24-MMP-A6 Mining and the Environment · December 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
EGBC National Exam — Mining and Mineral Processing Engineering, 09-MMP-A6 Mining and the Environment, 2018-Dec. 3 hours duration, open book (any non-communicating calculator permitted). SIX questions are printed on the paper; FIVE questions constitute a complete exam paper, and only the first five questions as they appear in the answer book are marked. Most questions require a concise, point-form-acceptable answer rather than a full essay. Every question is solved in full below (including all six, not just the five a candidate would normally submit) so this set also serves as complete study material.
Reference texts: Government of Canada, Fisheries Act and the Metal and Diamond Mining Effluent Regulations (MDMER, the current name for the exam's "Metal Mining Effluent Regulations"); Government of Canada, Canadian Environmental Protection Act, 1999 (CEPA); Government of Canada, Impact Assessment Act (successor to the 2012 Canadian Environmental Assessment Act named in the exam); Government of Canada, Species at Risk Act; International Network for Acid Prevention (INAP), Global Acid Rock Drainage (GARD) Guide; Price, W.A., MEND Report 1.20.1, Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials (1997/2009); Canadian Dam Association (CDA), Dam Safety Guidelines (2013/2019); Global Industry Standard on Tailings Management (GISTM, 2020); Vick, S.G., Planning, Design, and Analysis of Tailings Dams (1990); ATSDR, Toxicological Profiles for mercury; BC Ministry of Energy, Mines and Low Carbon Innovation, Health, Safety and Reclamation Code for Mines in British Columbia.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
i. Progressive reclamation is the practice of reclaiming disturbed areas concurrently with ongoing mining operations, as soon as a given area is no longer needed for active mining, rather than deferring all reclamation to the end of the mine's life.
ii. Physical stability intends that landforms and structures (waste dumps, tailings facilities, pit walls) remain stable indefinitely without ongoing active maintenance, resisting erosion and slope failure. Chemical stability intends that no ongoing or future release of contaminants (e.g. acid rock drainage or metal leaching) occurs, ideally without requiring perpetual active water treatment. Future use and aesthetics intends that the closed site is returned to a safe, productive end land use that is visually and functionally consistent with the surrounding landscape and acceptable to the local community.
i. The primary objectives are to re-establish a self-sustaining vegetation cover that controls erosion and dust generation, restores wildlife habitat and ecosystem function, and eliminates the long-term human and wildlife health and safety hazards presented by bare, unstabilized disturbed ground.
ii. Pre-Mining Planning Stage: (1) conduct baseline vegetation and soil surveys and plan for salvage/stockpiling of topsoil and seed bank material for later reuse; (2) select native, locally-adapted seed species and mixes suited to the anticipated final landform and climate. Sampling/monitoring is required at this stage – baseline soil and vegetation characterization establishes the performance targets that closure success will later be measured against. Progressive/Post-Closure Stage: (1) amend reclaimed soils (fertilizer, organic matter) and run species trial plots to confirm establishment success before committing to full-scale seeding; (2) maintain permanent monitoring plots tracking survival, percent cover and species diversity against approved closure criteria. Sampling/monitoring is required here too – it is the only way to demonstrate to the regulator that closure criteria have been met (triggering reclamation bond release) or that corrective re-seeding is needed.
iii. A short growing season and permafrost limit species choice and the practical seeding window (favouring cold-hardy native species and carefully timed seeding), and ground disturbance itself can trigger permafrost thaw and subsidence that alters the intended final landform and drainage pattern after revegetation is already established.
i. The primary objectives are to ensure long-term physical stability of the pit walls and benches (managing rockfall and slope failure hazard), to manage the water quality and public safety risk of any resulting pit lake, and to restore or blend the final void/landform with the surrounding topography for a safe end use.
ii. Pre-Mining Planning Stage: (1) carry out geotechnical characterization of the rock mass to set slope design parameters incorporated into the final pit design; (2) undertake predictive pit-lake water quality and hydrogeological modelling to anticipate long-term filling behaviour and chemistry. Sampling/monitoring is required at this stage – baseline groundwater levels and geochemistry are needed to calibrate the predictive models. Progressive/Post-Closure Stage: (1) install benching, scaling and public-safety access controls (fencing, berms, signage) around the final pit; (2) monitor pit lake water quality over time and apply active or passive treatment to any discharge if required. Sampling/monitoring is required – pit lake chemical and thermal equilibrium can take years to decades to establish, so ongoing monitoring is the only way to confirm the predictive models and detect an unexpected water-quality trend before it affects downstream receptors.
iii. Permafrost thaw around a pit lake can alter long-term wall stability and disturb the lake's thermal/chemical stratification, and seasonal ice cover affects both natural lake turnover/mixing and the practicality of operating a water treatment system through the winter.
