A Union Pacific Railroad train spilled a synthetic rubber substance into a southeast Nebraska creek Tuesday when it derailed near the Cass County-Otoe County line. One of the cars was loaded with polyisobutylene, a synthetic rubber, that ended up leaking into Wolf Creek, according to a spokeswoman for Union Pacific. Union Pacific told Sorenson the derailment is believed to have been caused by thermal misalignment, which occurs when the heat causes the rails to expand and push out of alignment. Hazardous materials crews from Union Pacific are managing the cleanup. Also responding to the scene were firefighters from Nehawka and Nebraska City, Cass County Emergency Management and Otoe County Emergency Management.
