University of Kansas
Rick Devlin obtained his Ph.D. from the University of Waterloo, where he subsequently worked for 4 years as a Research Assistant Professor. He moved to the University of Kansas in 2001 where he is now a professor. His research interests include in situ remediation of groundwater and aquifer characterization. He has published on in situ bioremediation, granular iron chemistry, and the development of the point velocity probe, PVP. Current research includes the application of the PVP to groundwater stream water interaction studies, and the development of an in-well PVP.
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Extensions of the Point Velocity Probe to Groundwater-Surface Water Interactions and Rapid Responses Using Monitoring Wells
In order to assess risk to people and ecosystems, the quantification of contaminant fluxes from groundwater to stream water is important. Conversely, the contamination of aquifers by losing streams that are polluted may be limiting for the use of the local water resources. In order to quantify pollutant fluxes across the stream water-groundwater interface experimentally, various tools have been employed including Darcy calculations, seepage meters, temperature profiles, and very recently, PVPs. The PVP tool was deployed in a stream in Grindsted, Denmark, to sample groundwater velocity on a dense grid similar to that employed for the temperature profiling. Early analyses of the data indicate that the PVP estimates of water flux matches those based on minipiezometer deployments and streambed slugtests, but with less time to obtain the data. Other methods compared well in relative distributions of flow rates through the streambed.
The original PVPs require dedicated boreholes and this can be an obstacle to their use since it may require special mobilization of drilling equipment. In an effort to bring the technology to professionals for initial investigations without the incursion of this additional cost, the probe was redesigned to perform inside typical monitoring wells. The new instrument was shown to function well in laboratory tests, yielding velocities with in about +/-10%, and general flow directions. As with any in-well technology, in field applications this instrument is susceptible to biases caused by the condition of the well screen and/or filter packs.