Drilling down into the geology of the Straits of Mackinac

Rock sampling work aboard the Highland Eagle will help shape Line 5 Straits tunnel project

This year, the Highland Eagle will be going deep—for safety and the economy.

The 236-foot-long marine vessel will be positioned in the Straits of Mackinac for the next several months, drilling for rock samples in preparation for Enbridge’s Line 5 tunnel project in Michigan.

On Wednesday, Enbridge hosted tours for elected officials, VIPs and media members aboard the Highland Eagle while it was docked in Detroit.

“The vessel we are about to tour is tangible evidence of our commitment to the $40-million 2019 engineering and geo-technical program,” said Guy Jarvis, Enbridge’s Executive Vice President, Liquids Pipelines, “which is being funded by Enbridge in the face of the State’s attempts to invalidate prior agreements and shut down the pipeline.”

Enbridge remains committed to moving forward with our Line 5 Straits tunnel project, a $500-million private investment in Michigan that could be under construction by 2021 and in service by 2024.

Placing the pipeline in a concrete tunnel, about 100 feet underground, would reduce the chances of a leak into the Great Lakes to virtually zero—and eliminate the possibility of an anchor strike in the Straits.

The Highland Eagle typically works in an offshore environment, performing investigative work for structures like wind turbines, bridges and subsea tunnels. The rock sampling work to be carried out aboard the Highland Eagle, and other vessels, will help determine the ultimate design and construction of the Straits tunnel.

Analysis of the samples will help determine the characteristics of the tunnel boring machine (TBM), which will be custom designed to suit the geology of the Straits. These rock samples will also determine characteristics of the tunnel’s concrete lining, and inform the precise placement of the tunnel.

"The Highland Eagle is a really big piece of our project because, at the end of the day, it's critical that we understand the geology of the Straits," said Enbridge project manager Amber Pastoor. "So by getting this information, by using this specialized vessel, we're going to make sure we can do that as safely and efficiently as possible."

The Highland Eagle was scheduled to leave Detroit on Wednesday evening for the Straits, where it will begin work by the end of July.

The Line 5 Straits tunnel solution is the best long-term opportunity to secure Michigan’s energy needs, while making an already safe pipeline safer.

Line 5 is a critical source of propane and light oil for Michigan. It meets about 55% of statewide propane needs and feeds regional refineries producing gas, diesel and jet fuel.

The tunnel solution ensures no interruption to the energy that heats homes, cooks food, powers industry, and keeps people mobile and connected. Shutting down Line 5 would lead to a serious disruption of the energy market, with potential job losses and higher energy costs.

“We don’t understand the State’s position to ignore offers we have made respecting shortening the tunnel timeline, further enhancing the interim safety of Line 5 while the tunnel is being built, and providing the State a key role in the governance of the project,” said Mr. Jarvis.

“In our opinion—and that of many others—(the State’s approach) is likely to result in significant disruption of the State’s energy market and potential job losses for Michigan residents,” he added.

(TOP PHOTO: Guy Jarvis, Enbridge’s Executive Vice President, Liquids Pipelines, speaks to Detroit media on Wednesday, July 10 in front of the Highland Eagle marine vessel, docked in the Port of Detroit.)