Historically, in situ testing of tailings has been primarily based on drilling techniques with the recovery of tube samples, coupled with standard penetration test (SPT), shear vane testing and laboratory test work used to assess the tailings properties. These techniques have limitations. In more recent time, the uses of cone penetrometer testing (CPTu) and associated analytical techniques have led to an improved understanding of tailings in situ properties.

A combination of both drilling and CPTu techniques is considered appropriate for identifying the key engineering properties of tailings. The results of the investigation can then be used in both stability and seismic liquefaction analyses.

Results from the investigation of two different tailing deposition regimes are presented together with their strength and liquefaction assessments.