Transport of organic contaminants within composite liner systems

Composite liners (a geomembrane in intimate contact with a mineral liner) are frequently used to line landfills and contaminated sites. It is therefore very important to characterise the behaviour of these systems even under extreme conditions. An investigation was undertaken to determine the influence of a mixture of concentrated organic contaminants on composite liner materials taken from test cells that had been dismantled after a 12-year permeation test. The organic hydrocarbons had permeated the HDPE-geomembrane and had then migrated or had been adsorbed within the mineral liners, depending on their properties. The obtained concentration profiles of the contaminant mixture components indicate that the various mineral layer materials have selective retardation abilities which correspond to the different parameters of the organic compounds as well as of the mineral layer. In addition, contaminant transport in the composite liners tested was modelled and the results of the model analysis compared with measurement data. An example (acetone) illustrates the calculated spatial and temporal contaminant concentration. The composite liners investigated exhibit a very good sealing capacity against the concentrated organic contaminants used. (C) 2002 Elsevier Science B.V All rights reserved.