You are visiting the web site of the EPSCI Program at the U.S. Dept. of Energy's Ames Laboratory, Ames, IA

CATCHING CONTAMINANTS ON THE MOVE
Quicker, easier and less costly installation is an important advantage of Ames Lab's new zero-tension lysimeter over conventional versions. Lysimeters monitor contaminant movement through soil and easy installation makes it feasible to install more monitors for a more accurate assessment of an entire site.

"Contaminant transport through the soil has traditionally been difficult to assess because of the tremendous variability of soil structure and porosity as well as the cost and time involved in installing monitors," says Ames Laboratory's Michael Thompson, designer of an improved device for monitoring the spread of underground contaminants. "The low cost and quick installation of our lysimeter means you can install a lot of them and get a better idea of the spatial and temporal variability of contaminant transport."

Monitoring the spread of contamination through soil should be easier now with Ames Laboratory's new zero-tension lysimeter.

The new technology is actually an improved version of conventional lysimeters. Less expensive and easier to install, it should help DOE scientists guard against the spread of contaminants at sites they manage and allow more effective response when contaminant movement is detected.

Zero-tension lysimeters collect water and contaminants that are mobile in the soil. Permanently installed to allow periodic sampling of soil solutions, the devices allow scientists to identify where environmental contamination has come from and where it has spread. While conventional designs consist of shallow troughs installed laterally, Ames Lab's new lysimeter consists of a screen-covered polycarbonate cup with sampling and vent tubes. To install it, workers pull up a core of soil, place the lysimeter in the ground and replace the undisturbed soil core on top.

While zero-tension lysimeters can be more effective than other monitoring devices, the conventional version is expensive, requiring costly large-scale excavations that disturb the soil and make it difficult to install multiple monitoring sites. Ames Lab's new lysimeter, however, costs about $60, and two workers can install it in less than an hour, making multiple installations easy.

"The structure and porosity of soils change at a very local scale, so allowing multiple installations is an important advantage," says Michael Thompson, principal investigator on the project. More monitoring sites should also allow scientists to more quickly zero in on the source of spreading contamination. Testing the merits of this new design, Thompson has led installation of the new lysimeters at DOE's Rocky Flats Environmental Technology Site in Golden, CO, and at a waste-water disposal site in Ames, IA.

BENEFITS:

• Quicker, Less Costly Installation - Installation is easier and less expensive than with conventional zero-tension lysimeters.
• More Complete Results- Easier, less costly installation allows multiple monitoring positions and therefore, a more complete picture of contaminate movement over an entire site, which helps scientists locate the source of spreading contamination more quickly.
• Minimal Soil Disturbance -Installation leaves natural soil pore structure unchanged, ensuring accuracy of sampling information.
• Safe, Automated Sampling Possible- Sampling can eventually be automated to minimize human visits to a hazardous site.
• Expanded Monitoring- Zero-tension lysimetry allows collection of suspended soil particles as well as dissolved contaminants.

BOTTOM LINE:

Offering expanded monitoring capabilities at a reduced cost, Ames Lab's new zero-tension lysimeter produces a more complete and accurate picture of soil and water flow to help the DOE guard against the spread of contaminants in the upper regions of the soil.

FOR MORE INFORMATION:

Michael Thompson, e-mail: mlthomps@iastate.edu, phone: (515) 294-2415

Please e-mail comments to: epsciwebkeeper@ameslab.gov.

Disclaimer

Last Modified: 1 April 2002 by dave eckels
Zero Tension Lysimeter: etd/technologies/projects/ztl/index.html