Nashville Product Supply Center - Executive Summary |
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The Nashville Product Supply Center is a food distribution warehouse that contains refrigerated areas for perishable items. The refrigerated areas of the warehouse are cooled by two separate anhydrous ammonia refrigeration systems. Anhydrous ammonia, a substance regulated by EPA, is one of the most economical refrigerants available. However, the properties of ammonia makes it necessary to observe certain safety precautions while operating the refrigeration system to prevent employee exposure, and to reduce the threat of exposure to nearby members of the community. The Nashville Product Supply Center has chosen to follow the EPA's Chemical Accident Prevention Rule, Program Level 3, to prevent a release of ammonia from the refrigeration system. The amount of ammonia estimated to be contained inside the cooler refrigeration system is 5,000 pounds, and the freezer refrigeration system contains 5,000 pounds. The Nashville Product Supply Center complies with EPA's Accidental Release Pr evention Rule, and applicable state codes and regulations to prevent a catastrophic release of ammonia. The ammonia refrigeration systems have also been constructed according to the International Institute of Ammonia Refrigeration guidelines (IIAR). The operators are required to complete a training and certification program to operate the ammonia refrigeration systems. The Accidental Release Prevention Program does not guarantee against an accidental release. An offsite consequence analysis was completed using a computer model to simulate a release of the ammonia from the refrigeration system. The worst case scenario considered the loss of the total charge of 5,000 pounds of anhydrous ammonia in the refrigeration system over a 10 minute period. The analysis showed that the ammonia vapor could travel approximately 1,741 yards, or 5,223 feet. There are approximately 5,800 residents that could be affected in the identified radius. There are sensitive populations and public recepto rs in the potentially affected area. The alternative release scenario, which is the most likely scenario, considered a release of ammonia from a broken line inside the building. A release of 1,500 pounds of ammonia over a 10 minute period was considered. The computer model showed that the ammonia vapor could travel approximately 242 yards, or 726 feet. There are approximately 250 residents, and public receptors (industrial/commercial buildings) in the potentially affected area. No administrative controls or mitigation measures were used to limit the chemical release distances for either scenario. A full copy of the offsite consequence analysis is included in Appendix A. The Nashville Product Supply Center has an established Emergency Response Plan to respond to accidental ammonia releases. The plan was developed in accordance with 29 CFR 1910.120 HAZWOPER Emergency Response Plan. The plan requires Fleming associates to exit the facility during a fire or ammonia release to a sa fe area. The emergency agencies will be notified of the emergency. The emergency agencies will notify any potentially affected neighbors. Fleming maintenance associates on the emergency response team have been trained to respond and assist the local emergency agencies with anhydrous ammonia emergencies at the Nashville Product Supply Center. The plan also addresses natural hazard emergencies, fires, bomb threats, civil disturbances, and utility outages. This location has experienced one ammonia release in the past 5 years from the freezer refrigeration system. A rupture occurred in the system and caused a total charge of 5,000 pounds of ammonia to be released. This event occurred in November 1995, and caused no known onsite or offsite impacts. The Nashville Product Supply Center wanted to evaluate the potential failures of the refrigeration system, and if the safeguards were sufficient to prevent a catastrophic release of ammonia. A Process Hazard Analysis was completed on bot h refrigeration systems on July 28-30, 1997. Planned changes to improve safety resulting from this analysis are documented in the Process Hazard Analysis report in the Accidental Chemical Release Prevention Program. Also, the guidelines from the International Institute of Ammonia Refrigeration (IIAR) will be followed where applicable, to manage the refrigeration system. |