Variation in Hydraulic Conductivity in Sandy Glacial Till: Site Variation Versus Methodology

Abstract: The sandy till of the Green Bay Lobe in Wisconsin is mapped as the Horicon Formation, a lithostratigraphic term that implies that certain properties of the unit can be recognized everywhere it occurs. A compilation of a limited number of hydrogeological studies of the Horicon Formation by Rodenbeck (1988) showed that hydraulic conductivity varies over three orders of magnitude in a medium that appears texturally and lithologically homogeneous. The overall objectives of this study were: (1) to determine if this apparent heterogeneity is real or a result of different testing methods at different scales, and (2) to examine the effects of the scale of measurement on different methods of determining hydraulic conductivity in such materials.