location of Coles Hill uranium deposit in Pittsylvania County
In the early 1980's, after the "oil shocks" of the 1970's stimulated investments in other forms of energy, there were ambitious plans to mine uranium ore in the Piedmont physiographic province of Virginia. According to the Richmond Times-Dispatch1
Since then, the estimate of available ore has climbed to 110 million pounds, worth perhaps $10 billion - "the largest unmined uranium deposit in the nation."2 However, Virginia banned uranium mining in 1982, before projects planned in Orange and Pittsylvania counties went into operation. At the moment, the state imports all of its nuclear fuel.
Efforts to lift the moratorium were not pursued vigorously after 1982 because the price for uranium yellowcake (the powdered uranium oxide ore) remained too low to justify investment in new mining operations. However, the Virginia Department of Mines, Minerals and Energy approved a permit for exploring 194 acres in Pittsylvania County in November, 2007.3
The Coles Hill Deposit in Pittsylvania County is northeast of Chatham, in the Mill Creek watershed. The creek drains into Bannister River, and ultimately Albemarle-Pamlico Sound - after passing through Lake Gaston, the drinking water supply for Virginia Beach.
Mining could involve excavating a large open pit mine up to 850 feet deep,4 followed by crushing the ore and separating the uranium from waste rock. An alternative technique is in situ leaching. Acidic fluids woud be injected into the ore underground, and the fluids ("pregnant" with dissolved uranium) would be pumped out and processed to separate the valuable uranium and to recycle the fluid.
Because most uranium mines are in arid locations, opponents to the proposed uranium mines in Virgiunia highlight the potential risks of radioactive mining and mill wastes escaping the site through runoff or groundwater seepage. Uranium normally interacts with groundwater to form the uranyl ion, [UO2]2+ This ion is very stable and soluble. When dissolved, radioactive uranium can spread throughout an area, and it is difficult to remove the contamination.5
However, according to a geologist at Virginia Tech, the Coles Hill deposit is not demonstrating expected migration of uranium through groundwater. A. K. Sinha was quoted in a Virginia Tech news release as saying "[t]here is a water table about 11 meters (36 feet) down, and the uranium-rich bedrock about 20 meters (66 feet) down. The uranium should have migrated to the next county, but it hasn't."6 As noted in the 2001 PhD dissertation on the geochemistry of the Coles Hill site by James L. Jerden, the deposit is a closed system. Uranium ions dissolved near the surface are redeposited "below the water table due to higher pH conditions of ~6.0 and relatively high activity ratios of dissolved phosphate to carbonate," trapping the uranium at the site in a natural storage facility.7