Cassco #11 Marshville - Executive Summary |
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The Cassco Refrigerated Services facility located in Marshville, North Carolina manufactures ice for wholesale/retail distribution. The facility, operating on approximately 15 acres, utilizes approximately 26,000 pounds of anhydrous ammonia as a refrigerant within an enclosed system for ice manufacturing and storage. The Cassco Marshville facility refrigeration system is a standard refrigeration design using anhydrous ammonia as its refrigerant. The system has four compressors, two operating at -30 F and two operating at +10 F. Each of the compressors has numerous protective controls (motor overload, high discharge temperature, high discharge pressure, low suction pressure, and low oil pressure) that will shut down the compressor if operating limits are violated. The compressors are normally run and shut down through the computer. The compressors receive anhydrous ammonia gas from one of two refrigerant recirculators (V3 and V4), compress it, and discharge the hot, high pressure ammonia through oil separators to two condensers located on the roof of the facility. The forced-air-cooled condensers transfer the anhydrous ammonia's heat to the atmosphere and return the condensed (liquid) anhydrous ammonia to the high pressure receiver(V1). High pressure liquid anhydrous ammonia is then transferred to V2, V3, and V4. The liquid anhydrous ammonia is pumped at an approximate 2 to 1 ratio from the recirculators to the evaporators, through liquid flow regulators where the flashing anhydrous ammonia removes heat from the various areas. From the evaporators, the anhydrous ammonia gas and liquid combination returns to the recirculators to begin the refrigeration cycle over again. An outside supplier delivers anhydrous ammonia 1 to 2 times per year to replenish the ammonia in the system. Anhydrous ammonia, when properly used, has proven to be a safe and reliable refrigerant. The sharp odor of ammonia provides its own warning agent. Practically all accidents involvin g anhydrous ammonia are the result of a lack of knowledge, misunderstanding, carelessness or poorly maintained or unsuitable equipment. The Cassco Marshville facility is committed to operating a safe and compliant facility for the protection of its employees, the general public, and the environment. The facility has multiple safeguards pertinent to the ammonia process. These include an ammonia detection and alarm system, exhaust purge fans, controls which shut down the compressors if operating limits are violated, and the capability of shutting the entire system down if required. Administrative controls are in place which limit the utilization of vessels at approximately 50% of their intended capacities. The company has developed an emergency response and action plan which includes notification of emergency authorities/agencies and the public, to evacuation and first responder duties. MANAGEMENT SYSTEM The Cassco facility has developed a management system to oversee the impleme ntation of the risk management program elements. A single person has been identified that has overall responsibility for developing, implementing and integrating the risk management program requirements. There may be different levels of responsibility assigned, depending on the size and complexity of the facility. A Risk Management Coordinator may be responsible for developing and implementing the overall risk management program, while other personnel may be responsible for developing and implementing the operating procedures element or developing a particular operating procedure. The management system is, therefore, operating at each of these levels depending on the way these responsibilities are carried out. The Risk Management Coordinator is responsible for all aspects of the development and update of the overall Risk Management Program. The coordinator will determine the necessity of establishing additional responsibilities for facility personnel concerning various operations at the facility. As other personnel are identified, they will be documented and lines of authority will be defined within the management system. By defining the lines of authority and roles and responsibilities of staff that oversee the risk management program elements it will: Ensure effective communication about process changes; Clarify the roles and responsibilities related to process safety issues; Avoid problems or conflicts among the people responsible for implementing elements of the program; and Ensure that the program elements are integrated into an ongoing approach to identifying hazards and managing risks. Management commitment to process safety is critical in the facility's risk management program. For process safety to be a constant priority, the facility will remain committed to every element of the risk management program. To maintain an integrated approach to managing risks, each RMP rule element will be implemented on an ongoing, daily basis and become a part of the way the facility operates. Risk Management Coordinator: Steven Helms Title: Maintenance Engineer Additional Responsible Personnel: None at this time. HAZARD ASSESSMENT As required by the Risk Management Program regulations, the Cassco Marshville facility has conducted offsite consequence analyses relative to the potential accidental release of anhydrous ammonia. The scenarios related to a worst case release scenario and an alternative release scenario. This involved calculating worst case and alternative scenarios utilizing the RMP*Comp modeling program. The facility considered worst case release scenarios relating to the V4 recirculator vessel within the enclosed ammonia system, as it would house the largest mass of a regulated substance at any given time. The release model considered the potential release of 10,700 pounds of liquid ammonia from the vessel, during a 10 minute release. The scenario endpoint was 0.5 mile. This scenario generated a toxic endpoint of 200ppm, the maximum airborne concentration below which it is believed nearly all individuals can be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms which could impair an individuals ability to take protective action. Alternative scenarios, or potentially more likely scenario, for the facility system were considered and it was determined that there is a potential loss of ammonia due to the loss of the recirculator pump line at the base of the V4 vessel. The potential release assumed the breaking of a 4" line and the release of 10,400 pounds of ammonia. The predicted distance to the 200 ppm endpoint is 0.2 mile. |