Flow Investigation for Landfill Leachate (FILL)

Abstract

A two-dimensional un-steady-state moisture flow model has been developed in order to describe the leachate flow process in a landfill. The unsteady variation of leachate mound head has also been considered in the saturated zone of the landfill to compute the time-varying leachate flow rates in both the lateral and vertical directions. The contribution of precipitation to the landfill leachate has been investigated by computing evapotranspiration and surface runoff due to side slope. The model was used to simulate the leachate flow rates in section 6/7 of Fresh Kills landfill, situated in Staten Island, New York. A comparison of the results was made with the Hydrologic Evaluation of Landfill Performance (HELP) model, which is based on a quasi-two-dimensional approach. Comparisons were also made with the results obtained from previous studies using the Environmental Protection Agency (EPA) water-balance model and investigating the real field condition. An underestimate of the surface runoff was observed in the case of the results obtained by the HELP model. The simulated leachate flow rates by the new model were found to be less than those obtained by other methods. The effects of the variation of the boundary condition, which depends on surface runoff and evapotranspiration, were examined to arrive at the better representation of the two-dimensional unsteady mechanism of leachate flow process in a landfill.