16-Civ-A3 Elementary Environmental Engineering · May 2017
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. National Exams, May 2017 — 16-Civ-A3 Elementary Environmental Engineering. Three hours; closed book with one candidate-prepared 8½ × 11 double-sided aid sheet; approved Casio or Sharp calculator only. Seven problems are printed, each worth 20 marks, and any five constitute a complete paper (maximum 100 marks). All seven are solved here, because the set is intended as a study resource rather than an exam script. Section marks are shown in brackets at the left margin of each question and are reproduced below.
Reference texts.
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.
| Control | Advantage | Limitation | Best-suited application |
|---|---|---|---|
| Technical — fabric filter (baghouse) for PM10; thermal oxidiser for chlorinated VOCs | Very high removal (99%+ of fine PM; >99% VOC destruction), reliable and well proven. | High capital and energy cost; baghouses are sensitive to moisture/temperature, oxidisers can form products of incomplete combustion (dioxins) if poorly run. | Large continuous fixed sources with high toxic loading — cement kilns, chemical plants, hazardous-waste incinerators. |
| Non-technical — pollution prevention / source substitution and permitting | Eliminates the toxic at source (no control to run or fail); often cuts cost and liability. | Not always technically feasible; requires process change, regulation and management commitment; slower to implement. | Facilities where a chlorinated solvent can be swapped for a benign one, or process redesigned — degreasing, coating, dry-cleaning operations. |
The two controls are complementary: source substitution (a non-technical, management/regulatory control) removes what it can at the root, and the residual toxic emissions are then captured by the appropriate add-on device. Under strict limits both are typically needed.
| Strategy | Discussion | Low-cost implementation |
|---|---|---|
| Technical 1 — waste diversion (recycling, composting) | Reduces the tonnage landfilled, directly extending remaining airspace and deferring a costly new cell. | Phase in curbside recycling and organics collection with existing collection routes; site a composting pad on municipal land; fund from avoided tipping fees. |
| Technical 2 — landfill optimisation and vertical/lateral expansion with gas recovery | Better compaction and permitted expansion add years of capacity; landfill-gas capture converts a liability (methane) into energy revenue. | Buy/lease adjacent land early while cheap, use daily-cover efficiency and heavy compactors, install gas wells incrementally as cells fill, sell gas/electricity. |
| Non-technical — source reduction, pricing and public education | Cutting waste generation (pay-as-you-throw, product stewardship, education) lowers everything downstream — the cheapest tonne to manage is the one never created. | Introduce user-pay (bag-tag) pricing and extended-producer-responsibility programs; run school and community education; near-zero capital. |
Implemented together and in that order — reduce, divert, then optimise/expand the landfill — the plan minimises overall cost by shrinking the waste stream first (which is free or revenue-positive) and only then investing in engineered capacity, with landfill gas offsetting operating cost. A 20-year horizon comfortably exceeds the 10-year capacity because diversion and reduction can readily cut landfilled tonnage by a third or more.
