This study, jointly sponsored by MESA and CSIRO Division of Soils, has established a series of 170 cored holes (benchmark sites) drilled to 10m depth where possible. Samples from the cores have undergone geomechanical and soil tests which include: Atterberg limits, particle size analysis, solute electrical conductivity and a new swell-shrink test (SST). This new test has yielded: strains (vertical, horizontal, volume), water contents at fixed suctions (pF 3.0 and sorption limit pF 6.34) and wet bulk density. A series of derived parameters from the SST are also presented and include: water content and suction at the shrinkage limit, and an instability index. A limited number of reactive soils and clays were examined using powder X-ray diffraction techniques to determine their mineralogy. More than 1500 m of core from this study have been retained for future reference at the DEM Drill Core Library, Tonsley