United States Cold Storage, Dallas - Executive Summary
United States Cold Storage, Inc. is committed to the safe operation of all our facilities to protect our workers, the public and the environment. This is accomplished to a great extent by a well developed, up-to-date and implemented Risk Management Program. All USCS facilities shall operate in a prudent and safe manner. It shall be the responsibility of the plant manager to ensure that all procedures are followed as set forth in our Risk Management and Process Safety Management programs. In the unlikely event of an accidental release it is USCS policy to immediately call the National Response Center, Local Emergency Response Committee, the local Fire Department and other agency(ies) that may be required. All USCS facilities will have an emergency response team to assist these agency(ies). |
United States Cold Storage, Dallas, is a public refrigerated warehouse that uses anhydrous ammonia as a refrigerant in a closed loop system. Anhydrous ammonia, most commonly known as ammonia, is an e
xcellent refrigerant and is commonly used in most of the world's industrial refrigeration systems. Ammonia has an excellent warning property, its odor. Ammonia's odor is familiar to most people due to the fact that it is commonly used in household cleaning solutions. Ammonia can be detected as low as 5 parts per million (PPM) and has an average life span of 7 days in the environment before it breaks down to its common elements nitrogen and hydrogen.
Typical items stored within USCS facilities are raw or processed food items that can be found in your supermarket or local restaurant. Temperatures range between -30 degrees to +45 degrees F. The refrigeration equipment and piping are located throughout the facility. The condensers and related piping are on the machine room roof with the piping to and from the freezers, coolers, truck and rail docks located on the warehouse and dock roofs. The machine room contains most of the large refrigeration machinery and vessels. In an unlikely
event of a refrigerant leak in a refrigerated space, the ammonia vapor would be contained inside the space, due to the vapor tight construction of the facility. It then may be treated and/or vented under controlled conditions. The facility is equipped with ammonia detectors throughout to help lessen any leaks that might occur and to provide an early alert.
USCS believes that prevention is foremost. All of USCS facilities are maintained by a staff of trained maintenance personnel. Most of these people are members of the Refrigerating Engineers and Technicians Association (RETA) and all Chief Engineers are members of the International Institute of Ammonia Refrigeration (IIAR) and hold a RETA Certification Level A. USCS has on staff at the corporate level an OSHA and EPA coordinator/trainer who is a certified OSHA Instructor. All facilities comply with OSHA's Process Safety Management without regard to the ammonia threshold quantity. All the vessels and piping have been installed acc
ording to ASME vessel and piping codes and applicable local Building, Fire and Mechanical Codes.
The facility's emergency response program is based on the OSHA requirements for 29 CFR 1910.38-Emergency Action Plan, OSHA's 1910.119, Process Safety Management and 1910.120 HAZWOPER standards. We have train employees for emergency response and maintain a written emergency response plan.
FIVE-YEAR ACCIDENT HISTORY:
The USCS Dallas facility has been operating at this location for the past 35 years. Within that history the facility has seen one refrigerant releases.
OFFSITE CONSEQUENCE ANALYSIS:
Worst-case release scenario analysis: As required by law under 40 CFR Part 68.25, Worst-case release scenario analysis, an analysis was prepared for the Dallas facility. The United States Environmental Protection Agency's Risk Management Program Guidance for Ammonia Refrigeration tables and charts and the USEPA's RMP Comp computer program for Ammonia was used for this analysis. This worst-c
ase release scenario is estimated to create the greatest distance in any direction to an endpoint of 200 ppm from the accidental release of anhydrous ammonia used as a refrigerant in a closed-loop refrigeration system. The quantity release was based on a "Worst-case" release scenario for a toxic gas liquified under pressure that is normally a gas at ambient temperature. The release was generated from the facility's High Pressure Receiver. Releasing 1644 pounds per minute for a 10 minute period with no passive mitigation system in place. The Dallas facility has offsite consequence.
The dispersion analysis used a wind speed of 1.5 meters per second and an "F" atmospheric stability class. With an ambient temperature of 77 degrees F (25C) and a relative humidity of 50%. Using a release height at ground level and a surface roughness class of Urban. Dense gas was used for gas density.
Alternative Release Scenario Analysis: As required by law under 40 CFR Part 68.28, Alternative release s
cenario analysis was prepared for the facility. The United States Environmental Protection Agency's Risk Management Comp computer program was used for this analysis. This alternative release scenario is estimated to create a distance to reach off-site in any direction to an endpoint of 200 ppm from an accidental release of ammonia used as a refrigerant in a closed-loop refrigeration system. The Bakersfield facility has offsite consequence.
Alternative release scenario #1 was a mechanical seal failure on an ammonia pump for the low temperature pump receiver. The mechanical seal failure was identified through the review of our process hazard analysis (PHA) for the Dallas facility's What-If Study. The failure scenario was identified under Subsystem(s) Low Temperature Pump Receiver, What-If question #3. Passive mitigation system was in place, the release took place inside the facility. The following administrative controls are in place: Engine room log is maintained with visual checks o
f all of the equipment including the ammonia pumps. Oil that is added to the refrigeration equipment is noted on the Daily Engine Room Log. Annual preventive maintenance of the refrigeration equipment includes the ammonia pumps. Housekeeping of the engine room area includes wiping up and investigating oil leaks and moping the floors on a daily to weekly bases.
Alternative release scenario #2 was used for the RMP's Alternative Release Scenario. The scenario is, piping failure on the high pressure receiver. The piping failure was identified through the review of our process hazard analysis (PHA) for the Dallas facility. The failure scenario identified under Subsystem(s) Charging Operation, What-If question #3. No passive mitigation system was in place, the release took place outside the facility. The following administrative controls are in place:Only trained operators are assigned to charging operations and operators stay with the truck driver at all times. A pre-charging inspec
tion is done before charging operation begins and all emergency response equipment is readily available.
The PHA re-validation recently performed for this facility produced no recommendations to improve safety. However the first PHA produced 11 recommendations to improve safety at the Dallas facility. Such recommendations included installation of new mitigation equipment and engine room operational controls.