Just before dawn in the east-central Wisconsin farming community of Weyauwega, the early-morning quiet of March 4, 1996, was interrupted by the sounds of crashing metal and burning propane. Thirty-seven tank cars of a Wisconsin Central Railroad train had derailed near an industrial area at the north...
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The process of hot tapping and "flaring" took the most time in the stabilization process. Fire department personnel stood-by with charged hoselines and rescue equipment to protect the contract personnel performing the hot tapping and flaring operations. Personnel from one company reported they had "never experienced an incident with circumstances that were as difficult or as large as Weyauwega." Baehnman indicated that "the total amount of liquefied gases involved was over 1 million pounds, which is reported to be the largest incident ever in the United States in terms of volume."
All but 10 percent of the last remaining tank car was showing above ground, so a decision was made to vent and burn the tank car because of a large rapid pressure increase in the tank. (Vent-and-burning had not been an option early in the incident because of the large number of tank cars and their close proximity.) Charges were placed on each end of the tank, opening it up to allow the remaining propane and LPG to burn freely. Venting a tank involves the placing of shaped explosive charges on the high end and low end of a damaged tank car. The resulting explosion opens up the tank car and allows the product to drain out and burn.
Firefighters were fortunate that no explosions occurred involving the propane and LPG tanks before the decision was made to move to a safer location. The National Fire Protection Association (NFPA) says that BLEVE times range from eight to 30 minutes, with the average being 15 minutes. The initial evacuation of personnel was two blocks for the first hour, then expanded to seven blocks and finally to 11/2 miles. The U.S. Department of Transportation's Emergency Response Guidebook (ERG), under Guide 22 for propane and LPG, recommends an evacuation distance of a minimum of a half mile if propane or LPG tanks are on fire.
As the days passed, the evacuated residents wanted to know when they would be allowed to return to their homes, so briefings were held each afternoon in three locations to update them on the progress of the incident. The incident commander cited the Waverly and Crescent City derailments to illustrate to the people what can happen when propane and LPG tanks BLEVE. This information helped people understand why they couldn't go back to their homes until they were told it was safe to do so.
There were no injuries to emergency responders or residents directly resulting from the derailment. One resident suffered an elbow injury from a fall during the initial evacuation; however, she was able to continue evacuating on her own. Another resident had a heart attack upon returning home; her home was not damaged and the heart attack was not attributed to the incident. Baehnman said "from the start of the incident, the tone of the incident would be driven by safety and not time." This approach and the fact that no BLEVEs occurred likely accounted for the lack of injuries to response personnel and civilians, and the minimal loss of property.
During and after the incident maintenance problems were experienced with some fire apparatus that had been constantly idling for almost three weeks at road blocks without being shut off. The primary breakdowns involved motors and electrical generators on the motors.
The cause of the derailment was thought to be a switching gate that malfunctioned or a section of broken rail. The accident is under investigation by the National Transportation Safety Board (NTSB) and a report should be out by the end of 1996.
Robert Burke, a Firehouse® contributing editor, is a Maryland-based certified Hazardous Materials Specialist and has served on state and county hazardous materials response teams. He has 16 years' experience in career and volunteer fire departments, attaining the rank of assistant chief, and has served as a deputy state fire marshal. He holds an associate's degree in fire protection technology and a bachelor's degree in fire science. Burke is an adjunct instructor at the National Fire Academy and the Delaware County, PA, Fire Academy.