Soft zones in the glacial till in downtown Edmonton

High-rise buildings in downtown Edmonton have generally been founded on spread footings in glacial till. Early geotechnical work proposed a geological model comprising uniform, very dense basal (lodgement) till. However, recent work shows that the till is more complex, being variable in both material type and consistency. A case history is described that exemplifies this variability. It is concluded that early experience with the dense tills has led to an overconfident approach to soil investigation in this area and that a thorough site investigation is required.