Williams, DJ, Scott, P, Johnston, D & Lee, G 2008, 'Rock Dump Design to Limit Potential Acid Drainage', in AB Fourie (ed.), Proceedings of the First International Seminar on the Management of Rock Dumps, Stockpiles and Heap Leach Pads
, Australian Centre for Geomechanics, Perth, pp. 207-217, https://doi.org/10.36487/ACG_repo/802_18
The design of rock dumps comprising reactive rock should aim to limit the potential for the release of acid
drainage to the environment. This requires the recognition of a number of contributing factors. Clean runoff
should be kept separate from mine water, by diverting runoff upslope of the dump and lining surface
drainage channels to be buried by the dump with benign rock. There is a need to selectively place benign
and reactive rock to encapsulate the reactive rock. The rock dump hydrology needs to be understood, in
particular the wetting-up of the dump by rainfall infiltration, in the context of the climatic setting, the surface
hydrology, and the groundwater regime. Finally, a low percolation cover is required over the top of the
dump, and side slopes should not be underlain by reactive rock and should be designed to minimise erosion.
The paper describes the application of these principles to the design of a new rock dump being constructed
at an existing open pit mine that has experienced acid drainage from a past rock dump. The design of the
new rock dump to limit the potential for acid drainage required a change in the mind set for rock dump
construction, and imposed a number of constraints on site preparation, construction of the rock dump, and
the sequencing of rock dumping, which had to be overcome.
EGi (1997) Geochemical characterisation, classification and scheduling of waste rock. Report to Century Mine by
Environmental Geochemistry International Pty Ltd, December 1997.
Williams, D.J. and Rohde, T.K. (2008) Rainfall infiltration into and seepage from rock dumps – A review. Proceedings
First International Seminar on Rock Dumps, Stockpiles and Heap Leach Pads, A.B. Fourie (editor), Australian
Centre for Geomechanics, Perth, Australia, 5-7 March 2008, 11 p.
Williams, D.J., Stolberg, D.J. and Currey, N.A. (2006) Long-term performance of Kidston’s “store/release” cover
system over potentially acid forming waste rock dumps. Proceedings of Seventh International Conference on
Acid Rock Drainage, St Louis, Missouri, USA, 26-30 March 2006, pp. 2385-2396.
Hydrology of Rock Dumps
Rock Dumps 2008, Perth, Australia 217