18-Env-A6 Solid Waste Engineering and Management · May 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.); 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) Explosion and fire hazard — methane migrating laterally through soil or utility corridors into buildings, manholes or other confined spaces can reach its flammable range (roughly 5–15% CH4 in air) and ignite. (2) Asphyxiation hazard in confined spaces where accumulated LFG displaces oxygen below safe breathing levels for workers or the public. (3) Greenhouse-gas contribution — methane has a global-warming potential roughly 25–30 times that of CO2 over a 100-year horizon, so uncontrolled fugitive emissions from an uncollected landfill are a disproportionately large contributor to a jurisdiction's overall GHG inventory. (4) Vegetation die-back and subsurface migration — gas migrating through the surrounding vadose zone displaces soil oxygen in plant root zones, killing surface vegetation and providing an early warning sign of an uncontrolled migration pathway.
