A unit upset at Shell Canada's Sarnia Manufacturing Centre was causing noticeable elevated flaring Tuesday afternoon.
The company reported a unit trip at the Corunna facility just after noon.
Flaring was expected for 12 to 24 hours as efforts to bring the unit back into service continued.
In a message on the Community Awareness Emergency Response (CAER) phone line, Shell said it was monitoring the situation and no action by the public was required at this time.
The company said the flaring system is an important process safety device at the refinery, and occasional flaring is a normal part of keeping the plant safe during restarts and unplanned disruptions.
