To access the remainder of this piece of premium content, you must be registered with Firehouse. Already have an account? Login
Register in seconds by connecting with your preferred Social Network.
Complete the registration form.
Before the offloading process could begin, at approximately 2:58 P.M., someone noticed that propane vapors were leaking from tank car 83013. Within seconds, before anyone could react to the leaking propane, a BLEVE occurred. The explosion and resulting fires killed five people instantly and severely burned the Waverly fire chief, who later died at a hospital.
That day, the sky had cleared and the sun had come out, raising the temperature into the mid-50s. One possible contributing factor to the incident indicated by the National Transportation Safety Board (NTSB) was an increase in pressure in the tank. A rising ambient temperature can cause the pressure in a tank to increase. Also, unknown at the time was that a portion of tank car 83013 had been damaged and weakened by the derailment. Emergency responders should keep in mind that railroad tank cars that are piled up on each other or that have banged into each other may have sustained damage. Moving them before offloading the product can lead to further damage or catastrophic tank failure, which occurred in Waverly. The combination of the two factors may have caused the BLEVE.
The explosion compromised most of the Waverly Fire Department's firefighting capability. Hoses that had been left in place in case they were needed were shredded by the explosion, leaving no immediate means of fighting the fires. Pieces of the tank car, burning propane and other debris were scattered over a wide area. One piece of the tank car was propelled 330 feet by the explosion. Noise and blast pressure from the explosion were felt several blocks from the scene. Numerous large buildings were set ablaze by the heat from the fireball, as were vehicles and other rail cars.
A second propane tank car was also set on fire by the explosion, but did not BLEVE. Fortunately, flame impingement on that car was below the liquid level and not on the vapor space. Liquid in a tank, even though flammable, will absorb heat from flame impingement and protect the tank shell from thermal damage.
At this point, the small town of Waverly was in chaos. Many emergency responders, including fire alarm police personnel and their equipment, had become victims themselves and were unable to assist those injured. Calls for help went out statewide, and over 250 emergency vehicles from 39 counties responded to Waverly.
Once incident command was established, the evacuation area was extended to one mile around the derailment scene where the second propane tank car was burning. Medevac helicopters were dispatched from the Fort Campbell Army Post in Kentucky to airlift burn victims to burn centers in Nashville and Louisville, KY; Birmingham, AL; and Cincinnati, OH. In all, 16 people died from the explosion or resulting fireball and 43 people were hospitalized with injuries. Numerous others were treated as outpatients. Sixteen buildings were destroyed and another 20 were damaged. Total cost of the damage in 1978 dollars was estimated at $1.8 million.
A team from the NTSB investigated the incident. An excerpt from its report stated: "The National Transportation Safety Board determined that the probable cause of the loss of life and substantial property damage was the release and ignition of liquefied petroleum gas from a tank car rupture. The rupture resulted from stress propagation of a crack, which may have developed during movement of the car for transfer of product or from increased pressure within the tank. The original crack was caused by mechanical damage during a derailment, which resulted from a broken high-carbon wheel on the 17th car which had overheated." (From NTSB-RAR-79-1, dated Feb. 8, 1979.)
After several BLEVEs of this type occurred in the 1970s - the Waverly incident and similar incidents in Kingman, AZ, in 1973 and Crescent City, IL, in 1979, among several others - the railroad industry retrofitted all tank cars carrying liquefied flammable gases by adding thermal protection, which protects against high temperatures that can weaken metal. Shelf couplers were developed to prevent cars from uncoupling vertically, and head shields were fitted to protect against punctures from the couplers. Since these retrofits were completed in 1980, there have been no BLEVEs of railroad tank cars in the United States.