Dean Foods Company, Inc. - Executive Summary |
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Dean Foods Company is a Virginia Corporation having a margarine manufacturing facility located in Sandston, Virginia. It is NOT affiliated with any other company or facitlity bearing that or a similar name. An integral part of the margarine manufacturing process is the use of refrigeration to "crystallize" the product and to maintain the finished product at proper storage temperature prior to shipment. At Dean Foods Company, the refrigeration system uses anhydrous ammonia as the refrigerant. It is estimated that the refrigeration system contains approximately 23,000 pounds of ammonia. Ammonia exists as a gas at atmospheric pressure, however, ammonia is found in both gaseous and liquid (liquified by pressure) forms within the ammonia refrigeration system, depending upon where it is located in the system. The ammonia refrigeration system is distributed throughout the production and storage areas of the facility. The largest concentration is in the various system tanks where the major ity of the ammonia present is liquified by pressure. Typical system pressures range from 5 PSIG to 200 PSIG. Dean Foods Company is covered by the OSHA Process Safety Management Regulations 29 CFR Part 1910.119 as well as similar State Regulations. The various elements of the Process Safety Management Program at Dean Foods Company form the core of the accidental release and emergency response efforts at the facility. Following the guidelines set forth under The EPA Chemical Accident Prevention Regulations (i.e. 40 CFR Part 68), the Worst Case Release Scenario was identified as a catastrophic failure of the outside receiver tank such as could occur due to impact from a de-railed tank car. It is estimated that an occurance such as this could release up to about 13,600 pounds of ammonia over a 10 minute period. Under worst case atmospheric conditions, it is estimated that such a release could result in concentrations of ammonia exceeding the level of concern concentration (i.e. 0.14 Mg/L ) over an area covering a downwind distance of about 1.5 miles and extending approximately 0.4 miles max in both directions perpendicular to the wind direction. Depending upon the wind direction, this release has the potential to impact private residences, schools, churches, other businesses, an interstate highway, and possibly airport runways and taxiways located at Richmond International Airport. Worst Case Scenario modelling was performed using both "RMPComp" and ALOHA with similar results. Additionally, a more likely alternate release scenario was investigated. This alternate release assumes that an evaporator located inside the facility is impacted by a forklift resulting in a catastrophic failure of its connected ammonia piping. It is estimated that an accident such as this would result in an 8,500 pound release of ammonia into the building. The largest impact of this release would be on the facility itself as the building would trap much of the ammonia inside thereby providing passive mitigation. The predicted impact area would be about 50 yards wide extending about 0.1 mile from the building. Modelling indicates that this release could impact nearby residences and/or an interstate highway depending upon wind direction. Alternate Release Scenario modelling was performed using both "RMPComp" and ALOHA again with similar results. Dean Foods has had one accident to report herein since the current facility was opened in 1983. This accident occured in 1997 and involved a small oil drain valve, which was being opened by a relatively inexperienced mechanic. This valve came partially apart resulting in a relatively small release of ammonia inside the facility. The situation was quickly responded to and corrected by more experienced personnel. However, it was alleged that one employee, who was not in the immediate vicinity of the leak, was injured by this release. This was the only known consequence of this occurence. The valve in question has since been changed t o a different type which cannot fail in the same manner, and all mechanics performing similar tasks have been given additional training. Dean Foods Company has a continuing commitment to process safety and as such has recently commisioned a professional engineering group and a professional safety consulting group to assist with mechanical integrity concerns, to review and offer suggestions relative to improved training, and to conduct a Risk Management Program compliance audit. This work should be complete, or nearly so, by the submission deadline for this RMP. |