On December 18, 2012, the NRC was notified by Clean Harbors that they had a release of chlorine gas from a tractor trailer staged on their property. The release created a plume of gas that migrated off of their property. The local fire department ordered an evacuation of a nearby prison and a shelter in place for several residential areas downwind. OSC Brescia and EPA START mobed to the scene to conduct air monitoring and assessment activties.