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18-Env-A1 Principles of Environmental Engineering · May 2017

Question 4 of 7: Population, Economic Growth and Urbanization as Causes of Environmental Pollution

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

National Exams — May 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; 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 4: Population, Economic Growth and Urbanization as Causes of Environmental Pollution (20 marks)

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.

(i)–(iii) Environmental Impacts and Engineering Solutions by Growth Driver

Industrial expansion, broad-based economic growth and urban expansion each stress the same three environmental media — air emissions, water demand and wastewater treatment — but through somewhat different mechanisms and at different scales, which is why the same nine-cell comparison is instructive: it forces a distinct pair of impacts and matching engineering solutions for each intersection rather than one generic answer.

2 Impacts & 2 Solutions(i) Industrial Expansion(ii) Economic Growth(iii) Urban Expansion
Air Emissions Impacts: increased point-source SO2/NOx/particulate/VOC emissions from added process and combustion units; higher facility-level GHG output.
Solutions: mandatory best-available-control-technology (BACT) scrubbers/baghouses/catalytic controls on new/expanded units; facility-wide emissions cap-and-trade or offset requirements tied to permitting.		 Impacts: higher aggregate vehicle-kilometres travelled and freight movement raising regional NOx/VOC/GHG loads; increased electricity demand raising emissions at the generating source.
Solutions: fuel-efficiency/zero-emission-vehicle standards and transit investment to decouple travel demand from emissions; renewable/low-carbon electricity procurement for new growth-driven load.		 Impacts: concentrated mobile-source emissions and traffic congestion; loss of vegetation/urban heat-island effect worsening local air quality and ground-level ozone formation.
Solutions: transit-oriented, mixed-use zoning to shorten trip lengths; urban tree-canopy and green-infrastructure requirements in development approvals.
Water Demand Impacts: large new process/cooling water withdrawals stressing local supply and competing with other users; potential lowering of groundwater tables near withdrawal wells.
Solutions: mandatory water-recycling/closed-loop process water systems; water-use permitting with withdrawal caps tied to environmental-flow requirements.		 Impacts: rising per-capita and commercial water consumption region-wide; increased demand for potable-quality water for non-potable uses (irrigation, industrial).
Solutions: tiered/increasing-block water pricing to incentivize conservation; expanded non-potable reuse (reclaimed water) systems for irrigation and industrial demand.		 Impacts: expanded service-area demand outpacing existing treatment/distribution capacity; increased impervious surface reducing natural aquifer recharge.
Solutions: low-impact development (LID) and green infrastructure to sustain recharge; phased water-supply master planning tied to development approvals.
Wastewater Treatment Impacts: higher-strength or novel industrial process wastewater exceeding municipal sewer-use bylaw limits; risk of upset to biological treatment from shock industrial loads.
Solutions: mandatory industrial pretreatment programs before sewer discharge; on-site treatment/pre-treatment trains sized for the specific industrial contaminant profile.		 Impacts: rising aggregate flow and organic loading to municipal treatment plants as consumption grows; increased nutrient (N/P) loading to receiving waters.
Solutions: staged capacity expansion/upgrade of treatment plants ahead of demand; tertiary nutrient-removal upgrades to protect receiving-water quality.		 Impacts: increased impervious area driving combined-sewer overflow (CSO) frequency and stormwater-driven hydraulic overload at the plant.
Solutions: separation of combined sewers or CSO storage/treatment facilities; distributed stormwater management (LID, detention) to reduce peak flows reaching the collection system.