ASPECTS OF THE DIFFERENCES IN THE ERODIBILITY OF THE WASTE ROCK DUMP AND NATURAL SURFACES, RANGER URANIUM-MINE, NORTHERN-TERRITORY, AUSTRALIA

Small-scale flume experiments on the waste rock dump of Ranger Uranium Mine, Northern Territory, Australia, show that the unmanaged surface of the dump is 10-100 times more erodible than adjacent natural hillslopes. Silt and clay are preferentially removed and their proportion of the total sediment load is enhanced over their content in surface sediment, There is strong evidence that a low threshold of erosion does not exist and that even the smallest of flows across the waste rock dump can erode and transport some surface material, The erodible dump surface and the preferential removal of silt-clay could degrade ecosystems both on the dump and off-site, Rehabilitation of the waste rock dump will require special attention to erosion and its management.