Fort Knox reclamation: journey began before mining started.
Although this region has been a hub of mining for more than a century, no buildings or roads are visible. But just more than a decade ago, this site on the side of Pedro Dome was carved into roads, piled with rocks, and bustling with traffic as huge shovels and dozers carved into the bedrock in search of gold. A steady parade of oversize trucks carried the ore to the mill at Fort Knox a few miles to the south.
This is the site of the True North gold mine. Between 2001 and 2004 it produced approximately 530,000 ounces of gold. More than 36 million tons of ore were moved in its brief lifespan.
Today, it's one of the few road-accessible sites in Alaska where it's possible to see the process of reclamation from start to finish, says Jennifer Pyecha, senior environmental engineer for Fairbanks Gold Mining, Inc., a wholly-owned subsidiary of Toronto-based Kinross Gold Corporation, which operates True North and Fort Knox.
The reclamation of the True North gold mine is nearly complete. In a few years, trees will cover the hillside, and aside from the road leading to it, it will be virtually indistinguishable from the hills around it. The process from industry to nature is a long and expensive one, a journey that begins even before mining starts.
Under Alaska law, mines must post a bond to cover the costs of reclamation, and reclamation plans must be approved by the Alaska Department of Natural Resources. The plans must be updated whenever there is a change to mining operations.
Reclaiming True North was a fairly straightforward operation, according to Pyecha and Fort Knox environmental manager Bartly Kleven. All the mining at True North was done above the water table. The only buildings on the site were for equipment maintenance. Because all the ore was trucked to Fort Knox for processing, no mill was necessary.
A Matter of Scale
But the process at True North is a snapshot of what Fairbanks Gold Mining will be undertaking when Fort Knox shuts down, a process that could start as early as 2018. Like nearly everything to do with Fort Knox, it's a matter of scale. Fairbanks Gold Mining posted a $3.6 million bond for True North reclamation. For Fort Knox, it was required to post a $96 million bond.
The goal is to return the mine to a stabilized and near-natural condition and ensure the long-term protection of land and water, Pyecha says.
"We want to try to match the contours of the original topography," Pyecha says.
The reclamation plan for True North encompasses an eight-year window, which begin in 2009 after the final shutdown, although some work was started in 2005 when operations were first suspended. At that time, the site contained roads and multiple waste rock dumps. Wetlands abutted some areas, which took special efforts to protect. Old trails that had once traced the site were re-established. During the permitting process, the mine plan had been altered to avoid the historic Davidson Ditch and reduce the impacts to wetlands.
Reclamation efforts began with recontouring the landscape and scarifying the surface. Scarifying creates eighteen-inch-deep ridges that trap moisture and minimize erosion. It also makes it easier for seeds to germinate and develop. But to plant seeds, you need soil, says Kleven.
"Topsoil is kind of a rare commodity on Alaska," she says. For that reason, mine operators had stockpiled the thin layer of organic material at the site when the mine was first developed. All organic material at Fort Knox is also piled into a big hill that visitors pass on the way into the mine site to be used for future reclamation projects.
The next step is to figure out what to plant. Kleven had previously worked at Usibelli Coal Mine near Healy, where she oversaw reclamation efforts, including aerial seeding. That gave her a good idea of where to start. Working with Alaska agricultural officials, Kleven's team came up with a combination of four grass seeds that would thrive in the cold climate, help build up the thin soils, and prevent erosion.
The mixture of 50 percent Arctic fescue; 20 percent Gruening alpine bluegrass; 20 percent tundra glaucus bluegrass; and 10 percent Nortran tufted hairgrass was broadcast over the site at the rate of nine pounds per acre. The area was fertilized in spring and fall.
Planting trees was the next big step.
Harvesting Local Seeds
Kleven says that when they started looking for seedlings in 2010, they could find none locally. So they approached Risse Greenhouse, located on Chena Hot Springs Road a few miles northeast of Fairbanks. Owner Glen Risse Jr. worked with an arborist at the University of Alaska Fairbanks to come up with a plan to harvest local seeds from black spruce, white spruce, birch, and alder trees.
In Interior Alaska's harsh climate, location is paramount when it comes to plant survival. The elevation of a site, whether it faces north or south, and if it is exposed or relatively sheltered play a large role in deciding what tree to plant and where to plant it.
"The big thing with plants, birch plants, is when you get seeds from about the same elevation, it works much better," Pyecha says.
The seeds were gathered between October 2011 and February 2012 and germinated in March, growing in ten-cubic-inch tubes. The trees were delivered later that summer and Fairbanks Gold found it had another problem: "We had all these trees--who's going to plant them?" Pyecha says.
After looking outside Alaska and around the state, Pyecha says they found a company just a few miles from Risse Greenhouse called Future Forests to plant the seedlings. The effort resulted in 12,700 black spruce, 8,400 white spruce, 6,000 birch, 3,000 alder, and 2,150 other seedlings grown as trials.
