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Modelling of pit lake filling scenarios using a coupled physical and biogeochemical model

Tailings and Mine Waste Conference (2015 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

Pit lakes are a common post-closure feature at mine sites where open pits are allowed to fill with groundwater and surface runoff. The large volume of pit lakes and their potential role in water management make them a focal point of closure planning. Pit lakes can be allowed to fill passively, or alternatively, filling can be engineered to best meet closure objectives. In this paper, engineered filling scenarios are modelled using PitMod, a coupled physical-biogeochemical pit lake model. The filling scenarios considered include: 1) slow filling, involving the routing of clean surface waters away from the open pit; and 2) staged filling, involving initial filling of the pit with contaminated seepages, followed by freshwater inflows. The model results indicate that considerable benefits can be realized for pit lake surface water quality under engineered filling scenarios. Benefits relate to: 1) development of permanent stratification (meromixis) and development of sulfate reducing conditions in anoxic lake bottom waters; 2) physical and chemical isolation of poor water quality in pit bottom waters; 3) development of surface water quality conditions more conducive to in-pit bioremediation; and 4) delay of pit filling, allowing greater time to reduce contaminant concentrations prior to pit lake overflow.

Conference Paper

eng

Vancouver : University of British Columbia Library

10.14288/1.0320882

Applied Science, Faculty of; Mining Engineering, Keevil Institute of

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