Northern Star Company - Executive Summary |
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The Northern Star Company is a vegetable processing plant located at 3171 5th Street, Minneapolis, MN. Anhydrous ammonia is used as a refrigerant at this facility to provide cooling for production and storage areas. The maximum amount of ammonia in the system at any one time is estimated at 31,400 pounds. There is also a 30,000 gallon propane storage vessel, located outside, on the southwest corner of the property. This is kept as backup fuel for the boilers should natural gas become unavailable. Worst-case Release Scenario for a Toxic Substance: Our worst-case release is the failure of the largest vessel in our refrigeration system. This vessel is called the High Pressure Receiver (HPR) and has a maximum capacity of 26,400 pounds. In calculating the area affected by this failure, the engine room enclosure, where the HPR is located, provides passive mitigation, reducing the toxic endpoint. The engine room has a volume of 24,000 cubic feet and roof ventilation produces 40 room air exch anges per hour. Using the tables and equations found in chapter 4 of EPA's "RMP Guidance for Ammonia Refrigeration", the toxic endpoint was calculated at 1.20 miles. Located within this radius is a population of 15,832 , seven schools, one hospital (University of Minnesota campus), residential housing, retail and industrial businesses. Alternative release scenario for a toxic substance: The alternative release toxic endpoint was also determined using EPA's "RMP Guidance for Ammonia Refrigeration" reference tables and equations. Based on past history, a pressure relief valve failure was the most likely cause of an ammonia release. Using the tables provided in the RMP Guidance, a 15 minute release of ammonia at 100 lbs/min would reach .10 miles. The estimated population, according to Landview III, within distance to endpoint is 30. There are also some residences, industrial and retail businesses. There are no schools or hospitals within this radius. Worst-case Release of a Flammable Substance: Our worst-case scenario for a flammable substance was determined using the reference tables in the EPA "RMP Guidance for Propane Users and Small Retailers". Based on the tables, the failure of our 30,000 gallon propane vessel would produce an 1 psi overpressure of .40 miles. This would affect an estimated population of 816, one school, residential housing, retail and industrial businesses. No hospitals are affected within this area. Alternative Release of a Flammable Sustance: Our alternative release is the failure of = inch pipe lasting for 10 minutes. Using the tables in the "RMP Guidance for Propane Users and Small Retailers", the distance for 1 psi is .10 miles. This would affect an estimated 30 people, a few residential housing and several industrial businesses. No schools are within this area. Accidental Release and Emergency Response Policies: The Northern Star Company has established an in-house emergency response team to quickly respond to and handle releases of Anhydrous Ammonia. The established steps include initial training under the OSHA regulation 29 CFR 1910.120 HAZWOPER. The facility has also established annual retraining for all personnel that are on the HAZMAT Team as well as periodic spill drills and plant wide evacuation drills to assure all employees are prepared in the event of an emergency. We are also coordinating efforts with the Minneapolis Fire Department to establish a joint training program. These established plans and procedures shall be periodically reviewed to assure that they are current and up to date. Emergency Response Program: We have trained the refrigeration operators and selected production and office personnel in Hazardous Waste Operation and Emergency Response, 29 CFR 1910.120. The trained personnel will assess each release situation and determine the appropriate emergency response to initiate. This could be simply tightening a packing nut or flange bolt or initiating a complete system shut down. Northern Star has established written operating procedures for the ammonia refrigeration system and has included in those procedures the Emergency Shutdown and isolation in the event of a release. We have also purchased Level B Chemical Suites, Self Contained Breathing Apparatus and other appropriate equipment to support the in-house HAZMAT team. This team will coordinate their efforts with the outside emergency services to assure the safety of all. Five Year Accident History: We have had three accidental releases of ammonia in the past five years. No one offsite was injured and there were no evacuations. There have been no accidental releases of propane within the last five years. General Accidental Release Prevention Program and Chemical Specific Prevention Steps: The Northern Star Company has not only complied with the EPA Risk Management Program but also the OSHA Process Safety Management regulation to assure that the Ammonia Refrigeration System is well maintained and employees are properl y trained and periodically retrained to assure they are kept up to date on any changes and new operations that may effect them. In addition, to maintain the mechanical integrity and safety of this process, this facility practices the following industry codes and standards: ASME Boiler & Pressure Valve Codes ANSI B31.3 Piping Code IIAR industry guideline for safety and good engineering practices NFPA guidelines for fire protection equipment Through regular audits, training, maintenance, testing and inspection programs Northern Star has established a history of safe operation and that community emergency action plans are current and training with community services is done for a safe response in the event of an accidental release. Planned Changes to Improve Safety: None at this time. |