18-Env-A1 Principles of Environmental Engineering · December 2017
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — December 2017 — 04-Env-A1 / Principles of Environmental Engineering. 3 hours duration; closed book with a candidate-prepared 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.); Sawyer, McCarty & Parkin, Chemistry for Environmental Engineering and Science; Mihelcic & Zimmerman, Environmental Engineering: Fundamentals, Sustainability, Design; Guidelines for Canadian Drinking Water Quality (Health Canada); Canadian Council of Ministers of the Environment (CCME) water-quality and municipal solid-waste guidelines; Canadian Environmental Protection Act, 1999 (CEPA) and Canadian Environmental Assessment Act (CEAA 2012); ISO 14040/14044 (Life Cycle Assessment); Bies & Hansen, Engineering Noise Control; 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) for a proposed coal-fired generating station systematically works through the plant’s life cycle to identify, for each major process step, the environmental issues it raises and the mitigation actions built into the project design and approval conditions to address them before construction and operation proceed — reducing pollution proactively rather than reacting to it after the fact. Applied to three key process steps:
| Process Step | Key Issue | Action to Address the Issue |
|---|---|---|
| Coal receiving, handling & storage | Fugitive coal-dust emissions to air; stormwater contact with exposed coal piles carrying metals/sediment to receiving waters | Enclosed/covered conveyors and transfer points, water-spray dust suppression, lined and bermed storage pads with contained stormwater collection and treatment |
| Combustion (boiler) | SOx, NOx, particulate matter and CO2 emissions to atmosphere | Flue-gas desulphurization (wet limestone scrubbing) for SOx, selective catalytic reduction or low-NOx burners for NOx, electrostatic precipitators or fabric-filter baghouses for particulate control, plus continuous emissions monitoring |
| Ash handling, cooling water & wastewater | Fly-ash/bottom-ash disposal with leachate risk; thermal and metals-laden cooling-water and process-wastewater discharge | Dry ash handling with lined, engineered disposal cells and leachate collection; cooling towers to reduce thermal discharge; on-site wastewater treatment (metals removal, pH neutralization) under a regulated effluent permit |
The EIA process ties each of these actions to binding approval conditions (permits, monitoring commitments) before the project can proceed, which is what converts the assessment from a paper exercise into an enforceable pollution-reduction tool.
Three key principles of sustainable development bear directly on choosing among nuclear, geothermal and natural-gas generation: (1) intergenerational equity — meeting present energy needs without compromising the ability of future generations to meet their own, which for an energy source means the resource (or its impacts) must remain manageable over the long term; (2) the precautionary principle — where an activity poses a risk of serious or irreversible environmental harm, a lack of full scientific certainty should not be used to postpone reasonable, cost-effective measures to prevent that harm; and (3) integration of environmental, economic and social considerations (the triple bottom line) — sustainable decisions weigh ecological impact, economic viability and community/social acceptance together rather than optimizing one at the expense of the others.
Selecting geothermal power: on intergenerational equity, geothermal draws on the Earth’s internal heat, which — provided a reservoir is produced at or below its natural recharge rate through proper reservoir management and reinjection of spent geothermal fluid — behaves as a renewable resource over the multi-generational timescale relevant to sustainability, unlike natural gas, which depletes a finite reserve and commits future generations to either continued extraction or a costly transition. From a life cycle analysis (LCA) perspective, geothermal’s cradle-to-grave greenhouse-gas footprint is dominated by the construction phase (well drilling, plant construction) rather than by ongoing fuel combustion, giving it one of the lowest lifecycle GHG intensities of any dispatchable generation technology — directly supporting the sustainability goal of minimizing cumulative environmental burden over the full system life, not just at the point of use. The precautionary principle is engaged by geothermal’s site-specific risks — induced seismicity from fluid injection, and the potential release of naturally occurring hydrogen sulphide and trace metals in the geothermal brine — which argues for conservative reservoir-pressure management, seismic monitoring and closed-loop reinjection even before those risks are fully quantified for a given site, rather than waiting for an incident. Finally, the integration principle is reflected in geothermal’s typically small land footprint and high capacity factor relative to intermittent renewables, supporting stable, long-term local economic development while avoiding the air-quality and GHG externalities of combustion-based generation — a genuinely three-dimensional environmental-economic-social outcome compared against nuclear’s high capital cost and long-lived waste-management burden, or natural gas’s ongoing combustion emissions and fugitive-methane risk.
