An independent Coastal Engineer was involved in the process of preparing the for the FMP. The Peer Review report assessed the treatment options and wher designs would be appropriate depending on environmental constraints.
Not a concrete solution…
While were once a common practice to stabilise the foresh Notseawalls a concrete solution… structures are no longer a preferred treatment. Over time seawalls h While seawalls once a common practice to stabiliseimpacts. the foreshore, understood to be were associated with a range of negative Verti structures no longer a preferred treatment. Over seawalls absorb waveare energy leading to the transference oftime erosion ontohave nei understood to be associated with a range of negative impacts. Vertical d During the construction of seawalls, the removal of vegetation, mod absorb wave energy leading to the transference of erosion onto neighbo shoreline and poor structural permanently th During profiles, the construction of seawalls, thedesign removal of vegetation,change modificat the shoreline shorelineprofiles, and remove the natural buffering systems that absorb and poor structural design permanently change the na
DEVELOPING conceptual designs
the shoreline and remove the natural buffering systems that absorb wav
Working Group members engaged Council's City Projects department to develop preliminary foreshore treatment design concepts. KEY CONSIDERATIONS INCLUDED:
An independent Coastal Engineer was involved in the process of preparing the conceptual designs for the FMP. The Peer Review report assessed the treatment options and where different types of designs would be appropriate depending on environmental constraints.
• T reatment options need to comply with Not a concrete solution… legislative requirements designed to protect While seawalls were onceMany of the seawalls in Marks Point and Belmont Souths are showing signs of a common practice to stabilise the foreshore, these ‘hard’ health, safety and the environment. structures are no longer awalls, scouring behind walls, degraded structures, and exposed materials are c preferred treatment. Over time seawalls have been increasingly Many of the seawalls in Marks Point and Belmont Souths are showing sign understood to be associated with a range of negative impacts. Vertical designs are unable to Vertical seawalls further provide no escape for wrack to wash out of the water absorb wave energy walls, scouring behind walls, degraded structures, and exposed materials leading to the transference of erosion onto neighbouring properties. • ‘Soft’ treatments such as sloping beaches and While seawalls were once a common practice During the construction ofin anaerobic conditions which has led to a significant community issue in the a seawalls, the removal of vegetation, modifications made to Vertical seawalls further provide no escape for wrack to wash out of the w revetments are favourable. ‘Hard’, permanent shoreline profiles, andtopoor structuralthe design permanently change the natural landscape of stabilise foreshore, these ‘hard’ in anaerobic conditions which has led to a significant community issue in Some areas may be restricted to the use of seawalls the shoreline the natural buffering systems that absorb wave energy. treatments such as habitat-friendly seawalls mayand remove structures are no longer a preferred treatment. due to limited land available, foreshore slopes and be considered in limited areas. Vertical seawalls are unable to absorb wave Some areas may be restricted to the use of seawalls
NOT A CONCRETE SOLUTION
exposure to weather processes. Where seawalls may
• •
• • •
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• •
be approved, the treatment need to consider the due to limited land available, foreshore slopes and energy and can permanently change the Consider local drainage structures and seagrass alignment of the foreshore, how to minimise exposure to weather processes. Where seawalls may natural shoreline. They provide no escape wrack build-up areas. potential impacts on neighbouring foreshores, and be approved, the treatment need to consider the for how to include environmentally beneficial features. seagrass wrack to wash out of the water, alignment of the foreshore, how to minimise leaving it trapped and rotting which has led Prevent active erosion, dissipate wave energy, The ‘Environmentally Friendly Seawalls’ guide is potential impacts on neighbouring foreshores, and available publicly online to provide ideas on how to to a significant community issue in the area and limit wave overtopping landward of the how to include environmentally beneficial features. improve the environmental value of seawalls structure. [9] The ‘Environmentally Friendly Seawalls’ guide is seawalls in Marks Point and (pictured right). Many of the ad-hoc available publicly online to provide ideas on how to Belmont South are showing signs of failure, Increase biodiversity and environmental values. improve the environmental value of seawalls with slumping [9]walls and scouring behind walls (pictured right). Allow water access and recreational use of the commonly seen. In constrained areas where foreshore. seawalls may be the only viable option, the design needs to consider the alignment of the foreshore, Consider coastal design principles including Many of the seawalls in Marks Point and Belmont Souths are showing signs of failure. Slumping how to minimise impacts on neighbouring fetch, wave height, and how to minimise impacts walls, scouring behind walls, degraded structures, and exposed materials are commonly seen. foreshores, and include environmentally Vertical seawalls further provide no escape for wrack to wash out of the water, leaving it trapped on adjoining properties. in anaerobic conditions which has led to a significant community issue in the area. beneficial features. The ‘Environmentally Friendly Seawalls’ guide is Consistent with requirements in the Marks Point Some areas may be restricted to the use of seawalls available publicly due to limited land available, foreshore slopes and Belmont South LAP. exposure to weather processes. Where seawalls may online to provide Foreshore works should be triggered bybe approved, the treatment need to consider the ideas on how alignment of the foreshore, how to minimise environmental change or events ratherpotential impacts on neighbouring foreshores, and than to improve the how to include environmentally beneficial features. specific timelines. environmental value The ‘Environmentally Friendly Seawalls’ guide is of seawalls (see available publicly online to provide ideas on how to Maintain the natural alignment of the foreshore. improve the environmental value of seawalls references section). (pictured right). [9] Consider the asset life and maintenance of treatments.
• C onsider potential land reclamation in areas of limited land widths or evidence of erosion scarps.
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LAKE MACQUARIE CITY COUNCIL
