Log In

Reset Password

How do you keep Colorado hikers from falling 300 feet down a mine shaft? Foam

Since 1980, officials have gated and plugged more than 13,000 inactive mines
Brady Kutscher unloads the equipment off his horse, Dale, while working with the Forest Service to plug a shaft at the Fourth of July Mine, Aug. 30 in the Indian Peaks Wilderness. (Hugh Carey/The Colorado Sun)

ARAPAHO PASS – The bent and broken tent frame draped with an old tarp is wedged about 10 feet down the mine shaft.

“That will work,” says Brady Kutscher, clipping his harness into a rope wrapped around old machinery at the entrance shaft to the Fourth of July Mine. He leans over the hole and shakes a bag about the size of a carry-on. Inside the bag, chemicals mix with resin, creating an exothermic reaction. Soon the bag is spewing foam into the shaft.

The foam keeps getting thicker as it falls on the tarp. After a few hours of Kutscher’s shake-and-dribble routine, the belching bags of falling foam form a plug that will harden into a permanent cap for the mine shaft.

“Pretty high-tech isn’t it?” contractor Shane Stratton says as he directs his fellow worker’s foamy cascade from the other side of the mine shaft.

To keep people and animals from falling down the 300-foot-deep hole, Brady Kutscher pours polyurethane foam into the main shaft Aug. 30 in the Indian Peaks Wilderness. (Hugh Carey/The Colorado Sun)

The Forest Service and the Colorado Division of Reclamation Mining and Safety do not like that mine shaft. They guess it falls about 300 feet down to the mile-long horizontal tunnel below – or adit – of the long abandoned Fourth of July Mine in the Indian Peaks Wilderness.

Trez Skillern, the Arapaho and Roosevelt National Forests’ abandoned mines program manager, says this shaft, with its wide entrance, long drop and proximity to a very popular hiking trail close to the Front Range ranks the Fourth of July Mine as “one of the scariest around.”

Hence the project last week that involved more than a dozen volunteers, officials, workers and nine horses taking three round-trips up the Forest Service’s Arapaho Pass Trail, hauling 150 bags of polyurethane foam 2 miles and 1,000 vertical feet into the wilderness.

After pouring the bags of the quick-hardening foam everyone calls “PUF” into the mine shaft – enough to fill about 50 cubic feet – and covering that foam with a layer of old mining debris, no hiker or animal can fall into the shaft.

Polyurethane foam hardens in the main shaft. One hundred and fifty bags of PUF was needed to fill the shaft from the tarps resting several feet below the surface. (Hugh Carey/The Colorado Sun)

“Think of it like a cork in a wine bottle, but we have to build the cork,” says Erica Crosby, senior project manager for the Colorado Division of Reclamation, Mining and Safety.

The whole project is all about keeping people from falling into the old mine. (And then trying to sue the Forest Service or state for not properly closing the mines.) It’s part of a mine-shuttering public-safety mission that began in the 1980s and has seen the state and Forest Service close about 13,000 abandoned shafts and tunnels.

The state and Forest Service closed the Fourth of July Mine tunnel in 2018. That involved placing a metal gate on the main adit below the mine shaft and shoveling debris into the shaft. Last summer, a volunteer with the Indian Peaks Trails Alliance notified the agencies that the plug to the mine shaft had collapsed.

An added challenge for the closure project at the mine shaft involves its location in the Indian Peaks Wilderness.

If the mine was not inside federal wilderness, the division of mining and the Forest Service would be using helicopters to deliver the foam and maybe even welding a steel gate over the opening to keep people and animals from falling in. But wilderness designation prevents machines, hence the horses.

“We would have been done already if this was with a chopper,” says Cindy McCullom, the Eldora-born owner of McCollum Excavating who started plugging mines for the state and Forest Service decades ago after a career working with helicopters in the Navy.

