Line 5 Straits span management program

Since building the Line 5 Straits of Mackinac crossing, Enbridge has employed a span management program to monitor the length of unsupported spans and make necessary repairs to prevent the movement of the pipes along the lakebed.

And since 2002, we’ve used a screw anchor support system to secure the twin pipelines running along the bottom of the Straits. These 10-foot-long steel screws are augered into the lakebed on either side of the parallel lines, and hold a steel saddle that permanently supports the lines.

In that time, Enbridge has installed 181 supports for Line 5 at the bottom of the Straits, with plans to install 20 more throughout 2020. These anchor supports have performed well in enhancing the safety of the line.

These anchor supports are part of Enbridge’s ongoing maintenance of Line 5. They are to ensure that the twin pipelines are adequately supported, and that Enbridge remains in compliance with the terms of its 1953 easement with the State of Michigan, as well as a consent decree reached between Enbridge and the U.S. Environmental Protection Agency (EPA).

Both the easement and the consent decree obligate Enbridge to support the pipeline. The easement agreement with the State requires supports to be placed no more than 75 feet apart, while the consent decree identifies a specific number and locations for installation of additional anchor supports.

Since currents may cause the lakebed to shift naturally, we keep a close eye on these spans with underwater vehicles that regularly inspect the exterior of Line 5 along the bottom of the Straits.

Enbridge’s ongoing work to inspect, maintain and modernize its transport system ensures that Line 5 remains in top condition—keeping the environment safe and securing energy delivery to Michigan and the Great Lakes region.

Ongoing inspections of the system will continue to guide the need for any additional anchors.