The Murray River is receding in the Riverland and, as the flood recovery begins, questions have been asked about what will become of the DefenCell system.
Key points:
- The River Murray flow peaked at Renmark on December 26 last year
- The DefenCell technology was trialled for the first time in Australia in response to the flooding
- Approximately 4.5km of the technology was deployed in the Riverland
The flood prevention technology was acquired by the South Australian State Emergency Service (SASES) to protect vulnerable infrastructure and assets in flood-affected communities.
The SASES said about 4.5 kilometres was used across the Riverland, with the most significant “single use being a 1.2km DefenCell levee in the township of Mannum”.
Renmark Paringa Council acting director for infrastructure Tarik Wolf said DefenCell provided a safety net.
“Along the riverfront, in Renmark we needed to install a 300-metre flood barrier extending from the visitor information centre to the Taylor Riverfront Precinct,” he said.
Simple but elegant
Mr Wolf said the system involved three distinct components.
“It consists of a steel gabion, which is about 3m long and 600 millimetres high,” he said.
“The steel cage houses a geo-textile fabric and then inside the geo-textile it is filled with sand.”
Now that the need for the DefenCell has passed and the extra freeboard is not needed, the council is beginning to explore its options for reusing or recycling the product.
“When it comes to removing the product, the sand will go back into council parks and gardens, top dressing of lawns, backfilling of trenches around irrigation systems — that sort of thing,” Mr Wolf said.
“We believe we’ll be able to remove the gabion cage and reuse it in future flood events and store it until then.
“We are finding damage on some of the cages as we pull them out, so we may need to pursue a recycling disposal path if they aren’t fit for purpose.
“The geo-fabric insert, which goes inside the cage, we’re thinking of using it in erosion control projects.”
‘A lot to learn’
Renmark was not the only council to trial the flood defence system.
Berri Barmera Council infrastructure manager David Plucker said they found the combination of traditional sandbags and levees with the new system to be effective.
“We used a mix,” he said.
“They were used in conjunction with sandbags along the riverfront.
“We haven’t seen a flood of this size for many years — we’re all relatively new at this.
“There’s a lot to learn from this and we can take a lot of things away from it and be better at it next time.
“All in all I think we’ve done very well throughout.
“I’d like to thank the public for being patient, we’ve got our own regular daily chores to deal with and we’ll get back to some semblance of normality as soon as we possibly can.”
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