Purity Daries, Inc. - Executive Summary |
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THE ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES In this facility, we use Anhydrous Ammonia, which is considered hazardous by the EPA. This chemical must be used to provide cooling for the process and the areas. It is our policy to have programs in place dealing with safety precautions in handling these substances and to prevent unnecessary human exposure, to reduce the threat to our own personal health as well as our co-workers, and to reduce the threat to nearby members of the community. It is our policy to adhere to all applicable Federal and state rules and regulations. Safety depends upon the manner in which we handle ammonia combined with the safety devices inherent in the design of this facility combined with the safe handling procedures that we use and the training of our personnel. SOURCES AND PROCESS DESCRIPTION The Purity Dairies' manufacturing facility is in the business of processing dairy products. Anhydrous Ammonia is the refrigerant used for the cooling process due to the low cost of the medium and the low temperatures that must be obtained. The ammonia is enclosed within a closed loop that removes heat from the products and storage rooms. The ammonia is evaporated by the products and cooling areas by removing heat from the products at low temperatures and pressures and then dispensing of the heat at high pressures and temperatures to outside air. There are two ammonia systems at Purity Dairies (one for the milk plant and one for the ice cream Plant). The milk plant contains 20,264 pounds and the ice cream plant contains 16,217 pounds of ammonia in their refrigeration systems. SUMMARY OF MAJOR HAZARDS CONSEQUENCE OF FAILURE TO CONTROL HAZARDS Health Hazards Ammonia is a colorless gas with extremely pungent odor. Liquid ammonia vaporizes to a poisonous gas cloud. Ammonia is a severe irritant of the eyes. It penetrates the eyes more readily than any other alkali. Contact with liquid anhydrous ammonia and concentrate d solutions can produce severe eye injury or blindness. Exposure of the eyes to high gas concentrations can cause temporary blindness and severe eye damage. Laceration or watering of the eyes can occur upon exposure to 150 ppm ammonia gas and higher. Ammonia is an irritant by inhalation. At increasing concentrations it can cause symptoms ranging from runny nose, coughing, chest pain, trouble with breathing, and death. It can cause severe breathing difficulties that are delayed in onset. Inhalation of concentrations of 2500 to 6500 ppm causes shortness of breath, bronchospasm, chest pain, and pulmonary edema (filling of the lungs with fluid) that may be fatal. Exposure of the skin to liquid anhydrous ammonia or high concentrations of the gas can cause first and second degree burns of the skin. Vapor concentrations of 10,000 ppm are mildly irritating to moist skin, while 30,000 ppm or greater causes a stinging sensation and can produce skin burns and blisters. These high concent rations of ammonia are corrosive to moist skin and other moist body tissues. Physical Hazards Ammonia or ammonia with oil or other debris is an explosion hazard when exposed to flame or fire. The Lower Explosive Limit (LEL) is 16% and Upper Explosive Limit (UEL) is 25% by volume in air. Elevated temperatures can cause containers of the substance to explode. Ammonia emits toxic fumes when exposed to heat. When heated to temperatures above 8500F, ammonia will emit hydrogen gas. The auto ignition temperature is 12040F if catalyzed by iron. Ammonia can react to form potential violent or explosive reactions with halogens (e.g., chlorine, bromine). It can react to form potential violent or explosive reactions with strong oxidizers, hypochlorite bleaches, silver compounds, mercury compounds, gold, other metals, and acids. Common Exposure Control Methods o Process enclosure o Local exhaust ventilation o General dilution ventilation o Personal protective equipment o Use of water o Ar ea monitoring (with alarm systems) Potential for Exposure to Ammonia The refrigeration operation is a closed system with no purposeful exposure to ammonia. As a closed system, exposure potentials are primarily related to equipment failure, fugitive emissions from improperly adjusted or worn valve packing, pump and compressor seals and pipe connector gaskets, or mistakes in operation of the system. WORST CASE SCENARIO The worst case scenario for the Purity Dairies is the release of 10,000 pounds of ammonia from the system's largest vessel, the -280F accumulator, in a 10 minute period. The toxic endpoint was determined by using the Marplot/Aloha computer-modeling program. With