City of Idaho Falls Water Pollution Control Plant - Executive Summary |
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Executive Summary Introduction Chemicals are widely used in industry, in the home, and in the environment. They are transported on roads, water, and railways. The Idaho Falls Water Pollution Control Plant (WPCP) uses chemicals, too; we use chlorine to disinfect our wastewater to provide safe water discharges to the environment and for landscaping or irrigation uses. The Idaho Falls WPCP chlorination system uses chlorine gas fed from liquid chlorine containers. Because storing large quantities of chlorine can be hazardous, we take our safety obligations in storing and using chlorine as seriously as we do providing safe, disinfected water to the environment. The following document describes what could happen in the event of an accident, the steps we take everyday to ensure a safely operating WPCP, and what to do in event of an emergency. Please feel free to contact David Smith at 208-529-1108 if you have any questions. Accidental Release Prevention and Emergency Response Policies The Idaho Falls WCPC and Idaho Falls Fire Department accidental release prevention policy involves a unified approach that integrates proven technology, trains staff on operation and maintenance practices, and uses tested management system practices. All applicable procedures of the State of Idaho and U.S. Environmental Protection Agency (EPA) Prevention Program are adhered to, including key elements such as training, systems management, and emergency response procedures. This document complies with the EPA's Risk Management Program (RMP), under Section 112 (r) of the Clean Air Act (CAA), Amendments of 1990, 40 Code of Federal Regulations (CFR), Part 68. This document summarizes our existing health and safety programs, our internal management response team, policies, procedures, and on-going actions that are designed to prevent or minimize impacts of accidental releases of chlorine to the environment. The Idaho Falls WPCP has prepared a detailed and comprehensive emergency response plan to handle any potential accidental releases and which is designed to safeguard both on- and offsite people. To date we have an excellent record in accident prevention. General Facility and Regulated Substances Information The Idaho Falls WPCP, operating since 1973, is located at 4055 Glen Koester Road, City of Idaho Falls, Bonneville County, Idaho. The WPCP is on a 15-acre property about 3 miles south of the center of town and adjacent to Snake River. Wastewater from the Bonneville service area is treated at the WPCP, and the disinfected water is either discharged into the Snake River or reclaimed for landscaping and irrigation uses. The wastewater treatment includes preliminary screening, primary settlement and treatment, secondary sedimentation and treatment, and chlorination and dechlorination before final discharge or reclamation use. The WPCP handles wastewater flows up to 36 million gallons per day (mgd), with an average flow of between 10 to 12 mgd. The WPCP currently st ores chlorine; a regulated toxic substances under the RMP regulations. Chlorine is stored in twelve, 1-ton steel containers containing a maximum of 12 tons of chlorine. This chlorine storage exceeds the listed threshold quantities in both the RMP Rules and in OSHA's Process Safety Management (PSM) Rules (29 CFR 1910.119). However, because Idaho is not an OSHA-regulated State, the Idaho Falls WPCP is not subject to the PSM Rules. Chlorine is delivered to the WPCP in 1-ton containers. Current processes only allow gaseous chlorine to be withdrawn from the 1-ton containers. In both the Tank Room and the Chlorinator Room, chlorine leak detectors monitor continuously for chlorine leaks. In the event of a leak, the detectors sound an alarm at the plant control panel; additionally, the tank area has both an audible alarm and a flashing warning light inside and outside of the building. Both the Tank and the Chlorinator Rooms are enclosed in the Chlorine Building. The Tank Room is equipped wi th an automatic chlorine scrubber ventilation system that automatically operates when parts per million (ppm) of chlorine are detected in the room. An emergency shower and eye wash station are provided on the outside of the building. Self-Contained Breathing Apparatus (SCBA) packs are available onsite in the Administration Building. The Chlorine Building has a fire sprinkler and fire alarm system in the event of a fire. The WPCP entrance is controlled by a gate at Glen Koester Road. Visitors and contractors must enter the administration building and be approved by Idaho Falls' WPCP staff prior to entry into the WPCP. The WPCP is staffed year-round, 24 hours a day. Electrical power is available to the chlorination and dechlorination facilities in the event of an emergency. The back-up generator starts within seconds of electrical power supply loss and supplies power to critical processes within the WPCP, including the chlorine leak detectors, lighting, and ventilation systems. Offsit e Consequence Analysis Results The offsite consequence analysis includes both "worst-case" and "alternative" release scenarios. In a worst-case scenario, the single largest vessel or pipe is evaluated for off-site impacts from chlorine. An alternative release scenario is defined as a more probable scenario, based on employee knowledge and experience, and on the facilities operational and safety record. The worst-case scenario used for the WPCP is the rupture of one 1-ton chlorine container, resulting in a release of 2,000 pounds of chlorine in a 10-minute duration. The chlorine 1-ton containers are in an enclosed building, which may result in passive mitigation of any chlorine release, but which was not considered. It was determined that passive or administrative controls would not be used to