In 1999 and again in 2002, accidents occurred as a result of the process of heating rail tank cars for unloading hazardous materials.
On February 18, 1999, a rail tank car, which was on the unloading rack at the Essroc Cement Corporation (Essroc) Logansport cement plant near Clymers, Indiana, sustained a sudden and catastrophic rupture that propelled the tank of the rail tank car an estimated 750 feet and over multistory storage tanks. The 20,000-gallon rail tank car initially contained about 161,700 pounds (14,185 gallons) of a toxic and flammable hazardous waste that was used as a fuel for the plant’s kilns. There were no injuries or fatalities. Total damages, including property damage and costs from lost production, were estimated at nearly $8.2 million. The National Transportation Safety Board (NTSB) determined that the probable cause of the accident was the failure of Essroc to develop and implement safe procedures for heating rail tank cars for unloading hazardous waste (i.e., toluene diisocyanate matter wastes). This lack of procedures resulted in the over-pressurization of the rail tank car due to chemical self-reaction and expansion of the toluene diisocyanate matter wastes.
On September 13, 2002, a 24,000-gallon-capacity rail tank car containing about 6,500 gallons of hazardous waste catastrophically ruptured at a transfer station at the BASF Corporation chemical facility in Freeport, Texas. The rail tank car had been steam-heated to permit the transfer of the waste to a cargo tank motor vehicle for subsequent disposal. The waste was a combination of cyclohexanone oxime, cyclohexanone, and water. As a result of the accident, 28 people received minor injuries. Residents living within one mile of the accident site had to shelter in place for five and one-half hours. The rail tank car, cargo tank, and transfer station were destroyed. The force of the explosion propelled a 300-pound rail tank car dome housing about 1/3 mile away from the rail tank car. Two storage tanks near the transfer station were damaged which resulted in the release of about 660 gallons of the hazardous material oleum.
The Federal Railroad Administration has identified involving heating of rail tank cars that did not result in death or injury. The NTSB investigated the Freeport, Texas accident and determined that the probable cause of the rupture of the rail tank car was over-pressurization resulting from a runaway exothermic decomposition reaction initiated by excessive heating of the hazardous waste material. The NTSB determined that BASF’s failure to monitor the temperature and pressure inside the rail tank car while the hazardous waste was heated in preparation for unloading contributed to the accident. As a result of its investigation of the Freeport, Texas accident, the NTSB recommended that PHMSA, in cooperation with the OSHA and the EPA, develop regulations that require safe operating procedures to be established before hazardous materials are heated in a rail tank car for unloading; at a minimum, the NTSB recommended that the procedures should include the monitoring of internal tank pressure and cargo temperature (NTSB Recommendation R-04-10; December 15, 2004).