Delimex - Executive Summary |
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A. Accidental Release Prevention and Emergency Response Policies Delimex is dedicated to operation of a safe facility for its employees and neighboring community. A safety committee has been established that is responsible for the implementation of the safety program and an Emergency Response Plan. This includes safe operation of the ammonia refrigeration system. Delimex has prepared risk and safety programs to ensure safe handling of the ammonia in the refrigeration system. Prior to starting operations in 1997, Delimex conducted the following technical studies to identify potential hazards and the appropriate mitigation measures: Process Hazard Analysis, a Hazard Assessment, and a Seismic Assessment. In addition, Delimex prepared a Risk Management Prevention Program (RMPP) prior to startup of the ammonia refrigeration system. Since Delimex is modifying the ammonia refrigeration system, they have updated the technical studies and management programs to help minimize the potenti al for an ammonia incident. B. Stationary Source and Regulated Substance The Delimex facility is located at 7878 Airway Road in San Diego, California. The facility started operations at this location in April 1997. At that time, ammonia was used as a refrigerant. The total quantity of ammonia at the initial startup was 6,520 pounds. The facility is undergoing an expansion that will require an additional 10,400 pounds of ammonia. The Delimex ammonia refrigeration system is a closed system that cycle the refrigerant, or ammonia, from liquid to gas and back again. The system, consisting of piping, valves, and process equipment, cycles ammonia through various physical states (high pressure liquid, low pressure liquid, low pressure vapor, high pressure vapor, then back to high pressure liquid) in order to provide refrigeration for product and process equipment. Changes in pressure are directly related to changes in temperature: lowering the ammonia pressure lowers its tempera ture. Low pressure (cold) liquid ammonia provides refrigeration 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 0 psig on the low pressure side of each system to 150 psig on the high side. Ammonia is the regulated substance at this facility. The maximum intended inventory of ammonia at the facility is 16,920 pounds. C. Hazard Assessment Summary Worst Case Release Result Summary Scenario Description: Release of the maximum quantity of ammonia that can be stored in the largest vessel in 10 minutes. The largest vessel in the system is the High Pressure/Thermosyphon Receiver, which has a capacity of 12,300 pounds of ammonia. Because the high pressure/thermosyphon receiver is located outside, no passive mitigation measures were applied. The total release rate is 1,230 poun ds per minute. This release rate was used to determine the endpoint distance of 200 ppm. The most pessimistic meteorological conditions were used: 1.5 meters/second wind speed, and F stability for an urban topography. The distance to the Toxic Endpoint of 200 ppm was based on the EPA's RMP Guidance for Ammonia Refrigeration Facilities, Exhibit 4-4 for a release rate of 1,230 lbs./min. This scenario reaches off site and may affect population receptors such as other industrial / commercial businesses. NOTE: The data provided in Items 2.5 and 2.6 have been rounded to two significant figures and one significant figure, respectively; therefore, the math may not propoerly correspond. Alternative Release Result Summary Scenario Description: A release of ammonia from a 1/4 inch diameter leak. This could result from a valve stem leak, a flange seal leak, or a line break. The release rate of ammonia due to the line pressure (150 psig) is 122 pounds per minute and continues until the e mergency response team can respond to the ammonia alarm. A conservative estimate is one hour resulting in a release of 7,320 pounds. It was assumed that this scenario occurred outside; therefore, no passive mitigation measures were incorporated. The meteorological conditions used were 3 meters per second wind speed, and D stability for a rural topography. The distance to the Toxic Endpoint of 200 ppm was based on the EPA's RMP Guidance for Ammonia Refrigeration Facilities, Exhibit 4-5. This scenario reaches off site and may affect neighboring industrial facilities. NOTE: The data provided in Items 3.5 and 3.6 have been rounded to two significant figures and one significant figure, respectively; therefore, the math may not propoerly correspond. D. Accidental Release Prevention Program and Chemical-Specific Prevention Steps Administrative Measures Delimex has prepared management programs for compliance with the Process Safety Management and Risk Management Program regulations. These management programs include, but are not limited to, operating procedures, mechanical integrity, incident investigation, management of change, contractor safety, and emergency response. In addition, Delimex has conducted studies to identify potential hazard associated with the ammonia refrigeration system and set up a structure to ensure that recommendations from these studies are addressed. Delimex personnel circulate throughout the plant, taking note of unusual conditions in any portion of any of the system 24 hours per day. If a leak is detected or observed by any Delimex employee, it is immediately reported to the chief maintenance technician and the refrigeration engineer. Action is promptly taken to mitigate the leak so normal operations can resume. Engineering Measures The ammonia refrigeration system has several monitoring and sensing devices. These devices will activate alarms when conditions vary beyond designated limits. The alarms are indicated on local instrum entation panels, the facility-wide alarm system, and remote alarms at the facility. Some alarms will be responded to manually while others are interlocked to another device. The ammonia refrigeration system at the facility is controlled and monitored using the following: process indicators and alarms; inspections; preventative maintenance; personnel training; safety meetings; incident investigations; and ammonia gas sensors. E. Five Year Accident History The facility started operations in April 1997. Since that time, there have been no release or "near misses" associated with the ammonia refrigeration system. F. Emergency Response Delimex has an Emergency Evacuation Plan that includes requirements for postings, reporting emergencies, evacuation procedures / routes (including re-entry and accountability), communications, rescue duties, etc. In addition, the Refrigeration personnel are currently completing the 40 hour Hazardous Waste Operations and Emergency Response training program. An emergency response shut down procedure for the ammonia refrigeration system will be incorporated into the Emergency Evacuation Plan. G. Planned Changes to Improve Safety The Process Hazard Analysis, Seismic Assessment, and Hazard Assessment (Off-Site Consequence Analysis) provided the mitigation measures outlined below to improve safety at the Delimex facility located at 7878 Airway Road in the city of San Diego, California. All mitigation measures were completed prior to startup of the new addition. Some of the recommendations made as a result of this Program are listed as follows: ** In the event of an emergency/ammonia leak and entry is necessary, use the hand-held detector and document the ammonia readings and maintain the records. ** Ensure that the local sanitary sewer is included on the emergency response list for notification in the event of a spill into the sewer. ** Incorporate an annual test of the high level switches for all of the vessels into the mechanical integrity program. ** Include testing the ammonia sensors (per IIAR guidelines) in the mechanical integrity program. ** Ensure that the valves in the Ammonia Emergency Refrigerant Control System box are labeled. In addition to the recommendations from the initial study, the facility is in the process of implementing the following administrative and engineering controls with an expected date of completion of March 15, 2001: ** Formally train an emergency response team for catastrophic releases. This program will include emergency response team drills, training, and Respiratory Protection. This is expected to be implemented at the time of startup (February 15, 2001). ** Install an alarm light on the outside of each engine room door to indicate an ammonia release. ** Coordinate emergency response drills and/or meetings to review emergency response issues and use of the Ammonia Emergency Refrigerant Control System with the local fire departme nt. |