Calculating hydraulic conductivity of fine-grained soils to leachates using linear expressions

Linear expressions are developed in order to allow the selection, in the waste landfill preliminary design stage, of the soils that can be used in the construction of compacted soil layers for liner and cover systems. These linear expressions were obtained from linear correlations between the hydraulic conductivity and the percentage of fines of Portuguese fine-grained soils. They are proposed, as an useful alternative to the guidelines existing in the bibliography and in current use, for the following three main reasons: a) laboratory tests were performed on natural fine-grained soils covering a wide range of mineralogical, chemical and physical properties; b) the laboratory-measured values of the hydraulic conductivity were obtained in hydrogeochemical performance tests carried out on soil specimens permeated directly with demineralised water, on soil specimens permeated with a synthetic multi-species acid leachate (pH = 4.6, electrical conductance ≅ 14000 μS/cm) after percolation with demineralised water, and on soil specimens permeated directly with the acid leachate; c) a quantitative assessment of the hydraulic conductivity, even though approximate, is preferable to a semi-quantitative one.