Aaron Vesledahl, the mine manager at Hudbay Mineral Inc., talks about the Copper World Mine at the site in the Santa Rita Mountains south of Tucson.

The Arizona Department of Environmental Quality approved a key permit Thursday for the Copper World Mine in the Santa Rita Mountains, saying it is aimed at insuring mine discharges don’t pollute the underlying groundwater.

The permit approval leaves just one more state OK needed by Hudbay Minerals Inc. before it can start construction and eventually begin operations. The mine already received approval of its reclamation plan from the State Mine Inspector’s Office and still needs approval of an air quality permit from ADEQ.

It’s a big win for Hudbay Minerals Inc., and a setback for mine opponents, who provided the majority of comments at two public meetings on the project and sent thousands of public comment letters, many of them form letters, opposing the permit to ADEQ.

In a news release issued shortly after ADEQ announced its approval of the aquifer permit, Hudbay said it’s pleased with the level of local support it received at public meetings on the permit and looks forward to providing significant social and environmental benefits for the community and local economy in Arizona.

It said the state action is a sign Copper World’s permitting process is “on track.” It hasn’t given a schedule for when it will or might start construction of or open the mine, and has declined to speculate on a possible opening date.

The company expects to increase its planned capital spending for the project for 2024 to $45 million from an original estimate of $20 million.

The approval closes what had been a contentious debate over ADEQ’s proposed Copper World permit, in which opponents including many people living near the mine site blasted the project’s monitoring well network, its ability to self-monitor groundwater wells for possible contamination, and the current lack of state groundwater quality standards for uranium.

Thursday, ADEQ said it made five changes to the aquifer protection permit in response to comments, including the addition of two monitoring wells at the mine site to check for pollution.

The permit covers a total of 16 facilities at the mine site at 9025 E. Santa Rita Road, about 12 miles south of Sahuarita and 28 miles southeast of Tucson.

The facilities permitted include five of the six open pits Hudbay plans for the site, along with a waste rock disposal area and two of three tailings disposal areas planned by the company.

The sixth pit, lying on the Santa Ritas’ east slope facing the Sonoita highway, will not be covered by the permit. That’s because state officials agree with Hudbay that pit — formerly part of the now-defunct Rosemont Mine proposal — will lose more water to evaporation and seepage than it will gain from rainfall runoff and groundwater seepage.

Also covered are seven ponds used to capture stormwater and to store various solutions left from mineral processing. A heap leaching facility is also covered by the permit, but Hudbay has already dropped it from its plans in favor of a different process to extract copper from ore.

The new permit’s requirements will allow the mine to operate while not causing or contributing to violations of state groundwater quality standards, ADEQ said. The mine will also meet state requirements to use the Best Available Demonstrated Control Technology “to employ engineering controls, processes, operating methods, or other alternatives to reduce pollutant discharges to the greatest degree that’s practicable,” ADEQ said.

ADEQ has estimated that Copper World’s mine life will be about 15 years, although Hudbay has said about 20 years for its first phase. The company has also said it could be mining the entire area of the mine site — including the former Rosemont Mine site — for a total of 44 years.

Production will be phased. The mine will extract about about 60,000 tons of sulfide ore and 20,000 to 45,000 tons of oxide ore daily.

In its news release, Hudbay said: “Over the proposed initial 20-year mine life, the company expects to contribute more than $850 million in U.S. taxes, including approximately $170 million in taxes to the state of Arizona.

“Hudbay also expects Copper World to create more than 400 direct jobs and up to 3,000 indirect jobs in Arizona.

“Copper World will offer competitive wages and benefits, and the company intends to engage in partnerships with local apprenticeship readiness programs and community-based workforce training programs across the skilled and technical levels to fill and maintain all positions.”

The company has received support for the mine project from several local unions, Hudbay said. That includes signing of a letter of intent for the project execution phase in May 2024, by the International Brotherhood of Boilermakers, Iron Ship Builders, Forgers and Helpers Local 627, The Laborers International Union of North America Local 1184, and The United Brotherhood of Carpenters and Joiners of America Local 1912.

After getting the Aquifer Protection Permit, the company expects to commence activities related to preparation of feasibility studies for Copper World, Hudbay said.

The Aquifer Protection Permit was issued after ADEQ received numerous comments criticizing an earlier, draft permit for the mine as inadequate. It also comes after two contentious public sessions in which mine opponents said the permit lacked tough enough conditions to make sure the groundwater is adequately protected.

The group Save the Scenic Santa Ritas, which hired three outside experts to critique the permit, declined to immediately comment on ADEQ’s approval. Group officials will review the permit documents overnight before commenting, said Save the Scenic Santa Ritas executive director Rob Peters. The group submitted 80 pages of written comments blasting the agency’s draft permit as inadequate.

Most notably, it said the entire permit’s approval should be withheld and that the permit should be revised before approval is given because of several changes in the mine plan Hudbay made after it submitted its permit proposal to ADEQ back in 2022.

ADEQ agreed the permit will need revising because of a new tailings storage facility and a reconfiguration of an already proposed tailings disposal site that came about after proposed permit submission. It did not, however, require Hudbay to amend its permit to account for its planned expansion of a waste rock storage area and and its plan to replace a heap leaching facility with a technology known as the Albion Process.

Changes that require permit revisions are common in large facilities and the permits can be amended later before those facilities are built, ADEQ said in approving the permit.

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Contact Tony Davis at 520-349-0350 or tdavis@tucson.com. Follow Davis on Twitter@tonydavis987.