News Release, Kansas Geological Survey, Sept. 7, 1999
The $226,000 grant was awarded to KGS researchers Jim Butler, Geoff Bohling, Li Zheng, and Carl McElwee to test a new technique for predicting how fast groundwater will move at a given site, which could improve strategies for contamination cleanup.
"Whenever there's groundwater contamination, the big question is how fast is it moving," said Butler, the grant's principal investigator. "It's important to know whether it's going to be two months or two hundred months before the contaminant reaches drinking water supplies."
As with other environmental problems, the funds available for cleaning up groundwater are limited. "We need to decide which sites pose the most serious risks and get those cleaned up first," said Butler. The technique he and his colleagues are proposing will not only help assess the threat at a contaminated site but will also help in the design of cleanup strategies.
Groundwater occurs in the pore spaces of underground rocks and moves at variable rates depending on the characteristics of the rock.
The problem, Butler said, is that rock characteristics vary tremendously, even over short distances. That variability makes it particularly difficult to predict how fast a contaminant is moving.
Some rocks are much more permeable--that is, water moves through them much faster, sometimes 100 times or more faster, than would be expected based on the characteristics of the neighboring rock.
"Obviously, the faster the groundwater moves, the greater the threat the contamination poses to neighboring water users," Butler said. "In addition, the existence of highly permeable zones in the rock can greatly reduce the efficiency of cleanup activities."
The trick is to identify those zones. To do this, KGS researchers will use ground-penetrating radar combined with a new type of pumping test to create a detailed image of the rocks between two adjacent wells, in much the same way as a CAT scan provides an image of the human body.
The three-year grant will support both theoretical computer modeling and experimental research in the field. The field work will be conducted at a site just northeast of Lawrence, which the Survey has studied for the last ten years. "We already know the characteristics of the rocks at this site," Butler said, "so we essentially have an underground laboratory that can be used to assess the potential of this new technique."