Hydraulic conductivity of Hindmarsh clay amended by polymeric additive

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 conductivityof 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 amendthe performance of CCLs, in particular, the capacity of containment against leachatepermeation. The investigations were favourable by outputting encouraging test results. The hydraulic conductivityof 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 amendedwith the polymeric additive, the Hindmarsh Clay promoted its capacity as hydraulic barrier, in particular, against the leachatepermeation. When exposed to the leachatein a modified rigid wall permeameter, amendedHindmarsh Clays outperformed plain Hindmarsh Clays by reducing hydraulic conductivityto the order of magnitude of 10-11 m/s. Three other additives were used to amendthe Hindmarsh Clay for the sake of comparison: fly ash, silica fumeand sodium hexametaphisphate. Results indicated that the polymeric additive shows better barrier performance than the other additives.