Enviros, Pima County won't appeal Copper World aquifer permit

The Aquifer Protection Permit for the Copper World mine southeast of Tucson is a done deal, now that permit opponents have chosen not to appeal the state’s approval.

The Arizona Department of Environmental Quality issued the permit on Aug. 29. Opponents including Pima County officials and the group Save the Scenic Santa Ritas had until Monday to file a request to appeal but did not, and no other appeals were filed.

This clears a major legal hurdle for the mine to be built. When constructed, it would mine copper from six open pits in the Santa Rita Mountains 28 miles southeast of Tucson and 12 miles southeast of Sahuarita. Copper World developer Hudbay Minerals Inc. also needs an air quality permit from the state — which is now pending — before it can build and operate the mine.

ADEQ said it will allow the mine to operate while not causing or contributing to violations of state groundwater quality standards. 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 provided 126 pages of responses to written public comments that were submitted that raised concerns about the permit.

“We are pleased to have received the APP,” Hudbay said Wednesday in a written statement. “This comprehensive permit ensures the protection of Arizona’s most vital resource — water. As the Copper World project advances, we remain committed to continued collaboration with Pima County and all stakeholders, prioritizing environmental stewardship while delivering significant local economic and employment benefits.”

In their detailed comments to ADEQ, Pima County officials and Save the Scenic Santa Ritas made it clear they don’t think the mine will meet all state requirements to protect the surrounding groundwater quality.

They cited the lack of liners to go underneath the mine tailings. In their place, the state approved a system of “underdrains,” a network of perforated pipes designed to collect drainage from low points along the base of the tailings and convey tailings seepage fluids to sumps and ponds to be collected for future reuse.

Save the Scenic Santa Ritas also alleged the mine’s monitoring well network will be inadequate and that the company’s projections for the consequences of any failure of its tailings dam are too optimistic. The group’s comments were supported by a dozen other groups along with the Tohono O’Odham and Pascua Yaqui tribes. County officials also argued that the ponds on the site designed to capture storm water might not be adequate to handle all the runoff generated by a 100-year storm.

But in a memo last week, Pima County Administrator Jan Lesher wrote, “I do not believe there is a substantive basis for Pima County to appeal the issuance of the aquifer protection permit.”

She told the county Board of Supervisors that the county submitted 55 comments to ADEQ on the permit, and the state agency made five substantive changes to the permit based on public comments.

One of those changes — a commitment to add two groundwater-quality monitoring wells east of the proposed Rosemont Mine pit on the mountains’ east slope — was requested by the county, she wrote. That pit was to be the centerpiece of the original Rosemont Mine proposal on the east slope, which was halted in 2019 by a federal judge. Hudbay intends to dig that pit now as part of its Copper World project that is otherwise centered on private land on the mountains’ west slope.

Of the four other changes in the permit in response to public comments, ADEQ most notably added a requirement that Hudbay submit a well construction and installation proposal for the Rosemont pit’s monitoring wells to ADEQ before installing them. The proposal must include, at a minimum, well construction diagrams, proposed well locations and a proposed installation schedule.

The agency didn’t respond to about 16 of the county’s comments, Lesher wrote.

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“However, most of our comments where ADEQ did not respond are outside of their authority or would not have likely changed the permit,” Lesher wrote.

Save the Scenic Santa Ritas’ Director Rob Peters said ADEQ’s responses to its 80 pages of comments were inadequate.

But he added, “We worked with our attorneys to closely examine appeal options and decided that there will be better regulatory opportunities to challenge Copper World’s plans. Unfortunately, Arizona law is so biased in favor of mining that it is difficult for citizens to contest agency decisions even when they fail to adequately protect our health.”

Peters declined to elaborate on what those opportunities would be.

In Hudbay’s statement, the company said that throughout the Aquifer Protection Permit process, “we worked closely with ADEQ to ensure that every step was thorough and compliant with the stringent state and federal regulatory standards. A robust public comment period that included the submission of thousands of comments in support of the project was a key element, providing valuable input from stakeholders. ADEQ carefully reviewed and responded to all comments received, ensuring that concerns were addressed and incorporated into the final permit decision.”

Here’s a sampling of ADEQ’s responses to written comments raising concerns about the permit, submitted last winter and spring.

1. MINE PLAN CHANGES. Several commenters said ADEQ should suspend Hudbay’s permit application until the company submits changes to reflect changes made to its mine plan since it submitted a permit application in 2022. The company has added plans for a new tailings disposal facility and a significant reconfiguration of an already planned tailings facility. It has also has said it would significantly expand its waste rock storage area. Those changes were contained in the company’s 2023 Copper World pre-feasibility study.

ADEQ response: The company must submit permit amendment applications covering any changes it proposes from its 2022 application. But “ADEQ does not have the legal authority to revoke, suspend, or modify an APP application or permit based on proposals revising the mine plan or made while acquiring federal permits. Design changes during mine development are common, and must be addressed through the established permitting process.”

2. TAILINGS DAM FAILURE. Consultants hired by Save the Scenic Santa Ritas said Hudbay’s computer model projecting the impact of any tailings dam failure only assumed that 1% of the maximum amount of tailings stored at the site would be released if a failure occurred. That contrasts what the group said is the average release of 25% of all tailings during a dam failure, let alone a 2019 dam failure in Brazil that released 90% of the tailings stored — a failure that led to 270 deaths.

ADEQ response: The 1% estimate was based on a detailed paper from British Columbia researchers. The Copper World estimate of “total outflow volume” during a dam breach is based on the amount of water stored in the tailings pond, the amount of tailings solids present and the amount of water contained in pore spaces in between particles in rocks and sediments, ADEQ said.

ADEQ has included requirements in its permit to insure the mine’s dam breach and emergency responses plans are updated throughout its operational life, the agency said.

3. BEST AVAILABLE TECHNOLOGIES. Opponents alleged the state’s standards for determining the best available technologies for mining practices are very outdated. The state hasn’t updated its best available technologies guidance manual for mining since 2004. Saying there have been substantial advances in tailings storage engineering in the past 20 years, commenters asked what evidence ADEQ can provide that these 20-year-old standards will protect drinking water.

ADEQ RESPONSE. The agency acknowledges Arizona’s Best Available Control Technologies manual for mining hasn’t been updated for 20 years. But it’s important to note the manual is a non-binding policy statement and doesn’t stop ADEQ or its applicants in designing and constructing facilities that exceed the manual’s standards, the agency said.

As a result, ADEQ said it is not bound to or limited by the manual and in fact, that Hudbay designed the facility using current best practices that meet or even exceed requirements laid down by state law.

Hudbay also committed to a global industry standard on tailings management that goes beyond current guidance outlined by Arizona’s manual, ADEQ said.