Modelling simplification of landfill processes by using methods of reliability theory

By the year 2005 most landfills in Germany will be closed down and begin the closing phase and later the after-care phase. So far there have been only a few scientific investigations concerning the hazard potential of stored waste for the environment. For this reason, it is necessary to predict how the hazard potential of landfills will vary after closure. The prediction can be made by describing the coupled processes of biodegradation and pollutant transport using models that are currently being developed. These models deal with highly non-linear differential equations having a large number of parameters. In order to permit application of the model in practice, it is necessary to reduce these to parameters which are essential to the reliability of the landfill. They have to be identified by sensitivity investigations with the aid of methods of reliability theory so that models can be limited to these essential parameters and the calculation effort as well as measurement of parameters (monitoring) can be considerably reduced.