David Kreamer, a professor of hydrology and an authority on groundwater contaminants at the University of Nevada, Las Vegas, disputed that assertion.
“I’m all for mining if it’s done responsibly with proper safeguards,” Mr. Kreamer said. But he called Pinyon Plain a potential “time bomb” that could have detrimental effects in a decade or so.
Mr. Kreamer said he was especially concerned about drilling activity at the mine that pierced an aquifer several years ago, releasing millions of gallons of water high in both uranium and arsenic.
To prevent the water from contaminating nearby areas, Energy Fuels is collecting it in a pool at the mine, where some of it evaporates. The company has also trucked the water nearly 250 miles to White Mesa, Utah, where the company owns the country’s only fully licensed and operating conventional uranium mill. The Ute Mountain Ute Tribe, whose members live near the White Mesa site, called last year for the mill to close.
In correspondence this year with Arizona regulators, Scott Bakken, vice president for regulatory affairs at Energy Fuels, said the company was also measuring the daily volume and conducting periodic sampling of the water pumped to the surface. Mr. Bakken added that Energy Fuels would increase the frequency of pumping to mitigate any risk to groundwater if water quality standards are not met.
The Arizona Department of Environmental Quality on Thursday gave the company the green light to continue, moving to grant an aquifer protection permit to Energy Fuels. The ruling, which is the latest stamp of regulatory guidance for the project, allows the company to use engineering controls to “reduce discharge of pollutants to the greatest degree achievable,” the agency said.
But members of the Havasupai Tribe, as well as hydrologists such as Mr. Kreamer, are also expressing concern that the uranium-heavy water released by the aquifer, despite the company’s efforts to collect it, could jeopardize the supply of water to nearby Supai Village, home to Havasupai families, and springs within the Grand Canyon itself.