SALT LAKE CITY (AP) — Operators of a Utah copper mine have announced plans to extend operations by using an experimental method of extraction they say is safe despite concerns about potential groundwater contamination.

The Salt Lake Tribune reports that officials with the Lisbon Valley Mine are seeking permits for an acid-based extraction method that involves pumping diluted sulfuric acid underground in San Juan County northeast of Monticello.

The new process could extend the mine’s lifespan for at least another 25 years, officials said.

ADVERTISEMENT

Environmentalists have raised concerns about long-term water contamination for nearby residents reliant on groundwater for drinking and livestock.

The Lisbon Valley Mining Company has managed the mine since 2008 when its former owner declared bankruptcy three years after opening, officials said. The mine has been hurt by decreasing global copper prices and trade disputes with China, company officials said.

The mine was five years delinquent on about $1.4 million of property taxes and recently won county forgiveness of about $250,000 in interest and penalties, officials said.

In response, the mining company submitted an operation plan to the state in October including plans to use an in-situ recovery mining method that would pump water and sulfuric acid into the ground to dissolve copper from the rock, officials said. That solution is then carried to the surface before the copper is separated without ever mixing with surrounding groundwater, company officials said.

If permits are approved, Lisbon Valley would be the first place in Utah to implement the acid-based in-situ recovery mining method, company environmental manager Alysen Tarrant said.

“We’re putting in millions and millions of dollars to prove up a technology that eliminates the need for open-pit mining and (that) could benefit the overall industry on a global scale,” Tarrant said.

The company expects the first pilot project to be installed in 2021 and estimates 2,700 wells would be drilled, company officials said. The mining could continue until 2045, officials said.

“It’s our home, our drinking water,” said Joan Wilcox, who lives on a nearby ranch that has been operated by the her family for over a century. “We make a living off of that ground.”

The ranch’s drinking well taps the shallow aquifer where the solution mining is expected to occur, Wilcox said.

A public comment period on the proposed permit is expected after its submitted, officials said. The plan also requires an environmental assessment and approval from the Bureau of Land Management.