The Mt Morgan mine, located some 30 km south-west of Rockhampton, is arguably the world’s richest current or historical gold mine. The site has been subject to both underground and surface mining operations since the late 1800’s. Poor quality surface and subsurface runoff from disturbed areas, and seepage from storages, has resulted in substantial environmental damage to the nearby Dee River. Mt Morgan has the dubious distinction of being classified as the largest and worst abandoned mine pollution problem in Queensland.
Water Technology staff undertook a study which quantified the existing hydrologic behaviour of the Mt Morgan mine site. Three numerical models were developed and calibrated against recorded data; a rainfall-runoff model, a groundwater model and a behavioural (storage) model. Once calibrated, a number of model runs were undertaken using 100 years of historical daily rainfall; this considered the impact of different sequences of wet and dry years. The results of these runs were used to develop statistics of mine water balance behaviour for use in site management and rehabilitation planning.
The water balance model was used to evaluate the effectiveness of a range of mine site management and rehabilitation options, inform the rehabilitation plan and assess the impact of a proposed reprocessing operation on the mine site water balance.