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Pilot program flourishes at former base

  • Published
  • By Rachel Zaney
  • AFCEC Public Affairs
What started as a pilot project at the former Chanute Air Force Base, Ill., in May 2009 is now flourishing ... literally!

Several rows of tall, lush poplar and willow trees line the perimeter of Landfill 3. While they look nice, their true purpose is preventing water that has come into contact with contaminants in the landfill, called leachate, from spreading offsite.

The concept of creating a buffer between the contaminated site and the outside world is a simple one, said Chanute's Base Environmental Coordinator Paul Carroll.

"We chose hybrid poplar and willow trees because they grow rapidly and absorb anything that comes near them," said Carroll. "The roots soak up leachate from the groundwater eight feet below the surface level and use it as a food source without doing any harm to the tree or the surrounding environment. The result is a combination of leachate containment and healthy trees."

The innovative idea to test this green cleanup technique came from the Air Force Civil Engineer Center's contractor, Shaw Environmental (recently acquired by CB&I) as part of a $38.7 million contract awarded in 2008 to complete environmental cleanup at 47 contaminated sites at Chanute. The project was the first of its kind in the AFCEC BRAC portfolio, so no one knew what kind of results to expect, Carroll said.

"The pilot project was to determine if an existing leachate collection system would be needed to supplement the poplar and willow trees buffer to manage contaminated groundwater," said Howard Sparrow, CB&I's project manager at Chanute. "After 3 years of testing, it was conclusive that we didn't need to turn on the collection system at all. The trees have proven to be the only cleanup method we need at Landfill 3."

Officials are now expanding the project to an additional two landfill sites at the former base. If the new buffers prove to be equally effective, the Air Force may save between $1.5 and $2 million over the life cycle of the project.

Not only is the poplar/willow buffer a self-sustaining cleanup system that requires minimal oversight, it also eliminates energy consumption and leachate treatment that would be required for almost any other cleanup solution, Sparrow said. The trees also take up greenhouse gases and help create an ecologically friendly habitat for local wildlife.

"The deer like the landfill areas so much now, we're having trouble keeping them away," said Sparrow.

Chanute is just one example of a location suitable for poplar/willow tree buffers. The Air Force is currently studying other projects to determine if these buffers could be as effective as they have been at Chanute.

"The trees do the best job in preventing the spread of leachate when the groundwater moves slowly because it gives their roots a chance to soak up as much as possible," said Amar Bumb, a scientist with CB&I. "Because the groundwater moves rather slowly at Chanute, the trees have helped us achieve our goal of containing the leachate to the landfill sites."

For landfills, the best and most cost-effective solution is containment rather than cleanup, Carroll said. 

When AFCEC transfers the property to the Village of Rantoul in the coming months, the deeds will include restrictions on future land use to ensure the property is never used for residential purposes or anything else that may disrupt the landfills. In addition to containing the potentially contaminated groundwater, caps have been installed to prevent rainwater from seeping into the landfills.

"The Air Force is very proud of the progress we have made at Chanute," said Carroll. "The poplar and willow trees are just one of the ways we are ensuring the protection of human health and the environment for the Rantoul community. We will continue to work with our regulatory and environmental partners to ensure the land is properly cleaned up before transferring the property to the Village of Rantoul beginning later this year."