Impacts of landfill leachate on groundwater quality in desert climate regions

Control and management of landfill leachate are the most important concerns to protect the surrounding environment, especially the groundwater. In this study, an attempt was carried out to design an approximate tool for finding the safe groundwater withdrawal away from the pollution sources. A case study was applied to a landfill site in a desert climate region, at Mufrihat, the south western region of the Madinah City, KSA. Three boreholes were adopted to monitor the groundwater quality close to leachate collection lake of the landfill site. A 3D simulation model, combining modular finite-difference flow model and the modular three-dimensional transport model, was applied to the leachate collection site to understand the fate and migration of the leachate from collection site bed into the groundwater. The focus of this work was to predict the distribution of heavy metal concentration with both time and distance and to determine the safe location for water extraction from this aquifer. Results showed a good match between numerical model results and experimental measurements. Based on this math and sensitivity analyses performed by the computer model, an empirical mobility model was generated to support the decision makers of this area and similar regions to estimate the safe location for water withdrawal according to the initial concentration of the element, pumping rate and contact time. The mobility model showed that the well located at a minimum of 113 m away from the leachate collection lake would be safe from all studied pollutants.