PKAA, Mineral Mountain Mine Closure Project

The Mineral Mountain Mine Closure Project is located roughly 3 miles west of the town of Nederland and 1 mile north of Eldora in western Boulder County on Pomeroy, Mineral, and Eldorado mountains. The project includes adits and shafts/stopes/prospect pits related to the Grand Island - Caribou mining district. Most mines were extracting vein minerals associated with intrusive stocks including silver, lead, gold, zinc, tungsten, and minor amounts of uranium. This is one of the oldest mining districts in Colorado, dating back to the 1860s and still contains active mines. The features are located in areas that are readily accessible to public using United States Forest Service roads and trails, and local landowners who recreate in the area. There is evidence of visitation to many of these sites, increasing landowner worry about possible injuries and liability. Access to the mine features is generally by rough 4WD roads and will require up to 4 miles of machine walk-in distances. Trailers and haul trucks will not be able to access these locations. Closure methods include machine backfilling, hand backfilling, Polyurethane Foam, Corrugated Steel Pipe, bulkheads, and monolithic plugs.