Landfill settlement and the impact on site capacity and refuse hydraulic conductivity

Abstract

A settlement model was developed for predicting the compression of each layer of refuse in response to the weight of overlying refuse in deep landfills. The compression of each layer was used to estimate its hydraulic conductivity which was used to simulate leachate movement through the refuse mound. The results indicated that low refuse hydraulic conductivity at the bottom of the landfill interferes with movement of the leachate down to the leachate collection system (LCS), and that a leachate mound can form in the refuse above an operating LCS. This leachate mound has the potential to cause leachate side seeps and could interfere with the landfill gas collection system. If these are concerns at a specific site, alternative LCS designs to high permeability layers on low permeability liners should be considered. However, the results also indicate that a leachate mound within the refuse is not necessarily indicative of the head on the liner.