The controversial Enbridge’s Line 5 pipeline tunnel project faces a 30-day public consultation period after the U.S. Army Corps of Engineers failed to clear the project of all environmental and legal concerns, resulting in further delay for the crucial project. 

A draft environmental impact assessment released by the U.S. Army Corps of Engineers on Friday indicates the body did not clear the 3.6-mile (5.8 km) tunnel project of all potential concerns raised by environmental activists and lawmakers. 

The proposed 5.8-kilometer pipeline tunnel would be constructed beneath the lakebed of the Straits of Mackinac to house the replacement section of the Line 5 pipeline. The pipeline section will consist of 20-inch diameter pipes buried beneath the sediment near the shore. 

Enbridge prefers to have the tunnel approved for federal permitting through the Army Corps’ review process to avoid having less environmental security and certainty. Other alternatives available for the project include bolstering the tunnels with protective materials or having the pipelines decommissioned. 

The company hailed the newly released impact assessment and the opportunity for public comment as a significant milestone in the project’s progress.

“It is the result of more than five years of rigorous and comprehensive permit review and stakeholder engagement including input from Tribes and is a critical step forward in planning a project that will modernize energy infrastructure, protect the Great Lakes, and ensure long-term energy reliability for Michigan and the broader region,” said Enbridge spokesperson Ryan Duffy.

Duffy added that Enbridge focuses on ensuring that the proposed tunnel and pipeline result in “the smallest possible environmental footprint,” adding that the tunnel’s design already reflects the company’s intent. 

Enbridge Line 5 pipeline, which spans 645 miles (1038 km), transporting crude oil from western Canada to eastern Canada through the Great Lakes, has been subject to a litany of legal battles. 

According to a news report published by Michigan Advance, some activists opposed to Line 5 operations said last week that the project needs more work before it can proceed. 

The public comment period will end on June 30.