Managing coastal erosion at Mettams Pool

The City of Stirling is working with the community to investigate engineering options to address ongoing coastal erosion at Mettams Pool.

Coastal Conversations

The local and wider community are passionate about the future of the City’s iconic locations like Mettams Pool and the ongoing impact of coastal erosion along our coastline.

Because of its inshore reef and pool, Mettams Pool is uniquely placed as one of the most accessible safe bathing areas along the City of Stirling coastline, particularly for children and families.

This is part of the reason the City has committed to hosting ongoing coastal conversations with residents and beachgoers to chat about their experiences of change along our coastline and what solutions are best for the community to preserve these most incredible natural assets. 

Our most recent conversation helped identify a preferred design for the water access ramp, which will extend out from the gazebo structure currently being repaired.  The City will be proceeding with the option below which provides a direct access ramp from the gazebo ramp, with a smaller footprint and impact on Mettams Pool.

In recent years the water access ramp at Mettams Pool had deteriorated and experienced several functional issues, including:

  • A slippery surface, creating hazards for accessing the ramp
  • A large drop off at the end of the ramp, making access into the water difficult
  • Safety issues during adverse conditions, with waves breaking across and over the structure, making access hazardous

The new straight ramp will mitigate the safety concerns with waves slamming into and across the ramp, providing a safer access option under most conditions than the previous ramp configuration. The replacement ramp will also accommodate changing sand and water levels and remove the large drop off which provided an impediment to access.  

The City has prepared an application for funding from the State Government to ensure the ramp is delivered next financial year.

Gazebo repairs are being delivered this financial year with completion expected by the end of March. The gazebo walls and beach access ramp were severely impacted by erosion with wall pointing eroded, wall instability and concrete slabs undermined. The repairs include demolition and reconstruction of the outer limestone wall, concrete hardstand around the inner seating area, and repair of the inner wall. 

Water Access Ramp design

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FAQs

Why is the City investigating coastal engineering options for Mettams Pool?

Mettams Pool, along with the rest of the City’s coastline, is experiencing significant loss of beach sand, retreat of the dune buffers protecting West Coast Drive and public amenities, and damage to existing infrastructure. This requires a range of short term actions to both protect access for beach users and maintain the amenity of the beach itself.

What is causing the coastal vulnerability at Mettams Pool?

The coastal vulnerability at Mettams Pool is a result of a number of factors including:

  • Changes to sand movements, in particular a reduction in the available sediment movement along the coastline
  • Severe storm events which are probably being exacerbated by climate change
  • Sea level rise which is projected to increase significantly in the short term and substantially (>900mm) in the longer term.

Due to a combination of the above, the coastal vulnerability is expected increase significantly in the future. These factors are already putting coastal assets at greater risk and requiring a more strategic approach to Coastal Hazard Risk Management and Adaptation Planning (CHRMAP).

What is coastal vulnerability?

Coastal vulnerability is the extent to which the coast is able to cope with the effects of erosion, storms and sea level rise.  Rising sea levels are the greatest threat as just 100mm of sea level rise is likely to cause a 10m regression to sand dunes to restore the nearshore sea bed levels.  In areas where this natural regression is not possible then beaches and adjacent infrastructure may become unsustainable without significant action

What is coastal adaptation?

Coastal adaptation refers to the actions taken to respond to climate change and coastal vulnerability. It aims to maximise the gains and minimise the losses associated with coastal hazards.

What is CHRMAP and does this affect Mettams Pool?

The state government, through statutory planning policy, requires developers and local governments adjacent to the coast to plan for rising sea level over the next 100 years.  Currently the projected rise is in the order of 1.0m.  The City is currently undertaking this formal process, called Coastal Hazard Risk Management and Adaptation Planning, referred to as CHRMAP, which will identify those assets that will become vulnerable over time and the measures that should be undertaken as they become necessary.

As this will require significant long term funding, and consideration of what should be protected or subject to managed retreat, only short term measures are being considered pending the completion of the CHRMAP process scheduled for October 2022.

How will the engineering options address erosion at Mettam Pool?

The City recognises the unique recreational and natural environment at Mettams Pool and is undertaking a number of short-term measures to secure this, pending the outcome and recommendations from CHRMAP.

