Hydraulic Conductivity and Landfill Construction

Compost quality and its function as a soil conditioner of recultivation layers – a critical review

“…Prior to the final complete sealing of waste deposits, a transition period is required in order to support the decomposition process while neither the atmosphere nor the groundwater is afflicted by contaminants. Thus, the construction of partially permeable layers is necessary to stimulate the biochemical decomposition processes in the waste body by controlled moisture with regard to potential settlements (Beck-Broichsitter et al, 2017;Rowe, 2011;Stępniewski et al, 2011).…”

“…It is the subtarget of the temporary landfill capping system to minimize the drainage of precipitation water towards the compacted surface sealing layer and into the underlying waste body by maximizing the evapotranspiration rate from the soil surface and the locally appropriate vegetation by improved plant growth due to compost addition (Laner et al, 2012;Stępniewski et al, 2011). In the European Union, aerobically composted organic materials are either used as organic fertilizers in agriculture or provide the structural and vegetative stability of recultivation areas (e.g.…”

Suitability of Boulder Marl and Marsh Clay as Sealing Substrates for Landfill Capping Systems—A Practical Comparison

“…The comparatively lower AWC values of the boulder marl can be explained, and are related to the smaller number of nCP and MP as mentioned previously [30], thus, an increasing AWC could be realized with compost addition [31] or with increasing compaction, as previously [32] pointed out. As result of this, a higher transpiration rate and water storage capacity could reduce the amount of infiltrating water, as described previously [33]. Considering the Ks values, neither the boulder marl nor the marsh clay are suitable materials for the sealing layer according to the authors of a past paper [2].…”

“…The natural permeability may be reduced by additional compaction [34], but it is well-known that a reduced number of coarse pores accompany soil compaction, along with smaller Ks values, especially in the top and bottom liner, when compared with uncompacted, natural soils [33]. Thus, even if these values cannot be reached, the consideration of shrinkage processes and anthropogenic anisotropic flow properties (Ks horizontal > vertical) of the liner can help make the top and bottom liners impermeable for the long-term.…”

“…The results suggest that several conflicts of interest exist (i.e., shrinkage intensity versus Ks values) and both materials are not usable as bottom liner with an exclusive purchase on the soil physical properties, respectively. Thus, the boulder marl is a more useful top liner material with its less pronounced shrinkage potential and can also be installed as bottom liner in combination with clayey substrates or geosynthetics and geotextiles, decreasing its comparatively higher permeability due to subsequent compaction during installation [33]. Alternatively, temporary capping systems mostly consist of semipermeable mineral liner to slowly shout down the so called 'bioreactor' and therefore, the investigated boulder marl with its permeability characteristics should be the material of choice as mentioned by [31].…”