Use of slag for the construction of the drainage layer at the landfill Schwanebeck.

The leachate of landfills is commonly contaminated. Hence, leachate has to be captured and further processed before discharged into the groundwater. The material used for constructing the drainage layer is usually natural gravel (16/32 mm). However, the German regulation also allows using wastes as material for the drainage layer when the long-term chemical and mechanical stability is given.The quality has to fulfill the state of the art defined in the “Bundesqualitätsstandards”
The landfill Schwanebeck was recently expanded. As material for the drainage layer (0.5 m) slags (electric arc furnace slags, 16/32 mm) were applied. Before using the slags, several experiments had be conducted to characterize the material and to prove long-term stability. This includes the long-term chemical behavior regarding high and low pH, determination of minerals and to contaminants (overall content, leachate). Furthermore, long-term mechanical performance (fragmentation, performance during high pressures) and the impact of the leachate on this factors was examined. The results underlined the chemical and mechanical stability. Thus, the slag could be used for the drainage layer. Overall about 5000 Mg of natural gravel could be substituted by the use of slag. the ecological footprint is reduced and the landfill operator benefits as slags are cheaper than natural products. Both characteristics of the slag and leachate have to be considered when testing their long-term stability.