  • Maintain and protect the southern zig-zag access to the beach and gazebo.
  • Demolish water access ramp, which is now too severely damaged to remain, and consider a replacement option to enable access to the water when beach rocks are exposed.
  • Underpin and provide support to beach steps from changing rooms (completed October 2020).
  • Upgrade handrails to northern steps to prevent from fall when dunes have receded (completed June 2021).
  • Protect and repair beach access ramp from changing rooms, this is critical as it acts as a groyne protecting the changing rooms/viewing deck from severe storms (works underway and scheduled for completion November 2021).
  • Undertake beach sand nourishment with up to 10,000 cu-m of sand imported annually in two operations, spring (Oct/Nov) and autumn (March/April).

How will the engineering options be evaluated?

The engineering options will be evaluated using a multi-criteria analysis frameworks, which will rank the engineering options based on the relative benefits of each option across a range of criteria. The analysis will consider the community values, environmental impacts, economic impacts and construction and operation/maintenance costs.

Will the engineering options impact facilities and amenity at and around Mettams Pool?

The final CHRMAP report will take into account the results of the community engagement process and reconcile those against the long-term risks to provide a schedule of protection, adaptation or retreat options.  Considerations for Mettams Pool will include:

  • Universal access to beach and water 
  • West Coast Drive functionality 
  • Cycling and pedestrian routes 
  • Public toilets and changing room 
  • Viewing deck 
  • Dunes and vegetation.

How much will it cost to implement the engineering options and how long will it take?

Once the CHRMAP process has concluded, taking into account community consultations, then an initial design for the preferred option can be undertaken.

Will the engineering options protect the functionality of West Coast Drive?

Yes. During construction works there will be temporary measures required to West Coast Drive, however, the ability to access properties, together with walking, riding and driving, will be maintained at all times.

Will the engineering options protect access to properties along West Coast Drive?

Although the CHRMAP process will consider this, the City does not see an option that does not protect the functionality of West Coast Drive. The retention of access to properties is considered paramount along with the coastal Recreational Shared Path.

Will the community continue to have access to Mettams Pool and beach area?

The City recognises the importance of Mettams Pool and beach for recreational swimming. Access to and use of this amenity will be retained for as long as possible although ultimately the result of rising sea level may require significant adaptation. The long-term outcome will be evaluated and determined through the CHRMAP process to be concluded by the end of 2022.

Are there any other potential vulnerable areas along the coastline between Scarborough and Watermans Bay?

This is briefly outlined in the Coastal Hazard Mitigation Strategy webpage available on the City’s website. 

What happens if we do nothing at Mettams Pool?

Without any coastal adaptation or mitigation works at Mettams Pool, erosion of the beach and dunes will continue.  Based on geophysical investigations that have been undertaken this could, ultimately, lead to the loss of all amenities, the coastal Recreational Shared Path and potentially West Coast Drive itself.

Recent storm activity, exacerbated by rising sea levels, has already required short-term action to repair and protect beach accesses and initiated a program of bi-annual sand nourishment to maintain the recreational amenity.  Once CHMAP is completed a longer-term strategy can be developed.

Are there any coastal risk management activities in place between Watermans Bay and Mettams Pool at the moment?

The City undertakes regular coastal risk monitoring and management along its coast.  Recent activities completed between Mettams Pool and Watermans Bay include:

  • The replacement of access stairs at James and Sorrento Streets
  • Dune protection at James Street
  • Cliff stabilisation and protection at Hamersley Pool. 

The Geotextile Sand Container (GSC) seawall, installed at Watermans Bay in 2010, sustained significant damage in the big storm of May 2020.  Repairs were undertaken in October 2020 which should see this seawall continuing to provide protection for another 10 years. This storm also severely damaged several beach accesses and most storm water outfalls along the City’s coastline, which have also been rectified.

How can I provide my feedback on the engineering options?

The 2019 Consultation for Mettams Pool is now incorporated into the CHRMAP process and will help to inform the upcoming community engagement process for the whole of the City’s coastline.

Please make sure you check back in for updates or if you have any questions or further feedback you would like to provide, please get in touch with the City's Customer Contact Centre on (08) 9205 8555.

Do you have any questions about this project?

For more background information about this project please refer to the FAQs. If you can't find the answer, please get in touch to ask a question with Jon Offer, Engineering on (08) 9205 8555.

Timeline

Community consultation open

Concept plans developed

Concept plans presented to the community

Preferred option design evaluated

Recommend option and draft strategy presented to Council

Works underway

September 2020

Sand nourishment

April 2021

Sand nourishment

27 November 2022

Gazebo repairs completed

In progress 2023

Water access ramp

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