Bubble curtain trial at Jurien Bay Boat Harbour
News for the Department of Transport
A curtain of air bubbles could be the solution to seagrass build-up and water quality problems at Jurien Bay Boat Harbour.
Department of Transport (DoT) Manager of Maritime Projects James Holder said as part of an ongoing investigation to improve conditions at the harbour a $150,000 trial was about to commence to test if an air bubble curtain could reduce the amount of seagrass wrack entering the harbour during winter months.
"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 which will be activated in advance of storm events," Mr Holder 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 and minimising annual build up causing poor water quality and fish kills in the harbour.
"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 last decade resulting in expensive maintenance dredging."
Bubble curtains have been successfully and extensively used overseas on commercial and environmental applications including for aeration, silt management, weed and pollution control. The technology has been implemented at other locations in WA including for a similar application on a smaller scale within DoT's Fremantle Fishing Boat Harbour.
Mr Holder said while the project team was hopeful of a successful trial, there were some uncertainties about the application of the bubble curtain at Jurien Bay.
"The total length of the bubble curtain across the entrance will be around 150 metres and its performance against the storm generated currents and seagrass wrack volumes in this location will need to be assessed," Mr Holder said.
"This is just one option the team is looking at and during the trial DoT will continue its investigation into other structural solutions to seagrass wrack build-up at the boat harbour."
Apart from activities associated with the installation and removal of the equipment, operations at the harbour will not be interrupted. A line of air bubbles breaking the surface at the harbour entrance will be visible when the trial is running.
DoT will closely monitor the effectiveness of the bubble curtain throughout winter and spring 2018 and the length of the trial will depend on performance.
Harbour users will receive information about the trial and others interested to learn more can visit the Jurien Bay Boat Harbour page.
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