Team Leader, Hydrogeology
+61 8 9211 1417
+61 8 9211 1402
The location and development of adequate groundwater resources is a key issue for many mining projects, especially those located in semi-arid and arid environments. Groundwater as a water source can offer various advantages, including a reduced seasonal fluctuation of supply to the point of use, the potential to integrate with mine dewatering and slope depressurisation needs, reduced evaporation losses and reduced sedimentation/ bacteriological treatment needs.
Development of a groundwater resource requires an assessment of resource potential, evaluation of potential yields and drawdown impacts and potential water treatment requirements.
MWH provides comprehensive groundwater resource services to assist our clients throughout the mining lifecycle, from grass roots exploration through aquifer testing, impact assessment, numerical groundwater modelling, wellfield design, construction and commissioning through operation, monitoring, maintenance and decommissioning. MWH prides itself on the ability to work with our clients to maintain focus on the project goals, while interpreting model results and data as they are compiled, limiting time spent studying extraneous data that has little effect on the intended evaluation.
MWH has experienced geoscientists that provide speciality knowledge in geochemical and hydrochemical studies to support mining projects and the natural resources sector worldwide. We have conducted geochemical and hydrochemical studies during every stage of the mining life cycle to fulfil various client objectives, from permitting and planning greenfield projects through to closing abandoned legacy mines. These capabilities, combined with our broad range of service offerings to the mining industry, enable us to deliver innovative technical solutions.
Our primary areas of expertise are acid and metalliferous drainage (AMD) prediction and modelling; AMD management and mitigation; contaminant fate and transport modelling; water quality characterisation and prediction, including pit lake assessment; and mine water treatment. MWH has conducted studies involving a variety of contaminants, including sulphate, metals and metalloids, cyanide, organics, and radionuclides.
Starting from the planning stage of a project, we support clients to identify key closure issues and appropriate mitigation and closure strategies. Data from AMD characterisation and predictive modelling, together with hydrological and hydrogeological site characterisation, form the basis for hydrogeochemical and fate and transport modelling that can be used to predict water quality impacts and identify potential risks to the environment. Viable management options for these risks can then be developed, evaluated and implemented as needed to meet regulatory requirements and minimise social and environmental impacts.
Water issues are becoming a considerable factor affecting growth and profitability of resource companies and water resource operators. Water risks occur in diverse operating environments. Companies and organisations that are able to proactively identify and mitigate water-related risks understand that water is a critical business asset which needs to be managed to preserve and create commercial value.
Addressing water management issues in an integrated fashion results in effective mitigation of water-related risks and allows a range of objectives to be met. Effective planning and adoption of a strategic life-of -mine approach to water management leads to significant environmental, social and economic benefits. Reviewing all water management aspects across the site allows identification of inter-related water risks and challenges. If these issues are addressed individually, costs may be too high to be borne by individual operational departments. When considered as a whole, the issues often become opportunities and provide the stimulus for integration of site-wide water management across operational departments.
In response to strategic water management, the resource industry needs to be proactive by strategically planning for, and managing, water resources to deliver the following benefits:
- Continued access to water for production and growth
- Reduced operating costs from efficient resource use
- Improved environmental outcomes and reduced environmental risk
- Enhanced reputation through better stakeholder relationships that consider community expectations
- More efficient working relationships with regulatory authorities.
Water and chemical mass balances create a management and strategic planning tool that can be used to evaluate the impacts of operational and environmental changes, as well as uncertainties at a mine site. Mining companies are increasingly turning to predictive models to better evaluate risk and retain operational flexibility over the life of a mine.
Water balance modelling can improve efficiencies by helping to identify poorly operating control systems and to identify and quantify leakage and seepage from infrastructure. Incorporating chemical analysis into the water balance analysis can improve understanding of the causes of poor mine water quality and predictive capabilities can reduce operational and post-closure water quality risks. Successful mine water management not only includes tracking and reporting water volumes and quality, it also includes the ability to forecast impacts due to:
- Operational changes, environmental uncertainties
- The inclusion and/or expansion of facilities
- Long-term planning for closure and relinquishment.
A water management strategy that is based on a site-wide model will help mine operators and managers make cost efficient decisions that help the mine to achieve and maintain regulatory compliance. At MWH we tailor our modelling tools and model complexity to the needs of the project, ranging from simple spreadsheet analysis to more complex GoldSim and PHREEQC approaches. Our modelling philosophy is centred on developing a thorough understanding of the site processes, then forming a conceptual and predictive model to help operators measure and understand mine water systems.
