At about 4:30 p.m. Friday afternoon, the eastbound onramp in Superior to Interstate 90 at Exit 47 became blocked when a tractor trailer carrying a variety of materials overturned where many trucks have accidents after a stop to fuel up. “Trimethylbenzene is the most worrisome because it is highly flammable, highly explosive and self-combustible,” said Incident Commander, Steve Temple with the Superior Volunteer Fire Department.

The St. Regis Fire Department and HazMat team were on site, but this was outside of their capabilities.

Temple said they used long distance cameras to look inside to be sure the temperature was not near 100 degrees because that is when the substance becomes volatile.

After declaring the temperature was safe, everyone, including Montana Highway Patrol and two tow trucks remained outside the 300-foot hot zone Temple established until the Missoula Regional HazMat Team arrived to take control of the scene.

No leakage was observed from the semi-trailer on its side, but a barrier had been established in case there was so that the chemicals could be contained.

Once the HazMat techs arrived, they wore protective equipment and were able to enter the trailer and isolate and contain the product. After the leak was contained and the product stabilized, the Montana Department of Transportation and the local fire departments took over the scene.

The driver was alone en route to Missoula and there were no injuries.