Offshore dredging an option to rebuild Stockton Beach

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Beach renourishment on the Gold Coast. Picture: City of Gold Coast

Posted September 25, 2019

Rebuilding Stockton beach with sand dredged from offshore presented a range of environmental, legal and financial challenges, a coastal engineer with 25 years working along the Hunter coastline says.

The dredging option is seen by some as the best way to rebuild the beach.

"It is technically achievable and could be used to solve the problem. I don't know that it is the "best" solution but I believe it is one of the better technically viable options available," Dr David Wainwright, who is a conjoint lecturer at the University of Newcastle, said.

"There remain issues around its legality under NSW law and whether anyone is willing to pay. It would almost certainly need ongoing maintenance after an initial dredging campaign. It's also important to consider whether any damage to the sea bed caused by dredging is justified. It could be used in conjunction with other strategies such as structures."

The process has been used successfully in Australia at the Gold Coast and internationally in the Netherlands, over the past decade.

But long-term effectiveness of the process varies from site to site.

"Each site is different and has its own quirks that need to be addressed. All of these types of projects have a limited lifespan - over time the sand is depleted again and needs to be topped up," Dr Wainwright said.

"Decision makers need to balance the value of what they are aiming to protect against the cost of a project to determine whether it is ultimately justifiable."

Almost 200,000 tonnes of sand was dumped on south Cronulla beach as part of a three-year renourishment program aimed at restoring the beach devastated during storms in 1974-75.

Almost 200,000 tonnes of sand was dumped on south Cronulla beach as part of a three-year renourishment program aimed at restoring the beach devastated during storms in 1974-75.

While dredging might seem like an appealing method of rebuilding the beach, it doesn't come cheap.

Gold Coast Council paid $15 million to pump 3,000,000 cubic metres of sand onshore in 2017.

Dr Wainwright estimated it could cost up to $5 million to renourish Stockton Beach in the short term.

"Economies of scale factor in here, and the ultimate cost would be affected by whether a contractor, possibly from overseas, with appropriately sized dredging equipment can be enticed to take on the project," he said.

Source: newcastleherald.com.au