9:50am - 10:15am
Groundwater Source Determination of an Underground Diamond Mine Utilizing Water Chemistry and Stable Isotope Analysis
1Institute for Groundwater Studies, Faculty of Natural and Agricultural Sciences, University of the Free State; 2Faculty of Natural and Agricultural Sciences, University of the Free State
An underground diamond mine historically experienced periodic groundwater inflow into the underground workings of the mine, resulting in unsafe working conditions. A conceptual model was developed to better the understanding of the groundwater situation at the mine. Water samples were collected at various points. The samples were analysed for major and minor chemical constituents and the stable isotopes of hydrogen and oxygen. Three sources of groundwater inflow into the mine workings were identified. The investigation illustrates that water chemistry signatures and stable isotope signatures can successfully identify different sources of water that flows into the workings of an underground mine.
10:15am - 10:40am
Integration of Regional and Site Scale Models for an Open-Pit Mine
1Piteau Associates; 2Round Mountain Gold Corporation
Numerical groundwater modeling has progressively become the standard industry tool to evaluate and predict hydrogeologic responses to mine dewatering. Experience has shown that most mine sites require at least two numerical models, each at distinctly different scales, to answer key water management questions. This paper draws on over 30 years of dewatering data from an open pit mine in Nevada, USA to illustrate the importance of scale selection on model development. It uses the experience gained from a 3-D regional-scale model and a 2-D pit-scale model to highlight how both are needed to adequately assess the mine’s water management system.
10:40am - 11:05am
Looking Deeper: Key Considerations for Planning Mining Hydrogeology Investigations using Deep Boreholes
1Golder Associates (UK) Ltd; 2Golder Associates Ltd
Hydrogeological investigations of the deep subsurface are becoming an integral part of mine design and development alongside the geological, geophysical, and geotechnical investigation programmes. Data obtained from these site and depth specific investigations improve hydrogeological characterisation, resulting in reduced project risk and uncertainty.
Deep hydrogeological investigations using deep boreholes (>500 m depth) require specialised planning, services and equipment, and testing procedures. This paper aims to present key considerations when planning and executing deep borehole-based hydrogeology investigations, drawing on experience across three different continents, to aid practitioners planning for similar programmes on mining projects.
11:05am - 11:30am
Application of Anthropogenic Organic Contaminants and Environmental Isotopes as tracers to determine water ingress in the Witwatersrand Goldfields
1Council for Geoscience, South Africa; 2University of South Africa, South Africa
Historical mining has led to environmental degradation in the Witwatersrand Goldfields ever since mining companies ceased pumping water from the mines. A study of using emerging organic contaminants as tracers to map the sources and pathways of water ingress into the mine voids is underway. Water samples from the surface, boreholes and shafts were collected and analysed. Atrazine and caffeine were the most persistent and displayed average concentrations of 0.176 ng/mL and 0.793 ng/mL in surface water respectively. Bisphenol A showed high concentrations in the subsurface with averages of 0.162 ng/mL and 1.082 ng/mL for wet and dry seasons respectively.