South32’s new proposed long-term route for mining traffic would enter SR82 between Circle Z Ranch and Lake Patagonia, following an existing gas line. Photo by Carolyn Shafer

South32’s timeline for its Hermosa Project is coming into focus, with a Board of Directors’ vote on the project expected in the coming months. Meanwhile, a permit application has been filed for temporary routing for both construction and mining activities, with Hermosa-related vehicle traffic on SR82 and SR83 set to radically increase as construction begins. 

Applications for permitting are set to be filed, and infrastructure construction, including well digging for dewatering, is underway. A new transmission line is in the process of being approved, as well.

Here is a round-up of what we know so far: 


A final investment decision is anticipated from the South32 Board of Directors in mid-2023, according to Jenny Fiori-Magana, South32’s Communications Director for the Hermosa Project. “[The decision] would be to approve a $1.7 billion capital expenditure to further progress South32 confidence in, and understanding of, the zinc-rich resource commonly known as Taylor, including by means of underground exploration,” she wrote to the PRT on April 27. “Next steps would be to further ramp up our construction activities and relevant local hiring and procurement to enable that work.” 

During an interview in February 2023 conducted by Mining Weekly, S32 CEO Graham Kerr stated that “Hermosa’s Clark deposit remains on track for initial pilot plant production in mid-2023 to deliver first qualification samples of battery-grade manganese to potential customers. Regional exploration activity is also expected to increase as the mine continues to explore at Peake and will start drilling at the Flux prospect, pending approvals.”


South32 filed an encroachment permit application with ADOT for the Cross Creek Connector road (CCC) in the Patagonia area, which South32 refers to as their “preferred short-term connection” to the state highway system. The company will file for flood usage permits in May Clearing, grubbing, and demolition have started along the Cross Creek Connector route. Construction of the intersections with SR 82 and Harshaw Rd. will not start until this fall. Vacant nonconforming structures will be removed before construction. 

The estimated completion date is November 2024. At that point, more than 800 – 900 employees, along with suppliers, will result in a significant increase in traffic in the area. 

Opponents are working to mitigate the potential effects of development of the Cross Creek Connector and the resulting traffic on local roads.


“South32 recently identified a new preferred alternative, [to a proposed routing of mining traffic though Flux Canyon] which closely matches the alignment of the Kinder-Morgan Gas line southwest of our site,” Fiore-Magana wrote. “We have shared news of this new long-term route directly with residents in Flux Canyon, with the community advisory panel during their regular public meeting, and in our recent community newsletter. Response so far has been largely positive.”


Construction of mine shafts will begin the second week of May. Completion of the second water treatment plant is expected by the end of June, after which dewatering can begin, according to Fiore-Magana. 

South32 has been permitted to discharge 6.4 million gallons/day of treated water into Harshaw Creek, raising concerns about the impact that this will have on the groundwater dependent ecosystems and potential for downstream flooding. Several legal challenges by Patagonia Area Resources Alliance opposing the Hermosa Project’s water permitting are pending.


UniSouce Energy Services (UNS) has developed plans for the new Rio Rico to Harshaw 138 Kilovolt Transmission Line Project to serve the Hermosa Project. South32 will fund the project. The AZ Power Plant and Transmission Line Committee voted in favor of granting UNS Electric a Certificate of Environmental Compatibility. The committee recommendation will be reviewed at an upcoming open meeting by the Arizona Corporation Commission. Final ACC approval would allow the project to move forward. 

The Rio Rico to Harshaw Line will involve the construction of an approximately 20 to 30-mile, single circuit transmission line mounted on steel monopole structures 75 to 110 feet tall and require 100-foot wide rights-of-way to cross private and government owned land in the County. 

To learn more about the Hermosa project, plan to attend South32’s Community Advisory Meetings, which are open to the public. The next meeting will be held on Wednesday, May 17, in Patagonia at the Wild Horse Restaurant.