West of the base, groundwater plumes in Roy, Sunset and Clinton are being treated and extracted from the ground. One plume in Roy flows through a 660-foot-long permeable "wall" of sand and iron filings 30 feet below ground. The iron yanks chlorine from TCE as it flows through, and the chemical breaks down more easily. Contaminants in the Roy plume came from a disposal site near the base's western fence. Base officials expect to have a finalized plan for the plume in 2007, and cleanup will take 30 to 40 more years.

An underground system exposes groundwater in Sunset and Clinton to air and vaporizes TCE. Those contaminants came from a flash pond on the base, where waste solvents were pumped and then incinerated. Some arsenic has been found there, too, because mill tailings had been used as ballast for nearby rail lines.

South of Sunset sits a Clearfield plume, contaminated from solvents and petroleum products from the old maintenance shops on the base. Base officials are still studying the contamination and don't have a formal plan for its cleanup.

Another plume — mostly contaminated with TCE — extends into Layton. Eight wells extract contaminated groundwater along state Route 193. On the base

Operable Unit 9 consists of five small plumes, located on the western, southern and eastern areas of the base. Still under investigation, those plumes — spreading from former stormwater retention ponds should have a formal plan in 2007. Some ponds have been filled in and covered to keep water from mixing with contaminated soil, portions of which have been removed from the base.

Three more contaminated areas lie beneath the base, but only one is responsible for the plume spreading into Layton. A former wastewater pond until the 1950s, it was fed by the base's aircraft-maintenance facilities. The pond is now a base parking lot, engineered to keep water from reaching contaminated soil.

Under one hangar, workers found hexavalent chromium from a former plating operation. The chromium will remain in the ground, protected from water by the hangar's concrete floor above it. When the building is removed someday, engineers will address the contamination. Several probes monitor the chromium to make sure it isn't moving.

Elsewhere on the base, the underground gas tanks at a former gas station have leaked and are still being investigated. The chemicals in the ground are gasoline components: toluene, ethyl benzene, benzene and xylene. Officials believe the groundwater plume there will not spread beyond the base.

Mo Slam, the Utah Department of Environmental Quality's remedial project manager, said he believes Hill officials are doing what they can to clean up their mess. "There's no magic bullet," Slam said.

The best Hill officials can do is continue work and be up front with the public, he added. Officials aren't aware of anyone who has become sick from exposure to these contaminants. Concerned residents may contact Barbara Fisher, the base's environmental public affairs coordinator, at (801) 777-4557.

"They bend over backward to address people's concerns," Slam said.

That's a big difference from when Poll's family first brought contamination to Hill's attention.

"'Stick your nose over the other side of the fence,'" is what the Polls were told, Elliott said.

"We recognize that on the trust scale, we're way down there," he added.

---

E-mail: jdougherty@desnews.com