Maroochydore Nearshore Beach Nourishment Trial

By tomorrow (Wednesday) afternoon those visiting the beach will notice a large sand dredge situated approx 300 metres out from Abduls’ Beach Access 150 (Peirce Park) Maroochydore. The dredge is part of a new trial of replenishing sand from out beyond the break water, unlike the past 10 years of sand being dredged from the built up sand banks inside the Maroochy River entrance and pumped along the sand dunes from Pincushion to Alex Surf Club, this project will have the dredge drop or spray sand out between the replenishment zone of Beach Access 151 -155 in a formation that will encourage sand migration towards the exposed beach.

This program is the same that has been conducted along Palm Beach, Gold Coast, identified as the one of the worst Gold Coast beaches to suffer from erosion from Cyclones and wild weather events.

Along with the sand dumping or rainbowing, Artificial reefs were built at Narrowneck in 1999 and Palm Beach in 2019., and according to the City of Gold Coast, the Palm Beach reef cost $18.2 million and has retained about 550,000 cubic metres worth of sand over its first two years.

Coastal engineer Evan Watterson, who helped design the reef, said such projects saved millions of dollars worth of damage to beaches over the long term.

“Over a 30-year period it definitely stacks up against beach nourishment,” Mr Watterson said.

“On top of that you get the benefit of the surf amenities, obviously makes it more economically viable, [and] even though it is a more expensive solution you get all these other benefits.”

The Sunshine Coast Council has not mentioned that they too will implement Artificial Reef programs along our coastline, though I’m led to believe that it is an idea that has not been scrapped off of the table.

I conducted a poll via an instagram story a week ago highlighting the councils beach nourishment trial , with 68% having voted ‘Yes’ with 28% voting ‘No’ to councils new trial.

Those who had voted ‘No’ were very concerned about the sand coming from an area foreign to our coast’s beaches, and also said ‘Leave it to Mother Nature’ to replenish the sand, which has been the case for hundreds if not 1000’s of years, however with the ever changing climate, contributing to the ever increasing erosion, the human factor has come into play to help combat the erosion and hopefully not just a band aid solution.

Here is the latest news from the Sunshine Coast Council .

• Last updated:
• 10 Nov 2022

We’re being proactive and exploring other ways to manage our beaches from the risk of coastal erosion in the future. As well as local sand renourishment pumping, nearshore sand nourishment is another method we could use to do this. This trial will help us understand how effective the technique is at Maroochydore.

Please complete the survey here to let us know your views on the trial before Friday 9 December 2022.

Project scope

Studies show that there is a limited supply of sand on the Sunshine Coast. Maroochydore Beach has been subject to significant erosion events and the addition of new sand from an external source will help to restore sand to the beach and protect the area from erosion.

Nearshore sand nourishment is one method available to help do this. It works by taking sand from another source in the coastal system, such as the Spitfire Channel, and placing it in the nearshore area off Maroochydore Beach.

The nearshore nourishment trial will provide critical evidence to support our understanding of the operational aspects of delivering additional sand to the Sunshine Coast using this sand nourishment method. It will also help us to optimise the ‘value for money’ considerations if we are to use this type of coastal management practice along our coastline in the future.

A technical advisory group has been established to highlight any technical issues or concerns that may arise during the trial. Councillors, Queensland Government, Sunshine Coast Council, Surf Lifesaving Queensland, Queensland Police Service and expert engineering consultants will be part of the group.

Project update

The Nearshore Nourishment campaign is scheduled to go ahead from 16 November to 24 November, with the dredge working 7 days a week, 24 hours per day (pending weather conditions). Sand placement will occur approximately every seven hours about 300m offshore between BA151 – BA155. Please see the placement map[410KB] for details.

Project details

The trial will be carried out with a trailing suction hopper dredge, which is a certified ocean-going vessel. It can dredge in depth of 25m and can carry (has a hopper capacity of) 2,900m3, which is the equivalent of hundreds of trucks of sand being released with each load.

The dredge will come from the Port of Brisbane. The Port of Brisbane Pty Ltd’s Marine Services teams is responsible for safe navigation of the 90km shipping channel. Dredging forms part of these operations and the Port of Brisbane owns a flagship vessel, the TSHD Brisbane, which is likely to be used for the nearshore sand nourishment work at Maroochydore.

The dredge will take the sand from the shipping channel and place it in its hopper or hull. The sand will be released at Maroochydore via “bottom placement” and rainbowing.

Bottom placement operation involves opening the doors at the bottom of the dredge hull above the position required and allowing the sand in the dredge hopper to fall onto the seabed below. Rainbowing involves spraying a sand and water slurry from the deck of the dredge into the nearshore zone.

The sand will be placed in a formation that will encourage sand migration towards the exposed beach, respectful of the site surf amenity.

