One of the most critical aspects of sustainable design and management in mining is closure planning and implementation.
We have the experience to develop closure plans that meet front-end and on-going permitting requirements. Closure planning and design involves a range of environmentally based disciplines, as well as socio-economic considerations and post-closure monitoring.
Mine closure planning
Our experts can prepare both conceptual and feasibility-level closure plans, typically required for permitting purposes and/or for costing purposes within PFS/FS studies. We also develop mine closure criteria, which are incorporated into designs of major facilities, such as linear infrastructure, Tailings Facilities, Heap Leach Pads, pits, etc. The primary environmental objective for the planning, design and implementation for closure is to arrive at acceptable levels of physical and chemical stability of the materials and facilities within the mine. In socio-economic terms, the local, regional and national communities related to the mining operation must transition to a sustainable situation during and after the operational life of that operation.
Remediation of abandoned mine sites
In many of our operating jurisdictions, legacy mining facilities, largely the responsibility of governments, require additional effort to reach acceptable standards of closure. While the technical expertise involved is similar to standard mine closure design, these 'abandoned' mine sites have particular requirements. It is common for the sites to have already entered into a contaminating state, requiring remediation of existing forms of pollution. We develop the studies and designs required to assist in remediating these sites and, ultimately, to return the site to a closed condition, where physical and chemical stability are within acceptable ranges of emissions standards.
Mine closure design and implementation
For mines nearing the end of their operating life, we provide the technical support required to finalize the detailed designs for closure construction and the decommissioning or re-purposing of facilities such as process plants and buildings. During the Mine Closure Implementation stage of the mine life, our Project Delivery capabilities allow us to manage broad scopes for closure works in a cost-effective and timely manner. We also assist our clients in implementing progressive closure schemes, which eases the year-on-year impacts of capital outlays for closure.
Geochemistry and water quality
One of the key disciplines in closure planning and design for mines involves the geochemical processes related to Acid Rock Drainage and Metals Leaching, and their subsequent impacts on water quality. Our approach to evaluating and minimizing impacts on water quality includes management of contact non-contact water sources within the mine to limit water that might require treatment prior to final discharge. Water balance and mass balance modelling assist us in predicting the ultimate quantity and quality of water to be treated, in the event that this is deemed necessary to meet effluent limits. Our experts also use modelling to design and evaluate alternatives of geochemical stability coverage for mine closure, taking into account environmental, technical and economic factors.
As a final step in mine closure planning and design, we offer expertise in process plant design, including Minewater Treatment plants, also known as 'Active Treatment'. Our specialists design and develop 'Passive Treatment' systems, typically as constructed wetlands. We will evaluate a range of options for our clients and have full capability to develop the designs for any preferred technical alternative.
When remediating a contaminated site, it’s important to consider the success and efficiency of closure measurements. Our bioaccumulation studies make it possible to understand how an ecosystem is adapting and functioning, how successful remediation has been, and identify any potential problems so they can be addressed in a timely manner.