Mid-Set Cogeneration Company - Executive Summary |
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EXECUTIVE SUMMARY Accidental Release Prevention and Emergency Response Policies Mid-Set Cogeneration Company stores and utilizes anhydrous ammonia in a selective catalytic reduction (SCR) process at their facility near Fellows, California. It is Mid-Set Cogeneration Company's policy to comply with all applicable governmental regulations. Further, it is Mid-Set Cogeneration Company's objective to be a responsible citizen of the community in all of its business activities. Mid-Set Cogeneration Company emphasizes safe and environmentally sound operating practices and procedures through their employee training programs. In addition to job specific training, operators and maintenance personnel receive training in fire prevention, fire control, accident prevention, safety, and first aid. Additionally, an emergency action plan has been prepared for Mid-Set Cogeneration Company and a chain of command to respond to emergencies has been established. Mid-Set Cogeneration Compa ny has developed a detailed Compliance Audit Checklist which is used to evaluate compliance with the Process Safety Management (PSM) standard and 40 CFR Part 68 (RMP regulations). At least every three years, Mid-Set Cogeneration Company audits these programs and any findings of noncompliance are documented and responded to and the deficiencies are corrected. Description of the Stationary Source and Regulated Substances Texaco Midway Sunset Cogeneration Company, a wholly-owned subsidiary of Texaco Producing Inc., formed a general partnership with the Del-Mar Energy Company, a wholly-owned subsidiary of Edison Mission Energy Company, for the development of the cogeneration plant. The partnership, named Mid-Set Cogeneration Company, owns and operates the facility. The plant began commercial operation in April, 1989. The Mid-Set Cogeneration Company facility is located in Section 36, T31S/R22E, MDB&M in the sparsely populated Midway-Sunset oil field. Fellows is the clo sest community to the plant. Cogeneration, in the case of the Mid-Set project, is the simultaneous production of thermal energy and electrical energy from the combustion of a single fuel source. Combustion of the fuel takes place in a gas turbine that is physically coupled to an electric generator. Waste heat from the gas turbine's exhaust flows into a heat recovery steam generator (HRSG). The HRSG extracts the heat from the exhaust gases and produces steam for thermally enhanced oil recovery. Electricity is produced at the same time via the electric generator coupled to the combustion turbine. Anhydrous ammonia is used at the Mid-Set Cogeneration Company facility to create a reducing atmosphere in the selective catalytic reduction (SCR) process. This reducing atmosphere in the flue gas helps convert nitrogen oxides to nitrogen and water as it passes through the catalytic reactor. The operation of the SCR system substantially lowers the emissions of nitrogen oxide s from the gas turbine. Liquid ammonia is stored in a 15,000 gallon (water capacity) storage tank. The maximum intended inventory of the anhydrous ammonia storage tank is based on the American National Standard Institute's K61.1 safety requirements and the Occupational Safety and Health Administration (OSHA) regulations published in Section 1910.111 of 29 CFR (and Section 509 of Title 8, CCR). These standards and regulations limit the maximum ammonia storage capacity of the tank to approximately 69,960 pounds. For purposes of the offsite consequence analyses, the RMP regulations define the toxic endpoint for anhydrous ammonia as 0.14 mg/l (200 ppm). This concentration has been established by the American Industrial Hygiene Association as the Emergency Response Planning Guideline Level 2 (ERPG-2). ERPG-2 is the maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing i rreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action. Worst-Case Release Scenario and Alternative Release Scenario Offsite consequence analyses are used as tools to assist in emergency response planning. The RMP regulations require the owner or operator of a stationary source to analyze the offsite impacts due to an accidental release of a regulated substance. The offsite consequence analysis for a Program 3 process must analyze the worst-case release scenario and an alternative release scenario. Since Mid-Set Cogeneration Company's SCR system is considered a Program 3 process, both release scenarios were evaluated in the offsite consequence analysis. The offsite consequence analysis must include an estimate of the residential population within an area potentially affected by the accidental release scenarios. This area is defined as a circle with a radius equivalent to the distance the release wou ld travel with concentrations at or above the endpoint. This circle also defines the area in which potential environmental receptors must be identified. The worst case release is defined by the U.S. EPA as the total release of the contents of the single largest vessel or pipe within 10 minutes. For liquefied gases stored under pressure, the entire contents of the vessel or pipe are assumed to be released as a vapor. A total vapor release is highly unlikely. However, this standardized worst case scenario was developed for emergency response agencies to use for planning purposes. An alternative release