GCS supplies a wide range of services to support the process of mine closure. These include (but are not limited to):
Environmental Risk and Liability Assessment is frequently the basis for making financial provision for mine closure.
Environmental Risk Assessment and Management is used to identify, quantify and then manage an operation’s real environmental risks. Diligent application of this approach ensures that all environmental risks are assessed, quantified and managed. In addition, associated economical requirements are understood in order to obtain closure. The process starts with an all-encompassing, conservative screening-level risk assessment, and then progresses towards a detailed quantitative risk assessment of those issues agreed as being critical by a multidisciplinary team consisting of all I&AP’s (including all regulatory authorities involved with the closure). The process has also been designed to be objective, robust and transparent.
Hydrogeology and Hydrological Assessments and Design: Hydrogeology (groundwater) impacts at mine closure typically include rebound of groundwater levels potential contaminant migration and decant control. Aspects that should be considered include hydrogeological characterisation by considering the source-pathway-receptor principles, leachate potential and quality, acid mine drainage, and salt-balances. Geochemical testing and modelling, water monitoring programmes as well as contaminant transport modelling is often employed to quantify the risks and the design mine closure management measures. Geophysical Surveys, drilling of monitoring holes and sampling are usually employed to map seepage zones at remote and abandoned mine sites.
Surface Water Hydrology measures and models are used to determine the impact of mine closure on the catchment in terms of water quality and yield. The hydrological study is aimed at developing measures to manage potential impacts on the catchment by dam simulations, the design of flood control and storm water management measures and the planning of irrigation, water supply, water resource development projects, separation of clean and dirty water, calculation of salt loads, and compliance assessments.
Source term evolution assessment and geochemical applications: The geochemical qualification and quantification of mine waste is an essential part of the waste facility closure process, establishment of risks and liabilities, as well as waste management and mitigation design. Old mine voids and waste deposits often have long-term liabilities. Pit lakes and mine water decant quality are important considerations during mine closure. The geochemical assessment aims to determine parameters such as waste seepage or mine water quality characteristics, laboratory reaction rates and Acid Rock Drainage Potential (ARD). Predictive Geochemical Modelling, together with Oxygen Dispersion Modelling, is undertaken to quantify water quality for different closure design scenarios. The data is also used to assist with the design of waste covers and unique cost-effective closure options.
Social and Economic Assessments with stakeholder engagement: The mine host communities, specifically those dependent on the mine for employment, as well as services and markets for local businesses, are vital considerations during the mine closure phase. This is particularly relevant for developing countries where it is important to ensure that communities remain sustainable and continue to benefit from developmental opportunities even after the mine has been closed. Effective mine closure involves multiple interrelated concepts, across social, environmental and economic spheres of development. GCS applies a systematic approach of demographic data and field surveys, land use assessment, risk identification, and management plan implementation in order to achieve sustainable mine closure thereby minimizing long term financial obligations associated with mine closure.
Geotechnical Assessments typically involve field investigations, characterisation of industrial and mine waste, and stability of the mine workings. The GCS Geotechnical team has established a cost effective and practical methodology to the development of the geotechnical risk models for mine closure.
Ecology and Soil Assessment: This is a key rehabilitation activity as appropriate soil cover ensures long term sustainability.
Soil surveys are taken from all disturbed areas to determine the appropriate soil cover in terms of both thickness and
nutrient status. Wetland rehabilitation and management is a critical component of the mine closure process and GCS
supplies key assessment and guidance at this stage.
Geographical Information Systems and Visual Optimisation Studies: As most mines cover large expanses of land, mine closure teams require digital terrain models to plan for closure. GCS geographic information system (GIS) technology is ideally suited for this purpose. GIS is a versatile tool for gathering, storing, accessing and distributing geographic information quickly and easily. GIS is used for monitoring and reclamation by analysing and mapping soils, vegetation, surface hydrology, and groundwater. GIS mapping allows rapid sizing and plotting of mine openings, waste piles and cultural features for accurate bills of quantities.
GCS also supplies a suite of other mine closure applications through our partners and suppliers which benefits our clients by creating a “one-stop-shop”. These include:
Water treatment (active and passive treatment applications). Engineered Bioremediation & Phyto-Remediation
Invasive Plant Control
Town and Rural Planning and Architecture
Decommissioning of Tailings and Waste Rock Dumps
Mine Land Rehabilitation