The Highland Eagle has started work in the Straits of Mackinac, gathering rock samples from the bottom in preparation for construction of a tunnel that would house a replacement for the aging Line 5 oil-and-gas pipeline.
Before traveling to the northern end of Lakes Michigan and Huron, the 236-foot-long deep-water drilling vessel stopped in Detroit on a sweltering hot July day, and Enbridge Inc. representatives took a group of reporters on a tour of the boat.
Guy Jarvis, Enbridge executive vice president, liquids pipelines, told reporters that the Canadian company can “see a path” for tunnel construction to begin by 2021 with it opening by 2024.
“The vessel we are about to tour is tangible evidence of our commitment to the $40 million 2019 engineering and geo-technical program which we are paying for even in the face of the state (of Michigan)’s attempts to invalidate prior agreements and shut down the pipeline,” he said.
In late 2018, former Michigan Gov. Rick Snyder, along with the Republican majority Michigan legislature, approved the plan to replace Enbridge’s Line 5 pipeline with a pipeline in a tunnel. But current Gov. Gretchen Whitmer and Attorney General Dana Nessel, who took office in January, have questioned the project.
Nessel determined that the law allowing the tunnel was unconstitutional and therefore agreements for the plan were void. Enbridge sued, asking a court to affirm the deal the company had made with the Snyder administration and to allow the plan to move forward.
In late June, Nessel filed in one court to dismiss Enbridge’s lawsuit and in another to have Line 5 shut down as soon as possible, after a reasonable period for people to have back up plans for propane supplies.
A few weeks later, on July 10, Enbridge representatives took a group of reporters on a tour of the Highland Eagle in Detroit.
What is the tunnel project and what is this boat’s role in it?
The tunnel would be roughly 4.5-miles long, 10-feet wide and some 100 feet under the Straits of Mackinac lakebed. Inside the tunnel would be a new 30-inch pipeline to replace the two 20-inch pipelines that currently run on top of the Straits of Mackinac lakebed, operating as Line 5.
This preliminary stage that Enbridge is pursuing is $40 million of the $500 million estimated total cost of the tunnel project. Just under $35 million is specifically for the geotechnical program and a little more than half of that is going to mobilizing the Highland Eagle, according to Amber Pastoor, the tunnel project manager.
A total of 24 boreholes will be or have been drilled in the Straits of Mackinac lakebed, six with a jack-up barge nearshore and 18 with the Highland Eagle. Each borehole will take about four days to drill, give or take a couple days, Pastoor said. The drilling will go until mid-October.
Who is on board this boat?
The Highland Eagle has on-board geologists who will analyze each of the rock cores removed by the drill to determine composition. This analysis is necessary for the design of the tunnel as well as to design the tunnel boring machine that Enbridge needs to custom fabricate to create the tunnel.
Enbridge needs to collect this geological information because data on the lakebed hasn’t been collected in this capacity since the 1950s when the Mackinac Bridge was built. Even then, the equipment wasn’t as advanced as it is now, nor did they need to explore as deep as Enbridge does for the tunnel.
“I have geologists calling me all the time going ‘Can we look at your samples? Can we look at what you’re drawing?’ and I think one of the really neat things is that Enbridge will definitely work with some of the institutions in the area when the pipeline is done,” Pastoor said. “We’ll look for a home for students and people in the region to be able to have the cores and be able to study them.”
The projected timeline would involve the tunnel being fully permitted and the tunnel boring machine manufactured by 2021, two years for boring the tunnel and another 6 to 9 months for lining the tunnel, testing it and placing the new pipeline, with the new pipeline in service by 2024.