July 16, 2020
In the wake of the Brazilian tailings dam failures, the safety of upstream dams is coming under intense scrutiny by the communities, investors and the mining companies. Upstream tailings dams depend upon the strength of the deposited tailings and there can be a wide range of conditions and variabilities within the deposited tailings. The strength of the tailings varies with the type of tailings (e.g. Fine tailings to Coarse tailings), deposition practices and changing ore types. Static liquefaction of tailings has been the cause of recent failures and although it is a long-recognized phenomenon, the conditions that can ‘trigger” static liquefaction are not well understood, and the awareness of these conditions are not widespread in the technical community. Common problems with assessment of stability of upstream dams are discussed along with practices to improve the safety of upstream dams.
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Harvey McLeod, P.Eng., P.Geo.
Harvey McLeod is a geotechnical engineer with 45 years of experience in all aspects of tailings dams. He has a degree in geological engineering from the University of British Columbia and a Masters of Soil Mechanics from Imperial College, London, UK. Harvey has worked on hundreds of tailings dams in all types of physical, climatic and social conditions in over 30 countries. He has been active with the International Commission on Large Dams (ICOLD) for 20 years and is currently Chair of the Subcommittee on Tailings Dams. Harvey supported the British Columbia Ministry of Energy and Mines with the Chief Inspector’s investigation into the Mount Polley tailings dam failure and was Chair of the Subcommittee on redrafting the tailings dam regulations. Harvey also chaired the Engineers & Geoscientists BC’s production of the Guideline on Dam Foundation Characterization, which was a recommendation of the Panel Report on Mount Polley. He also presented the RM Hardy Keynote Lecture in 2016.