Mojave Cogeneration Company - Executive Summary |
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Mojave Cogeneration Company (MCC) is required to comply with Section 112(r) of the Clean Air Act, which requires facilities with acutely hazardous materials or flammable materials over the regulatory threshold to prepare a Risk Management Plan (RMP). MCC stores up to 10,500 gallons of anhydrous ammonia, an acutely hazardous material on site at any given time. This amount is over the 10,000 lb threshold. MCC originally prepared a Risk Management and Prevention Program (RMPP) in 1989 pursuant to California regulations and has complied with OSHAs Process Safety Management (PSM) program. Both of these programs are similar in most respects to the Clean Air Act RMP program. Accidental Release Prevention and Emergency Policies MCC has a commitment to environmental compliance. As part of this commitment, MCC: 7 Developed environmental policies, standards and procedures, 7 Developed auditing procedures, 7 Established procedures to monitor regulatory requirements, 7 Established incentiv e and disciplinary programs, and 7 Promotes continuous improvement. Relative to compliance with the RMP program, MCC has a ten-year history of successful compliance with the existing California Risk Management Prevention Plan (RMPP) and the OSHA PSM program. Successful compliance has been a result of adherence to the above programs and future compliance is anticipated based on this formula. Facility and Regulated Substances MCC owns and operates a 55-megawatt cogeneration facility, referred to as the Mojave Cogeneration Plant (MCP), at the U.S. Borax boron mine and refinery in southeastern Kern County. The MCP began operation in 1990. U.S. Borax personnel, under an Operation and Maintenance Agreement, perform the day-to-day operation. MCC provides steam for the U.S. Borax mine and refinery. Ammonia is used to reduce the nitrous oxide emissions, which improves air quality. The emissions control operations include storage and handling up to 10,500 of anhydrous ammonia, a substa nce that the Environmental Protection Agency (EPA) has identified as an acutely hazardous material. The Federal and State of California governments have established a program for reducing the hazards associated with the storage and handling of such materials. The program was initiated by the Clean Air Act Amendments of 1990, Title III, Section 112(r) and codified in 40CFR Part 68. The California Accidental Release Program (CalARP) pursuant to Sections 25531 through 25543.3 of the Health and Safety Code has added additional regulations. As part of this program, MCC is required to prepare a Risk Management Plan (RMP) for its anhydrous ammonia storage and handling facilities. In an RMP, a facility reviews its processes, equipment and procedures in order to identify steps that could reduce the likelihood or consequences of a release of an acutely hazardous material. MCC requested the assistance of AVES, an affiliate of ATC Associates, Inc. (AVES) in preparing the RMP. The Worst-Case Release Scenario and the Alternate Release Scenario An RMP must consider the results of the following: 1. A hazard and operability study that identifies the hazards associated with handling an AHM due to operating error, equipment failure, and external events that may present a risk of an accident involving an AHM. 2. An off-site consequence analysis that assumes pessimistic air dispersion parameters, and other adverse environmental conditions for the worst case scenario and an alternative release scenario. A hazard and operability (HAZOP) study was completed at the MCC on July 30, 1998 for the RMP process. The hazards and operability study was conducted using two models: the "HAZOP" method was used for the ammonia delivery system, and the "what if" method was used for the ammonia storage tank operations. The basic events, which could lead to potential off-site impacts, are corrosion failure, external event, and on-site accidents. The worse-case and alternate r elease scenarios were developed from these studies. The off-site consequence analysis (OCA) requires analysis of two release scenarios: worst-case and an alternate release scenario. The worst-case release scenario, according to the RMP Requirements, must consider a release that empties the content of the ammonia system in a ten-minute period. This scenario does not take into account whether or not the release is probable. The alternative release scenario is designed to investigate the worst-case release that could happen within the lifetime of the facility. This scenario takes into account the combination of frequency and severity. The maximum capacity of the ammonia storage tank is 12,000 gallons. Written operating procedures and a high-level alarm prevent more than 10,500 gallons from being present in the 12,000 gallon