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Air Quality Division | Site/Facility of Interest

Hermosa Project — South32 Hermosa Inc.

Revised On: Feb. 10th, 2026 - 03:39 pm

This site/facility of interest online resource provides interested parties easy access to information about the Hermosa Project, owned by South32 Hermosa Inc., formerly Arizona Minerals Inc. (AMI).

Air Quality Permitting

On Feb. 9, 2026, ADEQ issued Permit No. 110322 (Revision to Permit No. 96653) to South32 Hermosa Inc. for the Hermosa Project.

Community Engagement

The public notice comment period began on Jan. 5, 2024 for the draft air quality permit and was extended to Feb. 26, 2024 | View 2024 Notice >

On Jan. 11, 2024, ADEQ held an informal community meeting to discuss the draft air quality permit | View 2024 Fact Sheet >

On Feb. 26, 2024, ADEQ held a public hearing for the public to comment in person on the draft air quality permit. Both the informal community meeting and public hearing were held at Patagonia Elementary and High School located at 200 W. Naugle Avenue, Patagonia, AZ 85624.

The public comment period for the reopened/revised draft air quality permit ended on Sept. 25, 2025 | View 2025 Notice >

On Sept. 25, 2025, ADEQ held an in-person public hearing to accept oral comments on the reopened/revised draft air quality permit. 

Documents

On Oct. 24, 2022, ADEQ received a Class I Air Quality Permit application from South32 Hermosa Inc.

On June 10, 2024, ADEQ issued the proposed final permit to authorize South32 Hermosa Inc. to begin actual construction, but not operation, of the Hermosa Project. On the same day, ADEQ submitted the proposed final permit and the response to public comments to the U.S. Environmental Protection Agency (EPA) for its 45-day review period.

ADEQ addressed comments on the proposed final permit received from EPA on July 24, 2024, and issued the final air quality permit to South32 Hermosa Inc. on Aug. 26, 2024. 

On May 30, 2025, ADEQ received an Order from the EPA Administrator that granted and denied in part a petition filed in September 2024 that objected to the permit. The Order required ADEQ to reopen and revise the permit within 90 days and solicit public comment. Construction activities for the project are not affected by the Order and can continue | View EPA Order >

ADEQ held a public comment period and public hearing for the public to review and comment on the reopened/revised draft air quality permit. Details can be found in the Community Engagement section. 

After thoroughly reviewing and considering all comments submitted during the public comment period, ADEQ made the determination to issue the proposed final air quality permit to South32 Hermosa Inc. on Dec. 19, 2025. 

ADEQ values the input we received during the formal public comment period, which resulted in changes to the proposed final air quality permit. ADEQ’s changes to the proposed final air quality permit are highlighted in the public comment Responsiveness Summary.  

As required, ADEQ sent the proposed final air quality permit and supporting documents to EPA for its 45-day review. EPA did not object the proposed final air quality permit, and ADEQ issued the final air quality permit on Feb. 9, 2026

For more information about South32 Hermosa Project, visit the Site/Facility of Interest section within the My Community page | View Page >

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