September 10, 2009
» The QueQue
Federal researchers are still looking for that silver bullet that will enable them to clean up contaminated and radioactive waters beneath so many toxic heaps, the result of decades of dumping of atomic weapons and nuclear power waste. One of the technologies gaining federal attention is also getting treatment from researchers at Texas A&M, Kingsville.
In a partnership with Uranium Resources, Inc., which operates the Kingsville Dome uranium mine a couple miles south of the city, Lee Clapp, associate professor of environmental engineering (left, with imported radioactive waste) is leading a team of students in a study of the ability of hydrogen to clean up shop.
Since in-situ uranium mining stirs a variety of heavy metals and other elements into the water column, the industry needs a way to clean the water after mining operations cease.
While heavily oxygenated solutions are used to break uranium out of its relatively stable position in sandstone and water sands, hydrogen appears to actually help bind it up again.
URI is paying for the hydrogen and for the work of research assistant Jose Manuel Cabezas; the U.S. Department of Energy is providing all the lab work and kicking in to pay graduate students for extra labor.
Critics point out that nearly every permit for in-situ uranium mining issued to date in Texas has been amended after the company was unable to clean the water up to pre-mining conditions.
In some cases, simple reverse osmosis can drop uranium levels from as high as 50 parts-per-million to below detectable levels, Clapp said. While that makes it feasible some sites, other water quality issues rule it out at many others. “If you just pump and treat, you are going to be doing it forever,” says Clapp.
So far, the hydrogen treatment at the Kingsville Dome has been taking the groundwater there from around 5,000 parts per billion to 70 ppb â?? approaching drinking-water quality â?? though Clapp admits, “Well, you probably wouldn't want to drink that.”
The EPA's drinking water standard is lower still, at 30 parts per billion.
`On a follow-up call, Clapp clarified that he'd happily drink one glass of water at 70 ppb uranium, considering the risk quantified in the EPA limits involves lifetime exposure. While the concept has come under attack recently, the broader scientific community still holds there is no safe dose of radioactivity.`
Monitoring of the Kingsville field study will last through the spring of 2010, Clapp said. And big questions remain to be addressed.
Will the uranium release back into the water column after the pumping has stopped? Will other chemical reactions re-release heavy metals or other toxics into the environment?
“Those are absolutely critical research questions we're looking into,” Clapp said. So far, he adds, “I think the results are pretty encouraging.”
While Clapp is in communication with researchers from the U.S. Geological Survey, keen on the work for possible use at contaminated federal waste sites, the City of Kingsville should be interested as well.
Mining production at URI's site has helped reverse the flow of sub-surface water so that it is now flowing back toward the city at a rate exceeding 100 feet per year. While uranium likely flows slower than the surrounding water, contamination thousands of times the EPA's drinking water limit is probably not something the local water utility would like to be stuck with.
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