18-Env-A1 Principles of Environmental Engineering · May 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2014 — 04-Env-A1 / Principles of Environmental Engineering. 3 hours duration; closed book with an 8.5×11 in double-sided aid sheet; Casio or Sharp approved calculator only. Any five questions constitute a complete paper (first five answers marked); all seven are solved below for completeness. Each question is worth 20 marks.
Reference texts. Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery (5th ed.); MWH’s Water Treatment: Principles and Design (3rd ed.); Guidelines for Canadian Drinking Water Quality (Health Canada); Canadian Council of Ministers of the Environment (CCME) water-quality guidelines; Canadian Environmental Protection Act, 1999 (CEPA); Andrews, Canadian Professional Engineering and Geoscience (professional ethics).
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.
An environmental impact assessment (EIA) systematically identifies the mine's activities, predicts their environmental effects, and builds mitigation into the project before approval — it works because it is applied at the planning stage, when process alternatives and mitigation are still cheap to change, rather than after construction when only end-of-pipe fixes remain. For a gold mine, the assessment is organized around the process steps of the operation:
| Process Step | Key Issue | Consideration | Mitigating Action |
|---|---|---|---|
| Site clearing & access roads | Habitat loss, fragmentation | Boreal forest, caribou range, First Nations traditional land use | Minimize footprint, consult affected communities, offset/reclaim equivalent habitat |
| Open-pit / underground extraction | Acid rock drainage (ARD) from sulphide ore exposure | Pit-wall and waste-rock sulphide content | Segregate potentially-acid-generating rock, engineered covers, water treatment |
| Ore processing (cyanide leaching) | Cyanide and heavy-metal release to water | Tailings pond seepage, wildlife exposure to process ponds | Lined tailings impoundment, cyanide destruction (e.g., $\text{SO}_2$/air process) before discharge, wildlife deterrents |
| Tailings storage | Long-term dam stability and seepage | Downstream watershed, fisheries | Engineered dam design with independent review, groundwater monitoring wells |
| Mine closure | Perpetual ARD and site reclamation | Post-closure water treatment liability | Progressive reclamation, financial closure bond, walk-away water-treatment design |
The matrix format is itself part of the mitigation: by forcing each process step to be paired with a specific issue and a specific, assignable action, the EIA avoids generic mitigation language and produces commitments that a regulator (in Ontario, under the provincial Environmental Assessment Act together with the federal Impact Assessment Act where triggered) can hold the proponent to during permitting and operation.
The Brundtland definition of sustainable development — development that meets the needs of the present without compromising the ability of future generations to meet their own needs — rests on three interlocking pillars: environmental integrity, economic viability and social equity, evaluated together rather than any one in isolation. Applied to electricity generation, no source is unconditionally "sustainable"; the question is how each performs against the three pillars over its full life cycle.
Taking wind power as the chosen source: over its operating life it produces electricity with essentially zero direct greenhouse-gas or air-pollutant emissions, strongly favouring environmental integrity and displacing fossil generation. A full life-cycle analysis (LCA), however, tracks impacts across raw-material extraction (rare-earth mining for permanent-magnet generators, steel and concrete for towers/foundations), manufacturing, transport, installation, decades of operation, and decommissioning/recycling of blades (glass-fibre composite blades are currently difficult to recycle and are a growing end-of-life waste stream). LCA studies consistently show wind's lifecycle greenhouse-gas intensity (roughly 10–15 g $\text{CO}_2$-eq/kWh) is one to two orders of magnitude below coal or natural gas, and its energy payback time (the time to generate the energy invested in manufacturing it) is typically under one year against a 20–25 year service life — a favourable energy-return-on-investment that coal and gas, which continuously consume a depleting fuel resource, cannot match. Where wind falls short of full sustainability is intermittency (requiring backup generation or storage, which carries its own life-cycle burden), land-use and visual/noise impacts on nearby communities (the social pillar), and the unresolved blade-recycling problem. The LCA-informed conclusion is that wind power scores strongly on the environmental pillar and favourably on long-run economics, but genuine sustainability requires pairing it with storage/grid solutions and a credible end-of-life recycling pathway for the social and full-environmental pillars to be satisfied as well.
