Effectiveness of Technical Safeguards for Earth Constructions with Contaminated Soils and Building Materials

摘要

Slightly contaminated soils and recycled materials can be used for earth constructions ifdefined concentrations of chemical substances are not exceeded and if technical safeguards are designed.As technical safeguard or as a technically safe installation the application of a sealing systemis usually considered. However, if the materials are of low permeability the use of additional clayliners or geomembranes for sealing reasons is not necessary. The German Road and TransportationResearch Association (FGSV) developed various construction methods for the use of contaminatedsoils and building materials for earth works (regulatory code MTSE). These can be divided into constructionmethods with sealing elements and construction methods without sealings, when low permeablesoils or building materials with environmentally relevant constituents are used. For a researchfunded by the German Federal Ministry of Transport, Building and Urban Development theeffectiveness of the different construction methods has been investigated by means of numericalsimulations. Thereby the seepage of embankments built according to the construction methods recommendedby the FGSV has been analyzed. The results show that the expected seepage of embankmentsbuilt according to the construction methods with sealings is very small and fulfills eventhe criterion for soil covers of landfills. For the construction methods without additional sealings,where low permeable soils or building materials with environmentally relevant constituents areused, a much higher seepage has been computed. To reduce the seepage of such embankments withoutadditional sealings the requirements regarding the permeability of the contaminated soils or recycledmaterials should be increased. Additional simulations show that the coefficient of permeabilityshould be lower than k = 1 · 10~(-8) m/s.