Estimating hydraulic properties of landfill waste using multi step drainage experiments
Date
2010
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Publisher
University of Delaware
Abstract
Laboratory tests were conducted on two types of waste samples in order to explore how the hydraulic properties and constitutive relationships of waste samples can vary. The first waste sample was idealized and composed entirely of newspaper. The second set of samples was made up of components typically found in municipal solid waste landfills. The tests used were developed by Han (2009) and performed as a continuation of his research. Saturated hydraulic conductivity, drainage, multi step outflow, and porosity tests were performed on a newspaper sample similar to those used by Han (2009), but packed to a higher compaction density. The results of those tests supported conclusions drawn by Han (2009). First, a dual permeability model is needed to accurately describe the hydraulic behavior of an idealized waste sample and it is likely that such a model would be necessary to describe real waste. Second, although physical manipulations of the waste (i.e. changing the compaction density) can alter the fracture properties of the waste significantly, there is very little variation in the matrix properties of the waste. This suggests that the matrix domain of landfilled waste should be similar if the compositions of porous materials in the landfills are similar. Four real waste samples with very similar compositions were studied using modified versions of the saturated hydraulic conductivity, drainage, and porosity tests developed for the newspaper samples. The data collected from the tests was inversely modeled using HYDRUS-1D and one of two assumptions. First, it could be assumed that the pore structure of the waste could be described by a single pore domain model. The second assumption was that the waste was better described as a dual domain system and the behavior observed in the drainage tests could be used to describe only the fracture domain. There was some variability observed among the hydraulic parameters and constitutive relationships of the four tests in this study, and a great deal more variability when the results were compared with similar studies in the literature.