Cassco Ice #22 Richmond-Sandston - Executive Summary

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The Cassco - Richmond-Sandston facility manufactures ice for wholesale/retail distribution.  The 25,500 square foot facility, located on four acres, utilizes approximately 12,000 pounds of anhydrous ammonia as a refrigerant within an enclosed system for ice manufacturing and storage. 
 
The Cassco Richmond-Sandston, Virginia facility refrigeration system is a standard refrigeration design using ammonia as its refrigerant.  The refrigeration system consists of four compressors, three operating as intermediate (+10 F) compressors and one operating as a low pressure (0 F) compressor.  Each of the compressors has numerous protective controls (motor overload, high discharge temperature, high discharge pressure, low suction pressure, and low oil pressure) that will shut down the compressor if operating limits are violated.  The compressors and the refrigeration system are continuously monitored and controlled by a computerized operating system. 
 
The compressors receive ammonia gas from two sep 
arate recirculator vessels.  The "low" compressor receives ammonia gas from the "low" side recirculator (0 F), compresses it, and discharges it through an oil separator to the condenser located on the roof of the facility.  The three "intermediate" compressors receive ammonia gas from the "intermediate" side recirculator vessel, compresses it, and discharges it through oil separators to the common condenser on the roof. The evaporative (forced-air, water chilled) condenser transfers the ammonia's heat to the atmosphere and returns the liquid ammonia to the small high pressure thermosyphon vessel inside the compressor room.  High pressure liquid ammonia is then transferred to the intermediate pressure (+10 F) recirculator vessel.  The liquid ammonia level is maintained in the intermediate recirculator vessel.  Liquid ammonia is transferred from the intermediate pressure (+10 F) recirculator vessel to maintain an operating liquid ammonia level in the low pressure (0 F) recirculator vesse 
l.  The liquid ammonia is pumped at an approximate 2 to 1 ratio from the recirculators to the various evaporator air units, and "shell and tube" ice making machines.  The liquid ammonia passes through liquid flow regulators where the flashing ammonia removes heat from the freezers and also from the water to produce ice.  From the evaporators and the ice machines, the ammonia gas and liquid combination returns to the recirculators to begin the refrigeration cycle over again. 
 
An outside supplier delivers anhydrous ammonia 1 to 2 times per year to replenish and maintain the ammonia level in the system. 
 
Ammonia, when properly used, has proven to be a safe and reliable refrigerant.  The sharp odor of ammonia provides its own warning agent.  Practically all accidents involving anhydrous ammonia are the result of a lack of knowledge, misunderstanding, carelessness or poorly maintained or unsuitable equipment. 
 
The Cassco Richmond-Sandston facility is committed to operating a safe and compli 
ant facility for the protection of its employees, the general public, and the environment.  The facility has multiple safeguards pertinent to the ammonia process.  These include an ammonia detection and alarm system, exhaust purge fans, controls which shut down the compressors if operating limits are violated, and the capability of shutting the entire system down if required.  Administrative controls are in place which limit the utilization of vessels at approximately 25% of their intended capacities. 
 
The company has developed an emergency response and action plan which includes notification of emergency authorities/agencies and the public, to evacuation and first responder duties. 
 
MANAGEMENT SYSTEM 
 
The Cassco facility has developed a management system to oversee the implementation of the risk management program elements.  A single person has been identified that has overall responsibility for developing, implementing and integrating the risk management program requirements. 
 
There 
may be different levels of responsibility assigned, depending on the size and complexity of the facility.  A Risk Management Coordinator may be responsible for developing and implementing the overall risk management program, while other personnel may be responsible for developing and implementing the operating procedures element or developing a particular operating procedure.  The management system is, therefore, operating at each of these levels depending on the way these responsibilities are carried out. 
 
The Risk Management Coordinator is responsible for all aspects of the development and update of the overall Risk Management Program.  The coordinator will determine the necessity of establishing additional responsibilities for facility personnel concerning various operations at the facility.  As other personnel are identified, they will be documented and lines of authority will be defined within the management system. 
 
By defining the lines of authority and roles and responsibiliti 
es of staff that oversee the risk management program elements it will: 
 
    Ensure effective communication about process changes; 
    Clarify the roles and responsibilities related to process safety issues; 
    Avoid problems or conflicts among the people responsible for implementing elements of the program; and 
    Ensure that the program elements are integrated into an ongoing approach to identifying hazards and managing risks. 
 
Management commitment to process safety is critical in the facility's risk management program.  For process safety to be a constant priority, the facility will remain committed to every element of the risk management program. 
 
To maintain an integrated approach to managing risks, each RMP rule element will be implemented on an ongoing, daily basis and become a part of the way the facility operates. 
 
Risk Management Coordinator:    Rick Bowles 
Title:    Operations Manager 
Additional Responsible Personnel:    None at this time. 
 
HAZARD ASSESSMENT 
 
As per the requirements of the 
Risk Management Program regulations, the Cassco Richmond-Sandston facility has conducted offsite consequence analyses relative to the potential accidental release of anhydrous ammonia.  The scenarios related to a worst case release scenario and an alternative release scenario.  This involved calculating worst case and alternative scenarios utilizing the RMP*Comp modeling program. 
 
The facility considered worst case release scenarios relating to the vertical recirculator within the enclosed ammonia system, as it would house the largest mass of a regulated substance at any given time.  The release model considered the release of 3,890 pounds of liquid ammonia from the vessel, during a 10 minute release.  The scenario endpoint was 0.3 mile.  This scenario generated a toxic endpoint of 200ppm, the maximum airborne concentration below which it is believed nearly all individuals can be exposed for up to one hour without experiencing or developing irreversible or other serious health effects 
or symptoms which could impair an individuals ability to take protective action. 
 
Alternative scenarios for the facility system were considered and it was determined that due to the facility administrative controls, the multiple safeguards pertinent to the ammonia process including being completely computerized, and the fact that the facility was constructed less than three years ago and placed into operation in 1997 and there has never been an offsite release at this facility, there was no alternative scenario which would have an offsite consequence.  However, if there is a potential loss of ammonia it would be due to a possible loss from a relief valve within the system.  The predicted release would consist of approximately 50 pounds of anhydrous ammonia released over a ten minute period.  The release inside the building would have no offsite consequence.  An outside release would possible have a 0.1 mile offsite consequence, yet would probably not leave the property, and there woul 
d be no offsite receptors affected.
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