Story by Adella Harding
Small Mine Development is dewatering at the underground Lee Smith Mine at Jerritt Canyon for the first time in years and drifting an underground connection between SSX Mine and Lee Smith in partnership with new owner First Majestic Silver.
Smith and SSX are the two producing mines at Jerritt Canyon 50 miles north of Elko, and SMD is contracted to mine them both. In 2019, Jerritt Canyon produced 117,985 ounces of gold, according to the Nevada Division of Minerals.
“The connection drift has been in development for some time now and is currently scheduled to be completed in August,” said John Featherston, SMD’s senior engineer for the Lee Smith Mine.
The total length of the drifting will be 4,500 feet, with drifting coming from both mines.
Connecting Smith and SSX “will open exploration potential between the mines,” provide a secondary escapeway for miners and improve ventilation, Featherston said. There also is the potential to dewater at SSX for mining using the same pipeline system, but the current drifting is above the water table.
“We think there is gold between Smith and SSX. There are probably two good exploration targets,” he said.
First Majestic Silver’s chief operating officer, Steve Holmes, said the connection between Smith and SSX “opens up incredible potential.”
SMD has roughly 106 employees at the Lee Smith Mine and 142 at the SSX Mine, and the company owns the mining equipment. However, the company subcontracts with First Drilling for core drilling and Stu Blatter Inc. for dewatering-related drilling.
There was dewatering in 2008 at Smith when previous owners shut down the mill at Jerritt Canyon, so the dewatering system “just sat and the water table returned, and there hadn’t been any dewatering since,” Featherston said.
A mine is dewatered so that miners can reach gold ore below the water table.
“We have proven reserves below the water table. It’s kind of virgin ground down there, but initial drilling shows more potential,” Featherston said. “So, this is going to help us. These are targets we know we have.”
The dewatering and mining of those reserves will add to the mine life at Smith.
Featherston said in an Elko Daily Free Press video shot at Lee Smith that zone four has a “very large ore body,” and will be the focus of dewatering for Smith, followed by zone two.
The completion of well No. 3 in the dewatering expansion is slated for June, but Featherston said the scope of the project calls for dewatering at 2,100 gallons per minute by Oct. 1. SMD began dewatering in the first phase of the dewatering effort after commissioning the system last August, pumping 700 gallons per minute at that time.
Featherston said the current system includes “lots of monitoring wells” to provide control. The earlier system did not have the monitoring wells, and the earlier system had shallow wells to lower the water flow. The new system is deeper and higher volume.
Currently, there are two wells in what Featherston refers to as zone two and the third well was being drilled in zone four using an innovative idea that allows the Lee Smith Mine to have larger drill holes for the wells. The drills SMD operated for the earlier wells limited the size of the holes.
Then came the idea of using a raise-bore machine, and SMD subcontracted with Stu Blatther Inc. out of Golden, Colorado, to operate a raise-bore drill at Lee Smith for the dewatering expansion project.
“Now, we are able to develop 13 and three-fourths-inch holes. We will go back and do the others larger, too,” Featherston said. “We need to standardize our well design. We’re still in the pilot testing phase of this.”
If the drilling with a raise-bore machine works, the design will become part of SMD’s book of knowledge for its underground contract work in Nevada and the West.
Once the water is pumped out, it goes into a pipeline that takes the water to the treatment plant. SMD pumps the water into a 265,000-gallon surge tank.
“The water we are pumping has a lot of arsenic and antimony, so the state requires that we treat the water to drinking-water standards,” Featherston said.
Once the water is treated at the plant operated by Jerritt Canyon crews, it goes to injection wells to put it back into the aquifer. Permitting for re-injection was handled by the state with the water quality to match the current water quality, said Scott Richey, senior geologist for the Humboldt-Toiyabe National Forest.
Jerritt Canyon is mainly on U.S. Forest Service land but “we manage the surface only,” Richey said.
The decision to dewater from underground rather than surface dewatering wells was based on time sensitivity and the underground capability to develop wells and save about 800 feet of well depth from the surface, Featherston said.
“It is very likely that Jerritt Canyon will need surface dewatering wells in the future to dewater areas that do not have underground developments in the immediate vicinity to develop wells in,” he said.
Featherston said that after the “stop and start” dewatering efforts that have happened over the years at the Lee Smith Mine, “we’re actually moving forward.” He has been at Jerritt Canyon since 2010, but SMD has been mining at Jerritt Canyon since about 2000.
SMD dewaters as part of its operation of the Lee Smith Mine under contract to produce gold for the Jerritt Canyon mill, but Featherston works closely with the Jerritt Canyon staff. ￼