HR: 0830h
AN: H31B-0470    [PDF]
TI: Field Comparison of Direct-Push Approaches for Determination of K-Profiles
AU: * Dietrich, P
EM: peter.dietrich@uni-tuebingen.de
AF: Center of Applied Geoscience, University of Tuebingen Sigwartstr. 10, Tuebingen, D-72076 Germany
AU: Butler, J J
EM: jbutler@kgs.ku.edu
AF: Kansas Geological Survey, 1930 Constant Ave., Campus W University of Kansas, Lawrence, KS 66047 United States
AU: Yaramanci, U
AF: Department of Applied Geophysics, Technical University of Berlin, Berlin, D-13355 Germany
AU: Wittig, V
AF: Geoprobe Systems, 601 N. Broadway, Salina, KS 67401 United States
AU: Tiggelmann, L
AF: GeoDelft, P.O. Box 69, Delft, 2600 AB Netherlands
AU: Schoofs, S
AF: GeoDelft, P.O. Box 69, Delft, 2600 AB Netherlands
AB: A large body of theoretical and experimental research has shown that spatial variations in hydraulic conductivity (K) are a significant factor in determining how groundwater and accompanying contaminants move in the subsurface. Therefore, a wide variety of direct and indirect techniques have been developed for the characterization of K variations at a site. Methods based on direct-push technology have much potential for use in shallow unconsolidated settings. However, the various direct-push methods differ in their expense, in terms of time, money, and effort, and the nature (qualitative vs. quantitative) of the information that they can provide. A field study was carried out at a test site near Nauen, Germany to evaluate and compare several direct-push methods for determination of spatial variations in K. The test site was established by the Department of Applied Geophysics of the Technical University of Berlin in collaboration with the German Federal Institute for Geosciences and Natural Resources. Extensive geophysical surface measurements (surface nuclear magnetic resonance, georadar, refraction seismic, and 2D dc geoelectrics), as well as data from a continuously cored borehole, are available. These data provide a controlled framework for the evaluation of different direct-push methods for the characterization of spatial variations in hydraulic conductivity. The following direct-push methods were investigated in this study: electrical conductivity (EC) and cone penetrometer (CPT) logging, slug tests, injection logging, and the direct-push permeameter (DPP). In addition, natural gamma (NG) logging was performed in pipe installed with direct-push technology. EC, CPT, and NG logging are very fast, but do not provide direct estimates of K. Their successful use for site characterization depends on the appropriateness of the applied empirical relationships. As shown by the results from Nauen, EC, CPT, and NG logging are often limited to the delineation of major units of relatively high or relatively low K. The other three methods, injection logging, slug tests, and the DPP, allow a direct assessment of the K distribution. Injection logging, which uses measurements of the flow rate and injection pressure to characterize K, is very fast ($<$ 1 min per interval), but can only provide information about relative variations in hydraulic conductivity. Slug tests in direct-push equipment can provide more reliable K estimates, but require much more time per interval (60 mins). The direct-push permeameter is a tool for the performance of small-scale injection tests that can provide reliable K estimates in a relatively short time (10 mins per interval). The DPP appears to have the most potential for providing K estimates with an acceptable level of efficiency and accuracy. At the moment, however, the DPP is limited to relatively shallow depths at some sites because the downhole pressure transducers cannot be used with hammer-assisted forms of direct push. At those sites, a combination of injection logging and slug tests is recommended for assessing K variations at depth.
DE: 0994 Instruments and techniques
DE: 1894 Instruments and techniques
DE: 5114 Permeability and porosity
SC: Hydrology [H]
MN: 2003 Fall Meeting