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Michigan Public Service Commission approves Enbridge’s Line 5 tunnel under the Straits of Mackinac

The Michigan Public Service Commission has approved a tunnel for Line 5 to run under the Straits of Mackinac.

The Commission determined that without the pipeline’s operation, suppliers would need to use higher-risk and costlier alternative fuel supply sources and transportation for Michigan customers, including those who use propane for home heating.

RELATED: Critics speak out against approval of Enbridge Energy’s Line 5 tunnel


However, the MPSC also says there’s a public need to protect the ecological, natural, and cultural resources of the Great Lakes. They have determined that replacing the pipes in the Straits of Mackinac with one pipeline inside a tunnel is the most efficient and effective way to do this.

The commission found that:

  • The replacement pipeline is a significant improvement over the existing dual pipeline configuration, and the underground tunnel will be an extra precaution against leaks.
  • Enbridge has demonstrated that an experienced firm designed the tunnel, and it will be built using state-of-the-art materials and practices that meet or exceed industry standards.
  • Enbridge has ensured the replacement pipeline will meets or exceeds current safety and engineering standards.

Enbridge can proceed with the construction of the replacement pipeline once the project is approved by regulatory agencies including the Mackinac Straits Corridor Authority and United States Army Corps of Engineers, with some requirements:

  • Enbridge must receive required governmental permits and approvals and make no significant changes to the route and location of the Line 5 replacement pipeline within the tunnel.
  • The pipeline must be the only utility located in the tunnel. No third party utilities will be allowed.
  • Exceed minimum federal regulations to ensure the safety, integrity and reliability of the new Line 5 pipeline.
  • Enbridge must submit a detailed risk management plan to the State of Michigan before construction.

Once construction of the tunnel and replacement pipeline is complete, Enbridge will deactivate the existing dual pipelines.

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