United Dairymen of Arizona - Executive Summary |
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EXECUTIVE SUMMARY Accidental Release Prevention and Emergency Response Policies United Dairymen of Arizona (United Dairymen) utilizes anhydrous ammonia in two of the refrigeration systems at their milk processing plant in Tempe, Arizona. It is United Dairymen's policy to comply with all applicable governmental regulations. Additionally, an emergency action plan has been prepared for United Dairymen and a chain of command to respond to emergencies has been established. Description of the Stationary Source and Regulated Substances United Dairymen owns and operates a fluid milk processing facility located at 2008 South Hardy Drive in Tempe, Arizona. At United Dairymen, anhydrous ammonia is utilized as the refrigerant in two refrigeration systems. These refrigeration systems supply process cooling for the ice makers and for the plate and frame heat exchangers for the chilled water and chilled glycol systems. The system which services the ice makers consists of two ammonia rece ivers, evaporative condensers, a screw compressor and oil cooler, reciprocating compressors, and suction accumulators. The major components of the second refrigeration system are an ammonia receiver, an evaporative condenser, a compressor and oil cooler, and a thermosyphon vessel. During normal operations, the anhydrous ammonia is distributed throughout each refrigeration system. However, during major maintenance activities on either system, the system being worked on can be "pumped down" to evacuate the ammonia from the system and stored the ammonia as a liquid in the receiver. The maximum quantity of ammonia that can be stored in the largest receiver is 7,400 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 max imum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible 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 United Dairymen's ammonia-based refrigeration systems are 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 scenario. This area is defined as a circle with a radius equivalent to the distance the release would travel with concentrations at or above the endpoint. The 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 United Dairymen, the alternative release scenario was selected based on the results of the Process Hazard Analysis (PHA) for the ammonia- based refrigeration systems. A credible release event with a high discharge rate would potentially have the greatest offsite impact. A release while draining oil from the ice banks or the suction accumulators was identified in the PHAs as the credible release event having a release rate high enough to cause an offsite impact, and therefore, was chosen as the alternative release scenario. United Dairymen has analyzed the offsite consequences of the worst-case and alternative release scenarios. For the worst-case release scenario, the release of approximately 7,400 lbs. of ammonia over a 10 minute period, the plume would travel 1.0 mile at concentrations at or above the endpoint. Sensitive receptor information is provided in RMP*Submit. Using 1990 Census data, the population potentially affected within the worst-case release scenario circle is 12,000 people. There are no environmental receptors within the worst case release scenario circle. In the alternative release scenario , the oil drain release was modeled as a release of liquefied ammonia stored under pressure. For a release of 74 lb/min of anhydrous ammonia, the model calculated that the plume would travel 0.1 mile at concentrations at or above the endpoint. The alternative release scenario circle includes the nearby industrial facilities, commercial businesses, and roadways. Based on observations of the area, there are no residences or sensitive receptors within 0.1 mile of the facility. Therefore, there would be no population impacts due to the alternative release scenario. Also, based on a review of the U.S.G.S. maps, there are no environmentally sensitive receptors that would be affected by the alternative release scenario from the United Dairymen facility. 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 United Dairymen to address the anhydrous ammonia system. The PSM program includes the following chemical-specific prevention steps: Written process safety information, including information pertaining to the hazards of ammonia, the technology of the process, and the equipment in the process has been compiled. Initial Process Hazard Analyses (PHAs) were performed and will be updated and revalidated at least every five years. Written operating procedures have been developed and implemented, and will be 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 pr oposed changes to the ammonia system. Pre-startup safety reviews will be performed when a modification is made to the ammonia system that is significant enough to require a change in the process safety information. Audits will be 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, United Dairymen has assigned overall responsibility for the RMP elements to the Director of Operations. The Director of Operations has the overall responsibility for the development, implementation, and integration of the RMP elements. Five-Year Accident History United Dairymen has not had any accidental releases from the ammonia-based refrigeration 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 United Dairymen 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 United Dairymen 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 Based on the PHAs performed in June, 1999, no changes were recommended. Through the accid ental release prevention program, United Dairymen regularly evaluates the need for any changes to improve safety. Currently, United Dairymen does not have any additional changes planned to improve safety. |