Specialist Environmental and Civil Engineering Services

Mine Residue Facilities

Metago's engineers have collectively over 100 years of mine residue disposal experience covering virtually all phases of mine life from feasibility studies to decommissioning, closure, remediation and post operational phase land use development. Our experience in tailings dam design covers vastly different environments around the world (Australia, Brazil Ecuador, Chile, Ukraine, Russia, Congo, Indonesia, Lesotho, Macedonia, Ghana, Tanzania, Uganda, Botswana, Namibia, Zambia, Mozambique, Mauritania, Mali, Madagascar and South Africa) in terms of climate, seismicity, topography, geotechnics, rheology, geochemistry, and water scarcity.

Our senior personnel have been involved in a wide range of minerals including gold, uranium, diamonds, coal, platinum, copper, nickel, chrome, vanadium, mineral sands projects oil, and natural gas. We have designed above ground, valley fill, subaqueous, in-pit and underground disposal facilities.

Metago's engineers have been exposed to a wide range of material transport and disposal methods including mechanical, hydraulic and integrated disposal. Hydraulic disposal covers paste thickened tailings through to conventional slurries.

Our comprehensive experience allows Metago to identify economica and environmentally acceptable solutions which take cognizance of long term liability, through the careful integration of:

• Site specific conditions.
• Geotechnical and geochemical characteristics of the tailings.
• Various possible disposal strategies.
• Closure objectives and constraints.
• Risk Management.

Heap Leach Engineering

Metago has carried out all phases of heap leach pad engineering from conceptual design through to detailed design, tender letting, construction management, commissioning and monitoring of operations. Services include:

• Ore placement and solution management issues.
• Geotechnical investigations of foundations.
• Heap leach pad and solution pond layouts and sizing.
• Waste balance assessments which includes evaluation of detoxification rates and requirements.
• Solution reticulation and application.
• Heap leach ore characterisation in terms of permeability and strength versus cement addition rate.
• Modeling of seepage regimes within different ore types and cement additions and stability analyses.
• Foundation settlement / deformation assessments taking into account liner deformation limits.
• Plastic liner (HDPE) design and specification.
• Ore geochemistry and solution quality changes within the circuit and with time (pH, cyanide, heavy metals release etc.).
• Closure strategies and planning.
• Tender and contract document compilation; tender letting and adjudication.

Heap leach engineering projects have been undertaken on various sites ranging from dry climates with scrub vegetation in Western Australia to wet humid climates in the tropical forest areas of Ghana.

Water Quality and Geochemistry

Metago has developed extensive skills in the field of the prediction and management of water emissions from mining and minerals processing activities, pollution prediction, monitoring and remediation. The ability to recognise and understand the complex cause and effect relationships between erosion, deposition, seepage, ARD, weathering, contaminant transport and hydrology places Metago in a position to engineer more appropriate technical solutions irrespective of the material, situation or environment.

Contaminants that Metago has worked with in the past include organic chemicals (e.g. PAH's, PCB's, benzene, toluene, ethyl benzene); cyanide; heavy metals associated with acid environments such as U, Cu, Ni, Fe, Mn etc.; contaminants that are relatively soluble in the neutral to alkaline environment such as Zn, As2O3 and Cr6+ and sewage effluents and sludge. Metago has pioneered several developments in the field of mine residue disposal design to improve the quality of water thereby reducing costs associated with corrosion and water treatment.

Metago can provide a range of field testing and monitoring services to meet permit or investigation objectives. Metago maintains a range of surface and groundwater testing equipment and makes use of the services of accredited laboratories. Experienced water quality professionals are available to provide services ranging from monitoring database development, GIS development, interpretation of monitoring results and optimisation of monitoring programmes.

Metago personnel have extensive experience in water quality problems relating to:

• ARD prediction and prevention.
• Eutrophication problems and their management.
• Design & upgrade in Waste Water Treatment plants.
• Design and upgrade of water treatment plants.
• Groundwater pollution plume detection, modeling and remediation.
• Water Quality Monitoring Planning & Implementation.

Solid Waste Management (Mining, Industrial and Municipal Waste)

Metago has extensive experience in the fields of waste management and enjoys an international reputation in this regard, having been involved in the design, construction and operation of solid waste facilities in many countries and for many organisations. Metago has contributed to the development and implementation of new proven technologies in this field that limit environmental impacts and improve the social acceptability of solid waste management.

Metago is able to provide a range of services to industries, mining and agricultural companies, municipalities and government departments including:

• Status quo reporting and technical performance audits.
• Design to bankable feasibility level.
• Construction and project management.
• Implementation programs, strategies and plans.
• Closure designs.
• Pollution investigation and remediation.
• Waste Management Facilities Auditing.

Geotechnical Engineering

Metago has extensive experience in the field of geotechnical engineering in soft soils and Metago has several employees that are recognised experts particularly in the fields of tailings beaching characteristics, flow slide modeling, seepage flow, stability analyses and consolidation.

Quantified Environmental Impact Prediction, Measurement and Mitigation

Metago employs or manages specialists who apply internationally recognised tools and techniques to predict and quantify emissions and impacts and integrate the impact assessment with facility design to minimise negative impacts and maximise benefits to the client and affected communities. A quantified benefit cost approach can be applied to enable informed decision making.

Risk Assessment and Risk-Based Site Remediation

The field of environmental engineering is characterised by complex and often poorly understood relationships between a large set of inter-related but often poorly understood variables. Thus compared to many other engineering disciplines, decisions are based on comparatively high levels of uncertainty. Where appropriate, Metago is able to offer clients a service wherein the level of uncertainty or risk associated with each significant variable is assessed and the cumulative effect of these uncertainties on a particular outcome (e.g. mine closure cost prediction) assessed. Using this approach, a risk profile is developed and used as the basis on which risk reduction opportunities can be prioritised and evaluated to provide maximum risk reduction per unit of expenditure. These risk management tools have been successfully applied at several operations both in Africa and Australia.