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.
Two major factors are: (1) storage duration, especially in warm/humid conditions — the longer putrescible (food/organic) waste sits before collection, the further anaerobic decomposition proceeds, generating volatile fatty acids, hydrogen sulphide and other malodorous compounds, and elevated ambient temperature accelerates this microbial activity; and (2) inadequate container design or sealing — open, poorly sealed, or infrequently cleaned storage containers allow decomposition gases and leachate to escape and allow moisture ingress that accelerates anaerobic breakdown, whereas sealed, regularly serviced containers substantially reduce odor release.
Both factors are within an engineer's control at the design stage: a shorter collection frequency (twice-weekly rather than weekly pickup for organics-heavy commercial generators) directly limits how far decomposition can proceed before waste leaves the site, while specifying gasketed, closed-lid containers with a defined wash-down/cleaning schedule addresses the second factor. Odour complaints are also one of the most common triggers of public opposition to a facility (see the siting concerns raised in Question 12), so designing storage duration and container specification conservatively is not merely an operational nicety but a risk-mitigation measure that protects a facility's social licence to operate. The same underlying decomposition chemistry — anaerobic breakdown of putrescible organics releasing odorous intermediate compounds — recurs at landfill scale in Questions 13 and 14 on landfill gas generation, so managing it at the storage stage is the first line of defence before waste ever reaches a collection vehicle or disposal facility, and is far cheaper than trying to control odour once it has already migrated off-site.
