Hydraulic conductivity of Hindmarsh clay amended by polymeric additive

Abstract

In Adelaide of South Australia, Hindmarsh Clay is one of major soil formations identified in subsurface where landfilling works rest on. The Hindmarsh Clay is typically stiff and low permeable which offers the chance of being deployed as the choice of material for compact clay liner (CCL) of a landfill facility. In this study, laboratory investigations were conducted to examine hydraulic conductivity of compacted Hindmarsh Clay and to assess the likelihood of using the Hindmarsh Clay as major material for CCLs. In addition to the investigations conducted on plain Hindmarsh Clay, a polymeric additive was added to the Clay to further amend the performance of CCLs, in particular, the capacity of containment against leachate permeation. The investigations were favourable by outputting encouraging test results. The hydraulic conductivity of compacted Hindmarsh Clays was in the order of magnitude of 10^−10 m/s (flexible wall tests), which meets the minimum requirement regulated by local environmental authority. When amended with the polymeric additive, the Hindmarsh Clay promoted its capacity as hydraulic barrier, in particular, against the leachate permeation. When exposed to the leachate in a modified rigid wall permeameter, amended Hindmarsh Clays outperformed plain Hindmarsh Clays by reducing hydraulic conductivity to the order of magnitude of 10^−11 m/s. Three other additives were used to amend the Hindmarsh Clay for the sake of comparison: fly ash, silica fume and sodium hexametaphisphate. Results indicated that the polymeric additive shows better barrier performance than the other additives.