Kensington Mine readies
for tailings expansion
By Tara O’Hanley
Coeur Alaska

bove the northwest side of Berner’s Bay and at the foot of Lion’s Head Mountain in the Tongass National Forest, 45 miles north-northwest of Juneau, Coeur Alaska’s Kensington Mine has grown to become the second-largest private employer in Southeast since it began operations in 2010.

Coeur Alaska’s parent company, Chicago-based Coeur Mining, is a well-diversified and growing precious metals producer. In addition to Kensington, it also operates mines in Nevada, South Dakota, and northern Mexico, as well as an exploration project in British Columbia. But the company says it is “all in” on Alaska.

Coeur’s 2022 annual report states the company has invested approximately $245 million in exploration, leading to increases of approximately 21 percent and 49 percent in company-wide gold and silver reserves, respectively, over the five-year period.

These investments are already paying off in Alaska, too. Coeur’s year-end 2022 Mineral Reserves and Resources report noted a 56 percent year-over-year increase in Kensington’s gold reserves: geologists identified several areas with high-grade gold mineralization that could potentially support new mining operations, adding 1.5 years to the life of the Kensington Mine. “That’s the first time since 2017 that we’ve had an increase in reserves and only the second time since modern mining started in Kensington, when we began commercial production in 2010,” says Stephen Ball, the mine’s general manager.

In 2022, Coeur Alaska received a final record of decision from the US Forest Service for its Plan of Operations Amendment 1 (POA 1). Coeur Alaska has been undergoing a permitting process to expand waste rock and tailings storage capacity to reflect its positive exploration results and continuous operational improvements. “Getting the increase of reserves was an important milestone to continue with our multi-year drilling and development plan,” says Ball. “It required a bit of forethought with the permitting, as we needed the additional storage capacity before we could push an aggressive exploration program to build additional reserves.”

Under the approved plan, Coeur intends to raise the height of Kensington’s existing tailings dam by 36 feet, which would increase tailings storage capacity by an additional 4 million tons. The company will also construct a 40-foot “back dam” between the Lower Slate Lake tailings treatment facility and Upper Slate Lake, as well as expand three existing waste rock storage facilities and build one new waste rock storage facility, for a total waste capacity increase of 5 million tons.

A Major Contributor
Kensington has been playing a vital role in the Southeast economy for decades. Today, in addition to ranking as the second-largest private employer in the City and Borough of Juneau (after Hecla’s Greens Creek Mine on Admiralty Island), Coeur also holds the honor of being the second-largest property taxpayer. “We’re proud of that standing,” says Rochelle Lindley, Coeur Alaska’s community and government affairs manager. “And, in fact, mining holds the top two spots for largest employers and taxpayers in the region.”

Expanding on this point, Ball adds, “Two of the six major operating mines in the state of Alaska are here in Juneau…. It’s an important part of our economy here. We are key purchasers for power, diesel, goods, and services, which helps to support a lower cost of living here in Southeast Alaska—not only in Juneau, but throughout the different villages.”

Coeur Alaska has been part of life in the Upper Panhandle since arriving in 1987. “We’ve been a member of this community for thirty-six years,” Ball explains. “When the Kensington mine began commercial operation in 2010, there were 1.4 million ounces of reserves and a 10-year mine life. Well, we’ve passed that milestone, and we still have reserves and mine life. Really, what we’re trying to do is expand that and continue to be a major contributor to the livelihood of this community here in Juneau and in Southeast Alaska.”

Giving Back
Coeur’s impact on local quality-of-life reaches beyond the nearly 400 employees on its roster, the goods it purchases, and the contractors supporting its operations. “We’re very active in the community,” Lindley says. “We try and participate and show up to as many things as we can. In 2022, we invested just under $400,000 into community giving. We’re really proud of what we can give back.”

One of these initiatives includes a longtime partnership with United Way through the Learn United Reading Tutor Program. The program launched in 2012 and places tutors in local elementary schools, helping to improve literacy before the third grade. The program has logged 485 volunteer hours in the past six months alone. In addition to volunteering, Coeur Alaska also supports that program financially, with a $10,000 direct donation last year.

