St. Clair River HDD Installation: FAQs

Do you have questions about the Line 5 St. Clair River HDD installation?

Please find below a series of Frequently Asked Questions (FAQ) on the project. You may find your questions has already been asked and answered—but if not, please e-mail us your question at

We want to keep communities near our pipelines informed of our efforts to ensure safety and environmental protection. We can’t promise to answer all questions, but if we answer yours, we’ll e-mail you directly and also add it to this FAQs page so it can benefit others.

Please keep it clean and respectful. Thank you.

Q: What is “horizontal directional drilling (HDD)”?

Horizontal directional drilling (HDD) uses advanced technology to drill an underground arc that travels down, under and back up to the surface on the far side of the river or crossing.

Qualified operators use specialized equipment to guide the drill to create a small diameter pilot hole to ensure that the angle, depth, and exit point of the crossing corresponds to carefully design engineering plans.

Once the arc is established, the hole is enlarged until its diameter is large enough to install the pipeline. Finally, a pre-welded pipeline segment is pulled through the underground hole to the opposite side of the crossing.

Q: Does Enbridge have any experience doing an HDD on the St Clair River?

Yes. There have been three Enbridge-related pipelines that have been directionally drilled successfully across the St. Clair River:

  • Enbridge replaced the crude oil carrying Line 6B at the St. Clair River in 2011.
  • The LINK pipeline (a 24 inch gas pipeline jointly owned by Enbridge Gas Distribution and Trans Canada Pipeline) was installed approximately 4.8 kilometers downstream of Line 6B.
  • Vector Pipeline (a 42 inch gas pipeline jointly owned by Enbridge Inc. and DTE Energy Company was constructed approximately 13.5 kilometers downstream of Line 6B. Enbridge oversaw construction of this new pipeline, which commenced operation in 2000. 
Q: What happens if this HDD is not successful?

Enbridge is evaluating several options that could be pursued in the unlikely event that the HDD is not successful. However, we believe there is a good likelihood of success based on our own experience with the HDD construction methodology.

This is proven technology. Numerous large and small diameter pipelines have been successfully installed using this technique, which has been successfully utilized to install pipelines across rivers and wetlands with minimal environmental impacts since the 1970s.

Over the past decade there have been at least three large diameter pipelines installed by a HDD technique across the St. Clair River.

Q: Does Enbridge need approval from federal regulators to replace the section of pipe?

Yes. U.S. and Canadian federal environmental agencies review and approve construction plans (Transport Canada; Canada via the NEB MOU, Department of Fisheries and Oceans via the NEB MOU; U.S. Army Corps of Engineers; Michigan Department of Natural Resources and Environment; and clearances from other agencies along with local building and work permits).

In Canada, the National Energy Board maintains regulatory oversight of all project activities. Enbridge submitted a federal permit application to the NEB in July 2018.

Pipelines and Hazardous Materials Safety Administration (PHMSA) and NEB project inspectors are expected to audit construction work during this project.
Q: What impact with the Line 5 St Clair River HDD Project have on local refineries? How long will the line be shut down?

The Line 5 St Clair River HDD Project is currently in the preliminary stages of planning and engineering. During construction Line 5 will continue to operate without the Project disrupting current service levels. We work with our shippers to plan line shutdowns, targeted in early 2020, to facilitate the change between the existing and replacement Line 5 pipelines.

Through this communication, Enbridge and its Customers are able to reduce the effect of the Project on productivity on receiving facilities based on their planned production, maintenance schedules, and other activities that affect the refinery independent of the Project scope of work.

Q: When will you start construction?

Engineering and construction planning for the Line 5 St. Clair River HDD installation is now underway. Construction will begin once all permit and authorizations are received.

Q: How long will construction take?

Once underway, construction is expected to last about four months. Federal permit applications will be filed by the summer of 2018.

There will also likely be some minor restoration and remediation work completed after the replacement pipeline is in operation.