24-MMP-A6 Mining and the Environment · May 2017
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, 2017-May. 3 hours duration, open book (any Casio or Sharp approved 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 an essay-format 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, sampling programs, prevention/treatment methods); Price, W.A., MEND Report 1.20.1, Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials (1997/2009) (acid-base accounting, NPR screening); Government of Canada, Metal and Diamond Mining Effluent Regulations (MDMER, the current name for the exam's "Metal Mining Effluent Regulations") under the Fisheries Act, s.36(3); Government of Canada, Canadian Environmental Protection Act (1999) and Impact Assessment Act (successor to the 2012 Canadian Environmental Assessment Act named in the exam); Species at Risk Act (2002); Ontario, Mining Act, R.S.O. 1990, and O.Reg. 153/04 (Records of Site Condition, under the Ontario Environmental Protection Act); Canadian Council of Ministers of the Environment (CCME), duty-to-consult and Indigenous engagement guidance for resource projects; Vick, S.G., Planning, Design, and Analysis of Tailings Dams (1990) (upstream/centerline/downstream construction, disposal practices); Canadian Dam Association (CDA), Dam Safety Guidelines (tailings impoundment construction); BC Ministry of Energy, Mines and Low Carbon Innovation, Health, Safety and Reclamation Code for Mines in British Columbia (current edition) (closure planning, revegetation, mine water management); ATSDR, Toxicological Profiles for arsenic and mercury.
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 (1 mark). Progressive reclamation is the practice of reclaiming disturbed land (regrading, capping, revegetating) as soon as it is no longer needed for active operations, ON AN ONGOING BASIS throughout the mine's operating life, rather than deferring the entire reclamation task to a single closure phase at the end of mining.
ii. Three global objectives (3 marks).
i. Primary objectives of revegetation (2 marks). Revegetation aims to establish a self-sustaining vegetative cover that controls erosion and dust (protecting downstream water quality and nearby air quality/human health), stabilizes and binds surface material against wind and water erosion, restores wildlife habitat and biodiversity value, and returns the site toward the agreed future land use and aesthetic condition – directly advancing the physical stability and future-use global objectives from Part A.
ii. Revegetation considerations by stage (5 marks).
| Stage | Assumptions/considerations/actions |
|---|---|
| 1. Pre-mining planning | Conduct baseline vegetation and soil surveys to establish reference conditions and identify locally-adapted native species suitable for the final revegetation design; strip and stockpile topsoil/growth medium separately from waste material during construction so it is preserved and available for later cover placement rather than being buried or lost. |
| 2. Progressive and post-closure | Sequence revegetation to follow disturbance as soon as an area is no longer needed (progressive reclamation, Part A), using the stockpiled growth medium and trial plots to confirm species performance before full-scale planting; adjust planting mixes and amendments based on early monitoring results (soil chemistry, pH, cover establishment success) rather than a single fixed prescription applied everywhere. |
Sampling and monitoring ARE required at both stages: baseline soil/vegetation surveys establish the reference condition against which success is later measured, and ongoing monitoring of cover establishment, species survival, and soil chemistry (particularly over any potentially acid-generating substrate, Question 3) is needed to confirm the revegetated cover is genuinely self-sustaining before reclamation financial security can be released – a visually green cover in year one does not by itself demonstrate long-term success.
iii. Northern environment considerations (1 mark). A short growing season, permafrost, and generally poor/thin native soils in northern Canada slow vegetation establishment substantially compared to temperate sites, favouring cold-hardy native species selection, extended trial-plot periods, and revegetation plans that budget for a multi-decade establishment trajectory rather than a rapid closure-then-release timeline.
i. Primary objectives of open pit reclamation (2 marks). Open pit reclamation aims to eliminate physical hazards to human and wildlife safety (steep unstable pit walls, uncontrolled public access to a deep water-filled void), ensure the pit walls and any remaining highwalls are geotechnically stable over the long term, and manage the eventual pit lake's water quality so it does not become a chronic contamination source or an attractive-nuisance safety hazard.
ii. Open pit considerations by stage (5 marks).
| Stage | Assumptions/considerations/actions |
|---|---|
| 1. Pre-mining planning | Design final pit wall slope angles with a long-term (post-closure, no active dewatering) stability factor of safety in mind, not just the operating slope angle; predict the post-closure pit lake water balance and geochemistry (inflow sources, evaporation, expected sulphide exposure on final walls) to anticipate whether the lake will require ongoing treatment. |
| 2. Progressive and post-closure | Install safety berms, fencing and signage around the final pit crest as mining retreats from each bench, rather than only at the very end; monitor pit lake filling rate and water quality against the pre-mining prediction, adjusting the closure water management plan (e.g. adding treatment or a controlled outflow structure) if actual chemistry deviates from what was predicted. |
Sampling and monitoring ARE required: pit wall geotechnical monitoring confirms long-term slope stability, and pit lake water quality monitoring throughout the filling process and beyond confirms whether the site meets its chemical-stability closure objective (Part A) or requires ongoing intervention.
iii. Northern environment considerations (1 mark). Pit lakes in northern Canada can develop seasonal ice cover and permafrost-influenced thermal stratification that changes mixing behaviour and oxygen availability compared to temperate pit lakes, affecting both water quality evolution and any planned habitat/fisheries end use; permafrost degradation around the pit rim as ground thaws in response to excavation can also introduce an additional, climate-driven slope stability risk not present at non-permafrost sites.
