Henderson Cold Storage - Phase III - Executive Summary |
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ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES Henderson Cold Storage has implemented emergency response policies in order to meet the following objectives: 1.) To save lives. 2.) To minimize and avoid injuries. 3.) To protect the environment. 4.) To minimize property damage. Henderson maintains an emergency response committee whose members are the designated emergency coordinators for the facility. The Emergency Action Plan provides the response organization and notification procedures, evacuation routes, ammonia health hazards, and mitigation procedures which will be implemented to respond effectively to emergency situations that may arise at the facility. This Plan is reviewed and updated at least once per year. This Plan was reviewed and updated to ensure compliance with the ARTAH regulations, as well as to incorporate any facility changes. STATIONARY SOURCE AND REGULATED SUBSTANCE The Henderson facility is located at 830 Horizon Drive in Henderson, Nevada. The facility uses ammonia as the refrigerant to provide cooling for the dock and freezer areas. Refrigeration process equipment at the facility operates continuously. Compressors and condensers cycle on and off to comply with system demand during operation. The ammonia refrigeration system provides cooling for cold storage areas. The refrigeration cycle begins with the transfer of high pressure liquid ammonia from the High Pressure Receiver (HPR1) to the Refrigerant Recirculators (RRP1&RRP2). The Recirculators cycle ammonia to the evaporators, where the liquid vaporizes and draws heat from the cold storage area. The ammonia vapor is drawn to the compressors and pumped to the condensers, where the vapor is condensed into ammonia liquid. This liquid flows to the thermosyphon which then feeds the Receiver. Changes in pressure are directly related to changes in temperature: lowering the ammonia pressure lowers its temperature. Low pressure (cold) liquid ammonia provides refrigera tion by removing ambient heat. Removal of ambient heat causes the liquid ammonia (contained within the system) to vaporize. Heat is later removed from the ammonia as it is condensed back into a liquid. Typical operating conditions range from approximately 4 psig on the low pressure side of the system to 160 psig on the high side. Ammonia is used as the refrigerant in the refrigeration process. The total ammonia inventory is 13,000 pounds. HAZARD ASSESSMENT SUMMARY Worst Case Release Result Summary: The worst case release scenario is a release of the total quantity of ammonia in the largest vessel in the ammonia refrigeration system, taking into account administrative controls that limit the maximum quantity in the vessel. The Intercooler has a capacity which is greater than the charge of the Phase III system, thus it is assumed to hold the entire charge of 13,000 pounds of ammonia for the worst case scenario. Since the intercooler is enclosed by the machinery room, pas sive mitigation effects were taken into consideration when determining the release rate of ammonia to the outside atmosphere. The most pessimistic meteorological conditions were used: 1.5 m/s and F stability. This facility is located in an urban setting. The maximum potential downwind distance to 200 ppm was determined using Exhibit 4-4 from EPA's "Risk Management Program Guidance for Ammonia Refrigeration Facilities", November 1998. This potential release scenario reaches off-site and may affect population receptors. No environmental receptors are affected by this potential scenario. Alternative Release Result Summary The alternative release scenario was that of a 0.25 inch diameter leak of high pressure liquid ammonia for one hour. The quantity of ammonia released in one hour at this rate is 7560 pounds. This release could occur due to a gasket rupture, pinhole leak, flange seal leak, valve bonnet seal leak, etc. In addition, this release could occur outside; therefore passiv e mitigation measures were not utilized. The meteorological conditions used were 3 m/s and D stability. This facility is located in an urban setting. The maximum potential downwind distance to 200 ppm was determined using Exhibit 4-5 from EPA's "Risk Management Program Guidance for Ammonia Refrigeration Facilities", November 1998. This potential release scenario reaches off-site and may affect population receptors. No environmental receptors are affected by this potential scenario. ACCIDENTAL RELEASE PREVENTION PROGRAM AND CHEMICAL-SPECIFIC PREVENTION STEPS Administrative Measures: The facility operates in accordance with the International Institute of Ammonia Refrigeration (IIAR) guidelines and standards including the following: IIAR Bulletin 107, "Suggested Safety and Operating Procedures When Making Ammonia Refrigeration Tie-ins" IIAR Bulletin 109, "Minimum Safety Criteria for a Safe Ammonia Refrigeration System" IIAR Bulletin 110, "Startup, Inspection, and Maintenance o f Ammonia Refrigeration Systems" IIAR, "A Guide to Good Practices for the Operation of an Ammonia Refrigeration System" Building Codes: The facility was constructed to comply with the current edition of all applicable codes, ordinances, regulations, and requirements of the local, county, state, and national bodies having jurisdiction at the time of construction. Engineering Measures: The ammonia system uses a computer system to bring equipment on-line, off-line, control the hot gas (compressor discharge) defrosting process, manipulate solenoid valves, and monitor the system for alarms. Ammonia sensors are used throughout the facility and are connected to the computer system. EMERGENCY RESPONSE PROGRAM The Henderson Cold Storage facility has a Response Plan for On-Site Emergency Operations. This Plan outlines the policies and procedures in place to respond to potential ammonia alarms or releases. The facility has several trained personnel to assist in an orderly evacuation as well as to diagnose the alarm condition. The Response Plan for On-Site Emergency Operations includes the facility emergency coordinators, the staff alerting list, emergency notification list, and the hazardous materials agency notification and procedures. This Plan then proceeds to detail the procedures for employees and management in the event of a fire, evacuation, compressor room shut down, blackout, and ammonia release/clean-up. PLANNED CHANGES TO IMPROVE SAFETY Below is a summary of the recommendations resulting from the Process Hazard Analysis study performed for the Henderson Cold Storage facility. The study was conducted on two separate dates, with Session 1 being the HAZOP performed on September 21, 1999 and Session 2 being the Walkthrough which was conducted on November 10, 1999. HAZOP (Session 1) R01: Include in Mechanical Integrity Program to visually inspect the pressure relief valves throughout the system to check if a valve has been activated. R02: Include cal ibration and testing of the ammonia detector and responses on an annual basis in the Mechanical Integrity Program. R03: Install safety shower and eyewash station immediately outside machinery room exit. R04: Exercise key valves that may be used for emergency response/isolation purposes on an annual basis. Include this procedure in the Mechanical Integrity Program. R05: Test the high level mechanical float to ensure proper function. R06: Ensure that operators/contractors working on the condensers (or other isolated portions of the ammonia system) follow lock-out/tag-out procedures. The above recommendations were accomplished by November 15, 1999. |