OREGON STATE UNIVERSITY

OSU has new ways to assess groundwater pollution

01/21/1998

CORVALLIS - A team of Oregon State University scientists is working to develop simpler, faster and more cost-effective methods to assess and clean up groundwater contamination in places such as Hanford Nuclear Reservation, military installations and petrochemical facilities.

The new OSU tests are five to 10 times less expensive and take much less time - hours or days, instead of months or years. They also give just as much or more information than the more traditionally used methods, which may take many years and cost millions of dollars to complete.

"Often times, with traditional methods, more money and time is spent studying the problem than on cleaning it up," said Jack Istok, a professor of civil engineering at OSU. "We think our new methods help us get into the field more quickly and inexpensively and get to the cleanup stage sooner. And we learn about the factors that influence the whole system - the physical, chemical, biological. Managers are a lot more willing to start clean up if they can see initial results sooner."

Rather than start with small experiments in the lab as most scientists do, Istok and his colleagues jump into the field right away.

"Otherwise," Istok said, "we might be studying the wrong problem or miss something totally obvious."

To initially assess a groundwater contamination problem, Istok and his colleagues devised a new "push-pull" method, where a known amount of test solution is injected into a single well, then later extracted, along with the groundwater mixture from the same well. Their test is much quicker than the more standard methods where test solutions are injected into one well, then measured in other wells in the aquifer.

The liquid extracted from the well may reveal a lot about the nature of the groundwater pollution, said Jennifer Field, an assistant professor of environmental chemistry at OSU. Field and her colleagues analyze the solutions from the push-pull tests in the Department of Agricultural Chemistry at OSU.

"This push-pull method can give us information about the aquifer, the chemical contamination and its biological characteristics, depending on what we inject into the well," said Field. "It can also give us information on how best to clean up the groundwater."

Working with the team to develop test solutions to inject down the wells in the push-pull tests is Michael Hyman, a microbial ecologist in OSU's Department of Botany and Plant Pathology. Hyman looks at the influence of microorganisms, especially their role in cleaning up fuel and solvent spills.

Once initial information is gleaned from the push-pull tests, the scientists build intermediate scale models of a section of the aquifer in OSU's Groundwater Research Laboratory in Corvallis. Hauling in large amounts of uncontaminated native sediments from an aquifer of interest, they build large pie-shaped wedges in which they conduct their "sandbox" experiments.

"In our sandbox models, we can simulate the movement of contaminants traveling through the aquifer," said Istok. "Once we know how a contaminant moves in the subsurface, we can also test how well a clean up method might work."

Istok has used these methods to assess and clean up sites at Hanford Nuclear Reservation, Hickam Air Force Base and on oil company property in the Pacific Northwest. They have addressed radioactive contamination, fuel spills and trichloroethylene (TCE), a common solvent and groundwater contaminant.