Jurien Bay Boat Harbour seagrass build-up may be solved by air bubble curtain

 The Department of Transport hopes a bubble curtain will reduce seagrass build-up in Jurien Bay Boat Harbour.
The Department of Transport hopes a bubble curtain will reduce seagrass build-up in Jurien Bay Boat Harbour.

A CURTAIN of air bubbles may be a solution to seagrass build-up at a boat harbour north of Perth.

Department of Transport maritime projects manager James Holder said the department was starting a $150,000 trial at Jurien Bay Boat Harbour as part of an ongoing investigation to improve conditions at the facility.

Mr Holder said it would test if an air bubble curtain could reduce the amount of seagrass wrack entering the harbour during winter.

“Weighted pipes, commercially manufactured to create a bubble curtain, will be anchored to the seabed across the harbour entrance and connected to an air compressor located on the northern breakwater,” he said.

“The bubble curtain generates a current, which is hoped to be strong enough to push seagrass wrack away from the harbour, potentially preventing its entry.

“If successful, the bubble curtain offers a low cost, environmentally friendly solution to a problem that impacted operations at the harbour and affected water quality over the (past) decade, resulting in expensive maintenance dredging.”

Mr Holder said storms would activat the compressor and the bubble curtain could minimise annual build-up that causes poor water quality and kills fish in the harbour.

Bubble curtains have been used overseas on commercial and environmental applications, including for aeration, silt management, weed and pollution control.

The department has used the technology at other locations in WA, including on a smaller scale within Fremantle Fishing Boat Harbour to contain rubbish.

Mr Holder said while they hoped the trial would be successful, there were some uncertainties about the 150m bubble curtain.

“Its performance against the storm generated currents and seagrass wrack volumes in this location will need to be assessed,” he said.

Mr Holder said during the trial, the department would continue investigating other structural solutions to seagrass wrack build-up at the harbour.

Visit www.transport.wa.gov.au/jurienboatharbour for more information.

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