McPhail, GI & Rye, C 2008, 'Comparison of the Erosional Performance of Alterative Slope Geometries', 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. 277-288.
The principal criterion in specifying a dump or heap leach pad slope geometry is slope stability which
requires that the overall slope of the facility be such that the facility remain stable under all reasonably
conceivable conditions. However, long-term erosional performance is also an important criterion and one
that frequently results in major construction costs to modify the slope geometry at closure. It is therefore
prudent to consider erosional performance in the course of evaluating slope stability.
The required geometry for long-term erosional performance has long been a concern of regulators who have
been under pressure from industry to provide guidelines that, if complied with, will ensure that the closed
facilities automatically satisfy relinquishment requirements without a need for detailed justification.
To date, most guidelines have stipulated a slope geometry made up of a series of benches with slopes
ranging from 18 degrees to natural angle of repose between the benches. However, observation of the
performance of such benched slopes has shown poor performance generally related to silting up and
overtopping of benches as well as severe gully erosion of the slope faces.
This paper documents the evaluation of a range of slope geometries using the erosion model SIBERIA. The
paper provides a quantitative comparison of their relative erosional performance and presents criteria and
guidelines for the selection of a dump or heap leach pad slope geometry to meet erosional performance
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Comparison of the Erosional Performance of Alterative Slope Geometries G.I. McPhail, C. Rye
288 Rock Dumps 2008, Perth, Australia