Question 2 of 6: Effluent Regulations (Metal Mines)

Question 2: Effluent Regulations (Metal Mines) (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.

A. Conditions for discharge without a transitional authorization (6 marks)

Section 6 of the MMER (carried forward unchanged as s.6 of today's MDMER) permits the owner or operator of a mine to deposit effluent containing a deleterious substance to water frequented by fish only if all three of the following conditions are met (the effluent must also be discharged through a final discharge point monitored under the Regulations' sampling, testing and reporting provisions):

• Concentration limits met. The concentration of each regulated deleterious substance in the effluent does not exceed the authorized limits in Schedule 4 (monthly mean, composite-sample and grab-sample limits) – arsenic, copper, cyanide, lead, nickel, zinc, total suspended solids and radium-226 (the 2018 MDMER amendments added un-ionized ammonia).
• pH within range. The pH of the effluent is equal to or greater than 6.0 and not greater than 9.5.
• Not acutely lethal. The deleterious substance is not an acutely lethal effluent, i.e. the effluent does not kill more than 50% of rainbow trout exposed to 100% effluent over 96 hours under the prescribed reference method (Daphnia magna lethality is also tested, but as a monitoring requirement).

Depositing tailings or waste rock into a natural fish-frequented water body is outside these conditions altogether: it is allowed only if that water body is first listed on Schedule 2 as a tailings impoundment area, which is the process described in Part B.

B. Approval process to deposit tailings to a fish-frequented natural water body

Depositing tailings to a naturally occurring water body frequented by fish is only permitted under the MDMER (under the federal Fisheries Act) if that water body is formally added to Schedule 2 of the Regulations as a designated Tailings Impoundment Area (TIA); this is a substantive amendment to a federal regulation, not a routine permit, and follows a multi-year, multi-agency process rather than a simple application. The proponent must first demonstrate, typically through an alternatives assessment, that no technically and economically feasible tailings disposal option exists that avoids depositing to a fish-frequented water body – this comparative assessment of alternatives is a foundational requirement Environment and Climate Change Canada (ECCC) expects before it will even consider a Schedule 2 listing. Because a Schedule 2 listing project of this scale virtually always triggers a federal environmental assessment under the Impact Assessment Act (the current successor to the 2012 Canadian Environmental Assessment Act named in the question) or, depending on timing and provincial arrangements, a coordinated federal-provincial review, the proponent must complete a full impact assessment addressing predicted effects on fish and fish habitat, water quality, downstream users and the receiving environment generally, together with a Fish Habitat Compensation Plan to offset the habitat that will be destroyed when the water body becomes a tailings pond – MMER s.27.1 requires this plan to be submitted to and approved by the Minister, backed by an irrevocable letter of credit covering the full cost of implementing it, before any deposit into a Schedule 2 water body may begin. The compensation plan, environmental effects monitoring (EEM) commitments, and closure/reclamation plan for the eventual TIA are all developed as part of this same assessment package and are reviewed by ECCC and Fisheries and Oceans Canada (DFO) before a Governor-in-Council regulatory amendment can add the water body to Schedule 2. Indigenous consultation is a mandatory, legally-grounded component of this process, not a discretionary courtesy: the Crown's duty to consult and, where appropriate, accommodate potentially-affected First Nations is triggered by the potential impact on Aboriginal or treaty rights (fishing rights in particular, given the water body's fish-bearing status), and meaningful engagement typically continues throughout project design, review and operation, sometimes formalized through impact-benefit agreements. Non-governmental organizations, local communities and other stakeholders participate through the impact assessment's public comment and hearing process, technical working groups, and follow-up EEM program reviews, and can materially influence conditions attached to the final approval (for example more stringent monitoring, additional compensation habitat, or a requirement to progressively reduce the tailings footprint). Only after the impact assessment concludes with a positive decision, the fish habitat compensation and EEM commitments are finalized, and the Schedule 2 regulatory amendment is made can the mine legally begin depositing tailings to that water body – and it remains bound thereafter to ongoing EEM reporting, water quality monitoring against MDMER limits, and progressive reclamation obligations for the impoundment area for the life of the mine and into closure.