The Stroh Brewery Company Portland - Executive Summary |
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EXECUTIVE SUMMARY The Stroh Brewery Company stores ANHYDROUS AMMONIA at the Blitz-Weinhard brewery in an amount that exceeds the threshold established by EPA for Risk Management Planning. The Stroh Brewery Company believes that risks associated with ANHYDROUS AMMONIA storage at this facility are well managed. SOURCE AND PROCESS DESCRIPTION Refrigeration is a critical component of malt beverage production. Refrigeration is required for chilling water and beer, and for controlling air temperature in beer storage cellars. Refrigeration is provided through the evaporation of liquid anhydrous ammonia by a heat source. Evaporated ammonia gas is contained in a closed loop system where it is mechanically compressed back into a liquid state and stored for re-use on demand. Liquid ammonia is moved by system pressure from storage through piping to locations where refrigeration is needed. SUMMARY OF MAJOR HAZARDS Ammonia is a hazardous substance. As a gas, it is severely irritating to the eyes and to moist skin and mucous membranes. As a liquid, contact can cause freezing and third degree burns. Exposure to high concentrations of ammonia gas or vapor (approximately 2,500 to 6,500 ppm) for up to two hours can induce chemical pneumonitis; burns to eyes, face, and mouth; severe local edema (fluid in lungs); and death after 30 minutes. The consequence of equipment failure or improper control of refrigeration system temperature and pressure could be a sudden release of ammonia. In the refrigeration system, ammonia is stored as a liquid under pressure, then evaporated into a low pressure gas state as it cools its intended heat source, then compressed into a high pressure gas state, and then condensed by cooling water once again into a liquefied state and returned to storage. Accidental release of ammonia could occur during any of these system processes. An accidental release of liquid ammonia under elevated pressure would create an airborne mixture of ammonia vapor and very fine liquid droplets that would not fall to the ground. The droplets would entrain air quickly as they tried to evaporate. Evaporation of the droplets would cool the air creating a cold mixture of air and ammonia vapor. The mixture would be denser than air forming a cloud that would tend to stay at ground level until evaporation to a gas was complete. A release of liquid ammonia inside a building would cause an initial overpressure condition due to flash vapor expansion and underpressure condition due to air cooling from droplet interaction. Instantaneous over- or under- pressure greater than 1 pound per square inch (psi) could cause explosion effects such as structural damage to windows and blowout panels; greater than 2 psi could cause explosion effects such as shattering of concrete or cinder block walls. In addition, ammonia can be explosive at concentrations between 15% and 25% by volume in air with ignition by a high intensity source. An accidental release of gaseous ammonia vapor at various temperature and pressure would create a buoyant ammonia jet less dense than air. The rate of release would be much less than that of liquid ammonia. CONSEQUENCES OF FAILURE TO CONTROL THE HAZARDS EPA has established a toxic endpoint value of 200 ppm as the maximum airborne concentration below which an individual could be exposed for up to one hour without experiencing serious health effects or symptoms that would impair the ability to take protective action. A worst case release scenario at the facility is defined as the release of 5,860 pounds of liquid anhydrous ammonia from a liquid storage receiver which represents the largest single container at the facility. The effect of being enclosed inside a building reduces the rate of release to 322 pounds per minute. According to a computer program (RMP Comp) an accidental release of 5,860 pounds of ammonia within a 10-minute period would reach the toxic endpoint at a distance of 0.7 miles. According to a 199 1 Bureau of Census computer database (Landview III), the worst case release would affect a population of 11,000 people, residences, schools, hospitals, public recreation areas, and commercial, office, or industrial areas within this radius. A more likely alternative release scenario at the facility is defined as a 1/2-inch diameter leak in ammonia manifold piping within a 10-minute period. Safety shutoff valves would activate in this instance as a release control. The ammonia system operating pressure is 130 psi and at this pressure the release rate would be 450 pounds per minute for a 1/2-inch diameter hole. The effect of being enclosed inside a building reduces the rate of release to 248 pounds per minute. According to a computer program (RMP Comp) a release of 248 pounds of ammonia for 10-minutes would reach the toxic endpoint at a distance of 0.1 miles. According to a 1991 Bureau of Census computer database (Landview III), the more likely alternative release would affect a po pulation of 160 people, residences, and commercial, office, or industrial areas within this radius. In either release scenario, release would not affect any environmental receptor such as a park, forest, monument, wildlife sanctuary, preserve, refuge, or Federal wilderness area. 5-YEAR ACCIDENT HISTORY There has not been any accidental release of ammonia from the refrigeration system since 1994 that caused any of the following: * on-site death, injury, or significant property damage; * known offsite death, injury, property damage, environmental damage, evacuation, or sheltering in place. EXPLANATION OF HOW RELEASES ARE PREVENTED Overall responsibility for coordination of the Ammonia Refrigeration System Risk Management Plan is assigned to the Manager of Plant Engineering. Utilities and Brewing Maintenance Supervisors, Operating Engineers, and Electrical and Mechanical Maintenance employees perform operation and maintenance of the refrigeration system. Each of these key personnel i s aware of the provisions of the Ammonia Refrigeration System Risk Management Plan and has contributed to the construction of the plan, the components of which are as follows: * Maintenance Good engineering practices, equipment manufacturer's recommendations, and operating experience determine the means for system inspection, testing, and preventive maintenance. Routine maintenance functions include: - periodic walk-throughs to find unusual or increasing vibration, incipient leaks, or other indication of potential failure that could lead to a release; - inspection of pressure vessels by State certified Factory Mutual Insurance engineers and pressure vessel inspectors; - periodic inspection and maintenance of pressure relief valves; - periodic inspection and calibration of liquid level, temperature, and pressure instruments, sw |