Animas River

The Animas River near Durango, Colorado, runs orange with contaminants after the Gold King Mine spill on August 6, 2015. (Credit: Butch Knowlton/La Plata County Office of Emergency Management)

At 11 a.m. on August 5, 2015, the icy waters of Cement Creek, just outside the scenic Colorado mountain town of Silverton, began to turn to mustard-colored sludge. By day’s end, three million gallons of acid mine drainage had poured out of the inactive, 120-year-old Gold King Mine. The tainted water coursed downstream into the Animas River where it horrified kayakers in nearby Durango, prompted water treatment plants to shut off their taps, and ignited alarming front-page photos in newspapers nationwide. Within four days, the surface water had cleared and, according to EPA measurements, returned to pre-spill levels of toxic metals. But the conversation started by the Gold King blowout had only just begun.

“This was a wake-up call,” says Linda Figueroa, a Mines professor of civil and environmental engineering who studies mine remediation techniques. “It lit a fire under the abandoned mine lands community, reminded the public that this is an issue, and prompted people to put it back on the front burner.”

As industry and government agencies grapple with what to do about the estimated half-million abandoned mines nationwide, and as the state looks more closely at how to address hundreds of legacy mines fouling thousands of miles of Colorado streams, Mines—with its multi-disciplinary expertise and collaborative relationship with industry and government—is poised to play a key role.

“Our primary objective is to build knowledge, not make money, so we can give problems longer-term attention at lower cost while educating the workforce of the future,” says Priscilla Nelson, head of the Department of Mining Engineering. Already, the school has a long history of supporting research that has advanced the way mines are operated and reclaimed. And with a growing focus on the environmental and humanitarian aspects of mining, the school hopes to cultivate a new generation of miners who see themselves as “stewards of the earth’s resources,” Nelson says.

As a neutral party, Mines also hopes to facilitate a stakeholder-wide conversation about what happens next. “What do we know and what do we not know? What new technologies need to be developed?” asks Nelson, who hopes to host a symposium on the subject this year. “Let’s sit down and talk about it.”

Mining, Then and Now

Pennsylvania Mine

The now-defunct Pennsylvania Mine near Keystone, Colorado, began undergoing a cleanup effort in 2013, led by Mines alumnus Jeff Graves ’13. For more information on this project, see our Alumni Profile on Jeff Graves. (Credit: Jeff Graves)

While much media attention has been paid to the number of abandoned, historic mines that riddle hillsides across the West, one positive development is often overlooked: Industry practices have changed dramatically since those mines were built. “There really is no comparison,” says Ronald Cohen, a Mines professor of civil and environmental engineering who has studied the history of Western mining. “The demands on industry are so much greater than they were back then.”

As early as 1870, a few vague guidelines existed for mine operators, but there was no agency to enforce them and no political will to strengthen them. Even in the mid-20th century, many Western companies still “viewed gravity as their friend,” says Cohen. They dumped their waste downstream while operating, and when it was time to close up shop, they left their tailings and rock piles behind and walked away.

“It’s not as if they were devils out to destroy the environment,” Cohen says, recalling a conversation with an old-time miner. “They felt they were supporting the economic development of their country and, during World War I and II, supporting the war effort. They thought they were doing something very positive.”

With the 1970 passage of the National Environmental Protection Act and the 1972 passage of the Clean Water Act (which regulates pollutant discharges into U.S. waters), things began to change. But even before those laws fully went into effect, a few forward-thinking companies were making
environmental sustainability a priority.

As it prepared to open the Henderson Mine near Empire, Colorado, in 1975, AMAX Inc. worked with Mines ecology professor Beatrice Willard to select a site that would be the least visible to tourists on their way to Winter Park to ski and have minimal impact on the Clear Creek Watershed. Instead of placing the tailings next to the mine, as was common practice, AMAX went so far as to build a nine-mile underground tunnel from the mine to the nearby Williams Fork Valley, where waste products could be disposed of with the least impact on the environment.

