Based on the presence of radioactive substances in nearby wells, the Environmental Protection Agency next year will investigate abandoned uranium mines in southwestern South Dakota, close to the site of a mining proposal undergoing federal review.

The agency recently completed a preliminary assessment that concluded an investigation is needed to determine if hazardous substances are harming the environment.

The site of the abandoned mines is 13 miles northwest of Edgemont, “within and adjacent to” a uranium mining project area proposed by Powertech Uranium Corp., according to the EPA.

The EPA said the investigation of the abandoned mine sites “is separate from” decisions about the proposed Powertech mine, which does not yet have all its necessary permits.

Mark Hollenbeck, project manager for Powertech, said he does not anticipate any effect on the Powertech project.

"If there was any cleanup, it would be surface cleanup, and it would not have any effect on us whatsoever," Hollenbeck said.

Opponents of the Powertech mine welcomed Thursday’s news.

Lilias Jarding, of the Black Hills Clean Water Alliance, said although the investigation of the abandoned mines and the permitting of the proposed mine are officially separate, the two could affect each other.

“I think if they end up having a Superfund cleanup going on right where the company wants to mine," Jarding said, "that could make things pretty difficult for them.”

That assessment irked Hollenbeck.

"This whole deal is just a guise by the 'antis' as another delay," he said.

The Superfund is the federal government’s program to clean up uncontrolled hazardous waste sites.

Only 1 percent of sites assessed by the EPA become a Superfund site, and many of those pose a major public health threat. The potential threat in the rural Edgemont area is primarily viewed as ecological because of the area’s low population density.

Dania Zinner, an EPA remedial project manager, said Superfund designation is not the only possibility for sites requiring a cleanup.

“The polluter could do it on their own, we could help with it, and there are other programs to clean up a site if it needs to be cleaned up,” Zinner said.

The EPA’s fact sheet on the abandoned mines near Edgemont says the agency would look for potentially responsible parties to assist or pay for investigations and cleanup of environmental problems they have caused.

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The EPA hopes to determine by late 2015 if a cleanup is needed. The site investigation probably will begin next spring or summer.

At least two domestic wells near the abandoned mines already have been found to contain levels of radium-226 that exceed safe drinking water standards, and one of those also has dangerous levels of uranium.

Other findings of the preliminary assessment include:

  • Surface soils near waste piles that contain levels of radionuclides above health-based standards and three times higher than background levels;
  • Surface soil and air samples with elevated levels of radionuclides that may pose a risk to nearby residents and workers;
  • And radionuclides in surface water samples from Pass Creek, Beaver Creek and the Cheyenne River.

An EPA fact sheet on uranium says human intakes exceeding EPA standards can lead to increased cancer risk, liver damage or both. Long-term, chronic intakes of uranium isotopes in food, water or air can lead to internal irradiation and chemical toxicity.

Uranium, which is used to fuel nuclear power plants, was found near Edgemont in 1952 before modern environmental regulations were enacted. Decades of mining followed until the mid-1980s, when mines were abandoned because of declining uranium prices.

The abandoned mines consist of waste rock piles, seven open pits, underground workings and two open tunnels.

The EPA’s preliminary assessment was requested by the nonprofit Institute of Range and the American Mustang, which operates the Black Hills Wild Horse Sanctuary.

Contact Seth Tupper at

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Enterprise Reporter

Enterprise reporter for the Rapid City Journal.