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Hill’s groundwater cleanup expected to last 65 years

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HILL AIR FORCE BASE — After decades of chemical dumping at Hill Air Force Base, groundwater cleanup here is expected to be completed in 65 years.

That will make 120 years and more than a half billion dollars spent since contamination started spreading from a number of unlined chemical dumps at Hill.

Many of the chemicals are known or suspected to cause cancer. In high concentrations, nearly all of them will kill you, but according to a 2003 report from the U.S. Agency for Toxic Substances and Disease Registry, it would take much higher concentrations than what is found around Hill. Even so, 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, meaning human exposure to contaminants is not under control.

The groundwater contamination spreads between 50 feet a year in Clinton and Sunset to 300 feet a year in Roy.

"We, as a corporate entity, feel terrible that we've created this kind of problem," said Bob Elliott, Hill's environmental-restoration chief.

Contaminants include trichloroethylene, or TCE, as well as chloroform, chromium, carbon tetrachloride, benzene, toluene and xylenes.

Steve Hicken, the base's remedial project manager, said, "We will be here to clean it up until it's done. It's not a short-term fix."

Assessing risks

Elliott, Hicken and Mark Loucks, the base's restoration operations program manager, stress that contaminants from the plumes are not in area drinking water because drinking water comes from reservoirs or a deep, productive aquifer known as the Delta Aquifer, which is separated from the contamination by two clay layers with another aquifer between them.

Contamination, which flows through a shallow aquifer, gets closer to the surface as topography slopes toward the Great Salt Lake.

Sometimes, as contaminants flow through the shallow aquifer, they evaporate through the soil and into homes. Some of the contaminants come up through springs.

The ATSDR report found "no apparent health hazard" for residents exposed to the chemicals through indoor air, direct contact or eating crops that absorbed contaminants. But residents expressed concern about the report's validity during its public-comment period and questioned its thin data set. They cited other studies that showed proximity to waste sites increases health risks.

The agency said it used local and national data to check contaminant levels and relied on actual chemical exposures to make conclusions, and the other studies' conclusions were coincidental.

Residents still have their doubts.

"If it's not dangerous, then why are they spending so much money?" asks Brent Poll, a South Weber resident whose family discovered the pollution and brought it to officials' attention.

Loucks said Hill and EPA officials are still concerned about long-term exposure. "There is the potential for someone to be exposed at an unhealthy level," he said.

Poll said he would like to see more testing more often, because some contamination has continued to seep outside of the maps the Air Force uses.

Base workers check contaminant levels in 1,494 monitoring wells on and off base. But Elliott said that doesn't mean Hill officials know where all contamination is. Sometimes, contamination has been underground for decades, and workers discover it when excavating around base.

The Air Force groups contaminated areas into 12 Operable Units. Plumes are found on the base and in the seven surrounding cities.

Although contamination in the groundwater plumes varies, TCE is common to each Operable Unit.

Beneath the cities

Contaminated groundwater in South Weber came from three chemical disposal pits, three landfills and two fire-training areas. Between 1958 and 1973, fire training meant dumping gallons of jet fuel on the ground around an airplane and igniting it. Some of that fuel soaked into the ground.

Loucks said one groundwater plume in South Weber from an unlined chemical dump "used to be the most contaminated site in the whole Air Force."

About 50,000 gallons of contaminants were disposed of in one of the unlined chemical dumps away from most base operations, he said. The contaminants pooled underground and were kept from spreading by the geologic makeup of the soil beneath. About 45,000 gallons have been removed so far, but it still could be 50 years before the area is clean.

Contaminated groundwater is pumped from the ground and treated until water can be sent through the sewer district, Loucks said.

On South Weber's west side, part of a contaminated plume reaches into Riverdale, but another plume is Riverdale's largest contaminated area — beneath the Craigdale subdivision.

Besides TCE, there are also remnants of other solvents, and six extraction wells on the base pull water out of the ground and treat it. It's the only base site where clean water is reinjected into the ground to increase the flow of groundwater, flushing out contaminants. Wells in the subdivision extract water and send it through the sewer district.

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