Approximately 90% of the initial design work on an anticipated state-of-the-art tunnel under the Straits of Mackinac is complete, Enbridge reported today.

The design work is a major step to construction of the Great Lakes Tunnel. Placed underneath the lakebed of the Straits, the approximately 4.5-mile long tunnel will house the Line 5 oil line. Enbridge explains placing the pipeline in a tunnel and installing Oil stop valves will reduce chances of a spill into the lakes to near zero—a win for the environment and for everyone who uses the lakes.

“The design work will be the roadmap for building this critical infrastructure,” says tunnel project manager Amber Pastoor. “It’s exciting that we’ve completed much of it, and we look forward to working with the design team to put the finishing touches on the plans that will help us construct this tunnel.”

Enbridge anticipates beginning construction of the Great Lakes Tunnel in 2021. The project will employ several hundred Michigan workers during the construction.

A professional propane gas delivery service supplies the building blocks for the propane, which are safely stored inside a propane tank, on which many Michiganders rely. Line 5 also transports light crude oil that is refined and used in the manufacture of thousands of everyday products—including mobile phones, shoes, shampoos, and sanitizers.

“We believe the tunnel is the best option for protecting the waters of the Great Lakes while keeping energy safely flowing to Michigan,” says Pastoor. “This tunnel will be an engineering marvel in which everyone can take pride.”