South32 says Hermosa construction is beyond mid‑point; company highlights water treatment, monitoring and local hire plans

Pat Reisner, South32’s representative, told the Santa Cruz County Board of Supervisors during an April 1 study session that construction for the Hermosa project has advanced past the halfway mark and that the company is making concurrent investments in environmental controls and local hiring.

Reisner said the two large site shafts were at different stages — "50% complete on one, about 65% complete on the other" — and that "total construction progress is now beyond 50%." He described the process plant, tailings filtration and modular construction methods designed to reduce the surface footprint and dust exposure.

On permitting, Reisner noted the Forest Service had issued the final environmental impact statement and a draft record of decision; he said a 45‑day objection period runs until about April 20, with a schedule showing a final record of decision in early July and a notice‑to‑proceed in early September. Reisner emphasized that the Forest Service review addresses only federal‑land activities — such as a 138‑kilovolt power line and some access and water‑infrastructure elements — while the mine itself is on private land.

Reisner described steps taken since the draft EIS: "There are about a 135 actions ... that we've committed to take, to mitigate impacts that were not in the draft," including avoidance of an endangered plant, expanded groundwater and spring monitoring, dark‑sky lighting design, and additional wildlife and equestrian crossings along access roads.

Water quality was a major focus. Reisner said the site intercepts naturally occurring groundwater and that two wells had elevated antimony levels. The company invested in two phases of upgrades — roughly $500,000 in total, he said — to increase the treatment plant’s capacity. "These upgrades have been completed. We've switched those wells back on. We are still seeing higher levels of antimony in the water coming from those wells. But the changes we've made to the plant are working," he said, adding the plant is monitoring inflow and discharge every two hours and treating discharge to below permitted limits.

Reisner also highlighted monitoring commitments in the community: South32 said it is running baseline air‑quality monitors in Sonoita, Patagonia and along transportation routes to measure metal constituents before operations begin.

On jobs and local benefits, Reisner said the project expects a peak construction workforce of about 900–1,000 and forecasted direct employment rising toward 600 over roughly 18 months. The company described memoranda of understanding with the Santa Cruz Center and Pima Community College to deliver skills training locally and said it has onboarded more than 115 Santa Cruz County vendors in the past year as part of a local‑procurement push.

Board members thanked Reisner for the update and asked for follow‑up dates on commissioning the remote operations center and the process plant; Reisner said commissioning for plant and associated facilities is expected to begin in the second half of next year and that hiring will ramp from mid‑2026 into late 2026.

The presentation included technical slides and an air‑quality dashboard the company said the public can review online.