Objective
The objective of this review is to identify key considerations for the siting and design of mines and associated activities during planning stage, to reduce potential groundwater impacts.
Design and Methodology
This review is based on sites where mining and associated activities have led to groundwater contamination. Data from multiple sites across Australia have been evaluated in terms of a source, pathway and receptor framework to identify common themes.
Original Data and Results
At each site, waste material (waste water and/or solid waste) from the mine or other associated activity represents the key potential contamination source. In addition to waste rock (overburden or tailings), other solid waste may be dispersed throughout the waste rock, placed in designated areas or encapsulated within engineered landfills. Waste water may be stored or irrigated on site.
Pathways between the source and receptor may be enhanced by mine activities, including artificially high permeability (e.g. mine voids and collapse), heterogeneous fill material and/or increased hydraulic gradients.
Common receptors include groundwater supply, the mine and neighbouring operations, as well as surface water and ecological features.
Common themes identified from the review were:
Groundwater data – often there is a disconnect between data collected for environmental monitoring purposes vs data collected to support site operations. This can delay collection of appropriate data to assess site contamination and identify potential risks to receptors;
Regulator involvement – there can be a disconnect between the expectations of regulators who are primarily focussed on operational compliance vs those that are focussed on environmental performance; and
Conceptualisation – a conceptual site model may not be required at the planning stage, but this is essential for contaminated site and risk assessment.
Conclusion
Most mine sites have contamination sources with the potential to cause groundwater impacts. The common themes identified highlight the importance of considering mine siting and design within a groundwater contamination assessment framework during the planning stage. Consideration of these themes may reduce impacts on groundwater during mine operation and closure stages, with associated environmental and financial benefits.