Evaluation of the Suitability of a Composite Liner System for Designing a Landfill Bioreactor on Confined Bedrock at Sammanthurai in Sri Lanka

The development of a low cost and environmentally friendly liner system is essential for countries like Sri Lanka because the high-density polyethylene liner is of high cost and much more prone to toxic conditions and failures. This research was carried out at Sammanthurai by using clay-waste polyethylene-clay composite liner and permeability tests were conducted that gave values between 6.3 x 10^-8 and 2.6 x 10^-8 cm sec^-1 under both saturated and unsaturated conditions at the hydraulic head of 86.2 cm. These low permeability values were achieved by laying and compacting one layer after another at the required soil consistency to make a composite liner system. In addition, the use of waste polyethylene based composite liner is more beneficial than the high density polyethylene liner because this waste polyethylene makes an active biofilter which is cheaper and environmentally friendly. The ground penetrating radar survey shows that the confined bedrock is 0.5 to 6.0 m and the water table is 0.4 to 0.5 m from the surface during the rainy season. Therefore, permeate from the liner system will accumulate in the drainage layer above the confined bedrock and that can lead to embankment failure. It is then very important to install a collection and management system to accommodate permeates that were 3.51 x 10^-2 cm sec^-1 and 3.86 x 10^-2 cm³ sec^-1 under saturated and unsaturated conditions, respectively. The ‘water permeates’ will be reused, thus, overcoming the lack of available water in the dry zone of Sri Lanka for managing wastes as a resource.

DOI: http://dx.doi.org/10.4038/tar.v21i3.3300

TAR 2010; 21(3): 266-274