Research by CQUniversity doctoral student Kartik Venkatraman is helping convince urban planners to dump the old practice of capping city landfills with clay, in favour of soil and trees.

Kartik has been doing the important technical monitoring and site comparisons to prove that phytocapping (where phyto means trees) is a better option and he expects the trend to be picked up throughout Queensland and Australia.

Kartik Venkatraman

His part-time PhD research complements his full-time role as Technical Services Coordinator with CQ Waste Management (part of CQ's the Central Queensland Local Government Association), involving work with 5 councils across the region.

"We'll soon see phytocapping implemented on a large scale in Central Queensland," Kartik says.

"Clay capping is expensive and cracks can form over time allowing water to percolate into the refuse. Clay caps also do not perform in all weather conditions and have shorter life. They don't have the porosity to oxidise or reduce methane gas.

"With phytocapping, we are using soil of a certain depth and trees of different species to reduce water infiltration.

"Much of the rain is held in the tree canopy and evaporates. The rest of the rain goes into the soil cover and is taken up by trees in the form of transpiration.

"Phytocapping also reduces methane emissions and the methane that does escape comes the through soil cover and root zone, which helps to oxidise it into a non-toxic biogenic carbon dioxide, so we are not contributing to global warming.

Kartik said the upfront costs for phytocapping were less expensive but the real savings came during the cap's 30-year mandatory  management period, as phytocapping's self-repair characteristic lowered labour requirements and overall costs.

"Phytocapping can contribute to the carbon pollution reduction scheme by reducing the amount of methane going into the atmosphere," he said.