Case Study 11:
THE ISSUE: Mine closure is a complex process requiring careful planning from the beginning of a project’s lifecycle. The planning horizon is measured in decades, and planners must deal with social, economic and environmental issues that will inevitably change over a mine’s operating life. What are the best practices that define successful mine closure and site reclamation?
THE KINROSS WAY
Returning land disturbed by mining to stable and productive post-mining land uses is fundamental to Kinross’ commitment to prudent and responsible stewardship of the environment. Working with our stakeholders, closure planning is an integral consideration during initial mine planning and is regularly updated as new information becomes available or mining operations are optimized.
When mining operations cease, Kinross proceeds with the demolition of facilities and completion of final reclamation, all the while maintaining compliance with permitted regulatory requirements. We work closely with regulatory agencies and key stakeholders to ensure that sound technical reclamation approaches are applied to the unique and specific characteristics of each site.
In 2011, our Mineral Hill mine was awarded the U.S. Bureau of Land Management’s Hardrock Mineral Environmental Award honouring best practice in mine reclamation. Below are some of the undertakings for which we were recognized.
Mineral Hill History
Kinross’ Mineral Hill mine is located adjacent to Yellowstone National Park in the U.S. state of Montana. Commercial gold and arsenic mining began in the area in 1880 and continued intermittently until 1948. Modern gold mining operations began in the late 1980s, ceasing in 1996 due to unprofitable metal prices. Reclamation activities began in 2000. In 2003, Kinross acquired Mineral Hill through its merger with TVX Gold, and the former TVX employees continued to advance their reclamation activities on behalf of Kinross.
Site Closure and Reclamation
Reclamation activities began with removal and/or rehabilitation of the mill and process facilities. Mine openings were secured to prevent unauthorized entry. Land throughout the site, including facility foundations and haul and drill roads, was re-contoured to its original grade. With approval from the Montana Historical Society, the site team removed a dilapidated arsenic mill and excavated the contaminated and potentially contaminated building debris and soils for secure final disposal. The mine team also reclaimed two tailings deposits that were remnants of gold and arsenic operations from the early 1900s. The 5.2 hectare tailings storage facility was drained, secured with an additional liner, and re-graded. An evaporation system was installed to handle the small amount of drainage from the tailings area, and the facility entered a period of care and maintenance.
In 2005, Kinross voluntarily undertook installation of an impermeable liner over the upper five acres and surface drainage channels of the tailings facility. By preventing water from entering the reclaimed tailings from the top, the amount of water draining from the tailings has been reduced to a trickle, minimizing the amount of residual tailings moisture that is collected for treatment and disposal.
In 2008, in the interest of public safety, mine personnel assisted the U.S. Forest Service in the closure of several mine openings in the vicinity, including two portals on our property. At some locations, the Forest Service and Kinross team was able to complete closure to restrict public access, while still preserving the cave-like habitat for bats and other small mammals.
Native plants, grasses and shrubs have been re-established over the entire site, and the reclaimed areas provide habitat for bountiful wildlife and a migration corridor for the northern Yellowstone elk herd. The site recently received agency approval for partial bond release for successfully vegetated areas and approval to decrease the permitted area from 172 to 37 hectares. Ongoing site activities consist of environmental monitoring and water management.
We believe that we have been able to achieve successful results largely through ongoing and substantial consultation and involvement with the community, the Montana Department of Environmental Quality, the U.S. Forest Service, the National Park Service and the Bear Creek Council. Future land use is of great interest to local stakeholders who have expressed support for public ownership of the property. The property has high recreational, wildlife, and historical values that are being evaluated.