reduce off-site impacts under this scenario. The 1-ton container rupture resulting in a chlorine release could be caused by catastrophic events, such as an earthquake. The released liquid is assumed to quickly volatilize and to disperse as a vapor cloud. The distance to the toxic endpoint was estimated using the EPA model RMP*Comp Version 1.06, and confirmed by the EPA's Risk Management Program Guidance for Wastewater Treatment Plants, October 1998. The toxic endpoint was conservatively set by the EPA to ensure public notification and local emergency response planning that takes into account the greatest possible impacted area surrounding the release point. In practice, this type of total release of a 1-ton container would be unlikely and would never occur during the lifetime of the WPCP. The toxic endpoint selected by the EPA was 3 ppm. In addition, all required EPA-model input parameters where included in completing this activity, including conservative meteorological conditions: Stability F class; 1.5 meters-per-second wind speed; 77-degree-Fahrenheit ambient temperature; and 50-percent average humidity. The results of the dispersion modeling analysis for this worst-cas e release scenario indicate that this scenario has an offsite impact of approximately a 3-mile radius. The alternative release scenario is a more-likely-to-occur release scenario. Based on the process hazard analysis performed for the chlorine system, an alternative release scenario was selected. Unlike the worst-case release scenario, active controls can be applied to minimize the leak or impacts. Active controls can consist of mechanical, structural, or human input. The scenario used for chlorine was a rupture of a pipe leading from the 1-ton container to the vacuum regulator. The containers, vacuum regulators, and associated piping are all in a building, and building mitigation was considered. The chlorine scrubber system, which is designed to capture and control the chlorine leak by evacuating the air in the Tank Room through a chemical scrubber (sodium bisulfate), was also considered. Sodium bisulfite reacts with chlorine gas such that a small percentage of chlorine is actually r eleased to the atmosphere. In this alternative release scenario, the amount of chlorine released was estimated to be approximately 5 pounds per minute. The same modeling approach was used for the worst-case release scenario, except meteorological conditions were adjusted to more common conditions of: Stability D class; 3.0-meters-per-second wind speed; 78-degree-Fahrenheit average air temperature; and 73-percent average humidity. The results of the dispersion modeling analysis for the alternative release scenario indicate that there is an offsite impact of approximately 0.1-mile radius. Summary of the Accidental Release Prevention Program and Chlorine-Specific Prevention Steps The Idaho Falls WPCP has a thorough Safety Management Program. Chemical-specific prevention steps include availability of SCBA, worn by the operators during connection and disconnection of the chlorine supplies; awareness of the hazardous and toxic properties of chlorine; and the presence of chlorine detecto rs and alarms. The Idaho Falls WPCP Accidental Release Prevention Program is based on the following key elements: 7 A detailed management system and clear levels of responsibilities and team member roles 7 A comprehensive process safety information that is readily available to staff and emergency responders 7 A comprehensive preventive maintenance program 7 A completed process hazard analysis of equipment and procedures with operation and maintenance staff participation and review 7 Use of state-of-the-art process and safety equipment 7 Use of accurate and effective operating procedures, written with operations and maintenance staff participation 7 A high level of operator and maintenance staff training 7 Implementation of an incident investigation, inspection, and auditing program using qualified staff Process and Chemical Safety Information Comprehensive chemical data have been assembled to include regulatory reporting and action thresholds, health hazard, and chemical exposure li mitations, as well as detailed physical properties of each regulated substance (chlorine). This information was compiled from numerous sources and is intended to be a one-stop source for the reader seeking data about these substances. This information includes chlorine background information, MSDS sheets, and chlorine reaction chemistry. Equipment safety information was meticulously compiled on the chlorine process, and specifications for each process are contained in one place for easy reference. On file at the WPCP are details that include maximum intended inventory; safe upper and lower temperatures; safe upper and lower pressures; and codes and standards used to design, build, and operate the processes. The WPCP also maintains procedures that are triggered to update safety information when existing information becomes obsolete. Process Hazard Analysis In 1999, a detailed process hazard analysis (PHA) was conducted with WPCP staff and administrative staff for the regulated proc ess. The team consisted of process operating and maintenance experts and process design engineers. The PHA technique used was the "What If" study, as per acceptable approach guidance from the EPA. The PHA was lead by a knowledgeable person on the type of process being reviewed. This review will be updated again within a five-year period or whenever there is major change in the process. A list of actions to resolve any found significant hazard review findings was prepared, and staff is currently working to resolve this action item list. Staff will document completion of any action item. Operating Procedures The Idaho Falls WPCP maintains up-to-date, accurate, written operating procedures that give clear instructions for the