24-MMP-A6 Mining and the Environment · Undated paper
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, undated sitting (the exam's own page header reads "National Examinations, May 2019"). 3 hours duration, open book (any non-communicating calculator permitted). Unlike most sittings of this subject, this paper's own Note 3 states "Complete all SIX questions" – there is no five-of-six choice, so all 120 marks are compulsory. Most questions require an essay-format or point-form answer; clarity and organization are explicitly assessed.
Reference texts: International Network for Acid Prevention (INAP), Global Acid Rock Drainage (GARD) Guide (ARD prediction, static and kinetic testing, treatment); Price, W.A., MEND Report 1.20.1, Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials (1997/2009); Government of Canada, Metal and Diamond Mining Effluent Regulations (MDMER, SOR/2002-222, the current name for the exam's "MMER") under the Fisheries Act (R.S.C. 1985, c. F-14); Government of Canada, Canadian Environmental Protection Act, 1999 (S.C. 1999, c. 33); Government of Canada, Impact Assessment Act (S.C. 2019, c. 28, successor to the 2012 Canadian Environmental Assessment Act); Government of Canada, Species at Risk Act (S.C. 2002, c. 29); BC Ministry of Energy, Mines and Low Carbon Innovation, Health, Safety and Reclamation Code for Mines in British Columbia (current edition); Canadian Dam Association (CDA), Dam Safety Guidelines (2013/2019 update); Global Industry Standard on Tailings Management (GISTM, 2020); Vick, S.G., Planning, Design, and Analysis of Tailings Dams (1990).
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 land concurrently with ongoing mining operations – e.g. re-contouring and revegetating a waste dump slope or a mined-out pit bench as soon as it becomes available – rather than deferring all reclamation to final closure.
ii. Global objectives: Physical stability – ensure pit walls, waste dumps and tailings facilities remain stable and safe for the long term (100+ years) without requiring ongoing active maintenance. Chemical stability – ensure reclaimed materials will not continue generating or releasing acid drainage or metal leaching in perpetuity, reaching a walk-away or minimal-maintenance chemical condition. Future use and aesthetics – return the site to a stable, productive, and visually acceptable land use compatible with the pre-mining or an agreed alternative end use, integrated with the surrounding landscape.
i. Revegetation's primary objectives are to stabilize exposed soils against erosion and dust generation (limiting airborne particulate exposure and downstream sediment loading) and to re-establish a self-sustaining ecosystem so the site no longer poses an ongoing physical or ecological hazard.
ii. Pre-Mining Planning Stage: (1) salvage and stockpile topsoil/organic overburden ahead of disturbance for later reclamation use; (2) select locally-adapted, native species and run growth trial plots to confirm suitability before large-scale disturbance. Progressive/Post-Closure Stages: (1) re-contour to stable slope angles and apply the salvaged growth medium and any needed soil amendments before seeding; (2) monitor vegetation establishment (percent cover, species survival) and adaptively adjust the seed mix or fertilization program. Sampling and monitoring are required: vegetation cover/survival surveys and soil-quality sampling must be carried out over multiple growing seasons to demonstrate self-sustaining reclamation success to the regulator before reclamation security can be released.
iii. Northern considerations: a short growing season and slow soil development narrow the revegetation window and require cold-hardy, native subarctic species; disturbing the surface vegetation/organic layer also risks thawing the underlying permafrost active layer, causing thermokarst subsidence that can undo re-contouring work.
i. Reclamation objectives for open pits are to eliminate or mitigate physical hazards to humans and wildlife (unstable steep highwalls, deep water-filled pits) and to manage long-term pit-lake and groundwater water quality so the pit does not become a perpetual ARD source or a wildlife hazard (e.g. waterfowl mortality on an acidic, metal-laden pit lake).
ii. Pre-Mining Planning Stage: (1) design final pit wall angles/benches and a pit-lake water-balance and geochemical model at the planning stage to predict long-term water quality; (2) plan selective placement of potentially acid-generating material away from the final pit walls and floor where feasible. Progressive/Post-Closure Stages: (1) install safety berms, fencing and warning signage around the final pit crest, and partially backfill benches where feasible to flatten slopes; (2) undertake long-term pit-lake water-quality and stratification monitoring, with in-lake treatment (e.g. lime addition) or an engineered outlet if needed. Sampling and monitoring are required, since a pit lake can take decades to reach chemical and physical (thermal/density) equilibrium, and slope stability must be confirmed over the same long timeframe.
iii. Northern considerations: a pit lake may be ice-covered for much of the year, limiting seasonal turnover and oxygenation and promoting meromictic stratification that traps metals in anoxic bottom water; permafrost thaw around the pit walls following excavation can also degrade long-term slope stability.