"ft really looks nice," Kleven says. "We want hunters to come back and trail users to come back."
The majority of True North's restoration is complete and the state has returned $3.1 million of Fairbanks Gold's bond money. Another $600,000 is outstanding, with three more years left on the reclamation clock.
In late August, the only indication of the former mine were a few pieces of metal pipe waiting to be hauled off. The eight-mile road from Fort Knox ends at a locked gate, becoming a grassy trail a few hundred feet inside the mine before vanishing over a hill amid waves of fescue. Alders and willows, some planted, some of which had seeded themselves, grow on the hillside. The ground is treacherous, as the ridges from the scarifying process are hidden under knee-high grass.
Already, local berry pickers have started foraging over the site, which is still closed to the public. Fox and sandhill cranes are frequent visitors, and a wolf den is located in one corner of the former mine.
"We've done a lot of work on the trail systems to make sure the trails are as good or better than they were," Kleven says.
The reclamation work at True North is just a warm-up for what is to come at Fort Knox.
Fort Knox Reclamation
However, at Fort Knox reclamation began even before the mine was built. The mine is just a few miles from where Italian miner Felix Pedro first found gold in Fish Creek in 1902, the discovery that led to the formation of Fairbanks. Over the following decades, Fish Creek and the surrounding drainages were heavily mined. When the sites were mined out, they were left as they were. Sediment concentration, uncontrolled run-off, and erosion seriously undermined wildlife habitat. Old mining equipment and mining shafts dotted the valleys.
In the early 1990s, Amax Gold, Inc., which developed the Fort Knox gold mine, used the opportunity to fix decades of mining damage and restore wildlife habitat. Working with the Alaska Department of Fish and Game, Amax's goal was to create viable populations of grayling within ten years. They met their goal in two.
The environmental work continued as Fort Knox was built and mining began. Kinross acquired Fort Knox in 1998 when it merged with Amax. Over the years, mine officials have continued to work closely with Fish and Game on restoration of the wetlands in the Fish Creek valley, downstream from the Fort Knox tailings storage facility.
In 2009, Fort Knox and Fish and Game were jointly awarded the prestigious Tileston Award for the Fish Creek reclamation. The award is presented by the Alaska Conservation Alliance and the Resource Development Council and recognizes projects that are good for both the environment and the economy.
Today, the Fish Creek wetlands support thriving populations of grayling and burbot, as well as moose, beavers, and bald eagles. Fort Knox has produced more than 6 million ounces of gold, to date, but time may be running out. While Fort Knox produced 379,453 ounces of gold in 2014, with similar amounts forecast for the next couple of years, there may not be enough higher-grade ore to make running the mill feasible past 2017.
According to Anna Atchison, Fort Knox manager for community and government affairs, the current mine plan shows the mill to be shut down in early 2018. Workers will continue to mine lower-grade ore, stacking it on the Walter Creek heap leach through about 2020. The heap-leach will be operated as long as it is economically feasible.
Once the heap leach is shut down, reclamation plans will begin in earnest. During active mining, the tailings facility is a zero discharge facility. After the mine closes, and once water quality levels are maintained, a spillway will allow water to flow into Fish Creek.
Based on the current mine schedule, reclamation of waste rock dumps will begin in 2021. That will entail contouring the heaps of rock and adding organic material, scarifying, and seeding, as was done at True North. "Large boulders that are uncovered during sloping may be left on the surface to provide topographic diversity, microhabitats for wildlife and vegetation, and to break the linear appearance of the final slope," according to Kinross' 2015 technical report on Fort Knox. The goal is to achieve 70 percent of the area to be covered by vegetation within three years of the final seeding and application of fertilizer.
Some buildings may remain at the site and reused for other purposes.
The pit, which is about a half-mile deep and a mile wide, will be allowed to fill with water. However, it may take decades for it to fill completely.
The water supply reservoir and Solo Creek causeway will remain in place for long-term recreational use and to maintain wetlands.
The lake, however, won't be available for public use until final reclamation is complete and a period of post-closure monitoring, expected to be about ten years.
The reclamation process will take years. But once it's done, the site will return to state ownership and be used as a recreational area overseen by Alaska State Parks, says an Alaska Fish and Game official.
But, if history is any guide, any reclamation should not be written in stone. Fort Knox was originally forecast to produce only 4 million ounces of gold and last for a decade. Under the current plan, that lifespan and production have been more than doubled. Kinross is actively exploring the Gil prospect a few miles from the mine, and things could change, Atchison says.
"We're going to do everything we can to keep mining as long as possible," she says.
Julie Stricker is a journalist living near Fairbanks.
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|Title Annotation:||SPECIAL SECTION: Mining|
|Comment:||Fort Knox reclamation: journey began before mining started.(SPECIAL SECTION: Mining)|
|Publication:||Alaska Business Monthly|
|Date:||Nov 1, 2015|
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