Mao, Y & Kam, S 2011, 'Closure of tailings dams', in AB Fourie, M Tibbett & A Beersing (eds), Proceedings of the Sixth International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 361-372, https://doi.org/10.36487/ACG_rep/1152_38_Mao
The preparation of tailings dams for closure is described in a mine closure plan that is typically prepared a number of years prior to mine closure. Tailings dams typically follow short term design criteria during the operational stage and then transition to comply with long term design criteria when they are prepared for the closure stage. Transition usually requires follow-up works which may not be foreseeable during the development of the closure plan. Changing site conditions and regulatory environment also are major factors to consider in closure planning for tailings dams. Late realisation of closure work components may contribute to an underestimation of closure costs and may result in delays in implementing closure.
Previous experiences in tailings dam closure can provide useful information to better assist with closure planning. Unless fully decommissioned or removed, tailings dams must remain stable and serve their intended function to safeguard the environment over the long term. The long service life of closed tailings dams merits careful consideration in design for closure. This paper provides an overview of some typical closure work components for tailings dams. Examples on carrying out these work components are discussed. It is the authors’ intention to outline a framework that may assist with early stage closure planning based on known and expected future conditions, so as to minimise project risk for closure of tailings dams.
The closure of tailings dams often involves four stages: (1) Investigative components, including geotechnical, environmental, hydrological and biological characterisation programmes to determine the need and the type of work components required for a dam; (2) Routine monitoring components, ranging from dam safety inspections, dam safety reviews to various monitoring programmes to evaluate the condition and performance of the dam; (3) Physical components of a dam that require upgrading to improve stability, pond and seepage conditions, aesthetics, spillway and drainage channel configurations, etc., (as determined from stages (1) and (2)); and, (4) Long-term management components, including care, maintenance and surveillance and managing corporate knowledge of the facility.
CDA (2007) Canadian Dam Association. Dam Safety Guidelines, Canadian Dam Association, 82 p.