The dredge will work for 24-hours a day. It will take around seven hours to complete a full cycle which involves taking sand from the navigation channel in Moreton Bay, steaming to Maroochydore, placing the sand offshore from the beach, and then steaming back to the navigational channel.

It is expected that up to 40,000 cubic metres of sand will be used for this trial.

Exclusion zones

During the seven days of the trial, parts of the beach and water will not be accessible at different times of the day.

An exclusion zone will be set up before the dredge arrives, while its operating and after it leaves so that the water can settle and be safe for users.

Please follow the instructions of council staff, lifeguards and staff on site.

These exclusion zones are for your safety and the success of the nourishment program.

Beach safety

Your safety is our first priority.

To ensure the safety of beach and water users, exclusion zones will be set up in the operating area.

An exclusion zone will be set up before the dredge arrives, while it’s operating and after it leaves so that the water can settle and be safe for users.

Please follow the instructions from council staff and lifeguards and read the signs when you are in the area before you access the beach and water.

These exclusion zones are for your safety and the success of the nourishment program.

Marine safety

Your safety is our first priority.

An exclusion zone will be set up before the dredge arrives, while its operating and after it leaves so that the water can settle and be safe for users.

You are required to stay clear of the exclusion zones around the dredge. There will be a lifeguard on a jet ski to monitor the exclusion zone.

Please follow their directions and check the current Notice to Mariners for updated information.

These exclusion zones are for your safety and the success of the nourishment program.

Morning operations

In the mornings, if weather conditions are safe, the placement technique will be rainbowing. This means:

• an exclusion zone will be set up from the high tide area to the placement area in the water
• for three hours, starting around 5am or 7am, there will be no water or land activities in the exclusion zone
• you will need to walk around the exclusion zone and a diversion will be in place to guide you (along the high tide)
• you will still be able to access the water outside of the water exclusion zone
• lifeguards will be onsite to let you know where these water exclusion zones will be
• you will be advised when you can enter the water again as plumes may impact the water area after the dredge has left the site
• we ask for your patience as we need to wait for these plumes to settle before allowing water users back in the area.

Afternoon and night operations

In the afternoons and during the night, sand placement will be via bottom dumping. This has less risk than rainbowing.

• The exclusion zone for the water will only be for one hour
• You will be able to walk along the lower tide mark during bottom dumping activities.

Specific placement locations will be managed from day to day and will change according to conditions. All placement will occur between Beach Access 151 – Beach Access 155.

Surf amenity

We have been working hard to trial placement shapes that may improve surf amenity along Maroochydore beach. We have been working with engineers that were a part of the Gold Coast Nourishment campaign for the Commonwealth Games to learn from their placement techniques so that Maroochydore can have the best chance at improved surf amenity.

We will also work with the University of the Sunshine Coast to analyse the surf before, during and after the placement to see if surf amenity has improved.

More information about this study will be published on our website when the results are in.A camera will be set up to monitor surf amenity and sand locations at BA150, this will be directed to the ocean only.

Placement locations

The placement locations listed above have been determined through environmental approvals and are not subject to change for this trial.

Due to these locations and the route the vessel will take, we will need to temporarily remove the shark nets for the duration of the campaign.

These will be reinstated at the earliest time when it has finished.

Removal of shark nets

Shark nets within the exclusion zone will be temporarily relocated 80 metres from the original location while the works are being conducted. For further information about the location of Shark Control Program equipment please visit the SharkSmart map.

Monitoring

After the nourishment operations have ceased council will monitor:

• the impacts on marine plants and the reef with divers
• the sand movement over time with hydrographic surveys
• the impacts to surf amenity through the University of the Sunshine Coast.

It is difficult to predict how long it will take for the nourished sand to move from where it will be deposited because this will depend on weather conditions.

Monitoring of the sand will continue for up to three months, depending upon the weather conditions and the sediment movement. The analysis of the data may take a further two months. It is hoped that the outcome of the trial will be known by early 2023. We will share results when available.

Overview

The Sunshine Coast local government area has approximately 60 kilometres of coastline, stretching from Caloundra to Peregian Beach.

Our sandy beaches are constantly changing due to natural coastal processes and associated weather patterns.

As a result, our beaches are vulnerable to repeated erosion during storms, increased swells, and other weather events, which can also impact important community assets such as roads, parks, car parks, pathways, playgrounds and amenity blocks.

We need to be proactive and explore other ways to manage our beaches from the risk of coastal erosion in the future.

For example, without enough sand on beaches, such as Maroochydore Beach, roads and pathways, parks and buildings behind the beach could be undermined during storms.

Nearshore sand placement is one method available to increase the resilience of beaches from severe erosion caused by storms, swells and weather events.

For more information please view the full list of frequently asked questions[202KB][202KB].

Contacts

For more information, please contact council.