Investigation of landfill leachate pollution impact on shallow aquifers using numerical simulation

The aim of this study is to assess the effect of leached pollutants from solid waste landfills on shallow utilized aquifers within the State of Kuwait. The objectives of the work were achieved through developing a 3D-VMF Flex numerical flow and solute transport model. The results of the study of Kuwait show that the pollutants longitudinal dispersivity should be less than or equal to 420 m coupled with a ratio of horizontal transverse to longitudinal dispersivity equal to 0.1 and a vertical transverse dispersivity to longitudinal dispersivity ratio equal to 0.01. The novelty of this research is that the developed model was for the first time simulating concurrently the three processes that control the movement of pollutants in the porous media under landfills in Kuwait: advection, dispersion and adsorption. The dispersion and adsorption model parameters were calibrated against measured pollutants concentration in the field. This study shows that the adsorption process plays an important role in controlling the migrantion of heavy metals and inorganic pollutions into shallow aquifers. This study calibrates adsorption coefficient (kd) for conservative pollutants such as Cl to be 1 × 10–7 (mg/l)−1, for nitrogen compound such as NO3 to be 1.2 × 10–7 (mg/l)−1 and for heavy metals such as Pb and Cr to be 1 × 10–5 (mg/l)−1. It was also concluded that conservative pollutants take about one year to leach to the closets observational point (2.57 km). It took the conservative pollutant plume about 16.5 years (6000 days) to reach the furthest observation point, which is 5.26 km away. These conclusions combined draw a priority action-plan for interested parties to take into considerations future works for land and environmental rehabilitation strategies including natural underground water resources management.