03 JANUARY 2025
Located in a historic mining district in the Patagonia Mountains of southern Arizona, our Hermosa project is currently the only advanced mine development project in the United States (US) that could produce two US federally designated critical minerals – manganese and zinc – both of which are essential minerals for the transition to a low-carbon world.
The Taylor zinc-lead-silver deposit at Hermosa has been designed using ‘next-generation mine’ principles, utilising automation and technology to drive safe production and efficiencies, and reduce environmental impact. Central to this design is managing impacts to natural and cultural resources.
Biodiversity and cultural resources
For more than ten years, a robust biological monitoring and cultural resource protection program has been in place at Hermosa, providing a baseline understanding of the natural resources and cultural resources of the area to inform our mine design and management approach.
Our biological monitoring includes conducting focused surveys for flora and fauna species throughout the year, as well as monitoring species habitats, seeps and springs, and riparian areas to support an understanding of vegetation trends and fauna use across the landscape. We have surveyed over 12,000 hectares of land to identify cultural resources present in the area and regularly engage with Native American tribes to understand how these cultural and biodiversity resources can be protected.
Information gathered from these surveys is used as an input into Hermosa’s design, with the aim of limiting impacts and achieving our goal of no net loss of biodiversity through application of the mitigation hierarchy. Examples of control measures that we are using to avoid and minimise impacts to biodiversity and cultural resources include:
- Clearance surveys for nesting birds and use of avoidance buffers and biological monitoring to protect nests;
- Use of archaeological monitoring when working with heavy equipment around sensitive cultural resources;
- Adjusting the timing of project activities to avoid disturbance during critical times of migration or breeding for certain species;
- Ensuring overhead powerlines incorporate design features to protect raptor bird species; and
- Implementing dark sky measures through shielding and light colour selections to reduce impacts to nocturnal species.
Water stewardship
Water is a valuable resource, especially in southern Arizona where arid ecosystems, extreme drought, and increasing temperatures resulting from a changing climate make water scarce. Water stewardship is therefore a primary concern that we share with communities in the region.
Featuring a limited footprint underground mine(1), Taylor has been designed with the aim of minimising environmental impact. Through efficient water use and one of the first new lined, dry stack tailings storage facilities in the US, we expect Taylor's water demand will be 75 per cent less than other mines in the region.
Building an underground mine requires extracting and relocating groundwater found near the orebody and critical underground infrastructure. The majority of this water is treated and released back into the environment. Through proactive engagement, we sought input from the community on our approach to managing excess groundwater and identified a community preference to maintain the water within the Patagonia Mountains.
In our recently submitted Mine Plan of Operations(2), we have proposed the discharge of excess groundwater into infiltration basins to support groundwater recharge(3). These infiltration basins will play an important role in Hermosa’s water stewardship by helping maintain groundwater reserves and reducing potential impacts on ecosystems that rely on groundwater sources.
Footnotes:
(1) The selection of an underground mining technique and a dry stack tailings storage facility has resulted in a surface footprint for the Hermosa project of 750 acres (303.514 hectares) which is substantially less than other mining techniques such as open cut which can span thousands of hectares.
(2) Required by the US Forest Service as part of the federal review process for project activities affecting National Forest system lands, the Critical Minerals Exploration and Mine Plan of Operations is a roadmap of operational activities at the Hermosa project located on lands managed by the Coronado National Forest.
(3) Infiltration basins are shallow depressions constructed on the land surface of an underlying aquifer. Water placed in the basin infiltrates through the soil, recharging the groundwater reservoir
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