18-Env-A1 Principles of Environmental Engineering · December 2015
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exam — December 2015 — 04-Env-A1 Principles of Environmental Engineering (Closed Book, 3 hours; candidate-prepared 8½×11" double-sided aid sheet permitted). Any five (5) of the seven (7) problems below constitute a complete paper; all seven are solved here as a full study resource.
Reference texts: Davis & Cornwell, Introduction to Environmental Engineering, 6th ed.; Metcalf & Eddy, Wastewater Engineering: Treatment and Resource Recovery, 5th ed.; Mihelcic & Zimmerman, Environmental Engineering: Fundamentals, Sustainability, Design; 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 (CEPA, 1999).
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 first strategy is establishing a vegetated riparian buffer and best-management-practice (BMP) program across the contributing watershed — setback distances between cultivated fields and the reservoir/tributary streams, planted with grass or shrub buffer strips that intercept and filter sediment, nutrients (phosphorus/nitrogen) and pesticide runoff before it reaches open water, combined with farm-level BMPs (nutrient management plans, reduced tillage, livestock exclusion fencing from watercourses). The second strategy is formally designating and managing a source water protection area/zone around the reservoir, following a multi-barrier source-to-tap framework: mapping time-of-travel zones around the intake, restricting or regulating high-risk land uses (manure storage, intensive livestock operations) within the most sensitive zones, and routine source-water monitoring for nutrients, pathogens (from livestock runoff) and algal-bloom indicators so early degradation is caught before it threatens the treatment plant's ability to produce safe drinking water.
The first main cause is the combustion of fossil fuels (coal, oil, natural gas) for electricity generation, transportation and industry, which releases CO2 that accumulates in the atmosphere because it is removed only slowly by natural sinks (ocean uptake, photosynthesis). The second main cause is land-use change, particularly deforestation and agricultural expansion, which both releases the carbon stored in cleared biomass/soil and reduces the remaining vegetated area available to sequester atmospheric CO2 going forward, while agricultural livestock and fertilized soils separately add methane and nitrous oxide.
A technical solution addressing the first cause is a shift to low-carbon electricity generation (hydroelectric, wind, solar, and nuclear in the Canadian generation mix) paired with electrification of transportation and heating, directly displacing fossil-fuel combustion at the source. A technical solution addressing the second is carbon capture and storage (CCS) at large point sources (power plants, cement/steel plants) combined with reforestation/afforestation programs that restore biomass carbon sinks, together attacking both the emission and the loss-of-sink sides of the land-use-change problem.
The first engineering method is a noise barrier wall — a solid, mass-law-governed barrier (concrete, masonry, or engineered composite panel) erected along the highway right-of-way tall and long enough to break the direct line-of-sight between traffic and the residences, attenuating noise by diffraction loss at the barrier top. The second is low-noise (open-graded/porous) pavement surfacing, which reduces tire–pavement interaction noise (the dominant highway noise source above roughly 50 km/h) at its source by allowing air to escape from the tire tread grooves into the pavement's void structure rather than being compressed and expelled as noise.
The preferred method for an existing highway next to an established residential community is the noise barrier wall: it delivers a larger, more reliable and more immediately verifiable noise reduction (typically 5–10 dB(A) at the first row of houses) than a pavement resurfacing program, requires no disruption to an operating highway beyond the barrier construction itself, and its benefit does not degrade with pavement wear the way low-noise pavement's acoustic benefit fades over its service life as the open-graded surface clogs with debris and requires periodic rehabilitation.
