By Rebecca Boyle
Fort Collins Now
Feburary 8, 2008
Powertech reps explain how the science and the geology of in-situ uranium mining will protect local groundwater
KINGSVILLE, Texas — A pair of horses in a pasture stood in the stiff wind, their necks forward as if bracing against the cold. They ignored the white pipes sticking out of the ground around them.
“That’s production area two,” Dain McCoig said, pointing his mud-crusted pickup truck in the other direction. “That’s in recovery right now.”
The pipes, some of which bend at awkward angles, rest above injection and extraction wells that have pumped oxygenated water into uranium-bearing porous rock.
Most of the uranium in that area is gone now, after Uranium Resources Inc., where McCoig works, spent several years coaxing it out of ancient fluvial sand beds. But it will take a long time—some opponents of URI say forever—to clean up the groundwater with which they did it.
A couple miles up Texas Highway 1118, a muddy field of newly drilled wells is starting work on the same aquifer, pumping oxygen into the groundwater to help bring out more uranium.
The wells are pretty unsightly, especially given the mud that encases visitors’ feet in three inches of sand-colored sludge. But after a while, the pipes that feed them will be buried under topsoil, and sorghum and cotton can once again grow. It will be harder to hear the wells’ airy, gurgling sound, much like the sound of a dentist’s tool used to dry out a patient’s mouth, and it will be difficult to see the thick yellow cords that power the wells.
In Northern Colorado, Powertech Uranium Corp. is a long way from drilling wells like these, which dot parts of Wyoming and South Texas. But once they’re drilled, Powertech says its 20-year planned mining operation will barely be noticeable—only 20 to 40 acres at a time will have well fields, and they will be re-covered with the same scrubby vegetation that grows in rural western Weld County.
Many residents in Northern Colorado are opposed to Powertech’s plans because the mining operation has to use groundwater from the Laramie-Fox Hills aquifer, the same aquifer that provides water to domestic and agricultural water wells in the region.
But many residents don’t know exactly what to expect, having never seen an in-situ uranium mine in person. With that in mind, Fort Collins Now visited Kingsville, Texas, home of URI, to see a uranium mining and milling operation.
About this series
With the possibility of an in-situ uranium mine opening near Nunn in the not-too-distant future, Fort Collins Now traveled to Goliad, Texas, to see how another community is dealing with the same issue.
The uranium mine there is about a year ahead of Powertech’s proposal for Nunn, and even though it isn’t yet fully permitted, it is being blamed for ruining the groundwater locals rely on to for both themselves and their cattle. Efforts to oppose the mine have divided the community, and provide a cautionary tale for those in Northern Colorado as Powertech’s proposal comes under scrutiny from neighbors, regulatory agencies and even the state Legislature.
To be fair, there are numerous differences between Powertech’s proposal and the in-situ operation in Goliad. The aquifer in Northern Colorado is better protected by surrounding layers of rock, for instance.
But what we found are numerous similarities as well: The fears of opponents, the reassurances of the mining companies, and the divisive nature of the issue are not unique to either area.
Perhaps most importantly, neither company can ensure that their mines will not harm the groundwater needed to extract uranium. They promise they will figure it out, and that the Earth's natural geologic processes will help protect the water. Those issues are explored in this story.
Stay with Fort Collins Now and www.fortcollinsnow.com for ongoing coverage of this issue.
URI mined for uranium in the Kingsville Dome, a swell in the land that covers oil, gas and uranium deposits, intermittently until the early 1990s, when uranium prices dropped. The company has been somewhat controversial, as residents in the area say they poisoned the Goliad aquifer, an ancient formation of river sands that lies beneath most of Texas’ Coastal Bend region.
Residents like Teo Saenz, who formed a group called South Texans Opposed to Pollution—STOP—wanted URI to clean up its wells before drilling new ones. He and other residents were upset when the new wells were green-lighted, and they accuse the state of relaxing pollution controls.
Kleberg County and STOP even filed lawsuits against the company and the state, claiming state regulators were too lenient.
McCoig, the senior engineer for URI, said some opponents have a “different interpretation” of some regulations, including ones that have changed since URI started mining. He and Craig Bartels, URI’s vice president for in-situ mining, said the Earth’s chemistry and geographical composition will help the mining companies restore the water to pre-mining conditions.
“When we’re done, you won’t even know we were here,” Bartels said.
Powertech officials have taken that promise even farther, saying they may leave the aquifer better than when they found it because some dangerous materials will be removed.
A passing knowledge of the physical sciences is vital to understanding how and why in-situ mining works, and why the mining companies say they can restore the groundwater.
About 35 million years ago, uranium-loaded volcanic ash, probably from tectonic activity in the Yellowstone National Park area, spewed into the air and settled over Wyoming and the Black Hills. Millions of years of geologic changes, including an ocean over most of the Great Plains, buried those deposits beneath Northern Colorado.
The area that is now the north Front Range was a marine barrier island, evidenced by the varying layers of sand, which forms on a shoreline, and shale, which forms as organisms die, fall to the ocean floor and are compressed by heat and time.
As the volcanic sediments were eroded away, oxygenated rainwater picked up the uranium on those sediments and carried it along.
In-situ mining duplicates this chemical process, by adding oxygen to the groundwater that flows around the uranium. The treated solution is called “lixiviant” and is essentially carbonated water. Powertech officials have even compared it to Perrier.
In Kingsville, oxygen lasts about 12 days before it is consumed by the other materials in the rock. Powertech is still completing research to find out those numbers for Northern Colorado, but as in Texas, it will be a relatively short period before reducing agents in the rock bring the uranium back to a solid state.
Those reducing agents include metals like iron, which likes oxygen, and microorganisms that use the oxygen for respiration.
