Powertech considers flooding to mine ore bodies above water table
Technique is unproven alternative to open pit mining; uranium stock website says proponents are "daydreaming"
Posted September 5, 2007, Updated February 22, 2007
In response to concerns about possible open pit mining near Fort Collins, Nunn, and Wellington, Colorado, Powertech Uranium Corp. is considering flooding several hundred acres of agricultural land to conduct what company officials refer to as "modified" in-situ leach mining. The uranium ore bodies are at a depth of 85-125 feet on six sections of land bordered by Weld County Road 100 on the north, County Road 92 on the south, County Road 19 on the west, and County Road 23 on the east (see map). Powertech has acquired the rights to mine on Sections 35, 3, 11, 15, and part of 14.
The uranium deposits in this southern portion, referred to as the Centennial area, are unsaturated, i.e., located above the water table. (The proposed northern mining area is called the Indian Springs area.) According to mining experts, in situ leach mining can only be done in a confined aquifer where water is under pressure. Typically, shallow unsaturated uranium deposits are extracted using open pit mining.
Powertech surely understands the political risks of trying to construct an open pit uranium mine less than seven miles from the city limits of Fort Collins, a growing city of 130,000 people. Making matters worse, much of the open pit mining area is located within the proposed growth management area of the Town of Nunn. The risk of windblown radioactive dust being dispersed over several miles makes permitting an open pit mining operation politically challenging. Hence, the idea to flood the mining area.
To contain the added water, trenches would be excavated and slurry walls would be constructed around the ore bodies. The trenches would be filled with a clay-water mixture, and cement or concrete can also be added to the mix. According to Lane Douglas, Powertech's former Project Manager, the slurry walls would need to be deeper than the ore bodies, which are located 85-125 feet below the surface. Millions of gallons of water would be pumped into the resulting impoundments. Powertech has not indicated what the water source would be for this project.
Powertech Vice-President Richard Blubaugh acknowledged in a private conversation that no uranium mining company has ever successfully operated an in-situ leach mine using this flooding/slurry wall method.
In a recent article on junior uranium companies, writer James Finch addressed this speculative method:
A few recently minted uranium juniors daydream of ISR-mining unsaturated uranium ore bodies or ore above the water table. (See recent interview for an expert opinion: http://www.stockinterview.com/News/04092007/Water-ISR-Uranium-Mining.html).
Powertech described the issue this way in a recent communication to project opponents:
We have suggested that we are looking at the possibility of a gravel quarry on the southern properties, where the ore bodies are much shallower. Where the ore is shallow, there may not be any water present surrounding the ore. We are looking at several methods of recovery for this shallow ore and we are considering removing the valuable gravel deposits over the ore and then removing the natural uranium ore to transport it to a mill facility. We have also identified another method wherein we can use slurry walls surrounding the ore to isolate the uranium, and through purchase of water rights, increase the water level for In-Situ Recovery (ISR) production. It will take more extensive testing before we make an application for either of these methods. However, Powertech’s preference would be to conduct ISR mining throughout the entire project. Economics and regulatory approval will dictate the mining method.
Investigation of aerial dispersion of radioactive dust from an open-pit uranium mine by passive vinyl collectors - Pettersson & Koperski
Slurry Wall, Cutoff Wall, Slurry Trench Technology Overview
Water: The Key to ISR Uranium Mining - Interview of Glenn Catchpole by James Finch
Uranium Industry Expert Talks Shop With StockInterview - Interview of Dr. Robert Rich by James Finch