Over a century ago, the Climax Mine first began mining and milling molybdenite ore. The mine, located at an altitude of roughly 10,000 feet in the Colorado Rockies, has produced substantial amounts of ore and continues operating today. Our mining operations are integrated with our reclamation projects, utilizing material mined for cover on historic tailings and stockpiles. Progress on large-scale reclamation projects is ongoing and includes reclaiming and revegetating historic tailings, restoring riverbeds and cleaning up legacy mines. Many of our reclamation projects have been recognized by the State of Colorado over the years. To address our environmental commitment, a team of project managers, technical experts and equipment operators are currently executing projects to reclaim areas no longer required for current or future operations. Mining reclamation can take on various forms and achieve different objectives in an attempt to mitigate environmental impacts of mining and restore land that has been mined to a natural or semi-natural state. In some cases, existing drainages are incorporated into the reclamation plan to receive clean stormwater runoff from reclaimed mine facilities. Dormant habitats are being re-established. New landscapes also open up the potential for future recreation opportunities.
Today, the preparation and planning of mine reclamation activities occur prior to a mine being permitted and are a standard part of modern mining practices. During the hardrock mining process, tailings impoundments and rock stockpiles are typically generated. Tailings are the sandy residual sediments that remain after extracting mineral of economic value from the ore. After the mineral has been removes, the remaining materials are discharged to a storage area called a tailings impoundment or storage facility on the surface near the mine. Rock stockpiles (including mine overburden) may contain low concentrations of sulfide and/or oxide minerals and are managed for possible future mineral recovery, but may also be suitable for reclamation or other projects depending on economics and technological improvements
Once tailings facilities and rock stockpiles are no longer needed in a operation, they can be reclaimed. Reclamation takes into account surface and ground water and air quality, erosion concerns from stormwater, revegetation of suitable plant species and designing/providing wildlife and/or aquatic habitats. The reclamation process generally includes re-sloping and contouring of the impacted areas, ensuring drainage channels are created to divert stormwater and limit percolation, establishing points for stormwater to discharge into existing drainages, capping the area with soil, and reseeding with native grasses and shrubs to encourage revegetation and promote wildlife habitat.
Reclamation sometimes involves removing old mining facilities, including mineral processing plants, shops and other structures, in addition to conducting additional technical studies to further refine mine closure/closeout activities. To address safety concerns, we close old mine openings such as shafts or adits, that were created decades ago as early miners explored for metals.
Reclamation in Colorado: A Biosolids Success Story
Large quantities of mine tailings were placed in a tailings impoundment in a drainage area, known as the Robinson Tailings Pond, adjacent to the Climax mine. Reclaiming and revegetating the mine’s historic tailings has been no small feat. Mining reclamation here is affected by a challenging climate and location, more so than at any of our other locations in North America. The average snowfall in the area is about 23 feet each year. Moreover, the subalpine climate hinders revegetation efforts as the frost-free growing season is reduced to roughly six weeks per year.
Reclamation of the 600-acre Robinson Tailings Pond has been ongoing for the past few decades. Capping the pond began in the 1980s and first required a combination of soil and rock to stabilize the surface. Once capped, the surface required a topsoil layer able to support plant growth. While rock was plentiful, the large amount of topsoil needed was not.
By the 1990s, the explosive growth of resort communities in the local region created an increase in biosolid production. In addition, ski trail expansion and booming construction generated extra quantities of wood residuals. Local wastewater-treatment districts were in need of a new response to biosolid management in conjunction with the need to dispose of wood residuals. Likewise, biosolids offered a cost-effective alternative for the organics and nutrients necessary for successful reclamation at the Climax mine.
In 1996, Climax established a pilot demonstration project for the use of biosolids in reclamation. Today, the biosolids and woodchips are mixed and composted on site to produce over 30,000 cubic yards of growth medium for reclamation each year. The high quality of the biosolids used at Climax meets all state and federal regulatory standards.
Climax has now reclaimed much of the land along Highway 91 and has planted numerous spruce, fir, aspen and willow tree saplings. Though the tough climate of the area affects our success, the results-to-date suggest Climax’s reclamation program can establish diverse, permanent vegetation communities capable of sustaining wildlife habitat.
A Stream Channel Restored
The Climax mine is also at the headwaters of three major river basins: the Arkansas River, the Eagle River and Tenmile Creek.
Due to past Climax mine activities, the East Fork of the Arkansas River had been buried under mine overburden and rerouted through a 7-foot diameter concrete culvert. The culvert returned the river to a channel to flow into a native channel downstream of the mine property.
Climax undertook a project to reconstruct a new riverbed to a more natural state. This project entailed the design and construction of approximately 2,000 feet of restored stream channel and 14 acres of the contiguous watershed through the historic Storke Yard of Climax.
Stream channel restoration, habitat construction and revegetation activities are particularly difficult at the site as a result of the high altitude, short growing season, harsh winters, intense summer thunderstorms, periodic flood events and poor soils.
The stream channel design was developed to maintain floodplain connectivity, mimic natural topography and pass stormwater runoff through a restored stream to establish aquatic wildlife habitat as part of a viable, self-sustaining ecosystem in the extreme climate of this region.
With construction of the stream channel completed in 2007, adjacent ridges and valleys were formed throughout the disturbed area. Floodplains and wetlands were constructed adjacent to the channel, providing habitat for riparian and wet meadow species.
Revegetation activities began soon after using composted biosolids from Climax’s award-winning biosolids program. Wetland and upland seed mixes were developed for the site. Several hundred new trees have been planted in the reclaimed area, as well as transplanted from adjacent areas, to contribute to the area’s structure and diversity.
Reclamation of Legacy Colorado Mines
Reclamation work was also done in areas that were not directly associated with the Climax mine itself. This includes Searle and Kokomo gulches which had numerous legacy mines in what was considered the Tenmile mining district. These historic silver, lead, zinc, gold and copper mines were incorporated into the Climax mine property in the consolidation of its land base during the 1980s. Climax voluntarily initiated a project to remove and reclaim old waste rock piles in the Tenmile mining district. As of December 31, 2013, 41 historic mine sites have been cleaned up and 37 have been completely reclaimed. Nearly 227,000 cubic yards of waste rock and soils were removed and 50 acres of land were restored.
For more information about Freeport-McMoRan’s reclamation efforts, take a look at our brochure Mining Reclamation in North America Supporting a Sustainable Future.