Historic photo of Gold King Mine

Miners work inside the Gold King Mine near Silverton, Colorado, in 1899. (Courtesy of Silverton Standard via USGS)

“They were 30 years ahead of their time,” says Bill Cobb ’81, MS ’89 who, as one of Willard’s students, visited the Henderson Mine frequently and had test plots for one of his classes at the site. Cobb is now vice president of environmental affairs and sustainable development for Freeport-McMoRan, which owns the Henderson Mine.

Today, a company wanting to develop a brand new, or greenfield, mine in the United States can expect to spend a decade and tens of millions of dollars navigating the regulatory process. In order to get their needed government permits, mine operators must thoroughly assess the potential impact they’ll have on air and water, design systems for mitigating these impacts, develop a detailed closure plan (including land revegetation), and put up millions of dollars of financial assurance that they will be able to pay for that plan when the time comes.

Even resurrecting a shuttered mine is a colossal undertaking. When Freeport-McMoRan reopened the Climax Mine near Leadville, Colorado, in 2011, it spent $250 million on a state-of-the-art water treatment plant. The multinational company also invests in equipment made with durable, cutting edge materials throughout its supply-chain and recycles machinery when it breaks, says Michael Kendrick ’84, president of the Climax Molybdenum Company, a subsidiary of Freeport. “At Freeport, we have not purchased a new piece of haulage mining equipment in the world since 2008. As trucks wear out, we rebuild them; we don’t buy new ones,” he says. “Not only does that have tremendous financial benefit, but big picture, it’s also good for the environment.”

Heightened attention to sustainability, combined with tougher regulations, means the mining industry footprint of the future can be far lighter than it was in the past. “Going forward, we should not end up with a legacy of even more problems” (from newer mines), says Bruce Stover, director of inactive and abandoned mine programs for the Colorado Division of Reclamation, Mining and Safety (DRMS).

That said, there is still a big mess to clean up.

A Challenging Clean-up


London Mine before and after reclamation

These images show the London Mine in Park County, Colorado, before and after reclamation efforts, made possible with Freeport-McMoRan funds. (Credit: Colorado Division of Reclamation, Mining and Safety)

In the early 1980s, state surveys pegged the number of legacy “hazardous mine features”—such as mine shafts and openings—at 23,000 across Colorado. (Stover suspects that number could be up to 30 percent higher.) Thus far, the state has safeguarded 9,700 of these features. Meanwhile, about 500 inactive Colorado mines are currently causing “measurable degradation” to stream water quality. In some areas, that degradation results from storm water flowing through waste piles and tailings. To address that, DRMS sometimes removes or buries waste piles.

But in 230 cases, contaminated water flows directly from underground mine tunnels. Of these, 47 are already being addressed with active treatment efforts (such as water treatment facilities and storage ponds), and 35 are being remediated in some way, Stover says. The other 148 are “still out there draining” into state waterways. But installing a water treatment plant at all of them is impossible. “It costs millions of dollars to build one, and then you have to pay to operate and maintain it until the sun burns out,” says Stover. Alternative technologies are critically needed, and that’s where Mines comes in.

As far back as the 1980s, Mines researchers have been exploring the idea of putting resident microbes to work to help chew up and detoxify waste at legacy mine sites. Today, pilot microbial bioreactor projects are in place in several locations in Colorado and Arizona.

Figueroa, who designs and researches bioreactors, cautions that at this point, they wouldn’t be a good fit for sites with higher water flow rates (Gold King can discharge hundreds of gallons per minute). For those, an active treatment facility works best. But at sites with lots of land to build a microbial system on and a slow, steady flow of acid-rock drainage, bioreactors could provide a cheaper alternative that requires less maintenance. “We could make the money go farther and attack more sites,” she says.

