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.