18-Env-A1 Principles of Environmental Engineering · December 2018
Question 6 of 7: Air Toxics Control, Environmental Standards and Solid Waste Management
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
National Exams — December 2018 — 18-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); Bies & Hansen, Engineering Noise Control; Andrews, Canadian Professional Engineering and Geoscience (professional ethics).
Question 6: Air Toxics Control, Environmental Standards and Solid Waste Management (20 marks)
(i) Controlling Lead Emissions from Mobile Sources and Refinery Fugitive Emissions
Control methods for lead emissions, mobile vs. fugitive refinery sources
Source
Control Method
Advantage
Limitation
Mobile (gasoline-fuelled vehicles)
Legislated removal of tetraethyl lead from gasoline (unleaded-fuel mandate), enforced through fuel-quality regulation
Eliminates the lead emission at its source across the entire vehicle fleet simultaneously, requiring no per-vehicle retrofit or ongoing monitoring once phased in
Legacy vehicles/equipment still requiring leaded fuel (some aviation, off-road) remain a residual source, and enforcement depends on fuel-supply-chain compliance rather than the vehicle itself
Fugitive (refinery process/storage/piping)
Leak detection and repair (LDAR) program on process equipment, valves and storage tanks, paired with vapour-recovery/enclosure systems
Directly targets the specific equipment responsible for fugitive losses, so it can be prioritized and verified component-by-component with measurable leak-rate reduction
Labour- and cost-intensive to sustain (periodic monitoring of thousands of components) and only as effective as the survey frequency — leaks occurring between inspection cycles are not caught until the next survey
(ii) Environmental Quality Standards versus Guidelines
Standards vs. guidelines, with examples and when each is superior
Approach
Example
When Superior
Standard (legally binding numeric limit, enforceable)
A provincial discharge-permit limit for a specific effluent parameter (e.g., a maximum BOD or ammonia concentration in a municipal wastewater discharge permit)
Superior where consistent, enforceable protection is required and non-compliance must carry legal consequence — e.g., point-source industrial or municipal discharges where the regulator needs a bright-line, prosecutable limit.
Guideline (recommended, non-binding numeric or narrative benchmark)
CCME water-quality guidelines for the protection of aquatic life, or the Guidelines for Canadian Drinking Water Quality
Superior where scientific understanding is still evolving, where site-specific conditions vary widely (background water chemistry affecting toxicity), or where the goal is to inform best-practice decision-making by many different actors (municipalities, industry) rather than to create one uniform enforceable number.
In practice the two are complementary rather than competing: guidelines are frequently the scientific basis from which a jurisdiction later derives a legally binding standard once consensus and monitoring capacity are established, so guidelines tend to lead standards in maturity, while standards provide the enforceability that guidelines by themselves lack.
(iii) Engineering Recommendations to Extend the Landfill’s Life by 10 Years
With the site at 80 % capacity and only 5 years of life remaining at the current rate, the recommendations are prioritized by cost-to-impact ratio — starting with the lowest-cost, fastest-acting measure and ending with the highest-cost, longest-lead-time measure, so the municipality captures the largest life-extension per dollar first while the higher-cost measures are still being planned and approved:
Priority 1 (lowest cost, fastest to implement): a municipal waste-diversion program (mandatory recycling and organics/green-bin composting). Diverting recyclable and compostable material out of the landfill stream directly reduces the tonnage requiring burial, extending life at comparatively low capital cost since it uses collection infrastructure that can often be phased in within the existing collection contract. If not fully implemented, the shortfall shows up immediately as a shorter-than-planned extension (the landfill approaches capacity sooner than projected), rather than any new environmental harm at the site itself.
Priority 2 (moderate cost): landfill operational optimization — increased waste compaction and daily/intermediate cover optimization (or a soil-cover alternative such as a geosynthetic cover) to increase the effective airspace-to-waste-volume ratio. Better compaction and thinner, engineered cover material recovers airspace that would otherwise be consumed by cover soil, at a moderate capital and ongoing operating cost. Under-implementation here mainly forfeits some of the available life-extension rather than creating a new hazard, provided the site's basic operating and cover requirements continue to be met.
Priority 3 (highest cost, longest lead time): vertical expansion (increasing permitted final grade/height) or horizontal footprint expansion where land and approvals allow, engineered with an enhanced liner/leachate and landfill-gas collection system. This adds real additional capacity rather than only using existing capacity more efficiently, but requires a new or amended environmental approval, significant capital for the liner/leachate/gas systems, and the longest lead time of the three measures — it is placed last because if the higher-priority, lower-cost measures are not implemented, expansion approval and construction can be pursued in parallel, but if expansion alone were relied on and its approval is delayed or refused, the site would reach capacity with no lower-cost fallback in place, which is the highest-consequence failure mode of the three.
