18-Env-A1 Principles of Environmental Engineering · May 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2015 — 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 and landfill guidelines; Canadian Environmental Protection Act, 1999 (CEPA); Impact Assessment Act, 2019 (Canada) and Alberta Environmental Protection and Enhancement Act; 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.
| Method | Advantage | Limitation | Most appropriate example |
|---|---|---|---|
| Fabric filter / baghouse (PM2.5, industrial fixed source) | Very high particulate-removal efficiency (often >99%) across a wide particle-size range, including fine PM2.5 | Bags are sensitive to moisture/condensation and high temperature, and require periodic cleaning/replacement, adding O&M cost | Cement kiln or metal-smelter stack gas with a high, steady particulate loading |
| Catalytic converter (VOCs/CO, mobile source) | Simultaneously oxidizes VOCs and CO (and reduces $\text{NO}_x$ in a three-way design) at the point of generation, with no separate collection/disposal step | Catalyst is poisoned by leaded fuel or high sulfur content and only reaches effective operating temperature after a warm-up period (limited cold-start control) | Gasoline/diesel highway-vehicle exhaust systems |
The two methods target the same broad class of air toxics (VOCs and fine particulates) at opposite ends of the source spectrum: the baghouse is a downstream, end-of-pipe capture device suited to a fixed source with a stable, engineered stack, while the catalytic converter is an in-line conversion device built into the mobile source itself, reflecting the very different collection opportunities a stationary stack and a moving vehicle exhaust offer.
| Strategy | Discussion |
|---|---|
| Waste diversion (recycling & organics/green-bin composting) | Diverting recyclables and organics from the waste stream directly reduces the tonnage requiring landfilling, extending the existing site's remaining life beyond the current 5-year projection while cutting landfill methane generation from diverted organics. |
| Landfill gas capture and energy recovery | Capturing methane generated by the existing landfill (for flaring or energy recovery) reduces greenhouse-gas emissions and can partially fund the diversion program; combined with progressive cell engineering, it can also increase the effective airspace/capacity of the current site. |
| Siting and permitting a new engineered landfill cell or regional transfer/disposal partnership | Because diversion alone will not eliminate the need for landfill capacity over a 25-year horizon, the plan must also begin the multi-year siting, environmental assessment and permitting process for either an expansion cell at the existing site or a regional disposal partnership, so that new capacity is ready well before the current site's 5-year limit is reached. |
An environmental guideline (e.g., a CCME water-quality guideline) is a science-based, recommended numerical or narrative target that is not legally binding in itself — it represents best-available scientific judgement of a protective level, but a facility that exceeds it is not automatically in violation of law. An environmental standard is a legally enforceable limit set out in a statute, regulation or permit condition, with defined compliance obligations and penalties for exceedance.
Guidelines are better where scientific understanding is still evolving, where conditions vary too widely across sites/regions for one binding number to be appropriate, or where the goal is to set an aspirational best-practice target that can be tightened over time without a legislative amendment. Standards are better wherever consistent, enforceable compliance is essential to protecting public health or the environment — drinking-water bacteriological limits or a point-source discharge permit, for example — because only a legally binding limit gives a regulator the authority to compel corrective action or penalize non-compliance.
