Leachate drainage volume of municipal solid waste landfills: field testing and hydro-mechanical modeling

The leachate drainage volume (LDV) of municipal solid waste (MSW) landfills is crucial to the operation of leachate treatment plant and development at the leachate level, but there is still a lack of reasonable evaluation methods. In this study, the evaluation methods, including both field measurements and numerical simulations, are proposed and applied in the case study of a MSW landfill in Southeastern China. For field measurements, 23 boreholes were drilled to test the leachate level distribution, and thus to determine the saturated volume (SV) of the landfill. The water retention capacity of the drilled samples was tested in a compression cell for a calculation of the undrainage volume (UV) of the landfill, and total LDV was obtained as SV-UV. The total LDV and SV were measured to be 2.31 × 10⁵ m³ and 1.08 × 10⁶ m³, respectively, which indicated a total leachate drainage percentage (LDV/SV) of 22%. For numerical simulations, a hydro-mechanical model is established to predict the daily LDV during layered landfilling. The model couples leachate flow and MSW compression, which are two fundamental processes determining daily LDV. As the model takes into account the leachate generation caused by the compression of MSW, the prediction has a good agreement with the measurement. If ignoring compression, the daily LDV will be underestimated by a percentage of 35%-50%. This study provides basic information and an assessment framework of leachate drainage volume and contributes to leachate management in landfills.