A manufacturer of a solid oxidizer experienced three successive hazardous material accidents/releases during a one-week period. This case study discusses the emergency response process and how it evolved as new information became available. The commodity, a granular solid classified as DOT 5.1, was known to be thermally unstable. The material was further known to be both water-reactive and susceptible to autocatalytic decomposition (that is, its decomposition products accelerated the rate of decomposition). During decomposition the material has the capacity to generate a large volume of noncondensable gases. The manufacturer transported the commodity in bulk using pressure differential hopper railcars.
After the occurrence of the first accident, the manufacturer implemented a rapid and effective emergency response to protect human health and the environment. Because this was a noncollision event, immediate consideration was given to the fleet of commodity-containing railcars in transit to customer sites. The technical challenges unique to rail transportation and railcar design greatly influenced the emergency response. These challenges and their resolution are discussed. Although the next two accidents resulted in loss of the commodity, there were no injuries or environmental impact. The subsequent accident investigation determined that the direct cause of the railcar decompositions was the inadvertent introduction of water into the bulk solid. Data collected during the emergency response phase played a crucial role in the subsequent root cause investigation and in the design of safeguards to reduce the hazard of decomposition in future rail shipments. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005