A general trend towards larger and deeper mines is resulting in a need to manage increasing volumes of water. Rapid mine development schedules and a requirement for integrated water management with efficient utilisation of water resources, means that the prediction of groundwater inflows through the mine lifecycle is important. Large open pits frequently demand the use of a higher proportion of in-pit dewatering methods. The desire to accelerate the rate of vertical development increases the dewatering volumes required. Deeper mines and the use of bulk mining methods also leads to the requirement for an increased consideration of pit wall and underground workings stability.
MWH provides realistic mine inflow estimates that consider uncertainty in the available information and the mine plan. Our approach is to work with the mine planners to develop mine dewatering strategies that meet production requirements, while minimising interference with mine production and are flexible enough to adapt to frequently changing mine plans.
Our staff have a breadth of experience, facilitating the selection of mine dewatering methods which are optimal for the mine design and hydrogeological setting. MWH has the engineering capacity to design the full range of dewatering and water disposal infrastructure.
Pit slope and underground mine working depressurisation can play a key role in minimising mine safety concerns, development costs and minimising the risk of production interruptions. MWH can help by working closely with project geotechnical engineers to provide a realistic assessment of rock drainability, provide pore pressure inputs to stability analyses and identify the drainage infrastructure and monitoring required to support pit slope depressurisation.
Mine Water and Chemical Balance Study Capabilities and Recent Experience
- Tailing storage facility water balances
- Comprehensive site wide water balance analysis
- Chemical mass balances Water audits
- Options evaluation
- Pitarrilla Mine, site-wide water balance modelling, Silver Standard Resources.
- Hamersley Iron Properties, water management program, Hamersley Iron.
- Rosia Montana Mine, site-wide water balance modelling, Rosia Montana Gold Corporation.
- Resolution Copper Mine, water and chemical mass balance modelling, Rio Tinto.
- El Morro Mine, water balance for filtered tailings assessment, Xstrata Copper.
- Carlota Mine, leach pad water balance, Carlota Copper Inc.
- Marlin Mine, site-wide water balance modelling, Montana Exploradora de Guatemala.
- Constancia Mine, GIS-based water balance analysis, Norsemont Peru.
- St Ives Gold Mine, TSF and heap leach water balance, Gold Fields, Australia.
- Pardoo Iron Ore Mine, pit lake water and chemical balances.
Mine Dewatering and Slope Depressurisation Capabilities and Recent Experience
Our Capabilities :
- Hydrogeological site investigation, including packer testing
- Conceptual and numerical groundwater modelling
- Mine inflow and drawdown impact predictions
- Dewatering system design and optimisation
- MAR system design and optimisation
- Dewatering system operation and maintenance manuals
- Pit slope and underground workings pore pressure and drainability assessments
Our Recent Experience:
- Pit depressurisation studies & review of dewatering methods Mining Area C, BHP Billiton.
- Dewatering infrastructure engineering, Cloudbreak, Fortescue Metals Group.
- Hydrogeological investigations, groundwater modelling, dewatering simulation and mine schedule requirements and environmental impact assessment, Nyidinghu, Fortescue Metals Group.
- Geotechnical investigations, Hope Downs 1 and Hope Downs 4, Rio Tinto.
- Dewatering investigation program and groundwater modelling to assess dewatering volumes and impacts, Hope Downs 4, Rio Tinto.
- Hydrogeological investigation for closure and numerical modelling of pit lake recovery in Leigh Creek, South Australia for Alinta Energy.
- Hydrogeological investigation and prediction of pit lake recovery and water quality post closure of 33 mining pits, St Ives, Gold Fields.
- Hydrogeological investigation and numerical modelling of the dewatering design, Roy Hill Iron Ore Mine.
Groundwater Resource Exploration and Development
- Identifying potential groundwater source
- Designing and implementing groundwater investigation programs including approvals
- Supervising groundwater investigation programs
- Providing reports to support approvals and licensing processes
- LOM water balance assessment
- Evaluating disposal options if required
Our Recent Experience:
- Groundwater investigation from grass roots to PBR/BFS approvals, Roy Hill Project, HPPL.
- Groundwater investigations testing, conceptualisation, numerical modelling and impact prediction, O’Callaghan Deposits, Telfer Gold Mine, Newcrest.
- Groundwater investigations, testing, numerical modeling to simulate dewatering requirements for trial mining pit and disposal options, Bungaroo Project, Rio Tinto.
