ST. PAUL — Construction workers and protesters are gearing up for the final — and likely most tense — phase in the completion of the Enbridge Line 3 crude oil pipeline in northern Minnesota.

The Calgary-based company is set to scale up its workforce beginning in June as it wraps up the construction of the 340-mile pipeline replacement. And workers on the line across northern Minnesota are likely to face demonstrators aiming to halt the project's advance.

Indigenous and environmental groups have said they'll organize thousands of protesters along the line next month and they've pressed Gov. Tim Walz and President Joe Biden to block the project. Both Enbridge and the coalition of opposition groups said they were gearing up for civil unrest along the line.

And a Minnesota Court of Appeals ruling expected out next month could overturn the project's permit from the Public Utilities Commission. The Red Lake Band of Chippewa and the White Earth Band of Ojibwe along with other Indigenous groups and environmental organizations challenged the project's permit and argued that Enbridge didn't prove the long-term need for oil in the state.

Enbridge reported that 60% of the replacement pipeline had been completed since construction started in December and the company expected to finish the project in the fourth quarter of 2021. Enbridge Chief Communications Officer Mike Fernandez said that more than 4,000 workers are set to head out over the next few weeks, a jump from the roughly 1,000 that had been on the line during a break in construction during the spring thaw.

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"We are in the final stages, you got 40% yet to go that will be completed within the fourth quarter of this year," Fernandez said, noting oil could start flowing late this year. "The other thing we're very much aware of is with the summer, the nicer weather, there's more likely to be protests ... we're braced for that last-ditch effort."

The project once completed is set to carry 760,000 barrels of oil (or 31.92 million gallons) per day from Alberta, Canada, to Enbridge's terminal in Superior, Wisconsin. The plan has faced fierce opposition from environmental and Indigenous groups that say the pipeline isn't needed, could spur an oil spill, violates tribes' treaty rights and increases reliance on oil at a time when worsening climate change requires a swift transition away from fossil fuels.

MORE ON THE LINE 3 PROJECT:

Enbridge has said it needs to replace the line built in the 1960s to increase capacity since the pipeline runs at half of what it originally pumped. And the company contended that putting in place a newer, stronger steel pipe could help prevent a spill.

The pipe running through northern Minnesota is set to be the final section to be completed. Replacement pipe running through North Dakota is finished and sections in Wisconsin and Canada have already begun pumping oil.

Dozens met outside the governor's residence in St. Paul Wednesday, May 26, and they urged Walz to block the pipeline. The Democratic governor has said he will let the process play out in the courts.

Advocacy groups have also requested intervention from the Biden administration to prevent construction from moving forward.

"We've tried everything up to this point, now we're calling on the people to stand with us because the process failed us," said Dawn Goodwin, co-founder of the Resilient Indigenous Sisters Engaging (RISE) coalition and a member of the Indigenous Environmental Network. "We've discovered that the process was never made to work in our favor. ... We've called on people to come and stand and learn what it means to be treaty people."

Tribal and environmental groups opposing the pipeline's construction have said they plan to organize hundreds of protesters at the site as the project enters its final phase. A group called Treaty People Gathering said it was organizing a June 5-8 demonstration in an effort to block the pipeline.

"We will not stand by and watch a fossil fuel corporation line its pockets as so much is destroyed, producing oil we don’t need," a website detailing the protest says. "We will gather in Northern Minnesota to put our bodies on the line, to stop construction and tell the world that the days of tar sands pipelines are over."

More than 250 people have been arrested in protests along the pipeline.

Follow Dana Ferguson on Twitter @bydanaferguson, call 651-290-0707 or email dferguson@forumcomm.com