Tunnels provide solutions for people, issues
A tunnel boring machine will be used to create the Great Lakes Tunnel under the Straits of Mackinac..
Advanced technology key in constructing today’s tunnels
Jan. 18, 2023
Editor’s note: This is the second part of an ongoing series regarding the importance of tunnels in North America, and around the world.
Tunnels can be a moving experience—from Boston to Seattle, and places in between like Houston.
They help move people, goods, even storm water.
Ninety feet below the surface, the Ted Williams Tunnel between the land-based approach and the east Boston portion of the Boston Harbor is the deepest such underwater connection in North America. Thousands of drivers safely move through the tunnel each day.
Westward, beneath Houston, is a system of tunnels 20 feet below Houston's downtown streets and more than six miles long. Having started out years ago as a tunnel between two downtown movie theaters, today it includes restaurants and service retail and connects 95 city blocks.
Farther west, with a different purpose, Seattle’s tunnel for a custom-built rail line is underway right now with a construction process that mirrors that of Enbridge’s planned Great Lakes Tunnel in the Straits of Mackinac.
Seattle and King County officials are boring a 2.7-mile-long, 19-foot-diameter tunnel through which to transport and store untreated sewage. It also will store the stormwater that comes with the city’s notorious heavy rains. To dig a tunnel, they are using a giant tunnel boring machine that grinds through rock and builds a tunnel as it moves forward.
Technology makes tunnels possible, safe
“While the purposes of the tunnels are different, Seattle is using a massive boring machine similar to what we will use for the Great Lakes Tunnel,” said Mike Moeller, Enbridge’s director of the Great Lakes Region.
“These types of tunnel boring machines are among the most advanced technological tools. They need to be customized to the geology and uniqueness of where they will be used and maneuver in a steady, methodical manner.”
Seattle began drilling its tunnel in 2021 and reached the halfway mark at the end of 2022. While Enbridge is funding the construction of the Great Lakes Tunnel, Seattle’s Public Utilities (similar to the Michigan Public Service Commission) is sharing the costs with King County’s Wastewater Treatment Division.
“Enbridge is paying for the construction of the Great Lakes Tunnel,” said Moeller. “We view the Tunnel as an investment in Michigan and our operations here.”
Enbridge is seeking permits to build the Great Lakes Tunnel to house a segment of Line 5 in the Straits that carries light crude and natural gas liquids, which are turned into propane. The company says the idea is to protect the waters of the Great Lakes while ensuring that energy keeps flowing to Michiganders. Placing the oil pipeline in a four-mile-long, 20-foot-diameter tunnel below the lakebed will eliminate the chance of an anchor strike to Line 5 and essentially eliminate the chance of a spill from Line 5 into the Straits.
“The Great Lakes Tunnel will enable this region to continue to safely receive safely the energy on which it depends, while enhancing environmental measures to protect the Straits,” said Moeller. “That’s a true win-win.”
The Tunnel could possibly contain other important utilities like high-speed fiber that would improve 911 and internet service in the Upper Peninsula of Michigan.
Enbridge is seeking permits from the Michigan Public Service Commission and the U.S. Army Corps.
“We’re ready to get going and build the Tunnel,” said Moeller. “Let’s build the tunnel, put people to work, protect the Great Lakes and make sure that people get the energy they need and depend on. We’re ready to get going on this important project.”