That might be one reason why uranium is so commonly found in coal or oil deposits, according to Mike Beshore, a Powertech geologist and the company’s senior environmental coordinator. Those materials are formed from ancient carbon-based organisms compressed over eons; it’s plausible that some of those critters consumed the oxygen the uranium rode in on.
When the oxygen was used up in those chemical and organic reactions, the uranium came out of the water. It was left behind in the rock, and the uranium-free water kept on moving. In Northern Colorado, the water moves at a rate of roughly 12 feet per year, and Powertech consultants say it is moving northeast, toward Grover and ultimately Nebraska.
The place in the rock where the uranium stopped is called a roll front, and it even looks like a roll in the rock, like a big “C” or a squiggly line of brighter color. It has been there for millions of years, embedded in the same tightly compacted sands that bear the Laramie-Fox Hills aquifer.
Above and beneath the sands are even more tightly packed clays and, in Northern Colorado, that’s the ancient marine shale. Powertech engineers say those layers will “confine” the aquifer so no uranium-bearing water will escape above or below the water table.
What’s more, the lixiviant that picks up the uranium will only take it so far before the carbonaceous material and other metals reduce the oxygen again, causing the uranium to precipitate out of the water.
URI takes care to design its wells in a way that ensures the uranium-bearing water is brought back to the surface so it can be processed. If there is an “excursion,” the term for oxygenated water moving beyond a well intended to capture it, then the uranium bits might drop back into the sandstone and fall down in an unreachable area.
Dain McCoig, senior engineer for URI, said the company invests everything into moving the uranium just the right distance.
“We can barely move it 100 feet,” he said. “That’s as far as we can ever hope to move it. The idea of it moving beyond that, or into town, is impossible.”
The same holds true for other metals that are circulated into the water along with the uranium, McCoig said.
“The rock dictates the chemistry underground,” he said. “The Earth is going to naturally try to move everything back to the way it had it.”
The companies point to that principle when they say there is no example in the country where in-situ mining is the cause of groundwater contamination.
They argue that in most cases, the groundwater near uranium ore is unsafe already, and that water up-dip or even down-dip of the wells should be fine before and after mining.
Besides thinking like a chemist, any resident who wants to understand in-situ mining also needs to think like a geologist.
Aquifers are sometimes considered underground bodies of water, like lakes or streams. But geologists think of them more like sponges, in which spaces in between particles are able to hold water.
Beshore, the Powertech geologist, compares the aquifer to a garbage can full of wet sand.
Sand particles are tightly packed, but there are still small spaces between each round grain, called pores. The pores contain water, which can be brought to the surface with pressure, using a well, and which moves very slowly.
A well drilled into an aquifer can increase pressure to draw the water toward it. It’s like two people at a trough, both drinking from a straw — if one sucks harder, more liquid will be drawn in that direction to fill the emptying space.
URI and Powertech said this principle would ensure there are no excursions of uranium-bearing water from the mining area.
Monitoring wells around each production area will be able to catch faster-moving materials, like calcium or chlorides, which are the veritable canaries in the mine—if they register in the monitoring well, that means water is moving outside the mining area, and the production wells would just pump harder to bring it back.
“I know people kind of scratch their head on that one, but it is really sound hydrological principle,” Beshore said. “Creating pressure gradients, controlling fluids, is a very easy thing to do.”
Once Powertech or URI gets the uranium out of the ground, a lengthy, complicated process must take place before it can be used in a nuclear power plant—or for any other reason.
About 99.3 percent of all uranium is U-238, an isotope that means the metal has 238 neutrons. Nature wants entropy to decrease, making things more orderly and as stable as possible, so the atoms want to get rid of their extra neutrons. This is what makes uranium and other heavy metals radioactive. They need to kick off neutrons to decay into a more stable element.
Uranium has 14 “daughter products” that are the progeny of this decay. Many of them are also radioactive, like radium and thorium; ultimately, uranium and its progeny decay into lead.
It takes a long while for this to happen, and it can be measured in what’s called half-life—it dictates that in a given amount of time, half of the atoms in a given radionuclide will decay. The half-life of U-238 is 4.5 billion years, which makes it “barely radioactive” in the basic definition of the word.
The other 0.7 percent of naturally occurring uranium, U-235, is an isotope with fewer neutrons, and it is much more radioactive—its half-life is 760 million years.
When uranium is taken from the ground and turned into yellowcake, an oxygenated, goldenrod-colored powdery form of uranium, it needs to be enriched so that more of it is made up of U-235. In the end, about 3 percent of the uranium is made into that isotope. Along the way, other potentially helpful radioactive metals are extracted from the enrichment process, like technetium-99 metastable, which is used in medical imaging.
What’s left can be made into uranium pellets, which are inserted into fuel rods, which go inside a nuclear reactor core. In a power plant, the core heats water that is turned into steam to power a turbine, which generates electricity.
Nuclear power plants are far more efficient at making electricity than coal or gas power plants.
Beshore, who lives in Fort Collins and works in a new Powertech office in Wellington, said he believes that kind of energy is the way of the future, especially if Americans want to help fight greenhouse gas emissions that are causing global warming.
He believes it strongly enough that he would grudgingly accept drinking from an aquifer using in-situ mining.
“If I lived out there, I probably wouldn’t be thrilled about it,” he admits. “Probably not. But I would be thrilled with the fact that we are moving to a cleaner energy source, so I would deal with it. And I would drink the water around our mining area, and I would have no problem living out there.”
He’s even considering buying a house in the area, he said.
He wishes more people supported nuclear power.
“Fort Collins is ‘clean and green’ and we should be promoting that,” he said. “We should step up to the plate. We should be setting the standard for uranium exploration, and ultimately nuclear power generation.”