Tech helps clear pollution

HILL AIR FORCE BASE — When you're trying to clean up contamination from 30 years of pollution, you have to get creative.

As engineers at Hill Air Force Base have sought to resolve the contamination, they have turned to new technology, which can save millions of dollars.

It's still going to be 65 years before the pollution is cleared from from the groundwater and soil around the base. By the time it's gone, the Air Force will have spent over $500 million. But Hill officials, including remedial project manager Steve Hicken, count on advances in technology to speed things up and bring costs down.

"We are continually looking at technology on the horizon," Hicken said. "It's not a static process."

Many of the chemicals in 16 underground plumes of water beneath and around Hill evaporate easily enough, but they need air to do so. When the chemicals are trapped underground, it takes decades or centuries for the environment to break them down.

These chemicals include trichloroethylene, or TCE, a degreaser that was once popular because it doesn't catch fire. Now, it's rarely used, though it can be found in some gun cleaners. But from the 1940s through the 1970s, workers at Hill dumped TCE and other solvents into unlined chemical pits around the base.

Hill and its surrounding area were declared a Superfund site in 1987 and added to the U.S. Environmental Protection Agency's National Priorities List. That designation means that human exposure to contaminants is not under control.

It turns out TCE may cause cancer in humans, so the base is charged with cleaning it, along with dozens of other chemicals, from the groundwater.

One technological development that the Hill engineers have employed is a permeable reactive barrier, or PRB. The only one in use in Hill's cleanup operations is located in a former rail bed at about 2750 West in Roy, and Hill officials are looking at the possibility of using it elsewhere.

Researchers at the University of Waterloo, in Ontario, Canada, discovered in the 1990s how iron reacts with TCE, and they developed PRBs to treat TCE contamination. Iron reacts with the TCE to strip chlorine off and render the remaining chemical nontoxic.

The PRB in Roy is 660 feet long, 32 feet deep and about 2 feet wide. If you could look underground, you would see what looks like a wall of iron granules and sand that's been there since November 2004.

Wells tapping into the Roy plume west of the base, beyond the PRB, show substantial decreases in TCE concentrations.