Numerical Analysis on the Seepage and Contaminant Transport through Seabed at Offshore Landfill considering Sea Level Variations

Abstract

The transport of leachate in seabed is affected by cyclic sea level variation due to tide at offshore landfill. In order to prevent leakage of contaminants in offshore landfill, low permeable bottom layer and hydraulic vertical barrier is indispensable. In this study, the seepage and contaminant transport in the subsurface considering sea level variations with embedded depth of vertical barrier were analysed by using SEEP/W and Visual Modflow program. Numerical modeling results show that cumulate discharge was increased and contaminants were more dispersed considering sea level variations after 50 years. Seepage flux and contaminant transport in seabed were greatly reduced when vertical barrier was installed at a certain depth of low permeable layer. Therefore, the determination of minimum embedded depth for preventing contaminant leakage is helpful for the economical design ofthe vertical barrier at offshore landfill with consideration of the cyclic sea variation.ndispensable. In this study, the seepage and contaminant transport in the subsurface considering sea level variations with embedded depth of vertical barrier were analysed by using SEEP/W and Visual Modflow program. Numerical modeling results show that cumulate discharge was increased and contaminants were more dispersed considering sea level variations after 50 years. Seepage flux and contaminant transport in seabed were greatly reduced when vertical barrier was installed at a certain depth of low permeable layer. Therefore, the determination of minimum embedded depth for preventing contaminant leakage is helpful for the economical design ofthe vertical barrier at offshore landfill with consideration of the cyclic sea variation.