A practical approach for calculating the settlement and storage capacity of landfills based on the space and time discretization of the landfilling process

The settlement of any position of the municipal solid waste (MSW) body during the landfilling process and after its closure has effects on the integrity of the internal structure and storage capacity of the landfill. This paper proposes a practical approach for calculating the settlement and storage capacity of landfills based on the space and time discretization of the landfilling process. The MSW body in the landfill was divided into independent column units, and the filling process of each, column unit was determined by a simplified complete landfilling process. The settlement of a position in the landfill was calculated with the compression of each MSW layer in every column unit. Then, the simultaneous settlement of all the column units was integrated to obtain the settlement of the landfill and storage capacity of all the column units; this allowed to obtain the storage capacity of the landfill based on the layer-wise summation method. When the compression of each MSW layer was calculated, the effects of the fluctuation of the main leachate level and variation in the unit weight of the MSW on the overburdened effective stress were taken into consideration by introducing the main leachate level's proportion and the unit weight and buried depth curve. This approach is especially significant for MSW with a high kitchen waste content and landfills in developing countries. The stress-biodegradation compression model was used to calculate the compression of each MSW layer. A software program, Settlement and Storage Capacity Calculation System for Landfills, was developed by integrating the space and time discretization of the landfilling process and the settlement and storage capacity algorithms. The landfilling process of the phase IV of Shanghai Laogang Landfill was simulated using this software. The maximum geometric volume of the landfill error between the calculated and measured values is only 2.02%, and the accumulated filling weight error between the calculated value and measured value is less than 5%. These results show that this approach is practical for satisfactorily and reliably calculating the settlement and storage capacity. In addition, the development of the elevation lines in the landfill sections created with the software demonstrates that the optimization of the design of the structures should be based on the settlement of the landfill. Since this practical approach can reasonably calculate the storage capacity of landfills and efficiently provide the development of the settlement of each landfilling stage, it can be used for the optimizations of landfilling schemes and structural designs. (C) 2017 Elsevier Ltd. All rights reserved.