Mine landforms in Western Australia from dump to landform design: review, reflect and a future direction

Abstract

Open cut mining in Western Australia (WA) has rapidly expanded in the last 60 years. Volumes moved per annum, once small, are now in excess of millions of tons per project. Dumping these volumes into stable formations a minimal distance from the pit as per model optimisation has proven a challenge, not only to the mining organisations, but to the regulators of those organisations, as optimal dumping design does not, in many cases, result in landforms that can be easily rehabilitated and closed. Stable, safe, non-polluting, rehabilitated landforms that meet a final land use while meeting the demands of the community and regulators has required a steady change in approach leading to the industry taking responsibility via a suite of gradual improvements in waste characterisation, landform design and managed construction over the last four decades. Commencing in 1989, the author became involved in landform rehabilitation for a multi-mine gold company, just as the Minerals and Energy Research Institute of Western Australia was conducting initial waste dump rehabilitation research in WA. Since that time, the author has consulted to many mines, and benchmarked mine closure widely across Australia and internationally, building capacity with mining professionals engaged in landform closure and rehabilitation by learning from successful, and not so successful, landform techniques applied at a wide variety of mine types. A review across this short but dynamic period of landform construction and rehabilitation shows that there has been the steady application of a range of sciences to support landform construction, primarily with waste characterisation and block modelling to control mine waste dumping, the use of early computer aided design tools and erosion modelling tools. In time this advanced to a suite of one, two and three-dimensional Landform Evolution Modelling (LEM) software programmes that are used extensively. However the review suggests that despite the industry's desire to proceed well, we are yet to take full advantage of the suite of geomorphic landform design tools available by application during mine planning, and that for some reason these have not been brought into common use in WA, unlike other major mining jurisdictions such as in USA. We briefly discuss the evolution of landform design tools as we look to the future and further work on effective application of landform design, and as the industry looks to design in solutions to the landform problems of the past. In WA landforms constructed under the historical context of emerging knowledge provides the capacity to inform and learn by comparison of both historical and current closure and rehabilitation activities. Landform rehabilitation is a time-dependent process. It's important that we reflect, review and determine a future direction while comparing the past and how our learnings can be applied to the challenges, we currently face in landform design, construction and closure.

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