Question 3 of 7: Solid Waste Management, Environmental Impact Assessment and Ethics

Question 3: Solid Waste Management, Environmental Impact Assessment and Ethics (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) Incineration vs. Landfilling of SWM Residuals

Once reduction, reuse and recycling are exhausted, the remaining residuals must go to either waste-to-energy incineration or landfill. Incineration's benefits are substantial volume reduction (typically 85–90% by volume), energy recovery (steam or electricity from the combustion heat, offsetting fossil generation), destruction of pathogens and organic contaminants, and a much smaller long-term environmental liability than a landfill because there is no multi-decade leachate or landfill-gas legacy. Its challenges are the air-pollution-control burden (particulate, acid-gas, NOx and trace dioxin/furan controls are all required to meet emission limits), the need to manage bottom and fly ash — the fly ash in particular concentrates heavy metals and often requires disposal as a special/hazardous waste — high capital and operating cost, and public opposition. It is also only economical above a minimum waste throughput and heating value.

Landfilling's benefits are lower capital cost and simpler, well-proven technology, but its challenges are the long post-closure monitoring period (commonly 30 years or more) for leachate and landfill gas — the latter is roughly half methane, a greenhouse gas over 25 times more potent than CO₂ over a 100-year horizon — the land area consumed, and the risk of groundwater contamination should the liner or leachate-collection system fail. A sustainable, environmentally responsible SWM program therefore treats incineration and landfilling as complementary, not competing: incinerate the calorific, non-recyclable residual fraction for energy recovery and volume reduction, and landfill only the non-combustible residue and incinerator ash that remains, always after the reduce–reuse–recycle hierarchy has been applied.

(ii) EIA for a New Lakeshore Power Plant

As the consulting engineer, four steps make up a defensible EIA for a power plant proposed on the shore of a large lake near a populated municipality:

1. Screening and scoping. Confirm the EIA is required (project type/size triggers) and, with regulator and public/stakeholder input, identify the significant issues to be assessed — here, thermal and chemical discharge to the lake, air emissions dispersion over the municipality, aquatic habitat and fisheries, and noise/traffic during construction and operation.

2. Baseline characterization. Collect pre-project data on lake water quality, aquatic ecology and fish habitat, ambient air quality, groundwater, and the socio-economic setting of the adjacent municipality, so that project effects can later be measured against a documented "before" condition.

3. Impact prediction, evaluation and mitigation. Model the predicted effects — thermal-plume dispersion in the lake, stack-emission dispersion over the populated area, construction noise and traffic — evaluate their significance against applicable guidelines (e.g., CCME water-quality guidelines, ambient air standards), and design mitigation measures (diffuser outfalls, emission controls, construction scheduling) to reduce significant effects.

4. Reporting, regulatory/public review and follow-up monitoring. Prepare the EIA report, submit it for regulatory and public review with an opportunity for the municipality and other stakeholders to comment, obtain approval with binding conditions, and implement a post-construction monitoring and adaptive-management program to confirm the predicted effects (and mitigation performance) actually occur as assessed.

Ethics scenario. Suppose that, during baseline characterization, the engineer discovers a locally significant fish-spawning area within the proposed intake/discharge zone that the client did not disclose and that, if reported, could delay approval or require an expensive redesign. Environmental ethics — and the engineer's professional duty under the EGBC/Engineers Canada Code of Ethics to hold paramount the safety, health and welfare of the public and the environment — requires the engineer to report the finding fully and accurately regardless of the client's schedule or cost pressure, escalate it within the firm, and, if directed to omit or misrepresent it, refuse to do so and, if necessary, report the matter to the regulatory authority.