Monday, August 29th, 2022, 4:18pm
From the USFS:
It’ll be slow-going on a popular trail into Indian Peaks Wilderness Area Tuesday, Aug. 30, while a working crew of horses pack supplies from the Fourth of July Trailhead near Eldora to seal a recently-exposed mine shaft.
The crew of pack animals will slowly make their way up the Arapaho Pass Trail (#904) from the trailhead to the 2-mile mark starting as early at 6:30 a.m., making three round trips with supplies throughout the course of the day. This trailhead also accesses Arapaho Glacier Trail (#905) and Diamond Lake trail (#975). Depending on weather and progress, work could be delayed or extended into the following day.
While the trail will not be officially closed, the public is asked to make alternate hiking plans. Hikers who cannot avoid the trail need to know trail etiquette around horses. Hikers coming from the opposite direction are asked to stand aside (preferably uphill) and allow all the horses to pass before continuing. Hikers traveling in the same direction behind the horses must keep their distance and hike a slower pace until the lead says it’s safe to pass. In both cases, hikers may be significantly delayed.
Located above timberline as a silver vein in 1872, the Fourth of July Mine was never rich enough to be profitable. Around the turn of the 20th century, the mine was renewed in search of copper. Historical records show that the main shaft was once 300 feet deep. In 2018, the USDA Forest Service worked with partners to close a long, connected adit. The current shaft, which was believed to be the primary entrance to the mine, was caved in until recently.
“There are scary shafts and really scary shafts. This is in the second category,” said Trez Skillern, the Arapaho and Roosevelt National Forest’s abandoned mines program manager. “The opening is 17-feet in diameter. We don’t know how deep it goes.”
The Forest has had a public closure order in place since the new opening was discovered in 2021. Environmental analysis determined the mine is free of water and acid drainage, and that the shaft is not suitable bat habitat.
Because the mine is in designated wilderness, mechanized equipment is not allowed. The horses will pack in supplies of polyurethan foam, which will be applied to the opening by hand. Once mixed and activated, the “PUF” will expand and harden, effectively corking the opening of the mine. It will take seven days for the material to completely harden, and then the cork will be covered with the non-hazardous mining waste rock already on the site to return the site to its historical look and protect it from the elements.
The project is being funded by the Forest and completed in partnership with the Colorado Division of Reclamation, Mining and Safety, who is supervising the work.
While Colorado’s mining history created much of its rich culture, it left behind dangerous shafts and adits that can have extensive underground excavations and be prone to sudden collapse. Rockfall and cave-ins around mine openings can occur without warning. Toxic gases and oxygen-deficient air can cause injury or death, even outside of the mine opening. Abandoned features may contain unstable explosives or poisons such as arsenic and cyanide. While these sites often attract visitors, it’s always best to observe them from a safe distance.