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.
The most effective strategy is a watershed-based source water protection plan centred on riparian buffer zones and upstream best-management practices (BMPs), rather than relying solely on treatment at the intake. Vegetated riparian buffers along the streams and shoreline feeding the reservoir intercept eroded sediment, adsorbed nutrients and agricultural/urban runoff before it reaches open water, while upland BMPs (erosion-control measures on construction and agricultural land, stormwater detention with sediment forebays) reduce the sediment load at its source. This approach works because it addresses the pollution pathway (overland/channel erosion) rather than only its symptom (turbidity at the intake), reducing the treatment burden and cost on the drinking-water plant, extending the reservoir's useful storage life (sediment deposition otherwise reduces capacity over time), and providing redundancy consistent with the multi-barrier approach to drinking-water safety (source protection is the first barrier, ahead of treatment and distribution).
Two main causes: (1) combustion of fossil fuels (coal, oil, natural gas) for energy, transportation and industry, which releases carbon dioxide that was previously sequestered underground, steadily increasing atmospheric $\text{CO}_2$ concentration; and (2) large-scale deforestation and land-use change, which both releases stored carbon directly and removes the vegetation that would otherwise continue sequestering atmospheric $\text{CO}_2$, compounding the first cause. Both increase the concentration of greenhouse gases that trap outgoing long-wave radiation, enhancing the natural greenhouse effect beyond its pre-industrial equilibrium.
A technical solution: carbon capture and storage (CCS) at large point sources (power plants, cement/steel plants) captures $\text{CO}_2$ from the flue gas before it reaches the atmosphere and injects it into secure deep geological formations, directly reducing net emissions from combustion sources that cannot yet be feasibly electrified or replaced.
Two engineering methods: (1) noise barriers or earthen berms constructed between the track and the residential area, which block the direct line-of-sight sound-transmission path from wheel/rail and engine noise to the receptor; and (2) rail and wheel maintenance (continuous-welded rail to eliminate joint impact noise, regular rail grinding to remove corrugation, and well-maintained wheel profiles) combined with reduced train speed through the noise-sensitive segment, which reduces the noise generated at the source rather than blocking it after the fact.
The preferred method is the noise barrier/berm: it is a path-based control that is independent of the railway operator's maintenance schedule and rolling stock (which the municipality typically cannot compel), gives a immediate and predictable noise-level reduction at the residential receptor once built, and (per the roughly 3 dB noise-exchange convention used in Canadian occupational/community noise practice) a well-designed barrier can achieve several decibels of insertion loss — a meaningful, perceptible reduction — whereas source-side maintenance improvements are incremental, ongoing and outside the community's direct control.
A technical principle applies hardware/engineering control directly to the source: fitting a vehicle with a catalytic converter (or, for heavy-duty diesel, a diesel particulate filter/selective catalytic reduction system) that chemically converts or filters pollutants at the tailpipe before they reach the atmosphere. A non-technical principle instead changes behaviour or policy so that fewer/cleaner vehicle-km are driven in the first place: a municipal transit-oriented land-use policy or a periodic vehicle emissions inspection-and-maintenance (I/M) program that keeps in-service vehicles operating near their certified emission levels. The two are complementary rather than competing — the technical control reduces the emission rate per vehicle-km, while the non-technical measure reduces either the number of vehicle-km driven or the fraction of the fleet operating with degraded (uncontrolled) emissions equipment — and an effective air-quality management plan for a mobile-source-dominated airshed uses both together.
