Question 7 of 22: Extending the Lifespan of an Existing Landfill

Question 7: Extending the Lifespan of an Existing Landfill (5 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.

• Establish the baseline. Topographic/volumetric survey (or LiDAR) to determine remaining permitted airspace, and review the current annual fill-rate to project remaining years at present operating practice.
• Waste characterization and diversion audit. Sample the incoming waste stream to identify readily-recoverable material (recyclables, compostables, C&D debris) still entering the landfill that could be diverted to extend life.
• Evaluate diversion-program expansion. Quantify the airspace saved by expanding recycling, organics/composting and construction-and-demolition diversion programs.
• Assess operational-efficiency improvements. Increase in-place compaction density (heavier compactors, thinner working face, more compaction passes) and use of alternative daily cover (ADC) instead of soil, both of which recover airspace otherwise consumed by cover material and un-compacted refuse.
• Assess vertical expansion (increasing final height). Geotechnical stability check of a steeper/taller final slope, liner and cap system capacity to accommodate the added load and grade.
• Assess lateral expansion. Availability and zoning of adjacent land, and whether existing buffer distances and permits would allow the footprint to grow.
• Consider waste-to-energy diversion of the combustible fraction to reduce the volume that must be landfilled going forward.
• Cost-benefit and financial analysis comparing the incremental cost of each life-extension option against the capital cost of siting and permitting an entirely new facility.
• Regulatory review and stakeholder consultation. Confirm what permit amendments each option would trigger, and engage the surrounding community early, since any expansion (vertical or lateral) is likely to require public consultation.
• Recommend a preferred combination of measures, ranked by airspace gained per dollar and by permitting risk/timeline.