Dewatering is critical to most mining operations. Yet it is not simply about pumping groundwater. The mine manager needs to extract the lowest volume of water, at minimum cost. Once extracted, water must be transported, stored, treated and disposed of - all the while minimising the environmental impacts of each activity. The operational costs of these secondary activities is much greater than the original cost of extraction. Accurately planning groundwater extraction for dewatering is critical to mine profitability.
Seepage into a pit or underground workings can seriously impact mine productivity. Groundwater extraction will reduce ingress, but can adversely impact groundwater-dependent ecosystems. The mine manager needs to minimise not only the cost of extraction, but also the secondary cost of transport, storage, treatment and disposal. Variable quality - both spatially and temporally - can constrain re-use, disposal and treatment, thereby increasing cost. Mine infrastructure to support water management (for example pipelines, pumps and lagoons) is expensive to build, operate and maintain.
Groundwater modelling can be used to define the expected drawdown efficiency, including rate of groundwater decline and shape of the drawdown cone. Groundwater modelling can also facilitate decisions related to drilling and construction of abstraction and monitoring bores, as well as the required pumping rates and pumping distribution. Uncertainty analysis of the results will enhance confidence in the decision making process. Appropriate groundwater modelling is key and must consider the:
- complex geometry and geology of the mine site including faulting and fractures
- presence of surface water bodies and wetlands
- spatial and temporal distribution of recharge
- groundwater salinity and density-dependent flow
- water quality
Simulation of mine dewatering and groundwater flow paths
MIKE Mine enables the synchronisation of your dewatering program to mine planning and production through the incorporation of real-time operational management tools. MIKE Mine centralises online and offline data, automates data analysis and forecasting, uses widgets to build customisable dashboards and makes these accessible – anywhere, anytime and from any device. Read more
FEFLOW is widely used for the simulation of mine dewatering, geothermal energy and underground structures. FEFLOW uses a finite-element solution to handle a broad variety of physical processes for subsurface flow and transport modelling. The finite element method allows flexible meshing strategies for detailed models of complex geologic structures, precise spatial representation of features such as rivers, fractures, drifts and wells and accurate representation of sloping layers and anisotropy. Read more
MIKE SHE simulates surface water, groundwater and groundwater-surface water interaction at the catchment scale. It is the global leader for modelling the impacts of dewatering on wetlands, streams and the ecology. MIKE SHE uses a finite difference solution to partition rainfall into runoff, infiltration and evapotranspiration, thereby allowing the simulation of surface runoff and flooding, stream flow (including operational control structures), unsaturated infiltration and recharge, spatially distributed actual evapotranspiration, groundwater flow and fully integrated and multi-species reactive solute transport. Read more