THE MINE NEXT DOOR: PART 10

Old timers recall places inside the Idarado that were full of magic and wonder, like the 100 level of the old Black Bear Mine, where the air used to be so cold and still that wafer-thin ice crystals the size of dinner plates grew on the back and ribs of the tunnel like giant, delicate butterflies. Due to warming conditions and disappearing permafrost in the high country, these crystals don’t form anymore. (Photo by Rick River)

Devon Horntvedt takes samples of acid rock drainage from a culvert near the Genessee Mine, the biggest zinc loader in Red Mountain Creek. (Photo by Samantha Tisdel Wright)

Dragonfly Lead Pilot Analyst Chris Putnam (at right) studies data feedback from an unmanned aerial drone hovering high above Idarado’s Pandora yard as his colleague Brian Skyles looks on. The Dragonfly team has been conducting extensive site characterization at the Idarado Mine over the past year. (Photo by Samantha Tisdel Wright)

Idarado’s Mill Level Tunnel has always been a watery place; it serves as a drain for upper levels of the mine. Over the past few years, however, the volume of water coming out of the tunnel has increased dramatically during peak runoff. A warming climate is the suspected culprit. (Photo by Brett Schreckengost)

Idarado has recently installed a remote solar-powered weather station in Marshall Basin to better monitor snow and weather conditions in the high country that impact the quantity of water in the Mill Level Tunnel. (Photo by Brett Schreckengost)

Lush teal-tinted grass thrives in an iron fen irrigated by the draining Hero Mine near the top of Red Mountain Pass – an example of how nature can remediate itself under the right conditions in this heavily mine-impacted environment. (Photo by Samantha Wright)

 

 

 

 

 

 

Old Mine, New Tricks

Prospecting for Innovation at the Idarado Mine

Part 10 in “The Mine Next Door” Series

by Samantha Tisdel Wright

The mining camps of the San Juans were the innovation boot camps of the late 1800s – the Silicon Valley of their time. The mountains, and the mines, were full of challenges looking for solutions.

Some of the most distinguished innovators of the era came here to solve them – from Otto Mears, the “Pathfinder of the San Juans”, to Lucien Nunn, Nicolai Tesla and George Westinghouse, the founders of the Ames Power Plant and AC electricity.

The old-school miners whose names have been lost in time were brilliant innovators too, solving problems on the fly with their wits, their brawn, and whatever tools they had on hand.

Anyone who has hiked up into the San Juan high country has surely come across a massive riveted boiler, or a stamp mill, or a boarding house teetering on the edge of a cliff and wondered to themselves – “How did they get that thing up here? How did they do that?”

When the Idarado Mining Company came along in 1939, it drove a new era of innovation in the San Juans.

Idarado’s founders figured out how to knit the disparate old mines between Ouray and Telluride into one enormous complex that went in one side of the mountains and came out the other. They pioneered the use of knock-off rock bits and diesel underground haulage. They developed a state-of-the-art flotation milling process. And they devised ingenious ways to transport and safely store the vast quantities of tailings that Idarado’s mills churned out on both sides of the mountains.

In the wake of Idarado’s closure in 1978, its cleanup sparked a burst of innovation in the emerging world of mine reclamation, introducing such concepts as source control and direct tailings revegetation that have since gone on to become standard mine remediation practices.

Now, well into the 21st century, Idarado and its parent company, Newmont Mining Corp., are driving a new era of innovation as they tackle Idarado’s biggest post-remediation challenges: solving the age-old riddle of acid rock drainage in Red Mountain Creek, and adapting to shifting conditions in the high country that have changed the way water moves through the mine.  

“Legacy mining sites are dynamic, changing environments, and it’s necessary to anticipate and respond to new challenges as they come up,” said Newmont’s reclamation boss Larry Fiske.

Red Mountain Rumble

On a hazy, hot evening in late June, Devon Horntvedt collects water samples from the Genessee Mine on the flank of Red Mountain #3. Smoke from the nearby 416 Wildfire obscures the Idarado yard across the valley, and the sun-ball hangs low in the bloodshot sky.

Horntvedt fills up some jugs with water, labels them, and lugs them into the back of his SUV. “It’s a special, weird place,” he says, looking around at the mine-riddled landscape.

Most of these mines were abandoned by turn of the 20th century, but when the miners went away, the mountains kept mining themselves, pouring millions of gallons of metal-saturated acid rock drainage into Red Mountain Creek, and scarring the landscape with skirts of bright orange ferricrete.

