en.Wedoany.com Reported - The Michigan Department of Natural Resources and the Department of Environment, Great Lakes, and Energy approved permits on July 15 for the Great Lakes Tunnel Project. The project plans to construct a tunnel approximately 4 miles long to house dual oil and gas pipelines that Canadian energy company Enbridge intends to lay beneath the Straits of Mackinac.

The Department of Environment, Great Lakes, and Energy had previously issued permits in 2021 for the energy giant's plan to replace the 73-year-old dual pipelines of Line 5 crossing the lakebed. Those earlier permits expired earlier this year due to years of complex legal battles at the state and federal levels.

A report from the Institute for Energy Economics and Financial Analysis in Canada showed that pipeline costs were initially estimated at $500 million in 2018 but had ballooned to at least $750 million to $800 million by 2022. Enbridge spokesperson Ryan Duffy declined to provide updated project costs.

In a press release, the Department of Environment, Great Lakes, and Energy stated that after a 16-month review, it concluded on Enbridge's subsoil and wetland permit application: "The public and private need for the proposed activity outweighs other public interest criteria."

The permits come with conditions. Enbridge must submit an improved wetland mitigation plan to address wetland impacts and add new conditions to mitigate effects on cultural resources in the area.

The Department of Natural Resources permit requires Enbridge to reduce impacts on rare plants and animals listed as threatened by federal and state authorities. The agency stated that Enbridge must preserve topsoil and collect seeds to restore populations of Houghton's goldenrod and dwarf lake iris after construction; only cut trees in winter to avoid disturbing bats; and set up construction zones to prevent damage to sensitive plant areas.

Duffy called the renewed permit from the Department of Environment, Great Lakes, and Energy "a significant step forward for the project to further protect the Great Lakes while ensuring uninterrupted energy supply supporting Michigan and the region." He added: "We are reviewing the new permit conditions issued today to assess any impacts on tunnel construction."

The Michigan League of Conservation Vectors condemned on its website Governor Gretchen Whitmer (Democrat) and her administration's decision to approve the tunnel permits.

"Instead of doing everything in her power to protect the Great Lakes, Governor Whitmer is enabling a Canadian oil company to hold Michigan taxpayers financially responsible for billions of dollars if something goes wrong," said Lisa Wozniak, CEO and President of the League.

The League claimed the proposed tunnel threatens tribal nation rights protected under the 1836 Treaty of Washington. "Tribal governments have consistently opposed the project, warning that an oil spill or construction-related damage could cause irreparable harm to sacred waters, fisheries, and culturally significant sites," the League stated.

According to previous reports by Engineering News-Record (ENR), preliminary construction on the tunnel began in 2019, studying sediment and rock samples to understand the straits' geology and inform tunnel design. Arup is the lead design engineer.

In 2024, Enbridge designated a joint venture of two tunneling companies—Barnard Construction Co. and Civil and Building North America—to lead tunnel construction, but work has not yet started.

The project will build an entry point on the south side of the straits to deploy a 500-foot-long tunnel boring machine, where a slurry plant will also be constructed to separate rock, clay, gravel, and water extracted from the tunnel. The separated water will be reused during tunnel construction.

The project's tunnel boring machine consists of thousands of components and will take three to four months to assemble.

The machine must excavate limestone, rock, and shale while lifting and sealing 1-foot-long reinforced concrete lining segments into place. The machine is planned to advance 40 feet per day, five days a week. The project plans to build a shaft on the north side of the straits for recovering and dismantling the machine.

During construction, saturation divers will conduct regular inspections and maintenance. They will live in surface pressure chambers for weeks at a time, planned to be transported to work via pressurized chambers at the tunnel boring machine's head.

The project still requires several other permits and approvals, including a federal permit from the U.S. Army Corps of Engineers.