Understanding internal erosion: a decade of research following a sinkhole event

Since the investigations and repairs to two sinkholes in the core of the WAC Bennett dam in Canada were completed in 1997, forensic analyses, field tests and university research have continued. The studies have provided fresh insights into the nature of internal erosion, and suggest that the presence and combination of three factors: material susceptibility, critical hydraulic load and critical stress condition, could determine the form of any defect related to internal erosion that may occur. It is proposed that the use of these three factors be considered as a basis for developing a framework for characterizing internal erosion.