- Groundwater investigations from grass roots to Public Environmental Review (PER) approvals for water supply and dewatering requirements, Hope Downs 4, Rio Tinto.
- Detailed groundwater investigations, testing, conceptualisation and modelling, Nyidinghu Project, FMG.
- Regional assessment of groundwater and surface water resources, Lower Burdekin Catchment, QLD Government
- Detailed groundwater investigations for an iron ore project, Marillana, BHP Billiton.
- Field groundwater investigation and testing, hydrogeological conceptualisation, HPPL, Mulga Downs.
Geochemistry and Hydrochemistry
- AMD prediction and waste rock characterisation, including static, leachability, kinetic, and mineralogical testing
- AMD management and mitigation, including passive and active treatment
- Geochemical and hydrochemical modelling (including PHREEQC and MINTEQ)
- Flow and contaminant transport modelling through saturated and unsaturated zones
- Water quality characterisation
- Pit lake assessment, including rebound and hydrogeochemical modelling
- Soil and waste rock characterisation for rehabilitation planning
- Waste rock and tailings planning and management
- Landform and closure structure design
- Mine water treatment
Our Recent Experience:
Murray’s Hill Iron Ore Deposit waste rock characterisation and AMD prediction, Hancock Prospecting Pty Ltd, Western Australia
- We undertook a geochemical characterisation programme to delineate the AMD potential of the various lithologic units likely to constitute mine wastes. The characterisation programme included ABA, NAG, leachability, and mineralogical testing. These results supported the development of appropriate management and closure activities.
Pardoo DSO Project pit lake assessment for closure planning, Atlas Iron, Western Australia
- We conducted hydrological and hydrogeologic investigations to inform the mine closure plan. These investigations assessed long-term pit water quality, existing pit water and salt balances, and potential for post closure groundwater and surface water impacts. MWH determined the stable level of the pit lake, identified concentration trends and predicted seepage rates, and evaluated the potential impact on regional receptors. The model was then used to recommend operational and closure strategies.
Mt. Gordon Copper Mine AMD treatment evaluation, Aditya Birla Minerals, Queensland
- We evaluated options for treating pit water impacted by AMD. MWH conducted a site investigation and data analysis to identify and assess water treatment options. It was concluded that a High Density Sludge (HDS) system was appropriate to reduce acidity, sulphate and heavy metals concentrations and meet discharge water quality standards.
Proposed Rosia Montana Gold Mine AMD prediction and water quality assessment, Gabriel Resources, Romania
- We conducted a baseline characterisation of geochemistry and water quality, including existing sources of AMD. This evaluation included water quality predictions, cyanide fate and transport assessment and analyses, a cyanide mass balance and an AMD prediction programme, which comprised static and kinetic testing, including field-scale testing columns.
Resolution Copper Mine AMD prediction and modelling, Resolution Copper Mining, United States
- We undertook an AMD prediction programme, including static and kinetic testing, to evaluate AMD potential within this block cave underground mine. We also conducted mineralogical testing on the humidity cell tests after testing was complete to identify secondary soluble mineral phases that could affect rinse-out chemistry. Calculated leaching rates were utilised in a coupled GoldSim water balance model and chemical mass balance model to predict water quality for the mine during operation, closure, and post closure periods.
Integrated Water Management
Our Capabilities :
- Water related risk evaluations
- Water supply planning and management
- Surface water control and stormwater management
- Groundwater management
- Water balance modelling
- Mine water treatment
- Mine water discharge management
- Potable water management
- Mine waste and acid mine drainage management
- Wastewater treatment, disposal and reuse
- Regional evaluation of water resources, groundwater and surface water conjunctive use.
Our Recent Experience:
- Water related risk assessment, Kinross Global Portfolio.
- Cerro Verde mine water availability and hydrologic impacts study, Freeport McMoRan Copper & Gold.
- Bungaroo Creek flood management assessment, Rio Tinto Iron Ore.
- Tailings dam reclamation and water management services including water balance modelling, Freeport – McMoRan Copper & Gold.
- Acid mine drainage treatment, Birla Mount Gordon Copper Mine.
- McPhee Creek excess mine water disposal evaluation, Atlas Iron ltd. Mine water treatment plant design, Gold Fields.
- Taharoa, iron sand mining groundwater and surface water management, New Zealand.
- Marillana, iron ore mining excess dewatering discharge study, BHP Billiton Iron Ore.
- Lower Burdekin water resource management study for a highly productive agricultural region, QLD Government.
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