Monash engineers are examining how to make better use of a resource that too often ends up down the drain.

By David Bruce

Associate Professor Tony Wong and researcher Ms Sara Lloyd are implementing the best elements of water sensitive urban design.

When the big rains come, the keepers of our reservoirs and agricultural land find reason to rejoice. But in the urban areas of our country, each rainstorm also takes away as good as it gives.

With each rush of stormwater, tonnes of soil and pollutants are carried directly into drains and open waterways and, eventually, into open waters such as Melbourne's Port Phillip Bay.

At Lynbrook Estate, a residential sub-division on Melbourne's south-eastern outskirts, Monash engineers from the Cooperative Research Centre for Catchment Hydrology have begun to change the way we look at stormwater runoff by implementing the best elements of water-sensitive urban design.

Their integration of a number of innovative elements in stormwater management is a first for Australia but, according to Associate Professor Tony Wong from the Department of Civil Engineering, Australians are beginning to realise that better urban design will lead to cleaner rivers, lakes and oceans.

Lynbrook's constructed wetlands and nods provide secondary water treatment, slowing the pace of run-off and further filtering out water pollutants.

"In Australia, the whole notion of draining stormwater directly into our river systems and bays is quite common," says Dr Wong. "It has always been the assumption that rainwater from roofs and road surfaces is clean. But it isn't. It is a polluted mix of metal-based chemicals such as copper, nickel, lead and zinc, as well as chemicals from agricultural products such as fertiliser."

With the support of Melbourne Water, the Urban Land Corporation and their consultants, Dr Wong and postgraduate student Ms Sara Lloyd have designed a street drainage system that uses natural vegetation and wetlands to clean and store the stormwater run-off before it is released into the bay.

Lynbrook's constructed wetlands and nods provide secondary water treatment, slowing the pace of run-off and further filtering out water pollutants.

Stormwater collected from houses and street surfaces in one section of Lynbrook Estate is directed into a trench that runs the length of a street. The trench is covered with grass swales and underlain with fine gravel that provide the primary stormwater treatment measures. The secondary treatment of the water is provided by a constructed wetland and a large pond that slow the pace of the run-off and further filter out the water pollutants.

"The treatment of stormwater run-off can no longer be considered in isolation to the broader planning and design of the surrounding urban area," says Dr Wong. "The unique feature of the drainage system at Lynbrook is not so much the individual parts of the infrastructure, but rather how they all complement each other in the one catchment area."

Apart from its ecological soundness, the integration of natural vegetation and wetland at Lynbrook Estate will actually be an attribute for this flat and featureless stretch of former farmland, typical of many new developments on the fringe of major cities.

"When it is landscaped properly, it can become a feature of the neighbourhood," says Dr Wong. "There is a small extra cost involved for the land-buyers in this sort of system, so we now need to wait and see if this is offset by the attraction of living in a clean and pleasant environment."

Natural Stormwater treatment methods are used at Lynbrook Estate.

		To find out more about postgraduate research opportunities in the Cooperative Research Centre for Catchment Hydrology, contact +61 3 9905 2704 or visit the website at www.catchment.crc.org.au