Performance evaluation of upper isolation layer and lower soil sorption layer in landfills disposing of radioactive cesium-contaminated incineration fly ash: Rainwater infiltration, cesium leaching, bentonite properties in outdoor soil tank experiment

Since radioactive cesium-contaminated incineration fly ash has a high leachability to water, both upper isolation layer to cut-off rainwater infiltration and lower soil sorption layer to retard the transport of leaching chemicals should be installed when disposing of such fly ash. An outdoor large-scaled soil tank experiment simulating a landfill disposing of them was conducted and continued for 3 years. This paper presents not only the rainwater infiltration and cesium leaching behavior observed through the experiment but also the change in the properties of bentonite used for the isolation layer after the experiment. Finally, the area that can be isolated from rainwater infiltration due to install of such upper isolation layer was estimated using FEM numerical simulation.