At 11 a.m. on August 5, 2015, the icy waters of Cement Creek, just outside the scenicÂ Colorado mountain town of Silverton, began to turn to mustard-colored sludge. ByÂ dayâ€™s end, three million gallons of acid mine drainage had poured out of the inactive,Â 120-year-old Gold King Mine. The tainted water coursed downstream into the AnimasÂ River where it horrified kayakers in nearby Durango, prompted water treatment plantsÂ to shut off their taps, and ignited alarming front-page photos in newspapers nationwide.Â Within four days, the surface water had cleared and, according to EPA measurements,Â returned to pre-spill levels of toxic metals. But the conversation started by the GoldÂ King blowout had only just begun.
â€œThis was a wake-up call,â€ says Linda Figueroa, a Mines professor of civil andÂ environmental engineering who studies mine remediation techniques. â€œIt lit a fire underÂ the abandoned mine lands community, reminded the public that this is an issue, andÂ prompted people to put it back on the front burner.â€
As industry and government agencies grapple with what to do about the estimatedÂ half-million abandoned mines nationwide, and as the state looks more closely at howÂ to address hundreds of legacy mines fouling thousands of miles of Colorado streams,Â Minesâ€”with its multi-disciplinary expertise and collaborative relationship withÂ industry and governmentâ€”is poised to play a key role.
â€œOur primary objective is to build knowledge, not make money, so we can giveÂ problems longer-term attention at lower cost while educating the workforce of theÂ future,â€ says Priscilla Nelson, head of the Department of Mining Engineering. Already,Â the school has a long history of supporting research that has advanced the way minesÂ are operated and reclaimed. And with a growing focus on the environmental andÂ humanitarian aspects of mining, the school hopes to cultivate a new generation ofÂ miners who see themselves as â€œstewards of the earthâ€™s resources,â€ Nelson says.
As a neutral party, Mines also hopes to facilitate a stakeholder-wideÂ conversation about what happens next. â€œWhat do we knowÂ and what do we not know? What new technologies need to beÂ developed?â€ asks Nelson, who hopes to host a symposium on theÂ subject this year. â€œLetâ€™s sit down and talk about it.â€
Mining, Then and Now
While much media attention has been paid to the number ofÂ abandoned, historic mines that riddle hillsides across the West,Â one positive development is often overlooked: Industry practicesÂ have changed dramatically since those mines were built. â€œThereÂ really is no comparison,â€ says Ronald Cohen, a Mines professorÂ of civil and environmental engineering who has studied theÂ history of Western mining. â€œThe demands on industry are soÂ much greater than they were back then.â€
As early as 1870, a few vague guidelines existed for mineÂ operators, but there was no agency to enforce them and noÂ political will to strengthen them. Even in the mid-20th century,Â many Western companies still â€œviewed gravity as their friend,â€Â says Cohen. They dumped their waste downstream whileÂ operating, and when it was time to close up shop, they left theirÂ tailings and rock piles behind and walked away.
â€œItâ€™s not as if they were devils out to destroy the environment,â€Â Cohen says, recalling a conversation with an old-time miner.Â â€œThey felt they were supporting the economic development ofÂ their country and, during World War I and II, supporting the warÂ effort. They thought they were doing something very positive.â€
With the 1970 passage of the National EnvironmentalÂ Protection Act and the 1972 passage of the Clean Water ActÂ (which regulates pollutant discharges into U.S. waters),Â things began to change. But even before those laws fully wentÂ into effect, a few forward-thinking companies were making
environmental sustainability a priority.
As it prepared to open the Henderson Mine near Empire,Â Colorado, in 1975, AMAX Inc. worked with Mines ecologyÂ professor Beatrice Willard to select a site that would be theÂ least visible to tourists on their way to Winter Park to ski andÂ have minimal impact on the Clear Creek Watershed. Instead ofÂ placing the tailings next to the mine, as was common practice,Â AMAX went so far as to build a nine-mile underground tunnelÂ from the mine to the nearby Williams Fork Valley, where wasteÂ products could be disposed of with the least impact on theÂ environment.
