A U.S. environmental review is expected to delay construction of the proposed Straits of Mackinac tunnel for Enbridge Inc.’s Line 5, the 540,000 b/d oil pipeline that serves Central Canada and the Midwest

The U.S. Army Corps of Engineers will require a formal environmental impact statement (EIS) for the Line 5 project, said Acting Assistant Secretary Jaime Pinkham of the Army for Civil Works. 

The Corps “received thousands of public comments and tribal input on the proposed project which warrant further review through an EIS including potential impacts to navigation.” The EIS “will ensure all potential impacts and reasonable alternatives associated with this project are thoroughly analyzed and will ultimately support a decision on the permit application.”

The $500...