The replacement of the section of Enbridge's Line 5 pipeline, which runs beneath the St. Clair River, has been successfully completed and is now in service.
The company said it used horizontal directional drilling to bury the new line even deeper than before for increased safety.
The line has provided essential service for the delivery of feedstocks to refineries in Ontario and Michigan for 65 years.
Spokesman Ken Hall said the estimated $20 million project was in the works for over a year.
"I'm very happy to report that we had no safety incidents whatsoever throughout the entire project, so again it was a really big safety accomplishment for the company," he said.
"I want to extend our thanks to the City of Sarnia, Township of St. Clair, the County of Lambton, and all of the residents that live in south Sarnia and in the Froomfield area near LaSalle Line for their patience and understanding during construction. It really was a great project and one of the reasons for that is we had really good support from all of our stakeholders."
Hall said they've also installed remotely controlled valves that will continuously monitor pressure readings on both sides of the river.
He said the start of the project had been delayed due to permitting issues, and the company was forced to ramp up safety policies due to the COVID-19 pandemic.
Valve to valve, the portion of line stretches about one kilometre from Sarnia to Marysville, Michigan.
Overall, Line 5 runs about 1,000 kilometres from Sarnia to Superior, Wisconsin.
Controversial plans for a new Line 5 pipeline tunnel under the Straits of Mackinac, is being challenged in court by the State of Michigan.