Advancements in Municipal Solid Waste Landfill Cover System: A Review

Municipal solid waste (MSW) landfill cover systems have evolved from being merely a soil cap to a multicomponent, nearly impermeable systems providing better control over infiltration and landfill gas (LFG) emissions. Recently, there has been a widespread development of alternative cover systems which addresses the shortcomings of conventional cover systems such as high construction and maintenance costs, susceptibility to damage due to desiccation cracking and freezing, and ineffective control of LFG emissions. Landfills are regarded as the third largest source of anthropogenic methane (CH4) emissions in the United States. Apart from CH4, landfills are a significant source of various other gasses such as carbon dioxide, hydrogen sulfide and several other odorous and non-methanogenic organic compounds. The modern engineered landfills typically install gas collection systems in addition to the conventional soil cover to mitigate LFG emissions. However, these systems are not always 100% efficient in capturing all the emissions. Moreover, at the older landfills where installing gas collection systems is not economical and practically feasible, the fugitive LFG emissions is a persistent problem. In this regard, alternative cover systems with wide range of cover materials have been explored to address the fugitive LFG emissions. This paper summarizes the advancements in the MSW landfill cover systems over the years, along with the core mechanisms underlying their function. Then, advancements in the alternative cover systems, including their advantages, are discussed. Finally, the research challenges/opportunities in the field of exploring alternate landfill cover systems are presented.