McCain Citrus, Inc. - Executive Summary |
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McCain Citrus, Inc., is engaged in the blending and packaging of a variety of natural fruit drinks in consumer-sized packages. The raw materials are kept refrigerated and finished products are kept frozen at reduced temperatures, and this requires a large refrigeration capacity. To supply the demand for this major refrigeration capacity, McCain Citrus operates an in-plant anhydrous ammonia refrigeration system consisting of six compressors, one common receiver, and associated pipes which carry the refrigerant to the appropriate storage and warehouse areas. This refrigeration plant was upgraded and expanded in 1995. McCain Citrus has long been committed to employee safety and being a good community neighbor. To this end, McCain Citrus maintains an active safety management program to prevent releases of ammonia. McCains overall approach to safety is to emphasize safe work practices and prevent accidents. A planned schedule of inspection and maintenance activities, augmented by worker training, is intended to prevent accidents and releases. In addition to the program of personal inspections, a system of automatic detection and alarm devices is employed to give early warning of releases. The detection system is integrated with off-site response providers, such as ADT. Senior management remains committed to a program of safety and safe procedures. Chemical safety is a serious responsibility at the level of Corporate Vice President, who directs the implementation of safe working procedures. The subject facility is located near the boundary of an industrial area and a residential area. The facility imports by truck a variety of juice concentrates and blends them into consumer products. Other materials such as packaging materials, pallets and wrapping and shipping materials are also brought onto the site. These liquids are kept refrigerated prior to final blending, and are kept frozen after packaging. They are shipped by truck to a number of locations for further distribution and consumer purchase. The refrigeration system is sized adequately for the amount of cooling needed, and is capable of holding 27,000 pounds of anhydrous ammonia in the system, which includes the compressors, condensers, receivers, and associated lines and chillers. All ammonia at the site is stored in the system. The worst case scenario is considered to be the rupture of the high-pressure receiver, which contains most of the ammonia at any given time. It is considered that this rupture would cause loss of all the ammonia in the system over a period of 10 minutes at a constant rate. The toxic endpoint is taken to be an ERPG-2 of 200 ppm for an exposure time of one hour, and was estimated at 1.95 miles from the source. The consequences are modeled in atmospheric stability category F weather conditions with a windspeed of 1.5 m/s. These assumptions are taken from the "Model Risk Management Program and Plan for Ammonia Refrigeration", prepared by Science Applications International Corporation, Reston, VA. These assumptions were adopted because of the significant cost of doing modeling studies that are site specific, and because the final conclusions were not likely to change significantly even though site-specific information was used. This scenario has off-site receptors. There are no active mitigation systems in use. Building enclosure was considered and dismissed as a passive mitigation system, as the enclosure is unreinforced cinder block construction, and not expected to withstand a 1 psi overpressure that is likely to occur on rupture of the high pressure receiver. The alternative scenario, one more likely to happen, is a gasket rupture or pump seal leak equivalent to a small orifice of diameter < to = inch. A typical rate of release would be 100 pounds/minute. Atmospheric Stability Category D with a moderate windspeed (e.g., 3 m/s) was chosen as close to average for many sites. The toxic endpoint of 450 feet was chose n from the model plan as typical of an urban site. This alternate scenario has off-site receptors. Passive mitigation to a release of 100 pounds/minute is considered to be the building in which the high pressure receiver and process piping is housed, because such a release would not be expected to inflict structural damage on the building housing the receiver. Such a release could be contained until automatic and manual shutoff systems could be activated. Responders could further mitigate the release by absorption in water from a fire hose, and neutralizing the resulting aqueous mixture with acids, or releasing the solution to the sewer. The facility complies with OSHAs PSM rule, and maintains a written Process Safety Plan onsite. The plan is augmented by employee training program, and a program of regular inspection and maintenance. There have been no accidents in the last five years. Moreover, McCain Citrus has operated the facility since 1984 without accidents. McCain Citrus personnel are trained to respond to minor releases and situations which are minor repair/maintenance problems. However, for major releases, the facility is integrated into the response plan of the local unit of the Chicago Fire Department. Facility personnel are trained in response actions which consist of minimizing damage to the facility while assisting the orderly evacuation of all personnel. Evacuation drills are conducted twice annually. McCains program of regular review and update of the PSM and Emergency Response Plan, employee training, routine inspections and regular maintenance has produced an accident-free history. The facility regularly evaluates and implements any appropriate measures to improve safety further. |