Pitch Mine site mitigation near Sargents continues

Uranium levels in Marshall Creek not meeting federal standards yet

By Katherine Nettles

Barrick Gold/Homestake Mining Company representatives presented Gunnison County commissioners with an annual reclamation update this spring on the former Pitch Mine site in Saguache County where uranium was mined until the late 1980s near Sargents, just west of Monarch Pass. It appears that while the mining company continues successful mitigation efforts and surface water management to prevent dangerous uranium levels from entering the ground water, drinking water and nearby creeks, one of which is a tributary to Tomichi Creek in Gunnison County, more permanent long-term goals are not yet attainable. 

Dave Wykoff, the Pitch Mine closure manager, and Clark Burton, director of the mine’s closure operations, reviewed the mine’s operational and closure/mitigation history for commissioners on January 28 during a work session.

The Pitch Mine was the site for Pinnacle Partners, Inc. underground uranium mining from 1959 to 1972, at which point Homestake Mining Company partnered with Pinnacle and Homestake eventually took over and conducted open-pit uranium mining operations from 1979 to 1984. All mining operations at the Pitch Mine ceased in the late 1980s, and reclamation of the site began in earnest in the 1990s. Barrick Gold merged with Homestake in 2001 and has been managing mitigation there ever since.

In 2015 the federal water quality division reissued a surface water permit for the Pitch Mine site and the standard was set around aquatic standards for 2,000 micrograms of uranium per liter (or less) that can be discharged from the site and into the nearby Marshall Creek. “We let them know we were in no place to be able to comply with that, because this was a dramatic change,” said Wykoff. The current state permit allows up to 2,000-4,000 micrograms per liter as a daily maximum for uranium concentrations. Barrick Gold has proposed a reduced water quality standard for Marshall Creek that might be more sustainable for the corporation to manage, and in the meantime has continued looking for a long-term solution.

Wykoff and Burton described the various pilot studies, programs, test work and engineering work that has been done to prevent ground or surface water from getting into the site where uranium is located. The main portal for the underground mining was plugged in the 1990s, and Burton said they continue to see reductions in uranium from that plugging process almost 30 years later. 

Biochemical reactors at the site have proven to be fairly effective at removing uranium from water, but water moves slowly through the system and treating the full amount of water discharged from the site would require a much larger facility. The reactors also only work in warm weather, three to four months per year, said Wykoff. 

Burton also said that according to statistical analysis, the uranium levels of water discharged from the site are trending down. “But we do expect it to plateau,” said Wykoff, since there is evidence that pre-mining uranium levels were already around what they are now and while most of the uranium that was once located on the ground surface has been removed, there is still another seven to eight million pounds of uranium at the site. “So there is always going to be a signature of it there, unless someone else decides to mine it.”

In conclusion, both Wykoff and Burton said they are seeking long-term reclamation solutions for the former mine site but there are effective mitigation efforts in place for now keeping the groundwater and ecosystems in Marshall Creek safe and there are no known concerns with drinking water in Sargents, justifying a reduced water quality standard from the federal agency. 

Hydrologic studies indicate Marshall Creek has minimal impact on domestic wells in Sargents, and all wells in Sargents currently meet drinking water standards. Wykoff said issues in the wells have been caused by proximity to septic systems, as most domestic wells were shallow, hand-dug and within the same ground zones as septic systems. 

Instream water quality testing is conducted monthly throughout the year, and 32 wells in Sargents have been identified for replacement. In 2024, 17 were drilled without issues and more will be drilled in 2025, said Wykoff.