South32's Hermosa Project Releases Mine Plan of Operations

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January 30, 2024


South32’s Hermosa project – the only advanced mine development project in the United States that could produce two federally designated critical minerals, manganese and zinc – released today its Mine Plan of Operations for proposed activities on federal land.

Required by the U.S. Forest Service (USFS) as part of the federal review process for project activities affecting National Forest system lands, the Critical Minerals Exploration and Mine Plan of Operations (MPO) is a roadmap of operational activities at the Hermosa project from start to finish located on lands managed by the Coronado National Forest (CNF).

Hermosa project is committed to transparency. South32 is voluntarily releasing the MPO earlier than required by federal statute in order to give the public a better view into how the company is proposing to manage and operate the project.

Usual MPO processes dictate that a publicly available version of any project’s MPO is not available until the lead federal agency handling the review issues a notice of intent to draft an environmental impact statement, which is not expected in the Hermosa project’s case until mid-May.

The MPO can be found here.*

The USFS has deemed the MPO “complete,” a term that indicates the agency has reviewed the plan and determined that it contains the necessary regulatory content to commence the required environmental review process informing a final agency decision for the approval needed for the Hermosa project’s operations on CNF land. An environmental review under the National Environmental Policy Act (NEPA) is required prior to the issuance of a permit. That process provides an assessment of potential environmental effects from the proposed exploration and mine development project. It also offers extensive opportunities for public input and comment.

As the first covered FAST-41 mining project, the environmental review process is streamlined – and is the same process used for other critical infrastructure projects that benefit the nation. FAST-41 also enables open lines of communication and transparency between all of the stakeholders in the process, ensuring a robust and rigorous review.

Because South32 is taking this step to publicly release the MPO earlier in the process, changes to the document are expected to occur as both the CNF and South32 finalize details within it. The Hermosa project is committed to working with federal, state, local and tribal governments and communities to incorporate feedback into how we operate the project. The MPO will be updated during and after the NEPA review process to reflect this feedback.  

The next step in the federal permitting process will be the CNF issuance of a notice of intent to prepare an environmental impact statement, which is anticipated in mid-May, 2024.

Quote attributed to Brent Musslewhite, Hermosa Project Director of Environment and Permitting:

“We are designing the Hermosa project from the ground up to be a safe and sustainable mine, combining state-of-the-art technology, to deliver minerals America needs for the clean energy future. We believe transparency is at the core of that approach, and that is why we are voluntarily releasing the MPO earlier than usual.

The MPO shows how we aim to achieve that vision across portions of the project that could impact National Forest System and surrounding land.

From the breadth of our environmental and water monitoring programs all the way through to protections put in place for an eventual responsible closure at the end of its life, the Hermosa project represents a different kind of mine with sustainability embedded in its design.   In our MPO we provide evidence of our commitment to sustainably develop a domestic supply of critical minerals in a way that unlocks new opportunities for Southern Arizona, improving people’s lives now and for generations to come.”

What is a Mine Plan of Operations?

The MPO represents a project overview for activities and safeguards put in place for Hermosa project activities on federal lands. It includes plans for mineral exploration, environmental monitoring and protection, underground development and mining, a dry-stack tailings storage facility and plans for end-of-life closure activities to conclude the project.

The purpose of the MPO is to ensure that the project meets all appropriate standards for operating, including protecting public and environmental safety. The description of the planned operations and environmental protection measures in the MPO are the foundation that informs the forthcoming analysis that will be completed and published in a draft and final environmental impact statement.

*Certain commercial information deemed market sensitive, confidential, or proprietary has been redacted.


About the South32 Hermosa project

Located in a historic mining district in the Patagonia Mountains of Southern Arizona, South32’s Hermosa project is currently the only advanced mine development project in the United States that could produce two federally designated critical minerals—manganese and zinc—both of which are essential minerals for powering the nation’s clean energy future. Learn more at

Media Relations

Lina Betancourt

T +1 514-210-1822


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