On May 30, energy giant Enbridge responded to demands from Michigan officials to expedite the shutdown of its existing Line 5 pipeline beneath a crucial Great Lakes channel by announcing it could complete the construction of a proposed oil pipeline tunnel by early 2024, shaving years off previous estimates.
The Canadian company sent Democratic Gov. Gretchen Whitmer a revised timeline for drilling the $500 million tunnel through bedrock beneath the Straits of Mackinac, the 4-mile-wide (6.4km-wide) channel linking Lakes Huron and Michigan.
Enbridge said in its statement that geotechnical site investigation activities are due begin imminently, with ‘increasing commitments to contractors’ ramping up over the summer months. The company’s timeline sees a design/build contract for the tunnel awarded next year shortly followed by TBM procurement. Tunnel construction could start as soon as 2021, with two years scheduled for excavation – through bedrock 100ft (30m) below the straits –at an anticipated average of 40ft (12m) per day.
Podcast Episode 3: Empowering Underground Professionals In The Use Of Risk Assessment And Risk Engineering Techniques
“Enbridge is fully prepared to proceed with the 2019 program, necessary permitting and construction of the tunnel, but it is awaiting the State’s decision on supporting that path forward,” said the statement. The company had originally said it could take seven to 10 years to build the tunnel, as part of a deal negotiated with Michigan’s former Republican governor, Rick Snyder, last year.
The statement came in response to comments made by Michigan Attorney General Dana Nessel, who said she would act by the end of June to shut Enbridge’s Line 5 pipeline if the company and Gov. Gretchen Whitmer hadn’t reached an agreement on the tunnel by then.
“Every day that Line 5 continues to operate is a day that our state is in great peril and that we could possibly see what could be the largest oil spill in American history,” Nessel said at a press conference on May 29. There are several legal mechanisms Nessel’s office could use to close the pipeline, she said.
The aging Line 5 pipeline transports about 23 million gallons of light crude oil and natural gas liquids per day through the Upper Peninsula, including the 4-mile stretch through the Straits of Mackinac.
In late March, Nessel in a formal legal opinion declared unconstitutional the law passed by the Republican-controlled Legislature last December creating an authority to oversee construction of a tunnel to house Line 5 and other utilities. She argued the law was invalid “because its provisions go beyond the scope of what was disclosed in its title.”
Whitmer quickly ordered state agencies to halt their work on the project based on Nessel’s opinion.
Enbridge’s statement responded: “Enbridge has committed to construct the tunnel as quickly as prudently possible and to advance a number of additional protective measures while we construct the tunnel. Given the Attorney General’s opinion that the previous administration tunnel authority is invalid, Enbridge engaged and has continued to engage the State about alternatives to address that concern.”