â€œThey were 30 years ahead of their time,â€ says Bill Cobb â€™81,Â MS â€™89 who, as one of Willardâ€™s students, visited the HendersonÂ Mine frequently and had test plots for one of his classes at theÂ site. Cobb is now vice president of environmental affairs andÂ sustainable development for Freeport-McMoRan, which owns theÂ Henderson Mine.
Today, a company wanting to develop a brand new, orÂ greenfield, mine in the United States can expect to spend aÂ decade and tens of millions of dollars navigating the regulatoryÂ process. In order to get their needed government permits,Â mine operators must thoroughly assess the potential impactÂ theyâ€™ll have on air and water, design systems for mitigatingÂ these impacts, develop a detailed closure plan (includingÂ land revegetation), and put up millions of dollars of financialÂ assurance that they will be able to pay for that plan when theÂ time comes.
Even resurrecting a shuttered mine is a colossal undertaking.Â When Freeport-McMoRan reopened the Climax Mine nearÂ Leadville, Colorado, in 2011, it spent $250 million on a state-of-the-art water treatment plant. The multinational company alsoÂ invests in equipment made with durable, cutting edge materialsÂ throughout its supply-chain and recycles machinery when itÂ breaks, says Michael Kendrick â€™84, president of the ClimaxÂ Molybdenum Company, a subsidiary of Freeport. â€œAt Freeport,Â we have not purchased a new piece of haulage mining equipmentÂ in the world since 2008. As trucks wear out, we rebuild them;Â we donâ€™t buy new ones,â€ he says. â€œNot only does that haveÂ tremendous financial benefit, but big picture, itâ€™s also good for theÂ environment.â€
Heightened attention to sustainability, combined with tougherÂ regulations, means the mining industry footprint of the future canÂ be far lighter than it was in the past. â€œGoing forward, we shouldÂ not end up with a legacy of even more problemsâ€ (from newerÂ mines), says Bruce Stover, director of inactive and abandonedÂ mine programs for the Colorado Division of Reclamation, MiningÂ and Safety (DRMS).
That said, there is still a big mess to clean up.
A Challenging Clean-up
In the early 1980s, state surveys pegged the number of legacyÂ â€œhazardous mine featuresâ€â€”such as mine shafts and openingsâ€”atÂ 23,000 across Colorado. (Stover suspects that number could beÂ up to 30 percent higher.) Thus far, the state has safeguarded 9,700Â of these features. Meanwhile, about 500 inactive Colorado minesÂ are currently causing â€œmeasurable degradationâ€ to stream waterÂ quality. In some areas, that degradation results from storm waterÂ flowing through waste piles and tailings. To address that, DRMSÂ sometimes removes or buries waste piles.
But in 230 cases, contaminated water flows directly fromÂ underground mine tunnels. Of these, 47 are already beingÂ addressed with active treatment efforts (such as water treatmentÂ facilities and storage ponds), and 35 are being remediated in someÂ way, Stover says. The other 148 are â€œstill out there drainingâ€ intoÂ state waterways. But installing a water treatment plant at all ofÂ them is impossible. â€œIt costs millions of dollars to build one, andÂ then you have to pay to operate and maintain it until the sun burnsÂ out,â€ says Stover. Alternative technologies are critically needed,Â and thatâ€™s where Mines comes in.
As far back as the 1980s, Mines researchers have been exploringÂ the idea of putting resident microbes to work to help chew upÂ and detoxify waste at legacy mine sites. Today, pilot microbialÂ bioreactor projects are in place in several locations in ColoradoÂ and Arizona.
Figueroa, who designs and researches bioreactors, cautionsÂ that at this point, they wouldnâ€™t be a good fit for sites with higherÂ water flow rates (Gold King can discharge hundreds of gallons perÂ minute). For those, an active treatment facility works best. But atÂ sites with lots of land to build a microbial system on and a slow,Â steady flow of acid-rock drainage, bioreactors could provide aÂ cheaper alternative that requires less maintenance. â€œWe couldÂ make the money go farther and attack more sites,â€ she says.
