offsite Consequence Analysis for a worst case release scenario and alternative release scenario. Pocatello's Prevention Plan includes information about safety, process hazards, operating procedures, training programs, maintenan ce programs, compliance audits, and accident investigation. The RMP offsite consequence analysis for both the worst case release scenario and alternative release scenario were performed for accidental release of the toxic gases chlorine and sulfur dioxide using the EPA software program, RMP*Comp. For Chlorine: The worst-case scenario analysis requires considering the release chlorine from the largest single vessel. The largest single vessel of chlorine is a one ton cylinder. The analysis considers a release rate of 200 pounds per minute, with a release time of 10 minutes. The topography is urban surroundings. However, the building is not used as a mitigation measure because the chlorine is delivered outside. The estimated distance to toxic endpoint is 1.3 miles. The alternative scenario analysis considers the release chlorine a 1/4 inch hole from a pigtail connection breaking. This analysis uses a release rate of 9 pounds per minute, with a release time of 222 minutes (Risk Man agement Program Guidance for Wastewater Treatment Plants, Chapter 4, Exhibit 4-15). The topography is urban surroundings. The chlorine cylinders are stored inside a building. However, the building is not used as a mitigation measure because the chlorine is delivered outside. The estimated distance to toxic endpoint is 0.1 miles. For Sulfur Dioxide: The worst-case scenario analysis requires considering the release of sulfur dioxide from the largest single vessel. The largest single vessel of sulfur dioxide is a one ton cylinder. The analysis considers a release rate of 200 pounds per minute, with a release time of 10 minutes. The topography is urban surroundings. The building is not used as a mitigation measure because sulfur dioxide is delivered outside of the building. The estimated distance to toxic endpoint is 1.3 miles. The alternative scenario analysis considers the release of sulfur dioxide from a 1/4 inch hole from a pigtail connection breaking. The analysis considers a r elease rate of 4 pounds per minute, with a release time of 500 minutes (Risk Management Program Guidance for Wastewater Treatment Plants, Chapter 4, Exhibit 4-19). The topography is urban surroundings. The sulfur dioxide cylinders are stored inside a building. The building is not used as a mitigation measure because the chlorine is delivered outside. The estimated distance to toxic endpoint is <0.1 miles. Estimating Offsite Receptors: FIVE YEAR ACCIDENT HISTORY There have been no accidental releases of chlorine or sulfur dioxide in the past five years. The objective of this plan is to continue this history and prevent any accidental releases, and to respond effectively and timely in the unlikely event there is a release. Pocatello's RMP includes an incident report form will be used in the unlikely event there is an accidental release. MANAGEMENT SYSTEM The roles and responsibilities of the staff that oversees the risk management program elements will help to ensure effective communication about process changes between divisions; clarify the roles and responsibilities related to process safety issues; avoid problems and conflicts among various people responsible for implementing elements of the program; avoid confusion and allow team work; and ensure that the program elements are integrated into an ongoing approach to identifying hazards and managing risks. PREVENTION PROGRAM (PROGRAM 2) Pocatello's Prevention Plan has integrated the seven basic elements - safety information, process hazard analysis, operating procedures, training programs, maintenance programs, compliance audits, and accident investigations into a risk management system. Safety information was used to perform a process hazard analysis and the results of the analysis were used to revise and update operating and maintenance procedures. Training programs to ensure employees to understand and manage risks have been revised and continued training is provided. PROCESS SAFETY INFORMATION Chl orine and sulfur dioxide have been used for many years in the chlorination and dechlorination process at Pocatello's Wastewater Treatment Plant. As references for chlorine and sulfur dioxide handling Pocatello uses The Chlorine Manual (The Chlorine Institute, 1986, 5th edition), Chlorine And Its Properties, (Capital Controls Company, Inc., 1990, Pub. No. 381-5), Sulfur Dioxide And Its Properties (Capital Controls Company, Inc. 1989, Pub. No.482-2), Material Safety Data Sheets (MSDS) BOC GASES, 1996;. and The City of Pocatello Operating Procedures for Chlorine and Sulfur Dioxide Cylinder Handling and Storage, 1999. OPERATING PROCEDURES Operating procedures and instructions are important for training personnel and insuring safe operations of the chlorine and sulfur dioxide systems. The standard operating procedures (SOPs) for operating the chlorine and sulfur dioxide systems and associate equipment are located in the operations office, maintenance office and operators lab whic h are accessible to all plant personnel. The SOPs cover everything from receiving the ton cylinders through valving the chlorine and sulfur dioxide to the various discharge points. They include the start-up and shut down of all the related chlorine and sulfur dioxide handling equipment. These SOPs are updated when ever there are any changes made to any part of the chlorine system. New employees are give general training in the hazards of chlorine and sulfur dioxide as part of their plant employee orientation. New operators are required to review and understand the chlorine and sulfur dioxide related standard operating procedures and given on the job training (OJT) on all chlorine and sulfur dioxide related tasks they are required to perform as part of their operational duties. The maintenance employees also receive OJT on the chlorine and sulfur dioxide systems before they are allowed to independently work on the chlorine or sulfur dioxide systems. Yearly refresher training is g iven on the nature and hazards of chlorine and sulfur dioxide. Documentation of this training is kept in the plant safety training records. MAINTENANCE Written procedures for inspection and testing are incorporated into a preventive maintenance (PM) program and have been in effect since construction completion in 1992. The PM is conducted in accordance with the manufactures recommended procedures and sound engineering practices. The PM program is operated by a computer system that generates the needed information when a piece of equipment is in need of inspection or service. Technical manuals for the chlorination/dechlorination processes consist of three volumes which are current and located in the maintenance library. Initial training on the chlorination/dechlorination systems were conducted by construction contractor and equipment manufactures at completion of construction. Safety training requirements for maintenance personnel are the same as for operations personnel. INCIDENT INVESTIGATION The intent of the incident investigation is to learn from past experiences and avoid future similar incidents. The incidents employees are expected to recognize and initiate the investigation process are the types of events that result or could have reasonably resulted in a major chlorine or sulfur dioxide release. This is what we may refer to as a "near miss," meaning that serious consequences did not occur, but could have. COMPLIANCE AUDIT The wastewater treatment plant is required under EPA regulations to conduct a self-audit and document compliance on a signed document every three years. The certification will verify that the procedures and practices are adequate and are being followed. A report of the findings of the audit will be developed. The Wastewater Superintendent or designee will determine and document a response to each deficiency identified in the compliance audit. Any deficiency noted in the audit will be corrected and documented as su ch. The wastewater treatment plant will keep the two most recent compliance audit reports on file for internal purposes and EPA inspection. EMERGENCY RESPONSE PLAN Any time a chlorine or sulfur dioxide emergency is apparent or suspected, the operator in charge will initiate the procedure to assess the severity of the emergency. The procedure requires a minimum of two individuals to be present when an emergency is apparent or suspected. A minimum of "Level B" respiratory protective equipment will be required. The reason for a two party assessment is due to staffing levels. Once the level of emergency has been assessed, the operator in charge will then make a determination as to what Action Response Procedure will be followed based on the information provided by the assessment. The operator in charge will immediately begin a record of the event. Small leaks that are contained within the chemical building area may be repaired or alleviated through immediate action of trained pl ant personnel. Large releases that may effect public and/or private receptors or risk personal injury to plant personnel will be responded to by the Regional HAZMAT Team. |