Dean Foods Company, Chemung, Illinois Plant - Executive Summary
EXECUTIVE SUMMARY |
Description of Facility and Regulated Substance Handled:
The Dean Foods Company Chemung, Illinois facility processes milk and milk products. The facility utilizes anhydrous ammonia as a refrigerant to maintain the proper temperature of milk, yogurt, and milk products within the facility. Anhydrous ammonia is an effective refrigerant that has been used for many years by most food processing facilities. Ammonia is normally a gas at ambient temperatures but is handled as a gas liquefied under pressure. The refrigeration system consists of a high-pressure receiver, evaporators, compressors, piping, and valves.
Accidental Release Prevention and Emergency Response Policies: The Dean Foods Company is committed to promoting safety for the plant, its employees and the surrounding area. The facility is complying with OSHA's Process Safety Management Standard (PSM), Title 29 Code of Federal Regulations (CFR) 1910.119, and EPA's Risk Management Program regulations (RMP), Tit
le 40 CFR Part 68. The purpose of these programs is to ensure that the refrigeration system is operated safely in order to prevent releases of ammonia from the system. In addition, these programs serve to develop procedures to minimize releases in the event that they do occur and to outline appropriate emergency response steps to take in the event of a release.
Worst Case Release Scenario: EPA's "Risk Management Program Guidance for Ammonia Refrigeration" (November 1998) and the International Institute of Ammonia Refrigeration's (IIAR) Risk Management Guidelines (1998) were the primary documents used to develop the worst case release scenario. The worst case release is one that is unlikely to occur. The purpose of the worst case release analysis is to support a dialogue with the community on release prevention. It is a conservative analysis and is not to serve as a rational basis for actual emergency response planning.
The worst case release scenario (as defined by EPA) is the rele
ase of the largest quantity of ammonia from a vessel or process line failure that results in the greatest distance to a toxic endpoint. The worst case release scenario for the refrigeration process is assumed to be a case where the total quantity of ammonia in the largest vessel is released. The release scenario was performed assuming that the vessel was filled to 90 percent capacity (the greatest amount that would ever be placed in the vessel). The vessel, however, is normally filled to 20 to 50 percent capacity. There were no passive mitigation systems (dikes, berms, drains, sumps or enclosures) considered in the analysis since the vessel is located outdoors.
The toxic endpoint used for this scenario must be where the ambient concentration of ammonia is 0.14 mg/L or less. This endpoint is a concentration below which nearly all individuals could be exposed to for one hour without serious health effects. Based Exhibit 4-4 in EPA's guidance, a release from the vessel would result in a
situation where public receptors would be within the distance to the toxic endpoint.
Alternative Case Release Scenario: The alternative case release scenario selected is one in which a relief valve lifts to relieve pressure in the system. EPA's "Risk Management Program Guidance for Ammonia Refrigeration" (November 1998) and the International Institute of Ammonia Refrigeration's (IIAR) Risk Management Guidelines (1998) were the primary documents used to develop the alternative release scenario. The alternative release scenario is one that is more likely to occur than the worst case release scenario.
The alternative release scenario must meet two criteria:
1) Must be more likely to occur than the worst case scenario, and
2) Must reach an endpoint off site, unless no such criteria exist.
A possible release scenario is one in which a safety relief valve lifts to relieve pressure in the system so that the system does not become overpressurized. An average relief valve capacity was u
sed for this scenario analysis. If a valve releases inside the building (as would be in most cases), the building can serve to minimize the release to the atmosphere. For this scenario however, it was assumed that the valve is located outside or in an area close to an open door or window, in which case building attenuation cannot be used. This is a conservative estimate that overestimates most releases that could likely occur at the facility.
Since the facility has installed ammonia sensors throughout the cooler area and in the compressor room, it is assumed that a release would last only ten minutes, which is EPA's default for such release scenarios.
The toxic endpoint used for this scenario must be where the ambient concentration of ammonia is 0.14 mg/L or less. Based on EPA's guidance, the alternative release scenario would result in a situation where public receptors would just be within the distance to the toxic endpoint.
Accidental Release Prevention Program and Chemical-Spe
cific Prevention Steps: As a part of its PSM Program, Dean Foods has established numerous programs that serve to prevent accidental releases of ammonia. These programs include:
7 Process Safety Information
7 Process Hazard Analysis
7 Operating Procedures
7 Mechanical Integrity
7 Management of Change
7 Pre-Startup Review
7 Compliance Audits
7 Incident Investigations
7 Employee Participation
7 Hot Work Permits
7 Contractor Safety
In addition, Dean Foods has installed a sophisticated system of ammonia sensors that can remotely close certain isolation valves in the event of a small release and thereby limit an accidental release of ammonia. These sensors are capable of detecting releases of ammonia at low levels, and are connected to a computer that will shut certain valves to the system if ammonia is detected. In this way, potential releases of ammonia are minimized.
Emergency Response Information: As a part of the PSM Program, the facility maintains an Emergency Response P
lan that was prepared in order to improve responsiveness to an emergency incident, and to increase the reliability of actions taken during an incident. As a part of this emergency planing effort, a team of employees has received emergency response training and has been equipped to respond to ammonia releases.
In the event of an emergency involving the ammonia system, it is the policy of the facility to request assistance as necessary by calling 911 which will notify the McHenry County Sheriff's Department, the Harvard Police Department, and the Harvard Fire Department.
In addition, the McHenry County Local Emergency Response Committee has included the Dean Foods facility in its local emergency response planning.
Five-Year Accident History: In the past five years there was one release that resulted in minor injuries to four employees. This release was of approximately 2,300 pounds of ammonia and was due to the inadvertent removal of a cap from a solenoid valve during a maintenance
procedure. The facility was evacuated for approximately twelve hours at the time, but none of the surrounding area required evacuation, and there was no environmental damage as a result of the incident. There have never been any accidents involving ammonia that caused off-site injuries, death, environmental damage, external evacuations, or shelterings in place.
Steps to Improve Safety: In response to the past release, the facility revised its written Standard Operating Procedures regarding valve maintenance and operation in order to prevent such an incident from occurring in the future. To additionally increase safety, the facility has installed ammonia sensors in various key locations of the facility as discussed above.
In addition, the facility will continue to operate and maintain the system in accordance with IIAR Guidance and will continue to implement its OSHA PSM Program in conjunction with the Risk Management Program.