Enbridge completes straits work, turns to tunnel design
Enbridge Energy finished its geotechnical work in the Straits of Mackinac on Sunday, concluding a phase that will serve as the foundation of boring and design plans for a more than four-mile tunnel to house the company’s controversial Line 5 oil pipeline.
This sets the stage for the Canadian energy company to plan the design of the tunnel and set about getting more permits for a construction project that the Whitmer administration opposes.
Enbridge extracted samples from 27 holes drilled on shore, in shallow, and at the deepest segments of the Straits. It capped the company’s $40 million investment in 2019 in the tunnel despite the state’s lawsuit seeking to stop it.
“It’s with this data now that we’ll be able to make some of the most important decisions about how we’ll design and construct this tunnel,” said Amber Pastoor, project manager for the tunnel.
The results will be particularly useful in determining the characteristics of the tunnel boring machine needed to complete the project as well as the exact alignment of the tunnel, Pastoor said.
After years of concern from environmentalists about the 66-year-old pipeline, Enbridge Energy entered into a series of agreements with Michigan last year that would require the company to pay up to $500 million to build a tunnel below the Straits of Mackinac lake bed to house Line 5.
The agreements made under Republican former Gov. Rick Snyder were challenged by Democratic Gov. Gretchen Whitmer and Attorney General Dana Nessel, who opined that the agreements were unconstitutional.
When negotiations regarding a shorter construction period were unsuccessful, Enbridge asked the Michigan Court of Claims to find the agreements were constitutional. A judge rejected Nessel's argument, but the Democratic attorney general has appealed the decision.
Nessel has a separate lawsuit pending in Ingham County Circuity Court seeking the shutdown of Line 5 on the argument that the pipeline constitutes a public nuisance and environmental risk.
Despite the ongoing litigation, Enbridge continued with its geotechnical work under an existing permit. Pastoor noted that the samples so far have been unsurprising.
“We had a sense of what we were going to find,” based on geological studies of the Straits, she said. “When you do a geotechnical investigation, it’s more confirmatory.”
The company is in the process of selecting the project’s design engineer and construction contractor who will work on the project's detailed design, Pastoor said. The designs can be worked on in tandem with additional applications to state and federal regulators.
The company is “optimistic” that it can continue meeting with Whitmer to negotiate the future of the project, spokesman Ryan Duffy said.
Whitmer ordered state agencies earlier this year to stop work on any permit requests for the tunnel project, but the permit for geotechnical sampling had already been awarded.
The recent Court of Claims ruling upholding Enbridge's 2018 agreement with the state allows Enbridge to apply for permits, Whitmer's spokeswoman Tiffany Brown, but "the matter is not finally resolved by the courts.”
In the meantime, Enbridge employees remain focused on the project and can adjust in the event of any potential changes to the timeline, Pastoor said.
“From the project perspective, we can take the geotechnical information we have now and move forward on detailed design,” she said. “That work is not going to be wasted.”
The company also has increased its use of support vessels in the Straits used to monitor any ships that come through for inadvertent anchor deployments following an anchor strike that gouged the dual spans in April 2018.
The two support vessels, which have only been operating during daylight hours, will now conduct 24/7 patrols, Duffy said.
“We’re still determining our plans for the winter,” he said.