Published: May 13, 2024 |

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The Idaho Board of Environmental Quality found that the agency it oversees issued an air quality permit for a proposed gold mine that significantly miscalculated allowable emission levels for arsenic-laden dust.

The board, in a ruling issued last week, remanded a portion of the permit that would govern dust and arsenic emissions for the Stibnite-Gold Project to the Department of Environmental Quality for more work.

Perpetua Resources wants to reopen and expand a long-dormant open pit gold and antimony mine near Yellow Pine and along the East Fork of the South Fork Salmon River east of McCall. It is in the process of seeking dozens of necessary state and federal permits to do so.

It has already received $34.6 million from the Department of Defense that covets a domestic source of antimony, a mineral used in munitions, and the U.S Import Export Bank has said it may lend Perpetua Resources up to $1.8 billion.

The company hopes to extract more than 4 million ounces of gold, 1.7 million ounces of silver and 115 million pounds of antimony, and has pledged to use a portion of its profits to clean up past waste at the mine site.

The mine could create up to 500 jobs and generate more than $60 million in annual tax revenue, according to the company.

But the mine adjacent to the Frank Church River of No Return Wilderness Area is opposed by the Nez Perce Tribe and the conservation groups Save the South Fork Salmon and the Idaho Conservation League.

They contend it will spill pollution into critical spawning habitat for threatened spring chinook, steelhead and bull trout and lead to other environmental problems. Tribal members continue to fish in the area, and the tribe is actively involved in salmon recovery there.

Last year, DEQ issued the company an air quality permit to construct that outlines the expected release of toxic pollutants from mining activity and steps to mitigate those releases in order to keep them below standards of the federal Clean Air Act.

The emissions are largely related to fugitive dust resulting from mining traffic along haul roads as well as drilling and blasting at the mine.

The Nez Perce Tribe and environmental groups challenged the permit, saying the company assumes it will have more ability to control public access and thus exposure to toxic pollutants than it is realistic, that the state agency allowed the company to work on permit details after public comment was closed, that it included a dust abatement goal that is unachievable and that it miscalculated ambient arsenic levels.

The board turned away all but one of the complaints. It agreed with the groups that DEQ permit writers used various analysis and calculations that underrepresented potential exposure to arsenic.

“The impact of this additional variable in the equation ultimately results in over a 75 percent reduction in the calculated exposure,” the board wrote of one of the calculations.

The groups welcomed the ruling.

Perpetua spokesperson Marty Boughton said the board sent the permit back to the DEQ for additional review but did not invalidate it.

“It goes without saying, creating a project that is protective of human health and the environment has always been at the heart of Perpetua’s mission and vision for the Stibnite Gold Project, and we’ll continue working with IDEQ to respond to this narrow additional review,” said Boughton.

Source: Moscow-Pullman Daily News

Perpetua Resources, through its wholly owned subsidiaries, is focused on the exploration, site restoration and redevelopment of gold-antimony-silver deposits in the Stibnite-Yellow Pine district of central Idaho that are encompassed by the Stibnite Gold Project. The project is one of the highest-grade, open pit gold deposits in the United States and is designed to apply a modern, responsible mining approach to restore an abandoned mine site and produce both gold and the only mined source of antimony in the United States. Further advancing Perpetua Resources’ ESG and sustainable mining goals, the project will be powered by the lowest carbon emissions grid in the nation and a portion of the antimony produced from the project will be supplied to Ambri, a U.S.-based company commercializing a low-cost liquid metal battery essential for the low-carbon energy transition. Perpetua Resources has been awarded a Technology Investment Agreement of $24.8 million in Defense Production Act Title III funding to advance construction readiness and permitting of the project. Antimony trisulfide from Stibnite is the only known domestic source of antimony that can meet U.S. defense needs for many small arms, munitions, and missile types.

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