Question 11 of 16: Strategy to Extend Landfill Life

Question 11: Strategy to Extend Landfill Life (6 marks)

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.

Landfill life extension is achieved along two independent axes — reducing the annual volume that must be buried, and increasing the airspace available to bury it in — and a robust strategy pursues both together. To reduce incoming volume: implement or expand diversion programs (curbside recycling, organics/yard-waste composting, construction & demolition debris recycling) to remove the largest divertible fractions before they ever reach the landfill face, supported by waste-reduction policy tools (pay-as-you-throw user fees, disposal bans on specific recyclable materials) that give residents and businesses a direct financial incentive to divert. To increase available airspace within the existing footprint: improve compaction practice (heavier/multi-pass compactors, thinner working-face lifts) to raise the achieved in-place density, adopt vertical expansion (a taller final grade, engineering permitting) where geotechnically and visually acceptable, and minimize the volume consumed by daily cover through alternative daily cover materials (tarps, foam, spray-applied products) instead of a full 150 mm soil layer, since daily cover soil itself displaces refuse airspace day after day. Where the site boundary allows, a formal lateral/horizontal expansion (acquiring adjacent land and permitting a footprint increase) is the most direct way to add capacity, though it faces the same siting/community-acceptance constraints as an entirely new site. Each of these measures should be quantified (in added years of remaining life) and compared, since a mature site combining a stronger diversion program with better compaction and reduced daily-cover consumption can often add several years of life at far lower capital cost than pursuing expansion alone.