Effects of Leachate Recirculation using Drainage Blanket and Horizontal Trenches on Slope Stability of Bioreactor Landfills

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4. Effects of Leachate Recirculation using Drainage Blanket and Horizontal Trenches on Slope Stability of Bioreactor Landfills

In this study, a numerical analysis was carried out using the finite element method to investigate the effects of leachate injection using drainage blanket and horizontal trenches on the slope stability of landfills. The numerical model was validated and the results were compared with the previously published literature. The effects of leachate injection using drainage blanket and horizontal trenches on pore water pressure, moisture distribution, and stability of slope were investigated for heterogeneous anisotropic waste conditions for different slope configurations, injection pressures, and height of landfill. The performance of drainage blanket and multiple horizontal trenches with horizontal spacing varying between 10 - 100 m was compared for different injection pressures, and their effects on the degree of saturation and landfill slope stability were evaluated. It was observed that the pore water pressure developed in landfill using a drainage blanket was less as compared to horizontal trenches. Based on the results of factor of safety and the required degree of saturation, the optimum horizontal spacing for trenches was found to be 50 - 70 m for various injection pressures of 49 kPa, 98 kPa, and 147 kPa. The results showed that more than 60% degree of saturation was achieved for both cases, i.e. drainage blanket and multiple horizontal trenches at an optimum spacing of 60 m for leachate injection pressure of 98 kPa. Therefore, the use of multiple horizontal trenches instead of a drainage blanket system would be beneficial in saving the cost of materials, construction, and long-term maintenance, without compromising on the performance of the bioreactor landfills.

9th International Congress on Environmental Geotechnics (ICEG2023)

Landfilling