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Mining News: Miners reclaim Alaska mines as they work Property owners’ intentions for land after minerals have been extracted is important element of planning for mine closures Shane Lasley Mining News
Reclamation is a critical element of modern mining and mine planning. In Alaska, companies who wish to extract minerals from the earth must first present a plan on how they propose to return the disturbed land to a reusable state and post financial assurances that they will complete the job.
Planning for what the site will look like and be used for begins before any mining is started. The information needed to design a successful reclamation plan is gathered from the mineral-rich lands during the exploration phase before the area is disturbed.
“When you start doing your development plan, you always consider closure and reclamation,” Bill Jeffress, principle consultant for SRK Consulting (US) Inc.’s Alaska office told Mining News.
To accomplish this, a miner must design the mine in a way that the lands disturbed by mining and ore processing can be stabilized and restored to near-natural condition that will ensure the long-term protection of land and water resources.
Minimizing the effects of disturbance during mining, minimizing or eliminating long-term management requirements and meeting state and federal regulatory requirements are also imperative elements of developing a mine plan.
Considering the end user Environmental and regulatory concerns are not the only elements that must be considered when developing a reclamation plan. Mining companies also must take into account how the property owner wants the land left after the minerals have been extracted.
“For the post-mining land use, it is usually the land owner that makes the determination what that post-mining land use is going to be,” Jeffress said.
In Alaska, government agencies, Native corporations and the general public all contribute in planning what projects will look like and how the land will be used after a mine is closed.
Mining companies with projects on State of Alaska lands must consider the Alaska Department of Natural Resources’ area plan for the region being mined, Jeffress said.
DNR’s process for developing area plans is driven largely by input from the affected communities. The first step of the process is to hold public meetings to identify the issues and concerns of the people of the region. Then, after a draft plan is developed, it is presented to the public for comment. The agency uses what it learns during the comment period to prepare the final area plan for the region.
Much of Alaska’s mineral-rich land is found among more than 40 million acres, or 16.6 million hectares, owned by Alaska Native corporations. Alaska Native leaders and corporation shareholders play a large role in deciding future uses and reclamation requirements on their lands.
Reclaiming Red Dog The world’s largest zinc mine, Red Dog, and the 40 million-ounce Donlin Creek gold project are both located on Native-owned lands.
Red Dog, which is on lands owned by the NANA Regional Native Corp. in Northwest Alaska, is in the process of permitting the Aqqaluk deposit. This expansion is expected to extend the mine’s life by 20 years and has changed the shape of the reclaimed lands.
Under the new plan, Teck Resource Ltd. plans to backfill Red Dog’s Main pit as it mines the adjacent Aqqaluk deposit, and the Aqqaluk pit will be turned into a lake after zinc, lead and silver minerals are removed.
The area contains high concentrations of metals and sulfides which, prior to mining, drained naturally into Red Dog Creek, making it uninhabitable by fish.
Jim Kulas, manager of environmental and public affairs for the Red Dog Mine, said the mine area will be reshaped and then capped with about 1.5 feet of compacted material to minimize water infiltration and to cut off oxygen from the highly reactive rock common to the area. The whole area will then be topped with topsoil and reseeded.
NANA, as a partner with mine operator Teck, plays an active role in determining the reclamation and closure plan at Red Dog.
Kulas explained that despite all of the engineering and precautionary tasks being performed at Red Dog, there is no way to guarantee that water leaving Aqqaluk Lake will meet water quality standards without first being treated.
“So we made a commitment through our closure plan that the Red Dog site will be continually operated and water treatment will be operated until such time as water would ever reach that point,” Kulas said.
To foot the bill for perpetual water treatment, Teck posted a US$304 million bond. The company plans to put this bond into a safe interest-drawing fund to provide operating capital for the water treatment program.
Closure planning at Donlin Creek The Donlin Creek gold project is leased from two Alaska Native corporations. Calista Regional Corp. owns the subsurface rights and Kuskokwim Village Corp. owns surface rights. Kuskokwim will play a large role in shaping the closure plan for the proposed open-pit mine.
While Donlin Creek LLC – owned 50-50 by NovaGold Resources Inc. and Barrick Gold Corp. – has yet to produce a definitive mine plan, the mine operator has drafted an overview of the anticipated reclamation plan.
Under the proposal, the open pit would be allowed to fill with water and become a lake over a period of many years. The company said the water quality of the lake would be continuously monitored to ensure that it does not become toxic to wildlife.
Donlin Creek LLC also informed its stakeholders that after the close of mining and milling activities, excess water would be pumped from the tailings storage facility to the pit lake. The waste rock facility and other disturbed areas will be re-contoured, covered with topsoil, and seeded with a grass mix. Over time, trees and plants native to the area would naturally reclaim the area.