Idarado never owned or operated the Red Mountain mines, but agreed to help remediate them through its negotiated Consent Decree with the State of Colorado back in 1992.

Today, thanks to these efforts, the historic mining district is threaded with concrete diversion channels, weep lines and collection boxes designed to funnel mine drainage around waste rock piles and in some cases pipe it back into the ground, keeping it out of Red Mountain Creek.

To date, these extensive source control remedies have gotten Idarado half-way toward its State-mandated objective to reduce zinc levels in Red Mountain Creek by 50 percent from pre-remediation levels.

The area is rife with extreme challenges – snow, ice, freezing temperatures, frost heaving, difficult working conditions, difficult access, a dearth of flat land, avalanches and rock slides, unreliable grid power, extreme acidity and high metal loads in the water from both natural background and mining sources – that challenge tried-and-true water treatment remedies such as an industrial-scale lime treatment plant.

So Horntvedt, a senior engineer with Newmont who works on remediation issues at Idarado and other legacy mine sites, is on a quest to find new solutions to the problem.

Carrot Farming in the Caldera

The distinct color of the Red Mountains between Silverton and Ouray was like a flashing neon sign to eager prospectors in the 1870s: DIG HERE!

They did. For years they plundered a crop of vertical, carrot-shaped ore bodies, called breccia pipes, spawning a dense cluster of mines and settlements on the slopes of the Red Mountains that yielded upwards of $30 million in highgrade ore in 10 short years – close to a quarter of a billion of today’s dollars.

The ore was deliciously rich, but tough to get at. Vertical shafts followed the breccia pipes for hundreds of feet straight down into the sour belly of the Silverton Caldera.

Water seeped into the mine workings, mixing with the local pyrites to form sulfuric acid – otherwise known as acid rock drainage or ARD. This water had such a low pH that it dissolved anything made of metal –  mine rails, shovels, machinery – even the very pumps that were supposed to get the water out. Nails disappeared in the rungs of ladders. Timbers dropped from ceilings. Hoist cables turned to powdery rust in a matter of weeks.

By the time the Silver Panic of 1893 rolled around, many of the ore bodies in the Red Mountain Mining District had already pretty much played out. The hot fat hustle was over as quickly as it had begun. And it came at a cost that is still exacted today in the ARD that seeps into Red Mountain Creek from these historic mines.

Mother Nature is a polluter too.

Dominguez and Escalante, who passed by the Uncompahgre River in August 1776 – well before any mining activity along Red Mountain Creek – offered clues in their journal to how the natural mineralization of the area impacted water quality, noting their Ute guide’s warning that “near [the river’s] source there is a spring of red-colored water, hot and ill tasting."

Recent studies have concluded that highly acidic surface water predates mining activity in the Red Mountain district by thousands, perhaps millions, of years. But of course, mining made things worse.

License to Learn

We’ve put a man on the moon, and multiple rovers on Mars. Why is it so hard to clean up Red Mountain Creek? The answer lies beneath the sunburnt skins of the Red Mountains, where a hidden world of chemical chaos reigns in the iron-rich environment.

Here, a vicious cycle of ferrous to ferric iron conversion creates ever-more acidic mine pools, dissolving more and more metals out of the surrounding rock. The process is exacerbated and accelerated by metal-munching colonies of microbes.

“It’s basically a mineralized free-for-all underneath our Red Mountains,” Horntvedt laughs, dragging his fingers through his shaggy red hair. Over the past few years, the brainy millennial has field-tested a couple of innovative new water treatment systems to help clean up this carnage.

First, he experimented with a passive treatment system that uses Iron Rich Media (IRM) to yank zinc out of the water. More properly described as activated ferromanganese, IRM is a waste product from the electric arc furnace recycling of scrap metal.

The stuff proved remarkably effective at quickly removing dissolved zinc from the circumneutral water draining from Idarado’s Treasury Tunnel. “The zinc just gets sucked into the iron – it’s pretty cool,” Horntvedt said. But when he tested it at the Liberty Belle – the most acidic old Red Mountain mine across the valley – the system completely melted down.

Still, Horntvedt says, it has definite potential – especially if paired with another system that could boost the mine water’s pH before passing it through the IRM.

Two years ago, Horntvedt vetted another experimental water treatment system from a Texas-based startup called Green Age Technologies. This system’s secret sauce is cavitation, a process that implodes and momentarily vaporizes water molecules with a burst of heat approaching the sun’s surface temperature, precipitating dissolved metals out of solution and capturing them in a membrane in the nanosecond before the water condenses to liquid form.

