An innovative floating wetland treatment system has been built in Australia as an experiment in improving water quality in residential developments. The treatment system—installed in a 2.5-hectare man-made lake at the Parklakes2 development in Bli Bli, Queensland—uses selected plant species to mitigate the impacts of stormwater runoff from the nearby estate by drawing excess nutrients and pollutants from the surrounding water.

Peter Schwammberger (r) will evaluate the performance of the wetland treatment system. Image credit: University of the Sunshine Coast.Research findings from the three-year project will help to determine best practices for using floating wetland treatment systems in and around residential estates.

While traditional constructed wetland systems have been an integral part of residential estates to treat stormwater for a number of years, the system at Parklakes2 is enabling stormwater treatment to begin early in the estate’s development, according to Christopher Walker, environmental manager of the engineering firm Covey Associates.

“With constructed wetlands, you typically have to wait until 60-80 percent of the development is complete before they can even start to be constructed," Walker says. "This is because sediment from ongoing construction works can impact the health of wetland plants, even with upstream site management.” In this instance, the floating wetlands sit on top of the water so this isn’t an issue and plant roots help to filter out sediment from runoff, Walker says.

"Another important aspect is that as the floating wetlands need to be installed on open water, it gives residents an aesthetic benefit and the area surrounding the wetlands is better utilized for parks, playgrounds and passive open space," says Walker. Previously, such systems have been retrofitted at a small scale into existing developments.