Role of Cover Systems to Control Methane Migration from Dumpsites

Abstract

The emission of landfill gases from dump sites due to anaerobic biodegradation of waste is a matter of increasing public concern as they significantly contribute to global warming. In order to assess the methane emissions from dump sites and to quantify the effects of clay covers and geosynthetic clay liners (GCLs) in reducing them, numerical simulations were conducted. From the simulations, it was noted that clay covers reduced the atmospheric methane flux fourfold and GCLs produced a sixfold reduction in comparison to open dumps. Atmospheric methane fluxes far above the safe limit were observed for the open dumps, which were significantly lower when covers were in place. Development of large pressures owing to reduced migration and continuous methane production were also observed when covers were present. A study of the effect of geotechnical properties of cover and material types suggested that they affect methane emissions significantly. Absolute permeability, porosity, saturation, and van Genuchten properties influenced methane migration to a large extent and hence should be taken into consideration in a cover design.