Evacuations and the Isobutene Event in Baton Rouge, Louisiana

During yesterday’s isobutene incident in Baton Rouge, officials issued an evacuation order for people in the immediate area. How did they decide how large an area to evacuate?

In most cases, emergency responders refer to the Emergency Response Guidebook, or ERG, which provides quick information about how to respond. For a small spill or leak of isobutene, the ERG recommends keeping people at least 100 yards away. For large spills, such as most of the contents of a tank truck, the distance increases to ½ mile. If a railcar or tank truck is involved in a fire, the risk increases substantially due to the possibility of a large explosion and people should be kept at least 1 mile away.

Having worked as an Atmospheric Scientist and Dispersion Modeler for over 30 years, my specialty is studying how toxic chemical clouds move through the air and developing computer models to predict the areas that may be at risk so that people can be protected. The evacuation distances in the ERG are determined by running computer models like those I develop while assuming the worst-case situation and seeing how far downwind the plume might be dangerous.

I did model the spill yesterday and my findings agreed with how Louisiana officials were responding and the area that was being protected, including the 500-yard radius for which evacuations were mandated during the controlled burn to remove the isobutene from the damaged tanker. I commend Louisiana’s hazmat and public safety teams for a job well done

Related articles:
Isobutene Leak on I-10 in Baton Rouge, Louisiana

IEM Modeling and Simulation Capabilities

Author: Steve Stage, Atmospheric Physicist/Dispersion Modeler