2007 Ground Water Summit


Monday, April 30, 2007
4:30 p.m. - 7:30 p.m.

Tuesday, May 1, 2007
9:30 a.m. - 1:30 p.m.

Tuesday, May 1, 2007
4:30 p.m. - 7:30 p.m.

Measurement of Centimeter-Scale Ground Water Velocities and Observations of Transient Heterogeneity in a Contaminated Aquifer

P.C. Schillig, J.F. Devlin, N. Kinnebrew, M.A. McGlashan and G.P. Tsoflias, University of Kansas

In the practice of aquifer remediation, groundwater velocity is an essential parameter for determining contaminant fate and transport.  This is true for natural attentuation as well as engineered in situ treatment systems such as reactive barriers, where the residence times of contaminants in the barriers are important. The point velocity probe (PVP) is a tool capable of measuring centimeter-scale groundwater velocities. The instrument returns estimates of velocity independent of Darcy’s Law, thus eliminating reliance on hydraulic conductivity estimates, or on hydraulic gradient estimates that are often only measurable at scales in excess of several meters.  The instrument functions by performing a mini-tracer test around the circumference of a cylinder. Breakthrough curves, using saline tracers, are recorded as electrical conductivity at discrete locations around the cylinder surface (the probe), which is in direct contact with the aquifer. Breakthrough curves are fit to the advection-dispersion equation which calculates an apparent groundwater velocity. Subsequent data reduction corrects for the probe geometry and yields estimates of both direction and magnitude of the average linear groundwater velocity. Numerous laboratory and field studies have indicated that the tool provides high quality measurements of velocity when compared to other instruments designed for velocity estimation, and when compared to the results of larger scale tracer tests and bulk hydraulic behavior. A field experiment applying the PVP to the measurement of flow variations in a bioremediating hydrocarbon plume was performed at the CFB Borden site in Ontario, Canada.  An array of multilevel PVPs installed across the width of a hydrocarbon plume, coupled with borehole radar and tomographic methods, provided consistent indications of time sensitive spatial heterogeneities in the zone of plume attenuation.  The identification and quantification of these processes have important implications for the assessment of plume fate and modeling.

P.C. Schillig, University of Kansas P.C. Schillig is a M.Sc. student in the Dept. of Geology at the University of Kansas. His research is concerned with the development and application of a point velocity probe for monitoring transient heterogeneity in a petroleum hydrocarbon plume.

J.F. Devlin, University of Kansas J.F. Devlin is an Associate Professor in the Dept. of Geology at the University of Kansas. His research interests include the relationship of permeability to reactivity of contaminants in groundwater, aquifer characterization, and granular iron performance in permeable reactive barriers.

N. Kinnebrew, University of Kansas N. Kinnebrew is a B.Sc. student in the Dept. of Geology at the University of Kansas. His research is concerned with the analysis of point velocity probe breakthrough curves relating apparent velocities to average linear groundwater velocities.

M.A. McGlashan, University of Kansas M. McGlashan is a M.Sc. student in the Dept. of Geology at the University of Kansas. His research is concerned with the application of borehole ground penetrating radar to evaluate aquifer variations due to microbial activity in a hydrocarbon plume.

G.P. Tsoflias, University of Kansas G.P. Tsoflias is an Assistant Professor in the Dept. of Geology at the University of Kansas. His research interests include the application of geophysical techniques to geological and hydrogeological problems including the characterization of fracture networks and porous media.


The 2007 Ground Water Summit