For the past several months the debate over mining in Minnesota has focused on PolyMet Mining's proposed copper-nickel mine, which is winding its way through the environmental review process.
But Twin Metals has been quietly completing its plans for a second and much larger project, one that could be a massive underground mine just a few miles south of the Boundary Waters Canoe Area Wilderness.
For nearly a decade, Twin Metals has been drilling deep holes thousands of feet below the Superior National Forest, searching for rich veins of copper and other metals. Unlike the proposed Polymet open pit mine, extraction would take place underground.
• 2012: Estimates grow of underground ore's amount, value
"We think it will be close to the largest underground mine in the U.S," Twin Metals spokesman Bob McFarlin said of the project, which would resemble a vast underground city. "You've got roads, lights, plumbing, electricity, air circulation — all those types of things that support an operation of 1,300 employees working underground in shifts, and moving a lot of material."
According to a draft site map Twin Metals unveiled earlier this year, employees would enter the mine at a new industrial facility near the Ely airport, about six miles south of town.
An underground road would slope downward, under Birch lake, to the mineral deposit several miles to the east, over 1,500 feet below the surface.
Workers would crush the ore in big caverns and then truck it to the surface for processing. The PolyMet mine, by contrast, plans to crush its ore inside a refurbished LTV Steel taconite plant.
Twin Metals is considering piping the finished concentrate about 15 miles south to a new facility outside Babbitt, near the existing North Shore taconite mine.
The company also would ship about half its leftover tailings — the ground up ore that remains after metals have been extracted — to the site. Workers would backfill the rest into the mine.
McFarlin said an underground mine could cost $2.5 billion to build but would offer environmental advantages over an open pit mine by limiting damage to the surface.
"We're estimating right now about 55 percent of the material that is commonly stored on the surface in mining operations across Minnesota, we'll be able to put that material underground," he said.
The proposal also promises tantalizing economic benefits, including more than 1,000 permanent jobs and upwards of 3,500 construction jobs. That's three times the number of jobs the PolyMet mine would create.
McFarlin said the rich deposits could potentially support over a century of mining. But those benefits aren't enough to win over critics like Ely resident Becky Rom, who said mining development in the region would mar a bucolic vacationland.
"Instead of being in the middle of a well-managed national forest, with clean water, and wonderful swimming and fishing, dark skies, they would be in the middle of an industrial place," she said.
Rom said that could harm more than two dozen resorts and businesses like Wintergreen Dogsled Lodge, which caters to 500 tourists every winter.
A 24-7 mining operation — even one largely underground — would bring noise, bright lights and heavy truck traffic, said Paul Schurke, the lodge's director.
"People come here for the solitude, for the peace and quiet, and for the beauty of the North Woods," he said. "All that is at threat."
But other resort owners support the possibility of mining. "I think it can be done safely," said Kerry Davis, owner of White Iron Beach Resort downstream from Schurke's lodge. A thriving mining operation, Davis said, could help Ely "get back to where we were, so it's a thriving community where we can raise families."
Copper-nickel mining skeptics like Schurke and Rom also oppose the proposed PolyMet project farther south. But they say Twin Metals is different, because potential water pollution would flow not into the St. Louis River, but past Schurke's lodge on White Iron Lake, and into the pristine lakes and rivers of the Boundary Waters.
"They're entering the holy of holies when they cross that line and go into the Boundary Waters watershed," Shurke said.
Twin Metals proposes shipping a portion of its leftover mine tailings to a new facility across the Laurentian Divide, in the Lake Superior watershed.
McFarlin, Twin Metals spokesman, said that largely aims to put the tailings closer to an active mining operation and to reduce wetland impacts. But he acknowledges the watershed issue has become contentious.
"That is of interest to a number of people, in reality regardless of where the tailings facility is, it would have to meet state and federal water quality regulations," he said. "If it were in the Boundary Waters Rainy River watershed, it would meet those regulations and standards. If it's in the Great Lakes watershed, it's going to have to meet those standards, and will do so."
Twin Metals is still about two years away from developing a specific mine proposal to submit for environmental review.
But its location just a few miles north of PolyMet, in a different watershed, could prove critical, Rom said.
"This type of mine, immediately upstream of America's most popular wilderness, causes us great concern," she said. "It's the wrong activity, in the wrong place."