Assessment of potential groundwater contamination under unlined landfills in Jordan

Jordan’s sole waste management option is landfilling. However, almost all landfills are unlined, lack any daily application of cover, and have no engineered final cover. There have been no reported incidents of water contamination so far due to the arid nature of the climate in Jordan. The low precipitation and high evaporation rates have been responsible for minimizing any buildup of water on the bottom liner. Deep groundwater tables in Jordan have also diminished the risk of leachate contact with groundwater. Nevertheless, a vertical leachate movement towards the water table does in fact exist due to hydraulic and concentration gradients. Thus, a proper assessment of the situation needs to both address the unique characteristics of the highly moist and highly organic solid waste in Jordan and also set a relatively wide time frame for modeling to ensure an accurate understanding of the risk of groundwater contamination for these facilities in the coming decade. This study used the hydrological evaluation of landfill performance (HELP) model to calculate the percolation under a six unlined landfills in Jordan using real measured values of municipal solid waste (MSW) physical and hydraulic parameters, weather data, and soil properties for the coming 10 years. Results have predicted that all assessed landfills will have annual leakage ranging from 174 to 205 m 3 . The study points out the alarming condition of the Dead Sea unlined landfill where an average annual leakage of 299m 3 has been predicted over a water table that is only 38 m below ground surface.