Early field tests for this new technology were so encouraging that Newmont offered its expertise and energy to help the startup develop a larger prototype in an attempt to prove the concept. But further testing in 2017 failed to produce the desired results.

Back to Nature

These days, Horntvedt is taking a step back and asking himself, “How would nature solve this issue if we just walked away?”

He sees the answer all around him – in the iron terraces and voluminous mats of algae that form at the mouth of the Joker Tunnel, the lush teal-colored grass that thrives in nearby iron fens, the ochre glomming onto rocks in the ferricrete bed of Red Mountain Creek, and even the barren, scary-looking scablands that spill down the hillside below the Genessee Adit.

“The fact that it looks like this, tells me the water was somehow becoming less acidic and dropping iron. And if it was dropping iron, it was dropping other metals. And it’s not entirely out of the question that it was actually better this way,” than piping it underground, he hypothesizes, “because it was letting nature do some of the work. The planet is actually trying to heal itself all the time.”

This summer, Horntvedt has been testing this theory, running field tests for a new kind of passive water treatment system that takes its inspiration from nature. The idea is to allow acidic mine water to spill over beds of crushed-up concrete loaded with acid-buffering lime to boost its pH just enough so that the iron will drop out of solution and start forming iron terraces on its own, like the ones he’s been studying down at the Joker Tunnel.

“The goal is to facilitate what nature is already doing, and make it better,” Horntvedt says.

Results from the field tests still pending, but Horntvedt hopes this simple, passive pH-boosting system, when paired with IRM, might get Idarado closer to its Holy Grail: a sustainable way to remove zinc sulphates from Red Mountain Creek.

"Truly, this is right up there on the edge of what we are capable of doing scientifically,” Horntvedt says. “So we are continuing to look for new ideas, new solutions, new ways to apply them, new puzzle pieces, and see if we can assemble them together to form what’s going to be a sustainable solution.”

The Water Whisperer

In his dreams, Mark Parker hears the sound of water.

Water dripping, trickling, like an underground grotto. Water flowing from far away. Water, getting closer. Water gushing out the portal of the Mill Level Tunnel.

Idarado is a wet mine on the Telluride side. Groundwater seeps into its maze through myriad cracks and faults in the mountains up above. During the RAP, Idarado built a network of hydrologic systems, collection points and pipelines to herd this groundwater-turned-mine-water around mineralized zones and down and out through the Mill Level Tunnel.

Here, it becomes Pandora site manager Parker’s problem to manage.

From the tunnel portal, mine water flows into a collection box, then is diverted into two separate collection pipes. One directs water across the property into a stair-stepping series of infiltration lagoons. The other sends water into an infiltration ditch that skirts the valley on the far side of the lagoons.

Both the lagoons and the ditch serve the same purpose – to contain the mine water and allow it to gradually evaporate or seep into the ground.

Most of the time, the passive treatment system works quietly in the background without much hassle.

But water management at Pandora becomes a much more intense endeavor during peak runoff (which generally happens right around the time of the Telluride Bluegrass Festival in mid-to-late June), when water discharging from the Mill Level Tunnel increases dramatically in volume – suddenly escalating from 800 to 8,000 or more gallons per minute.

Needless to say, during peak runoff, it’s all hands on deck. Parker and his crew conduct visual inspections of the lagoons and infiltration ditch, watch water elevations, adjust valves, and shuffle water from here to there through sleepless nights making sure nothing overflows.

“My job is to worry about things, and I’m very good at my job,” Parker says, with a rueful chuckle.

When in Doubt, Innovate

Over the past few years, peak runoff season has given Parker even more cause for worry. Something has changed about the conditions in the high country, causing the volume of water gushing out of the Mill Level Tunnel to inexplicably increase to up to 8,000 gallons per minute for a few hair-raising days and nights. This unprecedented deluge has tested the limits of both Parker and the Pandora infiltration system.

Idarado is working hard to get a better understanding of the root cause of this change – climate change is one suspect – and whether anything can be done to stanch the flow. In the meantime, Idarado does what it’s always done when faced with a new challenge: innovate.

Idarado has recently installed a remote solar-powered weather station that sends photos and data through the internet so that Parker can keep a constant eye on snow and weather conditions in the high country that impact the quantity of water in the Mill Level Tunnel.

Likewise, newly installed flow meters at the tunnel portal provide real-time data that Parker can access from wherever he happens to be.

In this “new normal” of more intense runoff events, the data has proven invaluable for Parker and his crew.

