The $700k dredging program that ‘robs Peter to pay Paul’Written by admin , July 14th, 2017 // Oil & Gas
SUNSHINE Coast Council will spend $700,000 to transfer 100,000 cubic metres of sand from the Maroochy River to the beach in an exercise described as “robbing Peter to pay Paul”.
A dredge was moved into place at Cotton Tree on Monday to continue a program started in 2013 with the transfer of 125,000 cubic metres of sand from the river mouth to the beach and continued in 2015 (75,000 cubic metres) and 2016 when 20,000 cubic metres were shifted to “top up” the beach.
The process effectively recycles sand from one place to another without providing any long-term benefit.
The pumping operation comes as the beaches are at their healthiest in years with life-long Sunshine Coast water man Bryan Weir saying he has never seen so much sand.
Mr Weir said Maroochydore Beach was an eight-lane highway at low tide and sand was in quantity to the very end of Point Cartwright which was now functioning like a beach break.
The same was the case at Kong’s Cove on the Mooloolaba side of Alexandra Headland.
Matthew Barnes, senior coastal engineer with BMT WBM, said the Alexandra Headland to Maroochydore stretch of beach and the the mouth of the Maroochy River formed part of the same system that has suffered a nett loss of sand over time that could only be re-nourished from an outside source.
Mr Barnes said while the current sand pumping exercise would provide some benefit to a beach the council has estimated has annual value to the economy of $80m, it was sand already in the system.
“It provides some benefit but doesn’t provide a huge storm buffer,” he said.
“It’s robbing Peter to pay Paul. It’s sand recycling rather than nourishment. To do that you need to bring new sand in.
“To get more sand into the system it has to come from outside.”
The coastal engineer said the most immediate solution was to purchase sand from the Port of Brisbane, bring it to the Sunshine Coast by barge and then bottom dump it near the shoreline from where it could be redistributed by nature.
Long-term an offshore sand reserve may be established, potentially south of Point Cartwright in 20 metres of water.
The Gold Coast, which is currently undertaking a massive re-nourishment program from Palm Beach to Narrowneck, has an almost infinite supply of sand off shore.
Mr Barnes said on the Sunshine Coast there is a much thinner layer of sand over bedrock making the exercise more challenging.
He said purchasing sand from Moreton Bay may be something the council considered trialling sooner than establishing its own sand reserve which he said would take significant planning and as a project was 30 to 40 years down the track.
“If there was a really big storm, money would be found to get sand back on the beach,” Mr Barnes said.
“In that case Moreton Bay sand would be the solution.”
A council spokesperson claimed the current nourishment works which would take three months were essential to the ongoing protection of the adjacent assets that relied on the beach and dune system to act as a buffer for protection from storm erosion.
“In addition to allowing the shoreline to respond to natural erosion events, it also helps ensure our beaches are in great shape for the upcoming summer season,” the spokesperson said.
“Extraction area is similar to the area which has been used previously, including the program of dredging carried out in 2016.
“This is the northern tip of the dynamic sand spit, as well as on the western side from about halfway up the spit.
“Outcomes of previous dredging projects have shown that this area replenishes itself within a short period of time.
That is exactly what happens according to Mr Weir who said the replenishment will be the sand that is about to be shifted onto the beach.