The buildings and equipment would be taken apart and removed. Some material would be buried in permitted on-site landfill trenches that would be covered with soil, as required by regulatory agencies.
It will be largely up to the Kuskokwim Corp. how much of the infrastructure will be left after the mine is closed.
40 years of reclamation Usibelli Coal Mines Inc. is a pioneer in restoring Alaska lands. The family-owned coal company initiated reclamation activities at its Interior Alaska mine in 1970, nearly seven years before these activities were required by federal law. Each year the company’s reclamation team re-contours the terrain, replaces topsoil and revegetates areas where the coal has been removed.
Each summer the coal mine hires college students to assist its engineering and maintenance departments in conducting reclamation work in the areas where coal has been removed. The reclamation crew plants trees, shrubs and grasses on newly re-contoured acreage. They also help with the construction of silt fences, water sampling, settling pond cleanup and collection of native seeds.
Not to be outdone by their older peers, schoolchildren in the Healy area also contribute to Usibelli’s reclamation program. Each year the younger students help collect alder cones which are sent to the University of Alaska Agricultural Experimental Center in Palmer to be cleaned and germinated. The seedlings are then transplanted to the freshly reclaimed areas, providing a head start to the natural regeneration process.
The company has transplanted more than 250,000 seedlings of willow, alder, or spruce on more than 5,500 acres of previously mined land.
Usibelli’s decades-long experience in reclamation has refined the science of revegetation, particularly in encouraging native species to retake the previously mined land.
The company said establishing grass in freshly reshaped areas is critical to stabilizing the surface for plants to take hold and add significant organic material to the soils. The seed mix used at Usibelli is a combination of commercially available native and introduced species selected for their suitability to the environment shortly after re-grading.
The initial grasses are an introduced species, which grows more quickly than native species. The root systems of these fast-growing grasses help minimize soil erosion and help capture the seeds of native species in the area.
As the soils develop and shade is provided by grasses and woody plants, the plant community changes into one dominated by local plant species, especially the woody plants that dominate the surrounding vegetation. The original grasses eventually disappear from the site.
According to Jeffress past reclamation at Usibelli and other sites have helped to refine the amount of grass seed needed to stabilize the soil, yet allow indigenous specious to reclaim the land.
“One of the ways I think everybody has benefited is the plants that they (Usibelli Coal Mines)use to get the reclamation started. Sometimes you will put some grass species in that will stabilize the soil, but they won’t be so concentrated that they inhibit the indigenous woody species from moving in.”
In the past, companies would have a tendency to plant too much grass seed, he said.
“It would look great, like a golf course, but you weren’t seeing the woody species like the willows or the alders moving in as quick as if you cut (the amount of grass seed) down,” Jeffress explained.
Usibelli closely monitors the restoration process by recording the success of plant growth and individual species survival rates. Lessons learned are then put into practice so the program has continued to improve over the years.
The reclaimed land at the Interior Alaska coal mine will be used for wildlife habitat, which was the predominant pre-mining land use, and is a primary use in the state’s land use plan for the area.
Many species of Alaska wildlife – such as Dall sheep, moose and caribou – feed on the young trees growing on the lands reclaimed by Usibelli once the coal is removed.
Restoring habitat at Fort Knox The primary end use of the land hosting the Fort Knox gold mine north of Fairbanks is also wildlife habitat. Fairbanks Gold Mining Inc., the Kinross subsidiary operating Fort Knox, has already restored wetlands and fish habitat to areas of Fish Creek that were destroyed by nearly a century of placer mining.
“The post-mining land use at Fort Knox will primarily be recreation and habitat, and that is consistent with the Tanana Basin Area Plan,” Jeffress explained.
The current plans are to open up Fish Creek, the creek draining the mine area, to public recreation while the Fort Knox Mine site itself will be designated wildlife habitat.
“The tailings impoundment, the pit and the heap leach area will all be reclaimed for wildlife habitat and it doesn’t have another use specified at this time. When you go…down to the Fish Creek area there are agreements in place today where that will ultimately become a public use area,” Fort Knox Environmental Manager Delbert Parr explained.
The Fort Knox pit will be transformed into a 150-acre-by-750-foot-deep lake surrounded by wetlands, creating additional fish and wildlife habitat.
The environmental manager said the tailings pond will be covered with a growth medium where it is needed and then revegetated.
“Future proposed reclamation will produce both wetland and upland sites to increase productivity of post-mining land use as wildlife habitat,” Fairbanks Gold Mining said in its reclamation and closure plan.
Kinross has posted a US$37.6 million bond with the State of Alaska to ensure that Alaska’s largest gold mine is transformed into an area that can be enjoyed by moose and humans alike.
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