Characterization of sand lenses and their role for subsurface transport in low-permeability clay tills

Glacial sediments dominate large parts of the geological topology in Denmark. They predominantly consist of lowpermeability tills, but fractures and sand-lenses constitute zones of enhanced permeability facilitating preferential flow. This study focuses on characterization of sand deposits with regard to appearance and hydraulic properties. The investigated sand lenses appear as thin sheets, elliptic lenses or small pockets. Most common are elongated shapes with large vertical and horizontal anisotropy deriving from the ice movement direction during deposition. It proved important to include the sand lenses in hydro-geological models to successfully characterize subsurface flow and transport, e.g. for remediation activities.