South Atlantic Facility - Executive Summary |
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Source and Process Description. The main operation at New Orleans Cold Storage is the warehousing and distribution of frozen bulk foodstuff. The facility consists of several cold storage rooms that are cooled by a main refrigeration system. An additional "blast" unit is used to maintain one room at very low temperatures (-30 degrees F.) Both refrigeration units utilize Anhydrous Ammonia (100% conc.) as the system coolant. The main refrigeration unit has a maximum capacity of 10,000 pounds of ammonia. The blast unit has a maximum capacity of 5,000 pounds. At this facility, both systems are independent. Summary of Major Hazards. The primary hazard associated with a release of Anhydrous Ammonia is exposure of persons and sensitive environmental areas to toxic levels of ammonia vapor. Anhydrous Ammonia is a toxic gas that is also a corrosive irritant to eyes, skin, respiratory tract and mucous membranes. Contact of evaporating liquid with skin will freeze the tissue, then produc e a caustic burn. However, the burn hazard should be considered secondary to the toxic effects from exposure to the gas. The toxic endpoint for Anhydrous Ammonia has been determined to be 200 parts per million (ppm). It is defined as the concentration that almost all persons can withstand for one hour without permanent adverse effects. However, aggravation of existing respiratory and skin diseases may occur at concentrations below the toxic endpoint. Consequences of Failure to Control the Hazards. Although the release of all the Anhydrous Ammonia (10,000 pounds) within a 10 minute period (considering a catastrophic failure of the main receiver) is extremely unlikely, these are the parameters used in the worst case scenario. In this case, the toxic endpoint was calculated to be 0.9 miles. Based on an interpretation of the USGS map, it is estimatedthat a maximum of 1,000 people reside within the vulnerable zone. The alternative scenario is based on an actual incident at anothe r facility at which approximately 2,500 pounds of ammonia was released into a cold storage room. In this alternative scenario, 3,000 pounds of ammonia is released within 30 minutes. The toxic endpoint is calculated to be 0.1 miles. At this distance, the residential population is essentially zero. There are no designated environmental management areas within the worst case vulnerable zone, however, Philbin Creek and associated marshlands are located to the South of the facility within the vulnerable zone. Explanation of How Releases are Prevented The primary mitigation system for this facility is the Engine Room enclosure. Although a catastrophic release would have ample opportunity to be vented to the atmosphere, the engine room enclosure would provide a significant degree of isolation in the more likely release scenario. An active countermeasure to any leaks or releases is the ammonia sensors in the engine room. If ammonia is detected, an audible alarm is immediately sound ed within the warehouse and an alert is sent to a 24 hour/day monitoring service. Other process controls include automatic cut-off devices in the event of deviation from prescribed limits (pressure, temperature, process level, etc.), check valves and relief valves. To further reduce the likelihood of an accidental release, an extensive inspection program has been established for all system components and operating parameters. This includes a daily inspection of compressors, pumps and associated equipment, and a weekly, monthly and annual inspection and maintenance schedule that is rigidly followed, ensuring a well-maintained physical plant. All operating procedures have been recently reviewed/revised and all personnel responsible for the proper operation of the refrigeration units have received refresher training in the procedures. These elements of this program will further reduce the possibility of an accidental release caused by human error. Steps Taken to Address Hazards. Th e primary methods for generating recommendations are through periodic review and/or revision of Process Hazard Analyses (PHAs), incident investigations and operational procedures review (Management of Change). These reviews provide a means for continuous improvement. As an example, in response to a recommendation from an incident investigation report from another facility, two sets of impervious body suits and self-contained breathing apparatus (SCBA) are positioned at all NOCS facilities. All engineers are trained in the use of this equipment as an enhanced way of personnel rescue, release response and rapid control. Response Action in the Event of a Release. Upon initial discovery of a leak or release, whether by sensor and alarm or personnel, a rapid and decisive response is critical to minimizing the potential impacts to off-site populations and other sensitive areas. As noted above, on-site control and mitigation, along with personnel evacuation and accountability, is coupled with a rapid notification plan to bring in local and state agencies for assistance in the event the local population may potentially be affected. |