a wind speed of 1.5 m/sec and a Stability Class of F in an urban topography the endpoint of the spill was determined to be .59 miles from the receiver. The plant site is located in the city of Nashville, Tennessee. The public receptors within a radius of .59 miles from the plant site are schools, resident s, and downtown office buildings with a population of 1554. In case of a major leak, passive mitigations in place are drains that go to a collection tank for the ammonia area. ALTERNATE CASE SCENARIO Alternate case scenarios for Purity Dairies were reviewed by the maintenance and operating sections. Considerations were given to the most probable cause of a leak within the system. The possible leak scenarios considered were: o Transfer hose rupture o Process piping failure o Process vessel or pump releases from seals, drains, bleeds o Rupture of a sight glass o Overpressure and release through relief valves After discussing these and the operations of the refrigeration system, it was decided that the rupture of a sight glass was the most probable cause of a leak within the system. Calculations were made considering the leakage of high-pressure ammonia liquid from the high-pressure receiver. The breakage would create a 0.5" orifice in the sight glass. At the system pressures, it was determined that a release rate of 180 lbs./min would be released for 7 minutes if this incident occurred. Wind speeds of 3.0 m/sec and a stability class of D were used. The toxic endpoint was determined to be .30 miles by using the Aloha/Marplot computer-modeling programs. The public receptors in this area would include residents and public recreational areas. The population of this area would be 666. There were no active or passive mitigation credits for this scenario. The Five Year History Purity Dairies had an ammonia spill of 980 pounds 2/3/97. An unloading truck backed into a pipe line on the Milk Plant Controlled Pressure Vessel. There were no deaths or injuries nor were there any property damages as a result of this incident. After investigating this incident, operating procedures were revised, a training program has been put into place and the piping has been guarded and replaced with a better design. Explanation of How Releases are Prevented Historically, e xposures to ammonia most often occur from: o Leaking valve stem packing glands while opening or closing a valve o Leaking at valve flanges or other piping connections o Pressurizing any equipment with sight glasses, especially the round type o Mistakenly venting gas through open equipment to the atmosphere o Malfunctioning pressure relief valves o Mechanical seal failures on compressors and pumps RELEASE PREVENTION PROGRAM AND PREVENTION STEPS Purity Dairies complies with the EPA's Accidental Release Preventative Rule with all applicable state codes and regulations for ammonia and propane. Management systems are in place to administer the RMP prevention programs for ammonia and propane. The Chief Engineer is the responsible person for leading this program. Purity Dairies Company is in compliance with OSHA's PSM rule for ammonia. The RMP's accidental release preventative program for ammonia is covered by the elements of the PSM program. Controls for the preventative programs ar e acquired by: o Effective preventative maintenance programs o Reviews for proper design o Development of and following operating procedures o A mechanical integrity program that includes equipment testing procedures o Training to be aware of potential exposure situations and using exposure prevention procedures and/or protective equipment. EMERGENCY RESPONSE PLAN This facilities emergency response program is based on the IIAR's "Risk Management Guidelines Program for Ammonia Refrigeration. An emergency response plan is in place at Purity Dairies to deal with incidents and emergencies that might take place on site. The site maintains it's own HAZMAT teams. Training for these functions is given annually per state requirements. Onsite drills are also scheduled as part of the emergency response plan to familiarize employees of the dangers of ammonia and propane and the proper response to alarms and evacuations. . The plan has been provided and reviewed with the Davidson County Lo cal Emergency Planner Center. Coordination with the LEPC has been made to notify them through the emergency response plan to respond to incidents that may affect the public. PLANNED CHANGES TO IMPROVE SAFETY Purity Dairies is putting together a training program to enhance the skills of the refrigeration operators and to increase their abilities to respond to emergencies. This includes refrigeration training courses, operating procedure reviews and drills. |