Coastal management grants for C. Y. O'Connor Beach

The City of Cockburn's response to the Cockburn Gazette, 29 June 2021 about CoastWest coastal management grants for C. Y. O'Connor Beach

Question: Why is this project so important to the future of CY O’Connor Beach?
Answer:
 Erosion has been a persistent issue at C. Y. O’Connor Beach for over 20 years with the foreshore and coastal assets at risk of damage and loss if no protection works are completed. Extensive works such as the relocation of dual use paths, dune revegetation and sand nourishment have been required in recent years to manage the erosion problem and while these do help mitigate the symptoms of coastal erosion, they do not fully address the issue. This trial will be the first step towards considering permanent installation of erosion control measures for the C. Y. O’Connor Beach coastline.
 
The City plans to implement long term erosion protection and control structures along C. Y. O’Connor Beach in a staged manner, subject to available funding, targeting the areas of highest risk first. An engineered fringing reef has the potential to control erosion while having minimal impact on the beach, as opposed to more obtrusive conventional groynes and seawalls. Although physical and computational modelling of the engineered reef modules has been undertaken, it will be the first full-scale trial of this type of engineered reef for erosion control in WA. The information learned regarding the performance of this reef can inform the understanding and design of similar “engineering with nature” erosion protection initiatives in WA and around the world. The project forms only a part of the broader erosion protection initiatives that the City is investigating and pursuing for the broader C. Y. O’Connor Beach coastline. While engineered reefs have been trialled and implemented in other parts of the world with varying success, this would be one of the first, if not the first, modular engineered reef project designed to achieve wave attenuation and erosion control in Australia.
 
The benefits of fringed reefs are that they are off-shore and therefore have less impact on beach amenity. The City undertook initial community consultation in 2019 to gain insight into how the community uses the beach, what it values and what it believes requires protection. Feedback indicated C.Y. O’Connor Beach is highly valued and efforts to protect it from erosion damage were welcomed. Options that minimise impact on the appearance and function of the beach were seen as more desirable. Erosion control will allow future generations to enjoy the benefits of a pristine beach environment for years to come.
 
Question: How will this fringing reef which is set to be installed work?
Answer:
A trial Engineered Fringing Reef of up to 100m in length is proposed to be installed about 50m offshore from an eroding area of beach adjacent to the C.Y. O’Connor Reserve at the end of Rollinson Road. The reef modules will be constructed from a low carbon concrete, similar to those in use at Coogee Maritime Trail. The reef concept is designed to help break down wave energy reaching the shore, slowing down coastal erosion. While erosion will still occur to some degree, it will happen at a reduced rate, minimising the quantity and frequency of sand nourishment, and allowing for a greater, more stable sand dune buffer to establish along the shoreline. The reef will be monitored for many years after installation to gain data about how it performs in erosion control and how it impacts the surrounding coastline. The modular reef can be reconfigured, reduced or extended if required. Over time, the reef modules will be colonised by marine flora and fauna as has occurred at the underwater Coogee Maritime Trail, creating another marine habitat that will also be accessible to divers and snorkelers.
 
In a separate but related project, a Geotextile Sand Container wall will be buried in the onshore dunes adjacent to the reef, to act as an erosion ‘backstop’ to protect park assets in rare super-storm events. This seawall and dune revegetation project is part-funded by a $59,630+GST CoastWest grant, also announced by Transport Minister Rita Saffioti on 24 June.
 
 

For more information contact

Media and Communications Officer
City of Cockburn

Email media@cockburn.wa.gov.au

Phone 08 9411 3551

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