Basic Terms and Knowledge: 24-MMP-A6 Mining and the Environment, May 2013, Q1

Question 1: Basic Terms and Knowledge (20 marks)

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.

True/False (2 marks each, 10 marks total)

True/false statements on Canadian mining regulation
#	Statement	Answer	Explanation
a)	In Canada mineral rights fall under federal jurisdiction.	False	Under s.109 and s.92A of the Constitution Act, 1867, ownership and management of Crown minerals and non-renewable natural resources within a province rest with that province; each province issues its own mineral tenure, leases and mining permits. Federal jurisdiction over minerals is the exception, limited to the territories, federal Crown lands (e.g. Indian reserves, national parks), uranium/nuclear substances, and offshore areas beyond provincial boundaries.
b)	Federal environmental approval is normally required for mining projects in Canada.	True	Most new metal mines and major expansions exceed the capacity thresholds on the federal Physical Activities Regulations (formerly the CEAA 2012 Regulations Designating Physical Activities), triggering a federal impact assessment, and almost every mine also requires a federal Fisheries Act authorization (Schedule 2 listing under the MDMER) if it discharges tailings or effluent to water frequented by fish – so while a small industrial-mineral quarry may escape both triggers, "normally" is an accurate characterization for metal mines.
c)	Fisheries are regulated by the provinces.	False	Fisheries and fish habitat protection are a federal responsibility under the Fisheries Act, administered by Fisheries and Oceans Canada (DFO) – this is precisely the constitutional lever (s.35 harmful alteration, disruption or destruction of fish habitat, and s.36 deposit of deleterious substances) that gives the federal government jurisdiction over mine effluent and tailings management even though minerals themselves are provincial.
d)	Progressive reclamation is a requirement under the Mining Act in Ontario.	True	Ontario's Mining Act and its Mine Rehabilitation Code (O. Reg. 240/00) require progressive rehabilitation – reclaiming disturbed areas as mining advances rather than deferring all rehabilitation to final closure – and a certified closure plan with financial assurance must be filed and updated throughout the mine's life.
e)	Liquid effluent discharges from metal mining operations to water frequented by fish are allowed in certain concentrations and circumstances.	True	The MDMER (under the Fisheries Act) is precisely a permission-with-limits regime: a mine listed on Schedule 2 may deposit effluent (including tailings) to a fish-bearing water body provided it meets prescribed authorized concentration limits (e.g. arsenic, copper, lead, nickel, zinc, un-ionized ammonia, total suspended solids, radium-226, pH) and undertakes Environmental Effects Monitoring – it is not a blanket prohibition.

Definitions (all eight terms defined; any five satisfy the mark scheme)

Definitions of geotechnical and closure-planning terms
Term	Definition
Phreatic surface	The upper boundary of the zone of saturation within an embankment, tailings mass or soil slope – the locus of points where pore-water pressure equals atmospheric pressure. Above it, soil is unsaturated or only capillary-wet; below it, positive pore pressure drives seepage flow governed by Darcy's law, $q = -k\,\dfrac{dh}{dx}$. Locating the phreatic surface is the first step in any tailings-dam or slope stability analysis.
Plasticity index	The numerical range of water content over which a fine-grained soil behaves plastically: $PI = LL - PL$, where $LL$ is the liquid limit and $PL$ the plastic limit. A high PI indicates a highly plastic, compressible, low-permeability clay; a PI near zero indicates a non-plastic silt or sand.
Atterberg limits	A set of standardized water-content boundaries – the shrinkage limit (SL), plastic limit (PL) and liquid limit (LL) – that mark the transitions of a fine-grained soil between solid, semi-solid, plastic and liquid consistency states, used to classify tailings and till materials and to anticipate their compressibility and strength behaviour.
Creep	Slow, continuous, time-dependent shear deformation of soil, rock or tailings under a sustained stress that is below the material's peak (failure) strength; it is the mechanism by which a tailings dam or pit slope can progressively lose stability over years without an obvious triggering event, and is monitored with inclinometers and slope-extensometer surveys.
Subsidence	Downward (and sometimes lateral) deformation of the ground surface caused by the collapse, caving or closure of underground voids (mined-out stopes, caved zones) or by drainage/consolidation of unconsolidated overburden – the principal long-term ground-stability hazard that an underground mine closure plan must characterize and, where necessary, control by backfilling, crown-pillar design or surface exclusion zones.
Financial surety/assurance (for reclamation)	A financial security instrument – a bond, letter of credit, cash deposit or trust fund – that a regulator requires an operator to post before and during mining, sized to cover the full estimated cost of reclamation and closure, so that the public (not the taxpayer) is protected if the operator becomes insolvent before closure obligations are complete.
Freeboard	The vertical distance between the maximum design operating level of water or tailings in an impoundment and the crest elevation of the retaining embankment, providing a safety margin against wave run-up, storm inflow and settlement so that the Probable Maximum Flood (or the CDA-specified design flood for the dam's consequence classification) cannot overtop the dam.
Probable maximum flood	The theoretical upper-bound flood that could conceivably occur at a site, resulting from the most severe realistic combination of Probable Maximum Precipitation and antecedent hydrologic conditions; CDA guidelines assign the PMF (or a specified fraction of it) as the design inflow flood for "very high" and "extreme" consequence dams such as most tailings facilities.

Topic.

Key relations. $PI = LL - PL$ (Atterberg framework); Darcy's law $q=-k\,dh/dx$ locating the phreatic surface; freeboard sized against the PMF per CDA dam-classification tables.

Why this works. Canada's federal structure splits authority by subject matter, not by industry: provinces own and manage the resource itself (minerals, most surface/groundwater), while the federal government retains narrow but powerful levers – fisheries, navigation, and (via the Impact Assessment Act) major-project review – that apply to mining because mines discharge to fish habitat and disturb large areas, not because mining itself is federally regulated. The geotechnical terms (phreatic surface, PI, creep, subsidence) are the vocabulary an engineer needs to reason about the two things that most often go wrong at a mine site over the long term: slope/dam stability and ground subsidence.

Common pitfall. Assuming "mining is regulated by the province" implies fisheries/effluent are too – the two operate on entirely separate constitutional heads of power and a mine must satisfy both regimes simultaneously; and confusing "progressive reclamation" (an ongoing operating obligation) with "final closure" (the end-of-life obligation) – Ontario's Mining Act requires both.

Source. Constitution Act, 1867, ss. 92A, 109; Fisheries Act; Government of Ontario, Mining Act; BC Health, Safety and Reclamation Code for Mines; Canadian Dam Association, Dam Safety Guidelines.

Question 1 of 6: Basic Terms and Knowledge

Question 1: Basic Terms and Knowledge (20 marks)

True/False (2 marks each, 10 marks total)

Definitions (all eight terms defined; any five satisfy the mark scheme)