Pacific-Ultrapower Chinese Station - Executive Summary |
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PACIFIC-ULTRAPOWER CHINESE STATION JAMESTOWN, CA Risk Management Plan For Anhydrous Ammonia EXECUTIVE SUMMARY June 1999 Pacific-Ultrapower Chinese Station (Pacific-Ultrapower) prepared a chemical risk management plan (RMP) in general accordance with California Code of Regulations, Title 19, Section 2735.1, et. Seq. The regulations are also referred to as the California Accidental Release Prevention (CalARP) program. Pacific-Ultrapower prepared the RMP to satisfy regulatory requirements and to demonstrate a commitment to evaluate and improve anhydrous ammonia handling system and practices at the facility. Pacific-Ultrapower has incorporated many safety features into the ammonia system at the facility as part of original system design. Pacific-Ultrapower will continue to improve ammonia-handling safety through the implementation of the prevention program elements of the RMP. The Pacific-Ultrapower facility is located approximately 6 miles south of Jamestown and 1.5 miles east o f the junction of State Highway 108 and State Highway 120. The area surrounding the facility is primarily open range land with a few private residences and a small industrial park. The Pacific-Ultrapower Chinese Station facility was constructed in 1985 and is operated by Constellation Operating Services. The Pacific-Ultrapower facility is a wood and biomass fueled power plant that produces electricity. Anhydrous ammonia is used at the facility to reduce oxides of nitrogen (NOx) produced when the wood and biomass is burned in the power plant. Ammonia is stored in a 12,000-gallon tank as a liquid under pressure. Ammonia vapor is drawn from the top of the storage tank and is injected into the boiler combustor. The RMP regulations require facilities to identify and evaluate chemical release scenarios resulting from potential failures of the chemical handling systems covered by an RMP. Program 3 requirements of the RMP apply to the Pacific-Ultrapower facility due to the quantity o f ammonia used. Pacific-Ultrapower is required to evaluate a worst-case release scenario (release parameters are defined in the regulations) and an alternative release scenario. A worst-case release scenario for anhydrous ammonia is defined by the regulations as "the greatest amount held in a single vesselreleased as a gas over 10 minutes." An alternative release scenario is identified as a release that is more likely to occur at the facility. The ammonia storage tank at the Pacific-Ultrapower facility has a capacity of 60,000 pounds of ammonia. The estimated maximum quantity of ammonia stored in the tank at any time is 51,000 pounds (administrative controls limit the maximum inventory to 85 percent of the storage tank capacity). Therefore, the worst-case release scenario for the facility is a release of 51,000 pounds of ammonia in 10 minutes. Catastrophic failure of the ammonia storage tank would be required for this scenario to occur. As required by the RMP regulations, pessi mistic atmospheric conditions, very conservative chemical dispersion characteristics, and a toxic endpoint of 200 parts per million (ppm) ammonia vapor were assumed. The predicted distance to the toxic endpoint for the worst case release scenario is 4.04 miles from the facility. Table 2-1 of EPA's Model Risk Management Program and Plan for Ammonia Refrigeration, November 1998, was used for the chemical dispersion analysis. Administrative controls were considered in the analysis. The alternative release scenario described in the above referenced EPA document was used by Pacific-Ultrapower. The release scenario is described as a <-inch effective diameter orifice leading to an airborne release, representative of a structural failure of a fitting in the pipeline or a gasket rupture. A release rate of 100 pounds/minute and average weather conditions were used in the evaluation. The predicted distance to the toxic endpoint is 1056 feet (0.2 miles). The RMP regulations require a rev iew of the accidental release prevention program and chemical specific prevention steps used by the facility. Pacific-Ultrapower has incorporated many safety features in the ammonia system to prevent system failures and to mitigate potential releases. The predominant safety concern with pressurized systems is inadvertent buildup of pressure exceeding pressure ratings or capacities of equipment due to ammonia expansion. The Pacific-Ultrapower ammonia system is continuously monitored by automated control systems that shut down components if deviations from normal operating conditions occur. Further, the system is equipped with pressure relief valves on all pressure vessels and most, if not all locations within the systems where ammonia could become trapped. The pressure relief valves on the storage tank are replaced every five years. Other safety features at the facility include: 7 emergency shutdown systems 7 fire alarms and sprinkler system 7 operating alarms that are frequen tly proven 7 physical barriers around the storage tank 7 caps on all lines 7 the ability to double block and bleed some of the line segments in the systems In addition to the physical features of the ammonia system at the facility, Pacific-Ultrapower has extensive administrative controls in place to maintain safe operation of the system. Administrative controls include, but are not limited to: formal training programs for system operators and mechanics, emergency training, a hot work permit program, a lock-out/tag-out program, a contractor safety program, incident investigation program, confined space entry program, mechanical integrity program, management of change program and an RMP auditing and inspection program. Written standard operating procedures (SOPs) are currently being revised for the ammonia system at the facility and will provide a basis for site specific operator training and a ready reference for operating and trouble-shooting the system. Pacific-Ultrapower is commi tted to maintaining the mechanical integrity of the ammonia system. A computerized preventive maintenance system is utilized to manage the maintenance of the system. Preventive maintenance at the facility includes shift, daily, weekly and periodic inspection, calibration, testing and overhaul of the equipment. The computerized system is used to track equipment performance and to create reports that are used by maintenance personnel to monitor the frequency of repairs and deviations from normal operating parameters. The RMP regulations require a review of the five-year accident history at the regulated facility. Pacific-Ultrapower reported no accidental releases of ammonia during the past five years. In the unlikely event that an ammonia release requiring emergency response occurs at the facility, Pacific-Ultrapower trained all operators and mechanics for emergency response. The facility has a written emergency action plan that identifies the roles, responsibilities and actions of personnel during an emergency. Pacific-Ultrapower will rely on local community responders to assist in mitigating ammonia releases at the facility. Pacific-Ultrapower will also rely on community responders for medical assistance and public evacuation or protection in place, if necessary. Changes to improve safety at the facility are ongoing. Many of the mitigation measures suggested by the process hazard analysis team have already been implemented. Others will be implemented during the next several months. The status of significant mitigation measures is as follows: 7 Initial SOPs have been prepared. Revisions will be made within the next several months. 7 Operator training is ongoing 7 All pressure relief valves will be replaced on a five-year schedule 7 Modify delivery procedures to include verification of tank levels 7 Labeling of valves and piping is being evaluated 7 PRV discharge locations may be modified to improve worker safety 7 Proving safeties that are not rout inely proven upon plant shutdown will be added to the preventive maintenance program Pacific-Ultrapower will respond to all suggested mitigation measures promptly. Schedules of proposed actions have been established by Pacific-Ultrapower. Management responses and support will be consistent with Pacific-Ultrapower's commitment to safe and environmentally responsible operations. |