Suite of environmental measures planned for tunnel construction rises to next level
Michigan’s freshwater resources are among the state’s most treasured natural assets and serve as a critical driver of its economy. As Enbridge advances toward construction of the Great Lakes Tunnel—which will require the temporary use of water drawn from Lake Michigan and the Straits of Mackinac—protecting and conserving these resources is a top priority.
Resource stewardship, sustainability and environmental protection are central to every aspect of the tunnel project, from construction to operations, and to the very reasons behind the Great Lakes Tunnel: preserving both energy delivery and environmental protection.
Enbridge is committed to employing responsible water management practices that limit environmental impacts while safeguarding the long-term health of the Great Lakes for future generations. That is why work at the Straits of Mackinac must begin with respect for the water itself and a clear commitment to stewardship.
Water temporarily drawn from the Straits will be used at different stages of the project, depending on the nature of the work underway.
For instance, some water will be needed to support excavation and tunneling during construction. Water is used in the slurry process as a tunnel boring machine excavates and brings rocks to the surface.
Enbridge will also use water to pressure test the new segment of pipeline. The pressure test confirms the pipeline is functioning as it should before it’s put into service.
“The significance of water helps shape our proactive approach to being custodians of the environment while safely providing vital energy through Line 5 in the Straits of Mackinac,” said Paul Meneghini, Enbridge community engagement manager in Michigan.
Over the past six years, Enbridge has conducted more than 40,000 field hours of environmental and cultural survey work in preparation for constructing the Great Lakes Tunnel to house a new segment of Line 5 in the Straits.
“Findings from the surveys helped determine the tunnel design, with the goal of creating the smallest environmental footprint, and minimizing, to the best of our ability, construction impacts on the environment, landscape and communities,” said Meneghini.
Reflecting Enbridge’s environmental commitment, Meneghini emphasized that, from the outset, its engineering team designed the Great Lakes Tunnel project to limit the amount of water required, while also prioritizing water quality as treated water is returned to the environment from which it is sourced.
As part of the multi-year, comprehensive regulatory process for building the Great Lakes Tunnel, Enbridge has applied for numerous federal and state permits, including a National Pollutant Discharge Elimination System (NPDES) permit.
"Our focus is on using the water needed for the project responsibly. Nothing less is acceptable."
Paul Meneghini
Enbridge community engagement
manager, Michigan
An NPDES permit is routinely required for construction projects whenever groundwater or stormwater could be released into a lake, river, or other surface waterbody.
Building the Great Lakes Tunnel will require a water treatment system to be built on Enbridge-owned property. The treatment system will manage all water associated with construction and is designed to help ensure that the water treated and returned to the lakes meets regulatory requirements. Water withdrawn from the lake will be returned to the lake, effectively recycling it.
“The temporary water treatment facility is a central feature of the Great Lakes Tunnel Project construction,” said Meneghini. “Meeting strict environmental standards, the goal is straightforward: take in water, use it safely, monitor rigorously, treat thoroughly and return it to the lake.”
The Great Lakes Tunnel project is important to Michigan’s energy and environmental future. Enbridge believes that building it in a way that respects the values of Michigan residents and gives careful attention to the local communities where construction will occur reflects a strong commitment to the state.