Lacy Stockton and her horse, Sarge, made several trips from the trailhead to transport equipment to the Fourth of July Mine shaft, with Shane Stratton in the background. The horses were needed because of the mine’s location inside the wilderness. (Hugh Carey/The Colorado Sun)

Miners dug silver ore from the Fourth of July Mine in the late 1800s. In the early 1900s, they switched over to searching for copper. Over the 300-foot mine shaft once stood a timber head frame, where miners and equipment were lowered into the main tunnel. The state has documented about 23,000 abandoned mine shafts and tunnels in Colorado.

“But there’s probably double that,” says Crosby, noting that her division’s Inactive Mine Reclamation Program has safeguarded about 13,000 abandoned mines and structures in Colorado since the inception of the program in 1980, including more than 3,500 in Boulder County.

This wilderness shaft-sealing project price tag is about $42,000, with the Forest Service paying $30,000 of that and the state’s division of mining covering the rest. The new federal infrastructure bill includes funding for coal mine remediation, which could free up money for the state’s effort to close more abandoned hard-rock mines across Colorado, Crosby says.

It usually takes close to three years to identify a mine that should be closed and go through analysis under the National Environmental Policy Act, known as NEPA, to close it. Since the Forest Service went through NEPA to close the Fourth of July Mine in 2018, the shaft-capping project was approved in only one year. It helps that there were no signs of bats in the mine shaft and bats can still come and go through the mine’s main tunnel down below, which is blocked by the steel-barred gate.

Bats also prefer caves to mines. There are no caves on the Arapaho and Roosevelt National Forests.

Horses carrying bags of polyurethane resin through the Indian Peaks Wilderness toward the Fourth of July mine. (Hugh Carey/The Colorado Sun)

The polyurethane foam does not harbor any so-called “forever chemicals,” found in polyfluorinated compounds – or PFAS – that are contaminating water supplies across the world. So the mine-capping foam does not shed dangerous chemicals like, say, PFAS-laden fire-fighting foam. The mine cap is backfilled with 4 feet of rock and dirt and includes a 6-inch pipe to drain standing water into the mine, so surface water “has minimal to no contact” with the foam, Crosby says.

The cap atop the Fourth of July mine shaft is about public safety more than anything else. The Forest Service and state are hyper vigilant to reduce the chance a hiker or pet can fall into an abandoned mine shaft or injure themselves in old mining structures.

Last year a 19-year-old college student was injured after falling 45 feet down an abandoned mine shaft while walking on private land near the Forest Service’s Switzerland Trail in Boulder County on a Saturday night.

In 2016, two teenagers were killed when the truck they were in crashed into an Arapaho and Roosevelt National Forests mine shaft in Boulder County around 2 a.m. on a Sunday morning. The family of one of the teenagers killed sued the federal government, arguing the Forest Service was negligent in closing the mine shaft.

That lawsuit was dismissed and the dismissal upheld by a federal appeals panel in 2020.

The Forest Service and state mining division were able to secure an emergency closure of the mine near Switzerland Trail last year following the several-hour rescue of the student. When the agencies showed up to install a gate on the mine shaft, they turned back people who had seen the news reports about the rescue and showed up with ropes and spelunking gear, Skillern says.

Brady Kutscher, left, and Shane Stratton fit a pipe down the mine shaft, for release of air, before filling the hole with hardening foam. (Hugh Carey/The Colorado Sun)

The “new challenge” for land managers and mine guardians, Skillern says, are the many social media sites and accounts that post about abandoned mines and structures in Colorado.

Those social media posts help the Forest Service and state officials more easily identify and find mines that should be closed. But they also draw more visitors to those sites.

A few years ago, Crosby’s team at the division saw online videos of spelunkers exploring an abandoned mine and were able to identify where the mine was located. They went to the mine to close it and found several more adventurers preparing to explore the mine tunnel. The explorers were very angry at the closure, Crosby said.

“We do some stalking online and they show us some places we need to go in and close,” she says, noting how the Colorado Division of Reclamation, Mining and Safety will soon roll out its own mine safety social media education campaign. “We don’t always like what we see, but we are using it to our advantage.”

The Colorado Sun is a reader-supported, nonpartisan news organization dedicated to covering Colorado issues. To learn more, go to coloradosun.com.