Bioreactors aside, Figueroa envisions other ways Mines couldÂ partner with the state and industry to move the dial forwardÂ on legacy mine cleanups: Rather than relying on boots-on-the-groundÂ surveys to locate troublesome mines, agencies couldÂ work with Mines students and researchers to devise ways toÂ use drones, satellite imaging, or remote sensing technologiesÂ like LIDAR (Light Detecting and Ranging). Instead of focusingÂ on surface water, stakeholders could collaborate with MinesÂ to research how water flows across the land and through theÂ tunnels and what changes occur en route. With that knowledge,Â they could devise better clean-up strategies.
â€œSo far, most of the emphasis is on surface water. At thatÂ point, you canâ€™t do anything but treat whatâ€™s coming out,â€Â Figueroa says. â€œMy first remediation strategy is not to do aÂ treatment process at all, but to divert the water so it doesnâ€™tÂ come into contact with the minerals that can make water qualityÂ worse.â€
A Solvable Problem
Several sources interviewed for this story say anotherÂ key piece of solving Coloradoâ€™s legacy mine problem is forÂ lawmakers to tinker with provisions in the Clean Water ActÂ that currently keep â€œgood Samaritansâ€â€”including miningÂ companies, state agencies, universities, and environmentalÂ nonprofitsâ€”from trying to partially tackle the problem. InÂ essence, if they cannot clean the water completely, they areÂ at risk of being sued for leaving it polluted, says Stover. â€œAnyÂ good Samaritan, after they finish their 70 percent cleanup,Â could be sued by a third party under the Clean Water Act andÂ be required to address the other 30 percent of the problem.Â So, if we canâ€™t do a 100 percent cleanup, we donâ€™t touch theÂ water,â€ he says. In Pennsylvania, which has a state GoodÂ Samaritan law to protect nonprofits, more than 50 mineÂ clean-up projects have been completed. Lawmakers areÂ currently mulling a similar federal bill.
Money is also an issue. In recent years, several governmentÂ agencies have cut their funding for legacy mine reclamation.Â In November, Colorado Senator Michael Bennet and othersÂ introduced a bill that would require mining companies toÂ pay into a federal hard-rock reclamation fund reserved forÂ cleaning up legacy minesâ€”a fund that could amount to asÂ much as $100 million per year. But that idea could be a hardÂ sell at a time when, due to falling commodity prices, miningÂ companies are taking a huge economic hit.
Mines professor Rod Eggert, who teaches natural resourceÂ economics, notes that some companies are already cuttingÂ back on capital investments as they work to â€œsurvive theÂ current economic storm.â€ But he rejects the notion that leanÂ times will dampen enthusiasm, and funding, for sustainableÂ mining efforts overall. â€œChallenging times reward thoseÂ who are most efficient,â€ he says. â€œThose with a long-termÂ commitment to the industry are keeping their eye on the ballÂ and working day in and day out to improve the way they mineÂ and the way they interact with the community.â€
As far as legacy mines go, Stover sees them as a â€œsolvableÂ problemâ€ withâ€”thanks to the Gold King Mine spillâ€”unprecedented attention on it. â€œIf we canâ€™t come up withÂ funding and resolve some of the legal issues now, weÂ never will.â€
In the meantime, some companies are already stepping upÂ to the plate, very carefully, to help. For instance, Freeport-McMoRan contributes $500,000 per year to Coloradoâ€™sÂ inactive mine reclamation program, helping the state to fundÂ the removal of solid waste materials from legacy mines leftÂ behind by someone else. â€œWe did not create these situations,Â and we are under no legal obligation to clean them up,â€Â says Cobb. â€œBut given our place in the hard-rock sector ofÂ Colorado, we feel like we need to contribute to environmentalÂ improvement of the state, and this is one thing we can do.â€
The company also funds restoration projects through theÂ nonprofit Trout Unlimited, and it supports Denver-basedÂ Environmental Learning for Kids, an education group thatÂ recently participated in a tree planting at the London Mine siteÂ above the town of Alma, where Freeport funds were used byÂ the state to clean up the site.
Going forward, Cobb would like to see Mines studentsÂ get even more involved in solving the problem of legacyÂ mines, perhaps helping to survey abandoned sites and comeÂ up with designs to clean them up. â€œWho knows,â€ he says, â€œaÂ few years down the road these students could be running anÂ environmental group for a mining company.â€