Landfills are the major repositories of urban wastes, and will continue to be built, so long as the humans live in communities. The costs of construction, maintenance and remediation of landfills have escalated over the years and research is therefore required to identify alternative techniques that will not only minimise the costs, but also demonstrate increased environmental performance. An alternative landfill capping technique known as ‘Phytocapping’ (establishmentof perennial plants on a layer of soil placed over the waste) was trailed in Rockhampton, Australia. In this technique, trees were used as ‘bio-pumps” and “rainfall interceptors” and soil cover as “storage” of water. The environmental performance of the phytocapping system was measured based on its ability to minimise water percolation into the waste. The percolation rate was modelled using HYDRUS 1D for two different scenarios (with and without vegetation) for the thick and thin covers respectively. Results from the simulations incorporating 15 years of meteorological data showed percolation rates of 16.7 mm yr-1 in thick cover and 23.8 mm yr-1 in thin cover, both of which are markedly lower than those expected from a clay cap.