Wyoming Refining Company - Executive Summary |
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This Risk Management submission for Wyoming Refining, Newcastle, Wyoming complies with the EPA Risk Management Program 40 CFR 68 as well as the OSHA Process Safety Management Program 29 CFR 1910.119. This submission treats the Refinery as a single process. The Risk Management and Process Safety Management Programs for the Refinery are applied uniformly to each operating unit as refinery-wide accidental release prevention programs. The Refinery is in compliance with both prevention programs and conducts reviews and updates of each program in order to certify and assure continuing compliance. Both programs require the Refinery to implement practices and procedures for accidental release prevention. These procedures include operator training and certification, standard operating and emergency operating procedures, emergency notifications, equipment maintenance and inspection procedures, process hazards analysis and hazards mitigation in equipment design and operation, management of ch anges to equipment, operating and maintenance procedures, emergency procedures, and emergency notification for additional public risk reduction. The Refinery must also adhere to recognized safe equipment design, materials design, and engineering standards. All of these elements of the Refinery risk management and release prevention programs are designed to limit the possibility of accidental releases of toxic or flammable materials and minimize effects of Refinery operations on the general public and its employees from injuries, fatalities, and property damages. The Refinery has a single toxic substance in excess of RMP reporting thresholds. Anhydrous hydrogen fluoride is used as a catalytic agent in the HF Alkylation process for the production of gasoline from isobutane and olefins. The HF Alkylation process has been used for decades by the petroleum refining industry in the production of gasoline with few accidental releases. Wyoming Refining has never had a significant release o f hydrogen fluoride from the alkylation unit and has had no reportable incidents or accidents involving the Alkylation unit during the last five years. The Alkylation unit is equipped with a water deluge system, which can be activated in the event that a release of hydrogen fluoride is detected. This emergency system mitigates the toxic effects of hydrogen fluoride gas by dissolving the gas in sufficient water to prevent dispersion of the gas to the atmosphere. This system is tested twice monthly in summer months to assure its reliable operation. In addition to the single toxic substance, the Refinery has inventories of butane, isobutane, butylenes, and propane, all flammable gases. Wyoming Refining has not had a flammable or explosive release of any of these materials during the last five years. The liquefied gases are held in pressure storage with water sprinkler systems for fire control. The worst-case scenario described in this submission for hydrogen fluoride is based on a 10- minute release of the reactor contents. Since the hydrogen fluoride in the reactor is a liquid under pressure, the released contents will flash into a small fraction of vapor and a larger quantity of cooled liquid. The vapor will be dispersed into the atmosphere, while the liquid will form a pool and more slowly evaporate and disperse into the atmosphere. Although the release is prescribed by the regulations to occur within 10 minutes as a near instantaneous release, the majority of the release is as a liquid, which evaporates and disperses more slowly over a period of up to two hours. The physical state of the in-process hydrogen fluoride naturally mitigates its dispersion and potential impact on the public even in the slow dispersion prescribed by low wind speed and low atmospheric mixing prescribed for evaluating the worst-case accidental release. The Alkylation unit is equipped with a high-volume water deluge system which captures released hydrogen fluoride by absorption and dilution in water, this preventing atmospheric dispersion. The water deluge system will prevent upwards of 95% of the release hydrogen fluoride from being dispersed downwind. The worst-case scenario prescribed by EPA presumes that this active mitigation system is not used as an emergency response measure. The toxic endpoint, that is, the air-borne concentration of hydrogen fluoride specified for evaluating public exposure by EPA is five percent of that which is suspected to possibly cause potential fatalities. The worst-case release scenario evaluated for this submission has a radius of public concern of 3.42 miles centered on the Refinery. Calculations with EPA dispersion models show that the potential fatality radius for the worst-case scenario is much smaller, 0.48 miles in the worst-case case atmospheric conditions. The alternative toxic case, that is, the case of accidental release, which is thought more likely to occur, based on historical industry data, is a reactor leak fr om a small equivalent diameter source. The alternative release, evaluated at more realistic atmospheric conditions which are favorable for atmospheric dilution, shows that the toxic endpoint will occur at a much smaller radius, 0.20 miles, with the radius of potential fatality limited to 164 feet from the source. It is likely in the event of a realistic release of hydrogen fluoride that potentially fatal effects of a release will be restricted to the Refinery grounds. The Refinery has four flammable materials in excess of RMP reporting thresholds: propane, normal butane, isobutane, and butylenes, all stored as liquefied gases. Of these, isobutane has the greatest potential for offsite effects in the event of an accidental release. Isobutane is stored in pressure storage vessels. Wyoming Refining has not had a significant accidental release of isobutane or any reportable incidents involving stored isobutane during the last five years of this report. The EPA worst-case accidenta l release scenario prescribes that the contents of a pressure storage vessel are emptied to the atmosphere during a 10-minute period. If the isobutane is released as a vapor cloud and subsequently ignited, the resultant explosion at an overpressure of 1 pound per square inch could cause significant damage and possible injuries at a distance of 0.50 miles. Since the isobutane storage vessels are located in an area that is relatively inaccessible it is unlikely that this scenario could be initiated through a catastrophic vessel failure. The Refinery considers that a limited release of isobutane from a small pipe leak equivalent to a one-half inch diameter hole would result in a fire that would potentially affect an area less than 0.1 mile from the source. Given the location of the isobutane vessels, this fire would likely have effects limited to Refinery property without offsite public impact. The pubic emergency response plan for a release of toxic or flammable materials is being developed in cooperation of the local emergency planning committee. Both the Refinery and the LEPC will develop plans for a public response to such an emergency. Emergency responses include public emergency notification, public evacuation or sequestration, as appropriate, and training of local police, fire, medical, and other emergency officials in handling, with trained Refinery personnel, a significant public emergency. The Refinery also trains and equips its personnel to handle leaks and fires that can affect employees and the public. Refinery personnel are considered the most important element in controlling and mitigating the effects of a process release. The Refinery is also conducting public awareness meetings to bring the potential for an emergency to public attention. |