tank. Generally, federal law restricts the level to 82 percent by volume. However, the law allows a tank to be filled to 87.5 percent to volume provided that 1) the ammonia temperature during filling remains above 300F or 2) the tank filling is stopped at the first sign of frost or ice formation on its outside surface and is not resumed until the frost or ice has disappeared. The high-level alarm is set at approximately 86 percent level by volume (10,300 gal). Both the worst-case and alternate release scenarios were completed according to the EPAs OCA Guidance with RMP*Comp. RMP*Comp is an electronic tool used to perform the off-site consequence analysis required under the Risk Management Program rule published by the Environmental Protection Agency on July 20, 1996, which implements Section 112(r) of the Clean Air Act. Both the OCA Guidance and RMP*Comp are available to the public and can be downloaded from the EPAs Chemical Emergency Preparedness and Prevention Office web site at http://www.epa.gov/ceppo. Worst Case Release Scenario Catastrophic release of ammonia from the storage tank. This scenario could result from a number of potential "accidents". While none of the accidents leading to this release were of high frequency, it was judged the most credible worst case. Alternative Release Scenario Release of the entire ammonia contents of the tank through an ammonia line pipe sheared near the tank. This scenario corresponds to a high flow scenario. Of the two scenarios modeled, the scenario with the worst off-site consequences extended the vulnerability zone to 6.4 kilometers from the facility. The worst case scenario would affect 2,100 residential receptors in Boron at a level above the CAAA Title III endpoint level of 140 mg/m3 (Based on 1990 U.S. Census data) and a conservatively estimated 1,000 residential receptors in Desert Lake. In addition, there would be a middle/high school in Boron and an elementary school in Desert Lake with combined populations of 650 students and 100 faculty (divided evenly between the two schools) that would be affected. No day care centers or hospitals were listed within the vulnerability zone. In addition, there were no official desert tortoise or other protected species habitat boundaries located within the vulnerability zone. No residential or sensitive receptors would be affected by the alternative release scenario, for which the vulnerability zone would extend approximately 0.60 kilometers from the facility. Boron is located to the southeast of the facility at a distance of approximately 5 kilometers. Desert Lake is located directly south of the facility at a distance of approximately 3 kilometers. General Accidental Release Prevention Program and Chemical-Specific Prevention Steps MCC complies with both the Federal/State RMP requirements, and OSHAs Process Safety Management (PSM) Program (Section 1910.119 of Title 29 of CFR or Section 5189 of Title 8 of CCR). Many parts of the PSM standards have been incorporated into the RMP regulations. MCC has employed engineering and administrative controls to contain or reduce ammonia relea sed. Engineering and Administrative Controls Engineering controls include equipment compatible with anhydrous ammonia, interlocks, electronic process monitoring, control instrumentation with alarms, ammonia sensors and water hoses. Administrative controls include: health and safety and process training for all employees, contractors and visitors, procedures for different aspects of operation, record keeping, proper installation of equipment, regular inspection, repair and maintenance for all equipment in used of anhydrous ammonia. The guardhouse controls all entry to the facility and personnel supervise any contractors and visitors. The Five-Year Accident History No accidental releases of ammonia have occurred during the lifetime of the plant. The Emergency Response Program MCC has coordinated with the Kern County Fire Department, the local emergency responders. MCC personnel are trained to report all releases to local emergency responders and to follow instructions from the responders. Planned Changes to Improve Safety As a result of the process hazard analysis the following modifications were suggested at the HazOp in July of 1998: 1. Add additional posts to the side of the tank closest to the control room. All other sides are protected from automobiles and forklifts. 2. Add post to protect the vaporizer from potential damage from forklifts. 3. Protect the pipe from the ammonia tank to the boiler structure. The following changes were completed in March of 1999: 1. Additional posts were added to the side of the tank closest to the control room. 2. A post was added to protect the vaporizer from potential damage from forklifts. 3. A support structure was added to protect the pipe form the ammonia tank to the boiler structure. |