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.
Household or business hazardous waste (paints, solvents, batteries, pesticides, fluorescent lamps) mixed into the MSW stream poses risks that MSW facilities are not designed to manage: it can contaminate leachate with heavy metals and organic toxins beyond what an MSW landfill liner/leachate collection system is engineered to handle, create fire/explosion hazards at transfer stations, MRFs and landfills (reactive chemicals, aerosol cans, lithium-ion batteries), and expose facility workers to acute chemical or biological hazards during hand-sorting. Under the Canadian Environmental Protection Act (CEPA) and provincial hazardous-waste regulations, its presence can also trigger regulatory non-compliance for a facility permitted only to accept non-hazardous MSW, and it undermines the marketability of otherwise-clean recovered material streams.
The practical response is layered rather than reactive: a well-designed system relies primarily on upstream prevention (household hazardous waste depots, take-back programs for batteries and electronics, public education on what may not go in the regular bin) so that hazardous items are diverted before they ever reach a collection vehicle, backed up by load-checking/inspection procedures at the transfer station or landfill gatehouse to catch what slips through, and staff training so that workers recognize and safely isolate a suspected hazardous item rather than continuing to process it. Facility operating permits typically require an incident-reporting and contingency procedure specifically for this scenario, since even a single drum of an unknown industrial chemical discovered mixed into an incoming load can require the receiving facility to halt operations entirely, isolate the load, and arrange specialized hazardous-waste disposal at significant cost and delay.
