Summit County mops up toxic legacy of silver mine at Peru Creek
August 4, 2014
More than a century ago, miners thundered through the mountains of Summit County, blasting apart rock that had barely moved for millennia. They left behind toxic drainage that has decimated fisheries and will impact an untold number of generations.
Though cleaning up the mess might seem unending, folks living and working in the High Country remain committed to the daunting task.
About 8 miles east of Keystone and a couple miles south of the 14,000-foot-plus Grays and Torreys peaks, the abandoned Pennsylvania Mine is considered the worst mine in the state.
The mine adds toxic heavy metal concentrations and acidifies water flowing into the Peru Creek, a tributary of the Snake River, which feeds Dillon Reservoir.
About 30 people attended a tour of the mine Wednesday, July 30, to see and learn about the progress of a three-year cleanup effort.
The project, which will cost about $3 million, could serve as a model for future mine reclamation efforts around the state, said Paul Peronard, on-scene coordinator for the U.S. Environmental Protection Agency.
The collaborative effort is currently under budget and ahead of schedule, he said, even with the added cost of helping Summit County fix the part of Montezuma Road that washed away in early June.
“This is very much a huge partnership,” said Jeff Graves, senior project manager with the Colorado Division of Reclamation, Mining and Safety.
Partnering organizations with the Colorado agency and the EPA include the Colorado Department of Public Health and Safety, the U.S. Geological Survey, the U.S. Forest Service, Summit County Open Space and Trails, Northwest Council of Governments and other supporting groups like the Snake River Watershed Task Force and the Blue River Watershed Group.
The tour’s participants included representatives from almost every partner group, a few Keystone residents and a handful of Keystone Resort employees.
Graves did most of the talking, explaining why the mine is toxic to begin with and how it is being reclaimed.
How does moving earth around create something toxic that pollutes the water?
Most of the gold, lead, copper and other metals mined in Colorado are found in ore deposits with metal sulfides. Drilling huge holes in the ground exposes those sulfides to air. Those compounds then combine with oxygen and water, and a chemical reaction occurs that creates sulfuric acid, spiking the acidity level of rivers and streams.
The process also releases heavy metals in higher concentrations into the water as it trickles over the rocks, turning creeks a ruddy, orange color. Plus hard-rock mining smashed large rocks into small pieces, which means more exposed surface area, intensifying the problem.
This oxidation of minerals happens naturally, but mining operations greatly accelerate the process.
According to the Snake River Watershed Task Force, formed in 2000, mining began in the Snake River watershed with the discovery of silver in 1864. Large-scale mining of silver, lead and zinc occurred until the turn of the century, with a short resurgence of lead production during World War II.
The mine is one of the largest contributors of human-caused heavy metal in the Snake River Watershed. Contaminants include aluminum, cadmium, copper, iron, lead, manganese and zinc. Exposure to these metals can cause irreversible and lifelong health problems in humans and wildlife.
For decades, government agencies and other interested parties faced issues of liability and funding when determining how best to tackle the Pennsylvania Mine cleanup.
“It’s quite a conundrum,” said Lane Wyatt, a water-quality expert with the Northwest Colorado Council of Governments. “The problem is you don’t really have anybody to point your finger to in places like this to say, ‘You’re responsible. You got to go clean this up.’”
Summit County Commissioner Karn Stiegelmeier said one method could have been to designate the mine as a Superfund site, which would have given the EPA control under federal legislation that cleans up uncontrolled hazardous waste sites. The county fought that, however, because of fears the label would bring too much industrial equipment and truck traffic, she said, as well as a stigma that would discourage hikers, bikers and campers from visiting.
The county wanted to retain some local control and preserve the area’s backcountry character.
Though every mine is different, cleanup efforts generally follow a pattern.
“They’re all variations on a theme,” Peronard said.
Engineers look to see which source of heavy metals is causing the most pollution, be it water flowing deeper inside the mine or over waste rock on the surface.
Below the Pennsylvania Mine, the Peru Creek is devoid of fish, insects and other aquatic life. The Snake River has life, but it is limited in diversity and abundance and found only in the lower reaches.
Project managers aren’t sure if the Peru Creek was ever home to fish. The natural metal concentrations before mining could have been high enough to prevent fish from spawning and living there.
The Snake River, however, should be good fish habitat; so one of the project’s goals is to make the river hospitable farther upstream.
So far, restoration work has involved directing water away from the toxic waste rock piles, covering that rock and adding or enhancing vegetation to prevent erosion.
Limestone was added in some places to raise the pH of the water, in an effort to force some of the metals to precipitate out of it into a settlement pond before flowing downstream.
Collapsed entries into the mine had be dug out and stabilized so engineers could investigate and problem-solve.
Lots of little changes, Graves said, eventually will combine to create large water quality improvements.
A GIANT PLUG
This year, Graves said, the state is working to place one of two bulkheads, or giant concrete plugs, about 500 feet inside the mine.
The bulkheads will serve several purposes. They block water from leaving through one large entry and stop water from flowing freely through the mine. Water will back up inside, reducing the amount of oxygen the metals and sulfides are exposed to, which should improve water quality.
“What water does come out will have less metals in it,” Peronard said.
The process aims to return the flow of water to what was happening before mining, with ground water seeping out of the mountain in many different places.
“It goes somewhere. The question is where and how much and what the chemistry is,” Graves said.
Underground construction will begin within the next two weeks in preparation for installing the bulkhead, a process that will take a couple months. Then the partner agencies will continue sampling and monitoring for improvement.
Already, Peronard said, the mine is showing positive results from last year’s preparation work.
“Visibly, we’re doing a lot better this year than we did last year. We haven’t turned anything red,” he said. “We’ve gotten to the point now where we can really manage the water coming out.”
Last year, the Peru Creek turned reddish-orange seven or eight times, he said, and this year that hasn’t happened once.
Although he is almost certain the work now being done at the mine will positively affect the water quality below, any improvements will be difficult to measure until the creek flushes out the toxins that are already there, which could take a long time.
“Don’t expect immediate results,” Peronard told the group at the end of the tour.