“[It’s] the first time since 2017 that we’ve had an increase in reserves and only the second time since modern mining started in Kensington, when we began commercial production in 2010.”
Stephen Ball, General Manager, Kensington Mine
Last year Coeur Alaska helped a local school develop signage after it adopted its new Tlingit name: Kaxdigoowu Héen Elementary School.
The new Fairbanks Service Center triples office space from 1,500 square feet to 4,500, partly to accommodate additional staff.
Span Alaska
A Coeur Alaska employee in the field supporting exploratory drilling.
The previous service center in Fairbanks was state of the art when it was built in 2001. The new warehouse is more than double the size.
Span Alaska
The company also works closely with Alaska Resource Education, a nonprofit organization that provides education about resources and resource development to teachers and students across the state. And it assists with shorter-term but equally impactful projects, as needs arise, which last year included helping the Kax̱dig̱oowu Héen Elementary School to develop new signage after it adopted a new Tlingit name.

“They have a new name. They have a new mascot,” Lindley says. “It’s an honor from the Lingít people from this area. And we were honored to be able to donate funds so that they can create new signage to represent their new title. Kax̱dig̱oowu Héen is the closest elementary school to our offices in Juneau, so it’s definitely a special project for us.”

Getting There
Alaska’s mining industry has been the focus of renewed interest since the 2022 passage of the Inflation Reduction Act. At the time, Brett Watson with UAA’s Institute of Social and Economic Research said that the $370 billion package has the potential to bring a “renaissance” to Alaska mining—but only if the state can find a way to circumvent hurdles that often slow down mining projects. Those include long timelines for exploration and construction in addition to a lack of roads and ports and high energy costs.

In the case of Kensington, these considerations are front and center. The mine’s remote location, nestled within the largest national forest in the United States, is accessible only by boat, plane, or helicopter. This has made it necessary for the operator to invest heavily in infrastructure—both to house the approximately 250 workers living on site at any given time and to generate the required power to operate a ball mill and crusher, provide power for electric drills, and treat and pump water within the facility.

Some logistic support may be on the horizon, however, in the form of a possible new ferry terminal on undeveloped land at Cascade Point. Talks are still in early preliminary stages, but if Goldbelt, Juneau’s urban Native corporation that owns the land, and state transportation official can establish feasibility and reach an investment decision, a shorter ferry route may result in lower transportation costs for goods and improved shuttle services for mine workers.

“It would be a benefit for us,” Ball explains. “Distance on the water is a safety concern. Lynn Canal can be extremely rough. It also has the potential to help our employees that live in Haines by providing more options for getting down to Kensington because it allows the Alaska ferries to go to a day trip.”

Expansions and Improvements
In the meantime, Kensington is busy implementing recommendations laid out in the Supplemental Environmental Impact Statement and Record of Decision associated with POA 1.

Specifically, under the US Forest Service’s Final Record of Decision, the mine will utilize third-party consultants to conduct independent Ecological Risk Assessments to perform ongoing evaluations of mine activities and establish an Independent Engineering Review Board to monitor the design, construction, operation, performance, and risk management of the planned expansions to the tailings treatment facility and dams.

The Final Decision of Record also provides an opportunity to improve fish habitat that was not possible under the original plan. Restoration activities are set to improve Dolly Varden spawning habitat by constructing deltas and stream channels, as well as converting the tailings treatment facility to a functioning lake with 28 feet of water cover at the mine’s eventual closure.

The fish habitat enhancement design stems from several investigations that the Alaska Department of Fish and Game undertook at Kensington during the review process. As a result of the dam raise and planned inundation of the lake and tributaries at closure, the fish will gain 0.2 miles more spawning habitat and 0.7 miles more rearing habitat compared to current conditions. The decision states that, under the Selected Alternative, there is a high likelihood that the tailings treatment facility—formerly Lower Slate Lake—will be restored to long-term fish habitat after closure of the mine. The result will be a net increase in wetlands in the area, long after operations have ceased.