scenario is a release that is more likely to occur than the worst-case release scenario. For Mid-Set Cogeneration Company, the alternative release scenario was selected based on the results of the Hazard and Operability Study for the ammonia-based SCR process. The worst credible release event with the highest discharge rate would potentially have the greatest offsite im pact. A failure of the ammonia delivery hose was identified in the Hazard and Operability Study as the worst credible release event having the highest release rate, and therefore, was chosen as the alternative release scenario. Mid-Set Cogeneration Company has analyzed the offsite consequences of the worst-case and alternative release. For the worst-case release scenario, the release of 69,960 lbs. of ammonia within 10 minutes, the plume would travel 3.1 miles at concentrations at or above the endpoint. Using 1990 Census data, the population potentially affected within the worst-case release scenario circle is 58. There were no sensitive or environmental receptors within the worst case release scenario circle. In the alternative release scenario, a failure of the delivery hose was modeled as a release of liquefied ammonia stored under pressure. For a release of 554 lb/min of anhydrous ammonia, the plume would travel 0.2 mile at concentrations at or above the endp oint. No residences are located within the 0.2 mile area around the Mid-Set Cogeneration Company facility. As such, there would be no population impacts from the alternative release scenario. There were also no sensitive or environmental receptors within the alternative release scenario circle. The modeling performed as part of this offsite consequence analysis does not take into account the use of the remote operated shutoff valves that were installed at the ammonia tank. These isolation valves take approximately 10 to 15 seconds to fully close and could greatly reduce the impact of a hose failure release. General Accidental Release Prevention Program and Chemical-Specific Prevention Steps A PSM program, which meets the requirements of the general accidental release prevention program, has been developed at Mid-Set Cogeneration Company to address the anhydrous ammonia system. The PSM program includes the following chemical-specific prevention steps: Written pro cess safety information, including information pertaining to the hazards of ammonia, the technology of the process, and the equipment in the process has been compiled. An initial Process Hazard Analysis (PHA) was performed and has been updated and revalidated at least every five years. Written operating procedures have been developed and implemented, and are reviewed at least annually. Safe work practices, such as lockout/tagout, confined space entry, opening process equipment or piping, and control over entrance into the facility have been developed and implemented. Each employee involved in operating the ammonia system has received initial training and refresher training at least every three years. Written mechanical integrity procedures have been established and implemented. A Management of Change (MOC) program has been developed and implemented to address all proposed changes to the ammonia system. Pre-startup safety reviews are performed when a modifi cation is made to the ammonia system that is significant enough to require a change in the process safety information. Audits are conducted at least every three years to evaluate compliance with the RMP regulations. Incident investigation procedures have been established. A written plan of action regarding the implementation of employee participation has been developed and implemented. Hot work permits are issued for all hot work operations conducted on or near the ammonia system. A Contractor Safety Policy has been developed and implemented. To ensure that the general accidental release prevention program and the chemical-specific prevention steps are implemented, Mid-Set Cogeneration Company has assigned overall responsibility for the RMP elements to the Executive Director. The Executive Director has the overall responsibility for the development, implementation, and integration of the RMP elements. Five-Year Accident History Mid-Set Cogeneration Company h as not had any accidental releases from the ammonia-based SCR system that have resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage in the last five years. Emergency Response Program Mid-Set Cogeneration Company has established an emergency action plan and a chain of command to respond to emergencies and to notify emergency responders when there is a need for a response. However, an emergency response program does not need to be developed for the facility since Mid-Set Cogeneration Company employees will not respond to accidental releases of ammonia, the facility is included in the community emergency response plan, and appropriate mechanisms are in place to notify emergency responders. Planned Changes To Improve Safety The PHAs were most recently revalidated in March, 1996. Several changes to inspection and offloading procedures were recommend ed based on the PHA revalidation. These changes were implemented by March, 1998. Through the accidental release prevention program, Mid-Set Cogeneration Company regularly evaluates the need for any changes to improve safety. Currently Mid-Set Cogeneration Company does not have any additional changes planned to improve safety. |