Investigation and Modeling of Two Composite Landfill Covers

The performance of two municipal solid waste landfill final covers was investigated. A field investigation of each landfill was performed, with test pits excavated and soil and geotextile samples collected. The investigation and analysis showed that the cover components were generally in good condition and performing their intended function in the field. Differential settlements that had occurred at both landfills were modeled with a finite difference code. The model results were used to calculate geomembrane strains and relate them to surface settlement characteristics. Using this method, two areas of differential settlement at one of the landfills were evaluated, and the geomembrane strains were found to be well below yield strains. In addition, a general design method for composite landfill covers spanning voids was developed with the finite difference model.