18-Env-A6 Solid Waste Engineering and Management · May 2016
Question 10 of 17: Landfill Project Risk Analysis
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Notes on this paper
National Examination, May 2016 — 04-Env-A6 / 18-Env-A6, Solid Waste Engineering and Management. 3 hours duration, closed book, one non-communicating calculator (Casio or Sharp), one letter-sized aid sheet permitted. All 17 questions constitute a complete paper (100 marks total).
Reference texts: Tchobanoglous, Theisen & Vigil, Integrated Solid Waste Management: Engineering Principles and Management Issues; Vesilind, Worrell & Reinhart, Solid Waste Engineering; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); CCME, Guidance Document on Landfill Gas Management; Canadian Environmental Protection Act, 1999.
Define the scope and receptors. Identify the facility's life-cycle phase(s) under review (siting, construction, operation, closure, post-closure) and the receptors of concern — nearby residents, groundwater/surface-water users, ecological receptors, workers and the public.
Hazard identification. Systematically list the potential hazard events — liner/leachate collection failure, uncontrolled gas migration/explosion, slope or cap failure, fire, odour/vector nuisance, and traffic accidents on haul routes.
Exposure and pathway analysis. For each hazard, identify the pathway by which a receptor could be exposed (e.g., leachate → fractured liner → aquifer → drinking-water well) and whether that pathway is currently complete or only potential.
Likelihood assessment. Estimate the probability of each hazard event, informed by the specific design's redundancy (double liner, leak-detection layer), site-specific geotechnical/hydrogeologic conditions, and historical failure-rate data from comparable facilities.
Consequence (severity) assessment. Estimate the magnitude of impact of each hazard should it occur — health, environmental, financial and reputational — if it is not intercepted by an engineering or operational control.
Risk characterization. Combine likelihood and consequence (a risk matrix or a semi-quantitative risk score) to rank hazards, focusing subsequent effort on the highest-ranked items.
Risk mitigation. Recommend engineering controls (redundant liner/leak detection, gas collection capacity margin), operational controls (monitoring frequency, inspection protocols) and contingency/emergency response plans for each significant risk identified.
Communication and review. Report findings in clear, non-technical terms to the municipality and, as appropriate, the public, and establish a schedule to periodically update the risk register as monitoring data and site conditions evolve over the facility's multi-decade life.
