Long-Term Performance of a Three-Layer Capillary Barrier Cover System in Humid Climates

An innovative three-layer (silt/gravelly sand/clay) capillary barrier cover system has recently been proposed for minimizing rainfall infiltration in humid climates. Its performance has been preliminarily verified by both physical and numerical modelling subjected to a short extreme rainfall. However, the long-term performance of this three layer cover system is not yet clear in humid climates, such as Hong Kong and Singapore, where an annual rainfall of over 2000 mm is expected. In this study, the long-term feasibility and effectiveness of this three-layer cover system are investigated. A series of numerical simulations were carried out based on a calibrated numerical model. It was found that the long-term feasibility and effectiveness of this three-layer cover system are investigated. A series of numerical simulations were carried out based on a calibrated numerical model even k_s in the clay layer increases to 5 × 10⁻⁹ m/s due to the occurrence of cracks, the long-term effectiveness of the three-layer cover system on preventing water into the waste is still satisfactory.