EPA probes toxic Colorado mine tunnels, investigates possible harm to human health — The Denver Post

On April 7,  2016, the Environmental Protection Agency proposed adding the “Bonita Peak Mining District” to the National Priorities List, making it eligible for Superfund. Forty-eight mine portals and tailings piles are “under consideration” to be included. The Gold King Mine will almost certainly be on the final list, as will the nearby American Tunnel. The Mayflower Mill #4 tailings repository, just outside Silverton, is another likely candidate, given that it appears to be leaching large quantities of metals into the Animas River. What Superfund will entail for the area beyond that, and when the actual cleanup will begin, remains unclear. Eric Baker
On April 7, 2016, the Environmental Protection Agency proposed adding the “Bonita Peak Mining District” to the National Priorities List, making it eligible for Superfund. Forty-eight mine portals and tailings piles are “under consideration” to be included. The Gold King Mine will almost certainly be on the final list, as will the nearby American Tunnel. The Mayflower Mill #4 tailings repository, just outside Silverton, is another likely candidate, given that it appears to be leaching large quantities of metals into the Animas River. What Superfund will entail for the area beyond that, and when the actual cleanup will begin, remains unclear.
Eric Baker

From The Denver Post (Bruce Finley):

Crews are debating whether to try to contain toxic mine drainage or funnel it out and clean it perpetually at huge expense

Colorado and federal authorities want to resolve the issue as soon as possible because today’s untreated flow into Animas headwaters — averaging 3,750 gallons a minute — may be hurting not only the environment but human health, officials said recently.

All it would take inside this abandoned Red and Bonita Mine tunnel is a turn of the blue screw on that bulkhead plug to stop hundreds of gallons of the [acid mine drainage] from leaking. But if the EPA crew does turn that screw, shutting a valve, the blockage could cause new toxic blowouts from other mountainside tunnels, veins, faults and fissures.

So, for now, the feds are letting Animas River mines drain, tolerating the massive toxic discharge that equates to more than a dozen Gold King disasters every week.

“We don’t want to discount the Gold King spill, but it is good to keep it in perspective,” said EPA project chief Rebecca Thomas, who’s managing cleanup at the now-stabilized Gold King Mine and 47 other mining sites above Silverton.

“Think about the millions of gallons draining each day. It’s something we should be paying attention to as a society – because of the impact on water quality,” Thomas said.

The environmental damage from contaminants such as zinc and aluminum (measured at levels up to tens of thousands of parts per billion) already has been documented: fish in Animas headwaters cannot reproduce. But questions remain about harm caused by lead in water at exceptionally elevated levels up to 1,800 parts per billion, cadmium at up to 200 ppb, arsenic at up to 1,800 ppb and other heavy metals.

The EPA this month intensified an investigation of possible effects on people at 15 U.S. Forest Service campgrounds, American Indians whose traditions take them to high valleys, and vehicle riders who churn dust along roads.

Lead contamination at the Kittimack Tailings, a popular 8-acre course for off-road riding, has been measured at 3,800 parts per million, which is 7.6 times higher than the federal health limit. EPA scientists, collecting water and dirt samples this month, planned to interview campground hosts, all-terrain vehicle tour guides and southern Ute tribe members — assessing possible exposures.

If people inhale or ingest contaminants around any of the 48 mine sites, cleanup at that site would be prioritized, EPA officials said.

The federal Superfund cleanup of toxic mines across 80 square miles in southwestern Colorado is shaping up as one of the EPA’s largest mining legacy projects, contingent on Congress and agency chiefs lining up funds. EPA restoration work here is expected to set the standard for dealing with a wide western problem involving tens of thousands of toxic mines contaminating streams and rivers, for which total cleanup costs have been estimated at more than $20 billion.