Idarado also plans to build an engineered concrete bulkhead 1,030 feet back inside the tunnel to better manage the mine water during peak runoff. Planning for the project, and discussions with regulators, have been ongoing since 2015.  If all goes according to plan, the bulkhead should be operational by the end of 2019.

The installation will be designed in such a way as to allow continued access into the inner workings of the mine, and it will be equipped with a valve and a 30-inch pipe to modulate the mine water flows when there are surges that overtax the Pandora infiltration system.

“Running the Idarado water system has always been a challenge,” says Fiske, explaining that the new bulkhead should remain open with water flowing straight through most of the time.  “It won’t change our overall approach; it just gives us more tools to accomplish the task safely during those high surge flow events – basically we are improving our ability to manage uncertainty.”

“We don’t want to choke it down and start building a mine pool,” Parker adds. “We just want to assure ourselves that on our end of it, when the water does come out, we’ve got room for it.”

Prometheus

Site characterization is the name of the game when it comes to understanding the nature of a place.

Consider a scene from the 2012 film Prometheus, where an interstellar crew flings floating balls into the air that zoom into a cave and relay data back to the spaceship’s bridge, allowing the crew to see a precise, 3-D holographic map of the alien world they’re about to explore.

Something similar has been happening lately at the Idarado Mine (except without any headless aliens in the tunnel).

Last fall, a Durango company called DragonflyAI deployed a fleet of unmanned aerial drones equipped with thermal imaging sensors to map some of Idarado’s high country features for source control evaluation – to figure out where the snowmelt and rain might be entering the mine from this high altitude zone. One suspected culprit: an open stope below a melting glacial feature in Middle Basin.

The high country data visualization will eventually merge with Dragonfly’s newly launched underground 3D mapping project called Tunnel Vision, offering volumetric data and pressure analysis to aid in the design of Idarado’s new bulkhead.

“Our goal is to tie all that together so you are looking at one 3D model of the mountain,” explains Dragonfly Lead Pilot Analyst Chris Putnam.

Horntvedt discovered the Dragonfly team at the Silverton Innovation Conference in 2017, and saw opportunity for site characterization at the Idarado Mine. He’s thrilled with the results of the collaboration so far.

“It’s a huge leap forward in what we knew the year before,” he says. “It’s really been a helpful tool and it’s only going to get better. That’s the really exciting part.” The technology is not foolproof yet, Horntvedt adds, “But, it’s getting there. That’s the theme of innovation.”

“Fail early and fail often,” agrees Brian Skyles, Project Lead/Business Development Associate at Dragonfly’s Grand Junction-based parent company HRL Compliance.

“And then, when you win, it’s so sweet,” Horntvedt says.

Idarado: The Next Generation

At an age when a lot of guys are still figuring out who they are and what they want to do in the world, Braxton Franz and Wyatt Collins are self-possessed, focused and competent.

“They are responsible for everything,” Parker says of his two full-time summer assistants, contracted to Idarado through the Ft. Collins-based firm Engineering Analytics.

The three of them are kicking back in the conference room at the Pandora office at the end of a long work day, as generations of Idarado workers have surely done over the past 60 years.

Franz and Collins tackle all the hard physical work they can handle at the aging decommissioned mine – property maintenance, water sampling, property visual inspections, ditch maintenance, erosion fencing on the tailings ponds, heavy equipment maintenance, snow plowing, helping to take care of the Bridal Veil hydroelectric plant, plus whatever else comes up – like dealing with peak runoff and assisting Horntvedt and Joe Smart with Idarado’s ongoing water sampling regimen. They also go underground from time to time to train with the mine rescue team.

Franz, 26, started working at Idarado four years ago, the first year peak runoff was off the charts. It wasn’t enough to scare him away. In fact, he loved it. The sense of mission, the autonomy, the challenge and variety of the work he was tasked with from the get-go, convinced him to stick around.

Collins, 21, came along a year later and loves it just as much. The two have developed a deep sense of reverence for the mining history of Ouray and Telluride since they started working at Idarado.

“I appreciate what they did with what they had,” Collins reflects. “It’s crazy. 21st century mining is not even close to what it used to be. It’s really impressive. I’ve gained a whole new respect for those old timers.”

As if on cue, Idarado’s Bridal Veil Hydroelectric Plant operator David Swanson wanders into the room. “I’m gonna start sending some stuff up to Blue Lake tomorrow,” he says. “It should be fun. I’ll need one of you guys, or both of you guys.”

“Yeah!” Franz and Collins say.

Swanney grins at the pair.

Engage.