24-MMP-A6 Mining and the Environment · May 2013
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, 2013-May. 3 hours duration, open book (any non-communicating calculator permitted). Six questions of equal value (20 marks each) constitute the bank; a candidate answers any FIVE. Most questions require an essay-format answer.
Reference texts: BC Ministry of Energy, Mines and Low Carbon Innovation, Health, Safety and Reclamation Code for Mines in British Columbia (current edition) (permitting, reclamation and closure planning requirements); Canadian Dam Association (CDA), Dam Safety Guidelines (2013/2019 update) (dam classification, tailings dam consequence categories, freeboard/PMF design basis); Global Industry Standard on Tailings Management (GISTM, 2020) (tailings governance, design and closure principles); Price, W.A., MEND Report 1.20.1, Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials (1997/2009) (acid-base accounting, neutralizing potential ratio screening criteria); International Network for Acid Prevention (INAP), Global Acid Rock Drainage (GARD) Guide (ARD prediction, prevention and treatment across the mine lifecycle); Vick, S.G., Planning, Design, and Analysis of Tailings Dams, 2nd ed. (upstream/centreline/downstream embankment construction methods); Government of Canada, Metal and Diamond Mining Effluent Regulations (MDMER) under the Fisheries Act; Government of Canada, Impact Assessment Act (successor to the 2012 Canadian Environmental Assessment Act); Government of Ontario, Mining Act (progressive rehabilitation requirements).
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.
A fourth, complementary technique – relocating or progressively shrinking the active decant pond away from areas scheduled for near-term reclamation – is often combined with the three methods above on real projects.
| Hazard category | Engineering investigation required |
|---|---|
| Ground stability / subsidence | Locate and characterize all old workings and crown pillars; stope/pillar stability analysis; delineate surface subsidence risk zones; design backfilling, pillar reinforcement or surface exclusion where subsidence risk cannot be eliminated. |
| Shafts, adits, raises and other openings | Engineer permanent closure of every opening – concrete bulkhead plugs, engineered caps, or bat-friendly gates where wildlife access must be preserved – sized to prevent public entry and structural failure over the long term. |
| Long-term mine water management | Predict post-closure water-table rebound and flooding rate of the underground workings; confirm the final discharge point(s) and design a passive or active (perpetual, if required) treatment system sized for the predicted long-term flow and chemistry. |
| Water quality / geochemistry (ARD-ML) | Characterize the residual acid-generating potential of exposed sulphide zones and remaining broken rock underground; assess whether controlled flooding of the workings (oxygen exclusion) is an effective, lower-cost long-term ARD control compared to perpetual treatment. |
| Surface infrastructure | Plan demolition and removal of buildings, plant and equipment; identify and remediate contaminated soils at fuel storage, assay laboratory and ore-handling areas; safely dispose of remaining hazardous materials. |
| Waste rock piles and stockpiles | Geotechnical stability analysis of surface waste piles; design erosion control and, where PAG material is present, a source-control cover per Question 3(c). |
| Surface tailings facility (if present) | Dam stability analysis, closure cover design and long-term seepage/water management per Question 5. |
| Roads and site access | Reclaim haul roads no longer needed; retain and maintain the minimum access required for long-term monitoring. |
| Biological reclamation and land use | Salvage and replace growth medium; select revegetation species matched to the agreed end land use; reconstruct wildlife habitat where required. |
| Long-term monitoring and maintenance | Design a monitoring program (groundwater and surface water quality, subsidence markers, structural integrity of bulkheads/plugs and dams) with defined trigger and contingency-action levels, and the maintenance regime needed to sustain it. |
| Financial assurance | Produce and periodically update a full closure cost estimate covering every item above, held as security per Question 1's definition of financial surety. |
| Consultation and approval | Indigenous and community consultation on end land use and closure objectives; regulatory review and approval of the closure plan itself. |
