Dakota Home Report Archive

1991 Symposium: The Dakota Aquifer in Kansas


A New Approach for Slug Tests in the Dakota Aquifer: Examples From Lincoln and Cloud Counties

James J. Butler, Jr.
Kansas Geological Survey, Lawrence, KS 66047

As part of the Dakota Aquifer Program of the Kansas Geological Survey, well tests are being conducted at five sites within the Dakota Aquifer in central and southwestern Kansas. This presentation will focus on the results that have been obtained from two sites in Lincoln and Cloud counties at which testing has now been completed. In both cases, the hydraulic conductivity of the Dakota Aquifer underlying the sites was found to be approximately 5 ft/day. This estimate was corroborated by both slug and pumping test results at the two sites. Since the performance and analysis components of a pumping test are considerably more involved than the same phases of a slug test, the viability of employing slug tests alone to assess the flow properties of an aquifer was also explored at these sites. A new approach using slug tests with observation wells was experimented with in this work. At the Cloud County site, the screens of the slugged and observation wells were located at different depths. An apparent anisotropy in the hydraulic conductivity of the interval separating the screens made it impossible to detect in the observation well any pressure pulse that could be associated with the slug test. At the Lincoln County site, however, wells screened over similar intervals were used. In this case, the approach seems quite promising. A pulse with an amplitude of 10% of the initial slug was observed at an observation well 22 ft from the slugged well. Results indicate that at this site a well separation of up to 100 ft could have been employed. Given that a slug test can be used to assess the flow properties over an aquifer volume tens of feet in radius, the need of a pumping test for assessing aquifer properties is questionable. An additional important feature of slug tests with observation wells is that a very reliable estimate of the storage properties of the aquifer can also be obtained. Storage estimates from conventional slug tests are notoriously poor. These ideas will be explored further at the remaining three sites where testing should be completed by May of 1992.

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Kansas Geological Survey, Dakota Aquifer Program
Original symposium held October 1991
Electronic version placed online April 1996
Scientific comments to P. Allen Macfarlane
Web comments to webadmin@kgs.ku.edu
URL=http://www.kgs.ku.edu/Dakota/vol3/symp/butler.htm