Mackinac Straits Corridor Authority backs Enbridge tunnel

The tunnel would connect the Upper and Lower Peninsulas to accommodate a replacement of that portion of Enbridge’s Line 5 pipeline that crosses the Straits of Mackinac.

"We’ll be making a safe pipeline safer—by replacing our Line 5 Straits crossing in Michigan with a pipeline secured in a larger tunnel, bored deep beneath the lakebed," the company said in a release. Adding, "While Line 5 has operated safely at the Straits for 65 years, we’re enhancing safety where it matters most. The replacement of Line 5 inside a tunnel will protect one of the most important natural resources in the world, and reduce the chances of a product release into the Straits to near zero."

The proposed tunnel is 4.1 miles (6.6km) long, mined by TBM approximately 100ft (30.5m) below the strait's lakebed. The finished diameter is likely to be 10ft, with a one foot thick concrete lining.

The estimated USD 500M project will be privately funded.

On October 3, the State of Michigan, the Michigan Department of Environmental Quality, and the Michigan Department of Natural Resources entered into an agreement with the resources company regarding the NGL pipeline tunnel and provision for the potential to accommodate use by other utilities.