The McAsphalt Industries terminal on Farewell Avenue, located on the shore of Lake Ontario in Oshawa, caught fire on Saturday morning.
Firefighters rushed to the scene just after 5 a.m. Saturday. Plumes of black smoke could be seen tens of kilometres away.
The industrial fire required dozens of firefighters to bring it fully under control, with some hot spots remaining a problem on Sunday.
Nearby businesses were evacuated on Saturday, while residents living to the north of the plant were ordered to stay inside and to keep their doors and windows shut.
"The areas south of Olive Avenue and east of Harmony Road in Oshawa, we have asked those people to shelter in place — and it is for their own health and welfare that they do that," said Susan King of Oshawa Fire, when speaking with CBC News on Saturday.
But people were allowed to return to their homes and businesses on Sunday morning.
The cause of the fire is not immediately known.