Simulation of groundwater mounding at a West Australian mine site

Few studies exist that investigate the potential impact of groundwater mounding due to mining near an environmentally sensitive area in a real world scenario. This paper presents a case study in which the development and extent of groundwater mounding due to mining near the Shark Bay World Heritage Property (SBWHP) in Western Australia (WA) has been simulated. A numerical model was developed that enabled a detailed simulation of groundwater level response to the discharge of a water saturated sand slurry during mining at the project site near Coburn in WA. The simulations showed that after a mining period of around two and a half years, a groundwater mound of around 2.5 m would develop along the margins of the open pit at the SBWHP boundary. 500 m further into the SBWHP, the groundwater mound is predicted to be around 1 m high. A depth to water analysis showed that the groundwater may come within 4 m of the surface in the area of a sand dune swale that traverses from SW to NE near the SBWHP boundary. The results of these analyses provide a perspective of mine-related impacts in a unique environment. The results have been included in an environmental impact assessment (EIA) and used for mine water balance predictions.