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.
A stormwater detention/retention (wet) pond is a typical end-of-pipe control measure. Two basic design features that provide downstream quantity and quality control: (1) a sized extended-detention storage volume above the permanent pool, with a controlled low-flow outlet, that attenuates the post-development peak discharge back down to (or below) the pre-development peak rate for the design storm — the primary quantity-control feature; and (2) a permanent pool with a sediment forebay and vegetated littoral/buffer zone, which provides quiescent settling time for suspended sediment and associated pollutants and biological uptake of nutrients before the treated runoff is released — the primary quality-control feature.
Two main engineering approaches: (1) carbon capture and storage (CCS) at large point sources, implemented in the short term by retrofitting post-combustion capture systems onto existing fossil-fuelled plants to cut their GHG output without retiring the asset, and in the long term by building the geologic sequestration and pipeline infrastructure needed to permanently store captured CO2, maximizing benefit by extending emission reductions to hard-to-electrify industrial sources (cement, steel) as well as power generation; and (2) transition to renewable/low-carbon generation, implemented in the short term through distributed measures such as rooftop solar, energy-efficiency retrofits and demand reduction that require little new grid infrastructure, and in the long term through grid-scale wind, solar and hydro buildout paired with storage and transmission upgrades to displace fossil generation entirely, maximizing benefit by eliminating GHG emissions at the source rather than managing them after combustion.
Two engineering methods to reduce highway traffic noise reaching an adjacent residential community: (1) noise barriers or earthen berms along the highway right-of-way, which physically block the direct line-of-sight transmission path between the traffic noise source and the residences; and (2) low-noise (open-graded friction course) pavement, which reduces tire-pavement interaction noise at the source by absorbing sound into the pavement’s open pore structure rather than reflecting it. The preferred method is the noise barrier: it provides consistent attenuation (typically 5–10 dBA) across the full range of vehicle types and speeds and does not degrade with pavement wear, whereas low-noise pavement’s acoustic benefit is smaller, is most effective at higher speeds where tire noise dominates over engine noise, and diminishes measurably as the pavement ages and its pore structure clogs — making the barrier the more robust, longer-lasting solution for a receptor as sensitive as an adjacent residential community.
A technical engineering principle applied to fugitive emissions control is a leak detection and repair (LDAR) program using optical gas imaging cameras or portable volatile-organic-compound analyzers to physically survey valves, flanges, pump seals and connectors, quantify any leak, and trigger a required repair once a leak exceeds a defined threshold — a hardware- and measurement-based engineering control. A non-technical principle addressing the same hazard is a management-system approach, such as an ISO 14001 environmental management system with documented work-practice standards, mandatory inspection frequencies, operator training and a corporate compliance-assurance policy — an administrative/organizational control that governs how consistently the technical LDAR program is actually carried out, rather than a piece of equipment itself. The two are complementary: the technical LDAR program finds and fixes individual leaks, while the non-technical management-system principle ensures the LDAR program (and every other emission-control measure at the refinery) is actually executed reliably, on schedule, and improved over time — a facility with excellent leak-detection instruments but no management system to mandate and track its use will still under-perform one with a disciplined program built on simpler equipment.
