First tilting weir targets national environmental problem

30 September 2001

Engineers from the University of Wollongong have successfully completed construction of the first tilting weir in Australia which will help combat the environmental problem of acid sulphate soils.

Acid sulphate soils devastate plant and marine life, undermine flood-works and cost Australia millions of dollars.
The first tilting weir is located in one of the largest flood mitigation drains on a farming site in Berry (near Nowra) in the vicinity of Broughton Creek on the South Coast of NSW.

Research team leader, Professor Buddhima Indraratna, of the Division of Civil & Environmental Engineering, said the tilting mechanism was the final part of the project ensuring that these weirs are more sensitive to tidal flows.
Acid sulphate soils form when pyritic estuarine sediments in the sub-soil are exposed to air and oxidise, forming sulphuric acid.

A variety of soil minerals react to the acid and release free aluminium, toxic to crops and marine life.
The weirs ensure the water table remains high enough to cover the acid sulphate soil so that it does not dry out and become exposed to the atmosphere. Farmers who install weirs will save on costly alternatives such as regularly treating soils with lime mixtures and soil replacements. A farmer working more than 100 hectares would need two weirs, and simple weirs could be built without much outside help.

Government authorities and farmers have recognised the research team's work.

"Farmers in the Shoalhaven regard us as more community workers rather than academics," Professor Indraratna said.

The project has received funding from Federal Government and State Government organisations (eg. NSW Agriculture, NSW Fisheries), the Shoalhaven City Council and also the support of the Shoalhaven River Watch. Significant Federal funding came via the HeritageTrust's Coasts and Clean Seas competitive grant scheme.

The Federal Member for Gilmore, Ms Joanna Gash, said it was a fantastic example of what can be achieved through the three levels of government working together with the University, small businesses and the community "to ensure that we can continue to enjoy and benefit from our stunning natural heritage in a sustainable manner for generations to come".

"I congratulate everyone involved in the project and look forward to working on the next challenges in Gilmore," Ms Gash said.

The on-ground work under the Coasts and Clean Seas project was managed by Dr Anand Tularam, assisted by postgraduate students William Glamore and Marcus Morgan.

Professor Indraratna said the next challenge for the research team was to design infrastructure systems which could be used in very low-lying areas rather than just for high areas. In this regard he said the team was seeking further funding support. NSW Premier, Bob Carr, recently announced the Shoalhaven flood plain as one of the seven acid sulphate soils "hot spots" in NSW.