The best place for a landfill
Kate Valley was chosen for the Landfill because the underlying geology makes the site an ideal location. Beneath the topsoil are silt and clay deposits (used for the Landfill construction) and beneath this is a layer of a low permeable material called Tokama Siltstone that extends down to depths of 200 metres. Low permeability simply means that water isn’t able to soak through the ground. With no known aquifers beneath the site the potential for water from within the Landfill mixing with groundwater is non-existent.
The greatest environmental protection
Even with excellent ground conditions providing natural containment, a multi-layered synthetic liner is also used in the Landfill. Construction of the Landfill begins with shaping and compacting of the silt and clay to form a smooth natural liner. The synthetic liner is laid on top of this surface. It consists of upper and lower layers of high-density polyethylene, on either side of a layer of geo-synthetic clay lining. This clay is designed to expand when it becomes wet to seal any punctures in the liner. Then a 500mm permeable gravel Liner Protection Material (LPM) is laid which both protects the liner and allows the flow of leachate to the bottom of the landfill where it is collected and treated (see section below). Finally 3 metres of uncompacted waste are laid on top of the LPM to further cushion and protect the liners. Together these liners and layers provide Kate Valley Landfill with a containment system superior to the standards used in both the European Union and the USA for municipal waste landfills.
Water collected from drains placed beneath this liner system, under the landfills waste pile is regularly tested for contamination. The results so far show no cause for alarm.