A chemical production unit flare at Dow's St. Charles operations has been emitting benzene and butadiene. The unit is expected to shut down for repair of a malfunctioning flare stack that led to evacuation of nonessential workers from the plant early on Saturday morning. The flare stack is part of the Olefins II unit's safety system. It allows material being processed to be diverted and burned off. But the cracks in the tower let the material escape without being burned. Cracks in the flare stack led to the release of hydrocarbons that posed a potential danger to the plant.
Concentration of the emissions was confined to the plant grounds. The road was closed and workers were sent home as a precaution.