Enbridge Inc. has retained a joint venture partnership between Barnard Construction Co. Inc. and Civil and Building North America Inc. (CBNA) to lead construction of the Great Lakes Tunnel in the Straits of Mackinac in Michigan.
In December 2023, the Michigan Public Service Commission approved Enbridge’s application to replace its Line 5 dual pipeline segments on the lakebed of the Straits of Mackinac with a single line built in a tunnel beneath the Straits designed as a utility corridor to connect Michigan’s peninsulas (OGJ Online, Dec. 4, 2023).
Enbridge operates Line 5, which has capacity to carry up to 540,000 b/d of crude oil and propane, with a crossing that sits on the bed of the straits. The 30-in. OD pipeline runs through the Upper Peninsula and Lower Peninsula of Michigan, but splits into two 20-in. OD pipes for the 4.5-mile crossing between the peninsulas. The tunnel plan would bore through rock beneath the bed and build a single 30-in. OD line through the tunnel.
The tunnel contract was awarded following a request for proposal (RFP) process initiated by Enbridge in 2022, the company said in an Apr. 30 update. The Mackinac Straits Corridor Authority (MSCA), which is charged with oversight for construction and operations of the Great Lakes Tunnel, agreed that the RFP conformed with requirements of the tunnel agreement. Financed solely by Enbridge, the Great Lakes Tunnel, once completed, will be owned and operated by MSCA, Enbridge said.
Barnard and CBNA will each retain a 50% partnership under the name Mackinac Straits Partners. Combined, the companies have built more than 100 tunnels in 15 countries equaling more than 372 miles of tunnel. A number of those projects involved geologic conditions similar to those that will exist in the Straits of Mackinac.
Enbridge is preparing to begin construction as soon as possible following the receipt of environmental permits for the tunnel project from the US Army Corps of Engineers (USACE), which has indicated early 2026 for permit decision making.
Enbridge has said the Great Lakes Tunnel project covers about 4 miles in length, will require no construction within the waters of the Straits, and is anticipated to impact less than one-quarter acre of wetlands. Enbridge submitted its application for the Great Lakes Tunnel project to USACE in April 2020.