Question 6 of 18: Long-Term Landfill Closure Plan

Question 6: Long-Term Landfill Closure Plan (3 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.

A long-term closure plan has to address the physical works, the ongoing monitoring/maintenance obligation, and the financial mechanism that pays for both, since a closed landfill remains an environmental liability for decades after it stops accepting waste. Final cover system: design and construction of a low-permeability cap (compacted clay or geomembrane), a drainage layer to shed infiltration, and a vegetated topsoil layer to control erosion and support final land use, built to the regulatory design standard in force. Post-closure monitoring: a multi-decade program (commonly 25–30 years under CCME/provincial guidance) of groundwater, leachate and landfill-gas monitoring at a defined well/probe network, with defined trigger levels and a contingency response if a trend is detected. Continued leachate and gas management: ongoing operation of the leachate collection/treatment system and the LFG collection/flare or energy system until generation rates decline to background levels. Financial assurance: a trust fund, bond or other instrument sized to cover the full post-closure monitoring, maintenance and any remediation contingency, since the responsible party must be able to fund the obligation even decades after final waste receipt. Land-use controls: deed notations/restrictions on future site use reflecting expected settlement and residual gas migration risk.