In July 2004, contaminants were detected in one of the monitoring wells surrounding the mining facility at Christensen Ranch.
This wasn’t that unusual, mining and regulatory officials say. Other excursions, as they are called, had occurred over the years. The monitoring wells are an early warning system, detecting benign chemicals long before more dangerous toxins can spread.
“It’s sort of like a smoke detector,” said Ron Linton, who oversees the licensing for Christensen Ranch for the Nuclear Regulatory Commission. “They will go back in and adjust their flow with their production practices within their ore zone to get those levels down.”
But according to documents from the Wyoming Department of Environmental Quality, Cogema — the company then handling the restoration effort — could not fix the problem or identify its cause. The company tested water from the area and examined their injection wells for defects, but told state officials they believed the contaminants had occurred naturally and were not from the mine.
For six years, the contaminants continued to spread, disappearing for short periods as the restoration progressed only to reappear again, records show.
“This really shouldn’t happen,” said Glenn Mooney, a senior state geologist who oversaw the Christensen Ranch site for Wyoming from the late 1970s until last July.
Mooney observed that the concentration of contaminants at the boundary had leveled, but “showed no hint that they may drop,” and warned that some of the chemicals found posed a considerable risk.
“The increase in uranium levels, a level over 70 times above the maximum contaminate limit for uranium, in a well that is located at the edge of the aquifer exemption boundary, is a major concern to WDEQ,” he wrote in a 2010 letter.
Christensen said he was never told about the excursions beneath his property and that, as far as he knew, several of the minefields had been fully restored. He said he expected to use the shallow aquifer polluted by the mining as a source of drinking water in the future.
Restoration is the most important backstop against the risk that contaminants will spread from the mining site after the mining is finished. Polluted water is pumped from the ground, filtered using reverse osmosis, and then re-injected underground. The worst, most concentrated waste is disposed of in deeper waste wells.
Yet the Nuclear Regulatory Commission approved Cogema’s restoration of minefields associated with Christensen Ranch even as the excursion remained unresolved.
The commission deemed nine mining fields there successfully “restored” even though records show that half of the contaminants in the aquifer, including the radioactive byproduct Radium 226, remained above their natural levels.
The Geological Survey’s study of uranium restoration in Texas found that no sites had been completely restored to pre-mining levels, and the majority had elevated uranium when the restoration was finished. The 2008 NRC review concluded that each of 11 sites at three mines certified by the agency as “restored” had at least one important pollutant above baseline levels recorded before mining began. The report concluded that restoring water to baseline levels was “not attainable” for many of the most important contaminants, including uranium.
Some regulators and mining industry executives call attempts to fully restore aquifers at uranium sites idealistic. Such water was often contaminated with uranium before mining began, they contend.
“When you restore it … you bring each individual ion down to a level that is within the levels that occurred naturally,” said Richard Clement, the chief executive of Powertech Uranium, which is currently applying for permits for a new mine in South Dakota. “It depends what you mean by 100 percent successful. Are people saying it is different than what it was? Yes it is. But is it worse? No.”
Efforts to restore the groundwater at Christensen Ranch had other consequences. While the water was supposed to be filtered and re-injected, millions of gallons were removed and disposed of permanently as a result of the process, lowering the ranch’s water table.
Water wells outside of the mine area that had routinely produced 10 gallons a minute struggled to produce a single quart, Christensen said. The water levels in the aquifer also dropped — in some places by 100 feet.
“They have always claimed that they could restore the groundwater,” Christensen said. “The main concern is there isn’t much water left when they get it to that quality. It never came back.”
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