KDI Home    Contact Us   

Researchers Find Easier, Cheaper Way to Treat Contaminated Ground Water

A team of applied mathematicians, statisticians, and engineers at Duke, the University of Texas, and Texas A&M have been studying how liquid flows through soil. Figuring this out is more complicated than it may seem. Soil structure is not uniform and the way that liquids flow through it often varies from one part to another. Also, sometimes the liquid interacts with contaminants in the soil, such as mechanical lubricants or dry-cleaning fluid. That interaction can affect the flow of the liquid and must be accounted for in the models. The KDI project team developed new modeling and computation methods that allow them to mimic the actual liquid flow.

Why is the study of liquid flow important? It gives us an inexpensive way to learn about soil structure. The alternative is to dig up core samples at specific points and analyze them in a lab-a costly, time-consuming process.

What are the practical benefits of this project? One key application is the clean-up of environmental radiation. The researchers looked at one set of data that involved a plot of ground at a military base that had been decommissioned. Fluids had been spilled at a mechanical garage there that later seeped into the ground and contaminated the soil. The soil needs to be cleaned up so that the contamination does not get into the ground water and pollute the drinking water supply.

The old-fashioned way to clean up the soil is to dig it up, treat it, and rebury it. This is time consuming and expensive. With data about water flow generated by this project, the researchers are developing new methods that involve pumping water through the contaminated region, pumping out the dirty water, and treating it. Using this method, the soil can be cleaned up without digging it all up. This new method is faster and cheaper than the traditional method.

To design these procedures for cleaning up the soil, engineers need to understand how the soil is structured. The models developed by the statisticians and applied mathematicians in this project yield data about soil structure from water flow experiments. Thus, by using water flow data, they can come up with the information about soil structure that the engineers need.

Soil structure information can also be helpful for exploring oil fields, particularly for secondary production. When you first drill an oil well, the oil gushes to the surface under its own pressure. But only about one-third of the oil comes out this way. The rest needs to be pushed out of the ground. Secondary production involves increasing underground pressure by pumping in water, natural gas, or steam. That increased pressure forces out more oil. With the soil structure information generated by the models developed for this project, engineers can figure out where to pump in the additional material so that the pressure forces the oil to the surface, rather than away from the drilling site.

As Herbie Lee, one of the investigators on this project, notes, "This was a great project in that it involved bringing together engineers, statisticians, and applied mathematicians to work together on a critical need for our society. We probably wouldn't have had this close of a collaboration if it weren't for a grant like this."

Back to Top of Page