New tool to improve cleanup at Tucson-area AF plant


The AF Civil Engineer Center has found a new method to remove toxins trapped in naturally occurring dense soils, like clay, in Tucson called Hrydrofracturing. 

During the 1950s to the early 1970s, Air Force Plant 44 in Tucson, a government-owned, contractor-operated manufacturing facility, disposed of metals and solvents which led to soil and groundwater contamination at the site, to include trichloroethylene and 1,4-dioxane.

The Air Force has made significant progress in the decades following, to remove these contaminates, but now with the help of advanced technology, the Air Force anticipates even greater success..

“Environmental hydrofracturing is a safe and effective way to accelerate site cleanup, and has been used since the 1980s,” said George Warner, restoration program manager at the Air Force Civil Engineer Center, which oversees cleanup of the project for the Air Force. “Dense clay soils, like those found in the Tucson area, have a tendency to trap contaminants in the soil and groundwater. This technology is used to enlarge or create small openings underground so that our existing cleanup methods are more effective.”

The innovative process will help accelerate biological remediation at the site, which refers to the use of micro-organisms such as bacteria that live naturally in the soil and use contaminants as a source of food and energy. As part of the environmental hydrofracturing process, a slurry solution derived from soy beans, laundry detergent, nutrients and these micro-organisms will be injected into the fractures, creating a stable environment for them to eat and digest the contaminants. This process breaks down the contamination and turns it into harmless compounds like carbon dioxide and water. Any trapped contaminants not digested by the micro-organisms will be removed by the existing “pump and treat” system.

The entire process is closely controlled and monitored, said Michelle Frandsen, remedial engineer at AECOM, the company contracted by the Air Force to conduct the cleanup.

The technology has been used successfully at other Air Force installations in the past, including F.E. Warren Air Force Base in Wyoming, and the former McClellan AFB in California.

At AFP44, expectations are that this technology can reduce cleanup time at the site by as much as 50 percent, said John Kim, AECOM project manager for the site.