Proposal to install hundreds of giant sandbags on Brighton beaches to prevent sand drift
HUNDREDS of giant sandbags — three times bigger than we’ve seen — would be placed on Adelaide beaches to prevent sand drift under a council and State Government experiment.
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HUNDREDS of giant sandbags would be placed on Brighton beaches to prevent sand drift under a Holdfast Bay Council and State Government experiment.
The council plans to use 270 sandbags to create nine groynes spanning 1km between Dunluce Ave in Brighton — just north of the jetty — and Gladstone Rd in North Brighton.
Huge amounts of sand disappeared from Adelaide beaches during fierce storms in July and September, prompting some geologists to fear sections of beach will eventually disappear because of poor sand retention measures.
Each groyne would begin at the low-tide mark and extend 24m inland, leaving space near the rock seawall for people to walk along the beach.
The groynes would be 1.3m high and 5.4m wide and consist of 30 sandbags each.
Each sandbag would be filled with 4.5 tonnes of beach sand.
If the proposal is approved at the council’s next development assessment panel meeting on December 14, it would be the first time such large sandbag groynes have been installed on South Australian beaches.
Mayor Stephen Patterson said the sandbag groynes were a “relatively non-invasive and affordable sand-retention measure” that would complement the State Government’s sand pumping system.
Several groynes made of sandbags a third of the size were installed on Somerton Park beach in 2008.
“Brighton beach is our first priority to trial the groynes, given that we’re already seeing the loss of beach at high tide and the impact of storm events there, and that this measure is highly likely to succeed in this location because of the nature of the tides and sand drift pattern,” Mr Patterson said.
Depending on the result of consultation completed earlier this month and the panel approving the proposal, the council intends to install the groynes before Christmas or, if this is not possible, in February, after the school holidays.
“Eventually, drifting sand will be trapped against the groynes, and the groynes will blend into the beach environment,” Mr Patterson said.
“The beach level will even out and we’ll return to an easily walkable beach, but initially there will be a noticeable visual impact.
“It’s a necessary measure that aims to protect coastal infrastructure and homes, and it’s a much softer, more natural approach than the concrete and timber groyne structures you see around Europe and the UK.”
Respected coastal geologist Ian Dyson said the “groyne field” was a “Mickey Mouse” solution that had failed when tried in Victor Harbor.
“You’ll have sand build-up on the updrift side and erosion on the other side of the groyne so you get this zigzag pattern of sand,” Dr Dyson said.
He said it would be an “eyesore” and was being done so the council and Coast Protection Board could be “seen to do something”.
An Environment Department spokeswoman said the groynes at Somerton Park had worked “to help maintain a walkable beach at higher tides” and like the new ones at Brighton were “not part of a protection strategy”.
“The trial groynes at Victor Harbor were part of a protection strategy (to stop erosion of a dune system) and were constructed to establish whether littoral drift was in fact occurring and in which direction,” she said.