Things are looking better on the surface of the Uranium Mill Tailings Remedial Action site, or UMTRA site just outside of Moab, Utah. Piles of waste from an old uranium mill are growing smaller. But under the surface it’s more complicated.
The soil has absorbed uranium and is slowly releasing the radioactive metal into the groundwater.
“That’s sort of the model of why many of these sites still have a persistent long-term source of uranium, bleeding into groundwater and potentially into inland waterways like local rivers,” says Dr. Kenneth Williams, a senior scientist at the Lawrence Berkeley National Laboratory.
He’s been working with the Department of Energy on a novel solution to this problem of uranium-contaminated groundwater. It’s called a hydroxyapatite permeable reactive barrier.
“The appetite technology is basically creating an underground sponge that has a very, very high affinity for removing uranium,” says Williams.
Williams and his team inject a solution into the groundwater that concentrates the uranium. The metal remains underground. But it’s no longer floating freely in the aquifer.
“It doesn’t take it out of the system but it removes dissolved uranium from groundwater and locks it up in a mineralogic form, in a form that’s stable under the natural conditions of the aquifer,” says Williams.
In theory that uranium could be extracted, either to use or satisfy regulations. Williams has tried the new method at a sister uranium mill tailings site near Rifle, Colorado with great results. Now his team will apply the technology to Moab’s UMTRA site.
“Moab is quite interesting in that there’s about tenfold more uranium in groundwater in the area where we’re going to be performing the proof of principle experiment later this fall then in Rifle,” says Williams.
Currently at the Moab site, workers pump contaminated groundwater before it meets the Colorado River. But that might no longer be needed with a hydroxyapatite barrier.
And if the method tests well in Moab, Williams says it could be scaled up.
“If you’re going to deploy this at scale, you would need to create a network of appetite sponges that people often describe as sort of a picket fence,” Williams explains. That “picket fence” could span the width of an entire groundwater flow, grabbing any uranium that crosses the barrier.
If the technology is successful it could have impacts not only near Moab but around the world, wherever uranium is found in water.
This story from KZMU was shared with Aspen Public Radio via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah and New Mexico including Aspen Public Radio.
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