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A steel headframe amplified the rumble of explosions under the salt desert scrub hills southeast of Yerington this summer. The blasts, discharging 1,900 feet below, continued for about 15 seconds with a volley that sounded like the grand finale of a fireworks show.

Yet for Nevada Copper Corp., the explosion July 13 marked a beginning not a finale.

The blast represented the recommencement preworks construction at Pumpkin Hollow copper project after a years-long pause while the company secured financing, analyzed drill results and conducted dewatering.

“Getting to this point, I look at it as, we’re just starting,” said David Swisher, Nevada Copper vice president of operations, explaining that the company aims “to build the quality team, finalize our construction agreements and then execute. Bottom line is execute.”

Pumpkin Hollow is a fully permitted underground and surface copper project in Mason Valley. In preparation of the mine’s first anticipated production by the end of 2019, underground mining and engineering contractor Cementation USA Inc. is on-site to continue the main shaft-sinking project it began six years ago.

“Our primary focus right now is getting ore hoisted out of the ground in the fourth quarter of next year,” Swisher said.

Next steps are lateral development and sinking a ventilation shaft while preparing the surface for a mill, plant, stockpiles, dry stack tailings and office facilities. Sinking the ventilation shaft is slated to begin this year, and the main shaft is expected to be completed in December.

“It will be a nice Christmas present for Nevada Copper,” said Paul Schmidt, Cementation project manager.

Core underground

Opposite of how many mines are developed, Nevada Copper plans to begin underground before pursuing surface operations. Land status directed the development schedule.

When Nevada Copper first acquired the property in 2005, it gained about 1,500 acres of private land and an array of claims on adjacent Bureau of Land Management land. Once permitted, the company began underground development on private property in 2012.

“Now that the shaft’s sunk, and the capital cost for the underground is lower than the open pit, we can start with a smaller capital cost, and it’s a higher grade ore, too, so we’ll get a little more copper,” said Tim Dyhr, Nevada Copper vice president of environment and external relations. “We are utilizing the asset that we built. In this case, because of the land status, we went with the underground first, and we are going to stick with that strategy.”

A 2014 federal bill permitted the sale of more than 10,000 acres, which encompassed the proposed mine site, to the City of Yerington. The value of the federal land was $1.8 million, funded by Nevada Copper. The city then conveyed all but about 900 acres to Nevada Copper for the development of the Pumpkin Hollow mine.

Dyhr credited U.S. Rep. Mark Amodei and former U.S. Sen. Harry Reid for supporting the measure in Congress. He also described the involvement of the community and a “eureka moment” when a local rancher suggested drawing the mine boundary lines on a map during a public meeting.

“I tell people it’s a charmed site,” Dyhr said. “I have been doing this many years, and I have never seen a site with such good engineering conditions … and environmentally.”

Water is the main environmental issue for Pumpkin Hollow, a new mine in a mostly agricultural community of about 3,000 residents. The mine plan provides for the protection and conservation of groundwater. Methods include using dry stack tailings, returning water to the ground and funneling excess water into hay production on a mine-owned farm.

“From other sites I have been at and developed in the past, this site is extremely unique in the fact that we have over 10,000 acres of private land, and that was the excellent work that Tim Dyhr did in the land transfer,” Swisher said. “It has set up the stage for us to work with our local communities because, as much as our shareholders are very important to keep sight of, equally important are our communities.”

Core community

On its 900 acres, the city plans to develop an outdoor recreation area and permanent venue for the Night in the Country annual summer concert. Yerington will also benefit from the mine’s property taxes, net proceeds tax and creation of about 400 jobs once the underground mine reaches full production over the next one to two years.

The legislation also designated the Wovoka Wilderness Area around Pine Grove in Lyon County.

For just the underground operation, Nevada Copper estimates the mine life at Pumpkin Hollow to be a minimum of 13 years. The estimate does not include surface and open pit works that are underway or potential that could be unearthed through exploration.

“Our singular focus is the underground, but we have a massive expansion potential — both underground resources and the surface resource,” Swisher said. “That and the fact that we’re the first ones — Nevada Cooper’s the first one to be able to start getting into a production decision before any other competitors in this mining district — puts us at a competitive advantage.”

Core culture

Nevada Copper’s leaders plan to use as much of the local workforce as possible, providing training when necessary to fill jobs.

“We get people who want to do the job, and they want to live in Yerington, and they love to live here, but they need a job,” Dyhr said.

The majority of employees already working for Nevada Copper or Cementation are locals.

“One of the things about this job is that it is close to town, so if you can find a place in Yerington… it’s 10 minutes to the job,” Schmidt said. “It’s not like a typical mine where you’re in Elko, and you’re driving an hour and a half [to work].”

Other contractors include Desert Engineering from Yerington for earthworks and concrete jobs, and Southwest Energy from Spring Creek to provide explosives material and training.

“The unique nature of starting up a project is we have the ability to set the culture,” Swisher said. “For us, it is extremely important that we set a proactive culture, and that culture starts with safety. It starts with everyone going home safe and healthy every day. And then making sure that we build a foundation of respect; we build a foundation of professionalism; we bring in quality, high-performing people.”

Core geology

Pumpkin Hollow core samples date to the 1960s, from shortly after original owner U.S. Steel Corp. searched for iron using airborne magnetics. About seven core sheds on the property overflow with rows of cylindrical and ground-up samples.

Over time, explorers found more than iron. The host rock, a high grade chalcopyrite magnetite skarn, also hosts copper.

“So instead, it became a copper project with more and more iron,” said Greg French, Nevada Copper vice president of exploration and development.

The Pumpkin Hollow resource is the “root” of the deposit, Dyhr said. The area is part of a world-class copper district with a history of copper mining across the valley at the former Anaconda Copper Mine.

“We have a lot of opportunity for more copper production in the state,” said Rich Perry, administrator for the Nevada Division of Minerals.

Once in full production, Pumpkin Hollow is expected to average 100,000 to 120,000 tons of copper concentrate per year, Swisher said. The concentrate will be distributed by rail then sent to a smelter in North America or abroad for processing.

Mining iron also is a possibility for the future if it becomes economical.

“The current plan is to get the copper mine into production. Down the road, we can always come back because a lot of the mining will be already done,” Dyhr said. “So the mine could go for a long, long time as it transitions from copper to iron.”

For now, however, the team is focused on getting the underground copper mine into production — a goal that became a little closer to reality after that landmark blast this summer.

“One of the most important things that companies of our nature need to keep in front of us is the longer term vision, tying in that shorter term goal, and that is making sure that we work for our shareholders,” Swisher said, “so it’s incumbent on us to make sure we do what we say we are going to do — that we follow through on our commitments.”

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Mining Quarterly - Mining, state and county reporter

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