Nunes Cooling Incorporated - Executive Summary |
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EXECUTIVE SUMMARY Nunes Cooling's accidental release prevention policy involves a unified approach that integrates technologies, procedures, and management practices. All applicable procedures of the EPA Prevention Program are adhered to. Nunes Cooling Inc.' emergency response policy involves the preparation of response plans which are tailored to the facility and to the emergency response services available in the community. It is also in compliance with the EPA Emergency Response Program requirements. The Nunes facility in Yuma is utilized for cold storage of produce prior to shipment. The facility uses anhydrous ammonia as a refrigerant in this cooling process. Due to the operations of the facility, large amounts of anhydrous ammonia are required for refrigeration. The facility uses 64,600 lbs of anhydrous ammonia for refrigeration. The offsite consequence analysis includes consideration of two release scenarios for this process, identified as "worst case release scenari o" and "alternative release scenario." The first scenario is defined by the EPA, which states that "the owner or operator shall assume that the ... maximum quantity in the largest vessel ... is released as a gas over 10 minutes," due to an unspecified failure. The alternative release scenario is one that is "more likely to occur than the worst case release scenario." Atmospheric dispersion modeling has to be performed to determine the distance traveled by the toxic substance released before its concentration decreases to the "toxic endpoint" selected by the EPA (0.14 mg/L for anhydrous ammonia), which is the Emergency Response Planning Guideline Level 2 (ERPG-2). This is defined by the American Industrial Hygiene Association (AIHA) as the "maximum airborne concentration below which it is believed that nearly all individuals could be exposed for up to one hour without which could impair an individual's ability to take protective action." The residential population within a radius c orresponding to the toxic endpoint distance has to be defined, "to estimate the population potentially affected." The worst case release scenarios at Nunes Cooling Inc. involves failures of the lines and all mitigation systems for the ammonia process. Because the ammonia systems tanks, pipes, pumps, and equipment are within proximity of each other, the total amount of ammonia that potentially could be released would amass to approximately 64,600 lbs. The offsite consequence analysis for these scenarios were performed for two sets of conditions. The first set followed conditions pre-defined by the EPA, namely release of the entire amount as a gas in 10 minutes, use of the one hour average ERPG-2 as the toxic endpoint, and consideration of the population residing within a full circle with radius corresponding to the toxic endpoint distance. EPA set these conditions to facilitate the performance of the offsite consequence analysis; however, the assumptions used may be unrealistic bec ause: Only the population within an elliptical plume extending downwind of a release point is potentially affected. This plume, or footprint, is approximately 6% (one-twentieth) of the area of the full circle. It is not appropriate to compare a 10-minute release to a one hour average standard. The one hour ERPG value can be modified using available time of exposure/concentration relationships to match the ten minute release time. When atmospheric dispersion modeling for the worst case scenarios were performed using the EPA assumptions, a distance to toxic endpoint of 4.6 miles and an estimate of residential population potentially affected of 13,500 were obtained for an ammonia release. This result was due to the majority of Yuma and the surrounding area being encompassed. The alternative release scenarios involved the rupture of a tank or line possibly due to vehicular damage or vandalism. The amount of ammonia released for the facility was predicted to be 540 lbs/min and t he toxic endpoint distance from ERPG-2 was 0.4 miles. The toxic concentration levels outside these endpoint distances are below the allowable standards for toxic substances established by AIHA. The typical meteorological conditions used for these scenarios was a Stability Class D, wind speed 3.0 m/s, an average air temperature, and an average humidity. The general accidental release prevention program is based on the following key elements: High level of training of the operators. Preventative maintenance program. Use of state-of-the-art process and safety equipment. Use of accurate and effective operating procedures, written with the participation of the operators. Performance of a process hazard analysis of equipment and procedures. Implementation of an auditing and inspection program. No accidental releases of anhydrous ammonia have occurred at this facility in the past five years. The facility is subject to the Program 3 requirements for Federal regulations due to the following reasons: The distance to a toxic substance endpoint for a worst case release is greater than the distance to a public receptor. The facility Standard Industrial Code (SIC) Classification is 4222. The facility North American Industrial Classification System (NAICS) number is 115114. Processes are subject to the OSHA PSM requirements. The facility does possess in excess of the threshold quantities established for anhydrous ammonia. The facility has its own emergency response program. This program includes an emergency response decision tree and a notification plan. Emergency response drills and drill evaluations are not conducted, but emergency operations and response procedures are reviewed once a year. |