The Sarnia Imperial site is in the process of restarting equipment following a maintenance turnaround.
"This is a planned startup and there will be a period of elevated flaring and noise, said Public & Government Affairs Manager Kristina Zimmer in a statement issued Saturday night. "Flaring is a regulated and environmentally approved measure to safely burn off excess product or materials used at our facility."
Zimmer said the turnaround employed a peak contractor workforce of 450 and was carried out with a focus on safety.