Geotechnical characteristics of some Southwestern Nigerian clays as barrier soils

Abstract

The geotechnical characteristics of some southwestern Nigeria clays were evaluated with a view to determining their suitability for use as barrier soils in waste disposal sites. Clay soils (consisting of twenty disturbed and twenty undisturbed samples) were subjected to grain size, consistency limits and permeability tests. In addition the clay mineralogy and major oxide composition of the soils were determined. The clays are well-graded soils of low plasticity containing adequate percentage clay size fractions and amount of fines showing soils with high specific surface which allow low migration of leachate. The coefficient of permeability ranges from 1.18 x 10^-4 to 1.45 x 10^-7 cm/s indicating low to practically impermeable soils. Clay mineralogy revealed the presence of mixed clays - kaolinite-bentonite and kaolinite-illite, hence, their capabilities to attenuate and contain leachate. The studied clays are good barrier soils.

Keywords: Permeability, Barrier Soils, Clays, Leachate, Containment, Attenuation