Assessing the sustainability of composite liner systems for municipal solid waste landfills: a triple bottom line approach

Municipal solid waste landfills require a liner system to prevent the migration of landfill leachate into the surrounding environment. Currently, liner system selection and design processes are primarily based on engineering performance, cost, and ease of construction and rarely consider sustainability. This study assessed the sustainability of four different composite liner systems, considering their technical equivalence through leachate infiltration rates and employing the triple bottom line (TBL) approach, which considers environmental, economic, and social impacts. The four composite liner systems evaluated included: (1) geomembrane (GM) over compacted clay liner (CCL) (denoted as GM/CCL), (2) GM over geosynthetic clay liner (GCL) (denoted as GM/GCL), (3) GM over soil mixed with lime and cement (SA) (denoted as GM/SA), and (4) GM over fly ash mixed with bentonite (FAB) (denoted as GM/FAB). The life cycle stages of each system, including material extraction, construction, monitoring, and disposal were also analyzed. The study was conducted for the DeKalb Landfill in DeKalb, Illinois, USA. Life cycle assessment was performed using the Eco-Indicator and TRACI method in SimaPro 8.0.1 to quantify environmental impacts. The results showed that GM/FAB was the most sustainable liner system in terms of environmental impact and second in economic and social impacts. On the other hand, GM/GCL was deemed the most preferred in terms of economic and social impacts.