“Breaking the ground” in Semakau Landfill: technological solutions for site investigation and material reuse

Semakau Landfill (SL) calls for practical solutions to extend its lifetime beyond 2035. Landfill mining combined with material reuse from the waste has been shown as a viable solution to urban landfills, but has never been applied to a landfill containing mixed waste material (MM) consisting of incineration bottom ash, incineration fly ash, and other non-incinerable waste. A series of innovative technological solutions for site investigation (SI) and material reuse aiming at “breaking the ground” in SL are proposed. Our project will be articulated around three key objectives: 1) SI and 3D spatiotemporal modelling of MM; 2) laboratory trial tests on MM processing and material reuse; and 3) decision support tool (DST) for sustainable SL management. In Obj. 1, conventional geotechnical SI techniques with geophysical and geoenvironmental techniques will be combined to provide wider coverage and detailed insights into the MM properties in situ. Subsequently, a series of laboratory characterization and aging tests will be carried out to supplement the 3D MM distribution and evolution model that will inform Obj. 2 and 3. In Obj. 2, a trial treatment train will be designed and tested for the retrieved MM. The processing units will be designed as modules allowing different configurations and sequences. The units will be co-designed between NTU and local industry partners, including Remex, NSC, and JFE. The target reuse applications are road construction, caisson infill, and landfill reclamation. In Obj. 3, a DST will be developed. We aim to deliver: 1) a suite of geotechnical-geophysical-geoenvironmental (SI) techniques and SI datasets of SL; 2) lab characterization and a 3D distribution and evolution model of the MM in SL; 3) treatability assessment of excavated MM and testbed design for treatment train; 4) reusability assessment of excavated and treated MM targeting caisson infill, road construction, and land reclamation; and 5) Optimal decisions for sustainable management of SL based on different decision-making criteria.