Field performance of a phytocap at Lakes Creek landfill, Rockhampton, Australia

Abstract

Purpose

Landfill capping is a mandatory post closure procedure in Australia to isolate the deposited wastes from the outside environment, mainly water. Compacted clay caps are predominantly used in Australian landfills. Recent studies have shown that clay caps have shorter life span and fail to prevent percolation of water due to cracking. This paper aims to discuss a new technology called “Phytocapping” that has been trialled at Lakes Creek landfill in Rockhampton.

Design/methodology/approach

In this technique, trees were used as “bio‐pumps” and “rainfall interceptors” and soil cover as “storage” of water. The field performance of the phytocapping system was measured based on its ability to minimise water percolation into waste. Tree growth, transpiration, canopy rainfall interception and methane emission were monitored over three years. The percolation rate was modelled using HYDRUS 1D code for two different scenarios (with and without vegetation) for the thick (1,400 mm soil) and thin (700 mm soil) phytocaps respectively.

Findings

Results from the modelling showed percolation rates of 16.7 mm yr⁻¹ in thick phytocap and 23.8 mm yr⁻¹ in thin phytocap, both of which are markedly lower than those expected from a clay cap. Results from monitoring and observations showed that 19 of 21 tree species grew well in the harsh landfill environment. However, the correct species selection is very important for the long‐term sustainability of the phytocap. Results also show that phytocaps can reduce a significant amount of methane emission from landfills.

Practical implications

The cost of landfill capping is escalating and is putting a lot of financial and legal pressure on the small and medium sized local governments in Australia. The phytocapping technique not only offers financial benefits but also has some environmental and commercial benefits.

Originality/value

The paper focuses on a new technology being used in waste management.

Citation

Venkatraman, K. and Ashwath, N. (2010), "Field performance of a phytocap at Lakes Creek landfill, Rockhampton, Australia", Management of Environmental Quality, Vol. 21 No. 2, pp. 237-252. https://doi.org/10.1108/14777831011025571