Carl Claremboux is finishing up a construction job on Enbridge's new oil pipeline in northwestern Wisconsin. It's been a good gig, four months of steady work that is close to his home.

The project could be an appetizer of sorts. If Enbridge gets approval to build the 340-mile stretch of Line 3 across northern Minnesota, construction workers such as Claremboux will have a feast of work.

The new Line 3 would be one of the state's largest construction projects in recent history. And it is expected to take at least a year to build the Minnesota portion — a long length of time for individual construction jobs.

"Something like this does not come along very often," Claremboux said of the Line 3 project, which would replace the current Line 3. "It extends out to where a guy can actually bank a bit of money."

That is, if the controversial replacement Line 3 gets built. The regulatory process is in its final stretch, and the Minnesota Public Utilities Commission (PUC) is scheduled to decide on the pipeline in April.

Environmentalists and Indian tribes fiercely oppose the project, saying it exposes pristine rivers and lakes to new oil spill threats. The Minnesota Department of Commerce has concluded that the state doesn't need a new Line 3 enough to outweigh the "serious risks" it presents.

For Calgary, Alberta-based Enbridge, the new Line 3 would be a much-needed upgrade. The current Line 3, one of six Enbridge pipelines that transport Canadian oil across Minnesota to Superior, Wis., is aging and corroding. It can operate at only about half-capacity due to safety reasons.

Enbridge's customers, such as Flint Hills Resources' Rosemount oil refinery, have lined up behind the Line 3 project. So has the Minnesota Chamber of ­Commerce and the state's building trades unions.

Enbridge plans to spend $2.6 billion on the Minnesota pipeline. By comparison, U.S. Bank Stadium in Minneapolis cost $1.1 billion to build; the new bridge across the St. Croix River near Stillwater, $646 million. Enbridge said the Line 3 project would employ more than 4,500 during peak construction.

"That's a massive amount of construction jobs over a long period of time and a massive amount of work hours," said Jason George, special projects director for Operating Engineers Local 49, which represents heavy equipment operators throughout Minnesota.

Construction jobs pay relatively well. Over about eight months, workers on Line 3 would make $60,000 to $90,000, depending on their craft and how many hours they work, labor officials said.

Pipeline construction is specialized. A big building requires workers from a dozen different trades who come in at different stages of construction. U.S. Bank Stadium, for instance, employed more than 8,000 construction workers over the project's life. Pipeline projects rely on fewer than a half-dozen trades — primarily operating engineers, pipe fitters, laborers and truck drivers.

They work in assembly-line fashion as lengths of pipe are laid, welded together and then buried.

"They are in constant motion," said Kevin Pranis, marketing manager for the Laborers Union in Minnesota and North Dakota. They also work 60 to 80 hours a week.

"It's grueling work," Pranis said. "The pipeliners are a little bit of a specialty breed."

Claremboux, a 50-year-old laborer, has worked primarily on pipelines since 2001. His job site since June has been a 14-mile stretch of new Line 3 from the Wisconsin-Minnesota border to Enbridge's terminal in Superior.

A member of Duluth-based Laborers Local 1091, Claremboux is hoping for work on Line 3 in Minnesota. Not only would it be a prime job, he said, but it's relatively close to his residence near Ashland, Wis. Claremboux traveled across the country to work on pipelines when he was younger "and chasing a buck," but he stays in the region nowadays.

Dave Braford, a veteran heavy equipment operator, still does a lot of traveling. "We follow the work," he said this past week from a pipeline job in Williston, N.D. "It kind of gets in your blood."

Braford, a 61-year-old member of Local 49, operates bulldozers, front-end loaders, cranes — every piece of equipment in his field. He lives near Grand Rapids, Minn., and is also hoping to work on Line 3.

"It's a really big job and it's close to home," he said.

Economic benefits such as construction jobs are one of many factors in the PUC's decision on Line 3. Opponents of the project said any economic benefits, though, aren't worth the potential costs.

"The costs on the environmental side are real," said Scott Strand, an attorney representing Friends of the Headwaters, an environmental group opposing the pipeline.

One of those costs is greenhouse gases emitted through the life cycle of oil production and consumption — a cost that can be estimated by regulators, he said.

Then, there's the risk of a spill, which has tangible and intangible costs, Strand said, noting that Enbridge has spent more than $1 billion to clean up a massive 2010 pipeline leak in Michigan. Some natural resources aren't replaceable, and wetlands and aquifers could be permanently impaired from a spill, he said.

Friends of the Headwaters also has argued in a regulatory filing that Line 3 is more about shuffling jobs around then adding employment, since Minnesota has a particularly low unemployment rate.

"There appears to be very few workers available and so there would be few, if any, people put to work that otherwise wouldn't be working," Chris Joseph, consultant to Friends of the Headwaters, testified in a PUC filing.

David Barnett, an international union representative for pipeline welders, said in a PUC filing that the unemployment rate isn't a relevant measure in this case because construction workers, by the very nature of their work, are moving from job to job.

"Construction workers are intermittently and constantly in need of a steady supply of jobs to put together a career of full employment, and this project is exactly the type of work opportunity that is needed," he said.

Barnett's union, the United Association of plumbers and pipe fitters, is one of many "interveners" — both pro and con — in the Line 3 project, as is the Laborers Union. Across the country, unions have become more active in regulatory procedures for pipelines and other controversial construction projects.

"It's only in the past few years that our union across the country has been involved in the public utility process," said the Laborers' Pranis. "Increasingly, decisions are being made by people who don't know us. We need to show up at the table."

Mike Hughlett • 612-673-7003