chlorine process. The WPCP ensures effective operating practices by combining them with operating and maintenance training programs. Standard operating procedures (SOPs) provide system descriptions, specifications, equipment inspection requirements, and operating p rocedures for the chlorine system. Procedures include startup, shutdown, and normal, alternate, and emergency operation. Also included are maintenance and troubleshooting procedures, consequences of deviation, and steps to correct deviations. Procedures are updated whenever a change occurs that alters the steps for safe operation. Operating procedures will be developed and in place before starting-up a changed process or before any new process equipment goes on-line. Operations and Maintenance Training Program Each WPCP employee presently involved in operating or maintaining the chlorine process is trained in a process overview and in detailed, applicable, operation and maintenance procedures. The WPCP helps its employees understand, through training, the nature and cause of problems arising from operations involving chlorine on site, and increases its employees' awareness with respect to these hazards. The WPCP's training program includes both initial and refresher training that cov ers 1) a general overview of the processes, 2) the properties and hazards of the substances in the processes, and 3) a detailed review of the processes' operating procedures and safe work practices. Oral reviews and written self-evaluations are used to verify that an employee understands the training material before the process work can be resumed. Training documentation includes the date of the most recent review or revision to the training program, the type of training required, and the type of competency testing used to ensure staff understands the training. Pre-Startup Safety Review and Mechanical Integrity Program The WPCP ensures that a pre-startup safety review is completed for any new, chlorine process at the WPCP, or for significant modifications to an existing chlorine process that requires a change in the process safety information. The WPCP maintains the mechanical integrity of process equipment to help prevent equipment failures that could endanger workers, the public , or the environment. The WPCP believes that this program is the primary line of defense against a release, and addresses equipment testing and inspection, preventative maintenance schedules, and personnel training. The mechanical integrity program includes the following: 7 Use of written procedures for maintaining mechanical integrity through inspection and testing of process equipment, based on instructions of equipment vendors, industry codes, and prior operating experience 7 Implementing written procedures by performing inspections and tests on process equipment at specified intervals 7 Training maintenance personnel in procedures for safe work practices, such as tagout, line or equipment opening, and avoidance and correction of unsafe conditions Internal Compliance Audits Internal compliance audits will be conducted every 3 years to verify compliance with the programs and procedures contained in the RMP. The WPCP will assemble an audit team that includes personnel knowledgeable in the RMP rule and process. This team will evaluate whether the prevention program satisfies the requirements of the RMP rule, and whether the prevention program is sufficient to help ensure safe operation of the process. The results of the audit will be documented, recommendations will be resolved, and appropriate enhancements to the prevention program will be implemented. Incident Investigation The WPCP investigates all incidents that could reasonably result in a serious injury to personnel, the public, or the environment, so that similar accidents can be prevented. The WPCP trains employees to identify and report any incident that requires investigation. An investigation team will be assembled and the investigation initiated within 48 hours of the incident. The results of the investigation are documented, recommendations are resolved, and appropriate process enhancements are implemented. Information found during the investigation is reviewed with affected staff, added or used to revise operating and maintenance procedures, and passed onto the training unit for their inclusion in existing training programs-if warranted-to prevent a future event. Five-Year Accident History Summary During the last 5 years, there was one reportable accident at the Idaho Falls WPCP that caused an onsite injury to an employee. No deaths, offsite injuries, property or environmental damage, evacuations, or sheltering in place has occurred. Some minor, incidental releases also may have occurred over this period, but they were quickly handled by staff, were neutralized, or posed no safety or health hazards. Appropriate investigation and documentation will occur in the event of another reportable accident. Emergency Response Program Summary The WPCP has established a written Emergency Response Program that employees follow to help them safely respond to accidental releases of hazardous substances. This program will be coordinated and reviewed by the City of Idaho Falls Fire Departme nt, which is a member of the Local Emergency Response Planning Committee. This program includes an Emergency Response Notification Plan. Emergency response drills and drill evaluations are conducted every 12 months; emergency operation and response procedures also are reviewed at that time. Planned Changes to Improve Safety The 1999 PHAs for the chlorine process identified some procedures that may improve the safety of the chlorination system. It is expected that the recommended actions be evaluated and, if found reasonable, implemented by December 1999. Implementation of these recommendations may further improve the safety of the covered processes. |