Dummy bombs may fight pollution

SUNSET — If you are a major branch of the U.S. military and you have somewhat of a pollution problem on your hands, it must be heartening to know that you may already own part of the cleanup solution.

And who knew that solution could include bombs?

For years, the Air Force has used the Utah Test and Training Range in Utah's West Desert to practice dropping dummy bombs made of iron.

And it just so happens that iron reacts well with a possible carcinogen known as trichloroethene, or TCE. Because of TCE in the various plumes of groundwater seeping underground from the base, the area was added to the U.S. Environmental Protection Agency's list of Superfund sites in 1987, and restoration efforts have been under way since 1990.

This spring, base engineers expect to try a new twist on an old favorite remediation effort — the permeable reactive barrier. If successful, this new effort could be applied to similar cleanup efforts across the U.S. Department of Defense.

Hill Air Force Base has purchased a crushing machine to turn the formerly useless hunks of iron left over from bombing practice into grains of iron sand. This is the first time bombs are being used to clean up pollution, said Mark Roginske, site manager over two plumes of pollution in Roy, Sunset and Clinton.

In the lab, the crushed bombs work just as well as iron purchased commercially, he said.

Officials plan to drill eight 12-inch bore holes 56 feet into the earth near the base boundary and fill the holes with iron grains from the dummy bombs. The borings will be placed across some of the highest TCE concentrations in the plume reaching into Sunset and Clinton.

As TCE-laden water seeps through the iron columns, which act like a filter, a chemical reaction will strip TCE from the water.

Monitoring wells will be placed in front of and behind the borings so officials can check the barrier's efficacy. And then they will wait.

After 18 months, if the barrier works as expected, it will be expanded across the entire plume, known as Operable Unit 5. And because other military installations have similar types of groundwater pollution, as well as nearby bombing ranges, more bombs could be crushed to treat the pollution, Roginske said.

But there's a cost associated with crushing the iron, and for the project to work, Roginske said, he has to answer an important question.

"Can we crush iron at a rate to make it economically feasible?"

For the test phase of the project, only 34 tons of iron will be needed to fill the eight holes.

But because of prior successes, Roginske is optimistic it will work.

In 2004, the base installed a 660-foot-long barrier, composed of iron filings and sand, below ground near a neighborhood in Roy. And it's worked great, Roginske said.

The mass of TCE in the plume has been reduced in half after groundwater seeps through the barrier, Roginske says. The barrier has next to no maintenance costs, but nitrate in the groundwater has caused a precipitate to form on the iron, reducing its ability to strip TCE from the water.

But it's still working, he said, adding that he's studying how to remedy the nitrate content of the water in Roy.

In Sunset, however, the groundwater has hardly any nitrate content. Some of the iron comes from Utah's training range and some is expected to come from Luke Air Force Base, in Arizona. And unlike the Roy PRB, for which the base purchased 950 tons of iron for $638,400, the Air Force already owns the iron.

E-MAIL: jdougherty@desnews.com