18-Env-A6 Solid Waste Engineering and Management · December 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
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.); Freeze & Cherry, Groundwater; CCME, Guidance Document on Landfill Gas Management; Canadian Environmental Protection Act, 1999.
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.
Four issues: (1) air emissions control and permitting — dioxins/furans, particulate matter, acid gases (SOx, NOx, HCl) and heavy metals must be controlled to meet stringent air-quality standards, requiring costly flue-gas treatment (scrubbers, baghouses, selective catalytic reduction) and rigorous permitting; (2) ash management — bottom ash and, particularly, fly ash can concentrate heavy metals and require characterization (and potentially hazardous-waste handling/disposal) rather than routine landfilling; (3) public acceptance and siting opposition — combustion facilities frequently face stronger public opposition than landfills due to air-quality and health perception concerns, similar in kind to (but often more intense than) the landfill-siting opposition of Question 12; and (4) high capital cost and feedstock (waste supply) commitment — combustion facilities require large up-front capital investment and typically need long-term "put-or-pay" waste-supply contracts to remain economically viable, which can conflict with a community's parallel goal of increasing waste diversion (less waste available to combust).
That last tension is a strategic planning issue as much as an economic one: a community that signs a 20–25 year put-or-pay contract sized to today's waste generation effectively commits itself to maintaining (or penalizing itself for reducing) that tonnage for the life of the contract, which can create a structural disincentive to pursue the very diversion programs discussed in Questions 1, 17 and 20. A defensible implementation plan sizes the facility to a conservative, diversion-adjusted projection of future waste generation rather than to current tonnage, so the combustion facility and the diversion strategy work together rather than against each other.