In the past, cleanup work at toxic mines in Colorado stalled because of technical difficulty, lack of will and scarce funds. No work has been done for years at the collapsing Nelson Tunnel above Creede, where millions of gallons of some of the West’s worst unchecked acid mine drainage contaminates headwaters of the Rio Grande River, despite a 2008 federal designation as a Superfund environmental disaster.

But EPA officials are pushing for this post-Gold King cleanup including 48 Animas sites, concentrated around Bonita Peak above Silverton, because an EPA-led team in August 2015 accidentally triggered a blowout — setting off a 3 million-gallon spill that turned the river mustard-yellow in three states and sent contaminants nearly as far as the Grand Canyon.

This month, EPA project leaders, bracing for winter snowfall that limits what they can do until summer, anticipated a mix of different solutions at the various sites — each unique with different conditions. They’re considering construction of water treatment plants, like the temporary plant set up to neutralize and filter drainage from the Gold King Mine.

That plant has cleaned 273 million gallons of water over the past year before discharging it into Cement Creek, one of three main headwaters creeks flowing into the Animas River. Meanwhile, six surrounding toxic mines along Cement Creek drain an untreated sulfuric acid flow measured at 1,476 gallons per minute to 7,590 gallons.

A water treatment plant can cost up to $100 million with annual operational costs as high as $1 million.

EPA officials said they’ll combine installation of water treatment systems with bulkhead plugs to hold acid muck inside mountains. And the feds also are exploring use of “bio-treatment” systems using plants and plastic devices to filter and remove contaminants.

The overall cleanup is expected to take years.

“Ideally, we would come up with a way to take care of the water that did not involve a lot of very expensive, in-perpetuity water treatment,” Thomas said.

There are questions dogging hydrologists and toxicologists as they embark on remediation studies.They want to know how mining tunnels, dozens of natural fissures and faults, and mineral veins are connected.

“That is a big puzzle piece,” Thomas said, because subsurface links will determine whether bulkhead plugs safely can be used to contain toxic muck without raising water tables and triggering new blowouts.

They want to know how much acid water is backed up in major tunnels, including the American Tunnel and the Terry Tunnel, and in the Sunnyside Mine. The Sunnyside was the largest mine in the area and the last to close in 1991. EPA officials said natural faults or fissures may connect acid water backed-up Sunnyside water in the American Tunnel, where bulkheads have been installed, with the Gold King Mine.

Canada-based Kinross Corp., which owns Sunnyside, is considered a potentially responsible party, along with Gold King owner Todd Hennis, liable for a share of cleanup costs.

And EPA officials say they are monitoring underground changes that may be affecting flows from at least 27 draining tunnels — called adits — that contribute to contamination of Animas headwaters. The state-backed installation of plugs over the past decade may have triggered the rising groundwater levels that documents show the EPA and state agencies have known about for years.

For example, orange sludge oozed from a grate at the Natalie Occidental Mine — one of the worst sources of untreated mine waste — north of the Silverton Mountain ski area.

EPA on-scene coordinator Joyel Dhieux inspected it this month, hiking beneath snow-dusted mountain peaks. The backed-up sludge obscured a culvert installed years ago by state mining regulators. A huge tailings heap, leaching contaminants into a creek, suggested significant underground tunnels.

“The sludge could create a blockage in the mine that could increase the risk of a blowout. … This will require thoughtful planning,” Dhieux said. “Kittimack could be easy. You go in and remove the mine tailings. This one, it could be a more complex solution because of the risk. … This is an ‘unknown unknown.’ I honestly don’t know what the mine works look like behind this grate.”

And then there’s the problem inside that Red and Bonita Mine tunnel where a bulkhead plug is installed but not closed. Dhieux and her crew determined the plug, installed in 2015, 15 feet thick and framed in steel, appears solid.

If the EPA closes the bulkhead, she and other EPA officials said, it will be done very slowly. They’re considering a partial closure, as a test, next summer. The plan is for dozens of researchers to fan out across green mountain valleys, while contractors inside the tunnel turn the screw, watching for sudden orange spurts.

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