18-Env-A6 Solid Waste Engineering and Management · May 2014
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.); 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.
(1) Increase pile size — a larger pile mass retains the heat generated by microbial activity more effectively (lower surface-area-to-volume ratio), resisting heat loss to cold ambient air. (2) Cover or insulate piles (tarps or insulating covers) to conserve internally-generated heat and to shed excess moisture from snow and rain, while still allowing some gas exchange. (3) Reduce turning frequency in cold weather, since turning releases retained heat to the atmosphere — rely more on passive aeration (e.g., perforated pipe within the pile) to maintain oxygen supply without losing heat. (4) Site layout and windbreaks — sheltering piles from prevailing winter winds, and stockpiling extra dry bulking agent in advance to manage the higher moisture that snow-melt can add to the feedstock.
