Site investigation of soft tailings deposits using a hovercraft

Large volumes of tailings are produced annually by the gold mining industry of Western Australia (WA). This material is hydraulically discharged into large storage facilities using sub-aerial deposition methods. A considerable proportion of the gold produced comes from highly weathered rock, resulting in tailings with significant clay contents. Consolidation of these materials can be very slow, particularly if occurring under the effects of self-weight alone. Therefore, disposal management strategies are particularly reliant upon allowing successive layers of tailings to dry sufficiently before the next layer is deposited. In order to investigate and therefore optimise the behaviour of these tailings storages, it is necessary to develop a method of gaining access to the tailings at all stages following deposition. For this purpose a small hovercraft has been modified and fitted with equipment to enable shear vane tests, piston samples, BAT water samples, CPT and spherical penetrometer tests to be conducted in locations that would otherwise be inaccessible. Results gained from a number of site investigations on active tailings storages have enabled full characterisation of these sites to be accomplished and have shown this to be a viable approach. Examples of typical data are shown from these investigations.