Bioreactors aside, Figueroa envisions other ways Mines could partner with the state and industry to move the dial forward on legacy mine cleanups: Rather than relying on boots-on-the-ground surveys to locate troublesome mines, agencies could work with Mines students and researchers to devise ways to use drones, satellite imaging, or remote sensing technologies like LIDAR (Light Detecting and Ranging). Instead of focusing on surface water, stakeholders could collaborate with Mines to research how water flows across the land and through the tunnels and what changes occur en route. With that knowledge, they could devise better clean-up strategies.

“So far, most of the emphasis is on surface water. At that point, you can’t do anything but treat what’s coming out,” Figueroa says. “My first remediation strategy is not to do a treatment process at all, but to divert the water so it doesn’t come into contact with the minerals that can make water quality worse.”

A Solvable Problem

students measuring water quality parameters

Junior environmental engineering students measure water quality parameters for their field session client, Clear Creek Watershed Foundation. (Credit: Deirdre O. Keating)

Several sources interviewed for this story say another key piece of solving Colorado’s legacy mine problem is for lawmakers to tinker with provisions in the Clean Water Act that currently keep “good Samaritans”—including mining companies, state agencies, universities, and environmental nonprofits—from trying to partially tackle the problem. In essence, if they cannot clean the water completely, they are at risk of being sued for leaving it polluted, says Stover. “Any good Samaritan, after they finish their 70 percent cleanup, could be sued by a third party under the Clean Water Act and be required to address the other 30 percent of the problem. So, if we can’t do a 100 percent cleanup, we don’t touch the water,” he says. In Pennsylvania, which has a state Good Samaritan law to protect nonprofits, more than 50 mine clean-up projects have been completed. Lawmakers are currently mulling a similar federal bill.

Money is also an issue. In recent years, several government agencies have cut their funding for legacy mine reclamation. In November, Colorado Senator Michael Bennet and others introduced a bill that would require mining companies to pay into a federal hard-rock reclamation fund reserved for cleaning up legacy mines—a fund that could amount to as much as $100 million per year. But that idea could be a hard sell at a time when, due to falling commodity prices, mining companies are taking a huge economic hit.

Mines professor Rod Eggert, who teaches natural resource economics, notes that some companies are already cutting back on capital investments as they work to “survive the current economic storm.” But he rejects the notion that lean times will dampen enthusiasm, and funding, for sustainable mining efforts overall. “Challenging times reward those who are most efficient,” he says. “Those with a long-term commitment to the industry are keeping their eye on the ball and working day in and day out to improve the way they mine and the way they interact with the community.”

summer field session group

Chemistry professor James Ranville (second from left) leads students in analyzing water samples from streams near mining operations during the Department of Chemistry’s summer field session. (Credit: Mark Ramirez)

As far as legacy mines go, Stover sees them as a “solvable problem” with—thanks to the Gold King Mine spill—unprecedented attention on it. “If we can’t come up with funding and resolve some of the legal issues now, we never will.”

In the meantime, some companies are already stepping up to the plate, very carefully, to help. For instance, Freeport-McMoRan contributes $500,000 per year to Colorado’s inactive mine reclamation program, helping the state to fund the removal of solid waste materials from legacy mines left behind by someone else. “We did not create these situations, and we are under no legal obligation to clean them up,” says Cobb. “But given our place in the hard-rock sector of Colorado, we feel like we need to contribute to environmental improvement of the state, and this is one thing we can do.”

The company also funds restoration projects through the nonprofit Trout Unlimited, and it supports Denver-based Environmental Learning for Kids, an education group that recently participated in a tree planting at the London Mine site above the town of Alma, where Freeport funds were used by the state to clean up the site.

Going forward, Cobb would like to see Mines students get even more involved in solving the problem of legacy mines, perhaps helping to survey abandoned sites and come up with designs to clean them up. “Who knows,” he says, “a few years down the road these students could be running an environmental group for a mining company.”