A systems engineering and risk assessment-based approach for the design of landfills

The long-term performance of modern landfills is governed by a set of systems, including the landfill cover and the bottom barrier. In order to minimise the environmental impacts of a landfill, a systems engineering approach may be adopted for the landfill design. Such an approach requires analysing the interactions between the different components of each system involved and then evaluating the response of the entire system assembled to quantify its overall engineering performance. The effectiveness of the lining systems is demonstrated through the verification that the risk for human health and the environment due to pollutant migration is limited to an acceptable level. This risk is quantified through the calculation of the pollutant concentration in the groundwater, which is expected to remain less than some prescribed level at a compliance point. The paper describes a simplified approach to the analysis of pollutant transport, which allows the pollutant concentration in the groundwater to be calculated under different boundary conditions and taking into account the role played by several geosynthetics, such as geonets, geomembranes and geosynthetic clay liners, which are used in landfill lining systems.