Northbank Foreshore Stabilisation Project

The City of Fremantle is working to assess the condition of a section of the Northbank Foreshore and develop options to address foreshore erosion.

The Northbank foreshore shoreline is subject to erosion. Historical foreshore reclamation (or riverbank realignment) has altered the shape of the shoreline and the river is trying to establish a new shoreline position between its natural and modified location. The erosion is caused by a combination of waves (from wind and boat wakes), tidal currents and storm surge.

We've engaged GHD to investigate the issues impacting the foreshore’s stability and recommend options to minimise future erosion and preserve the amenity of the public foreshore.

This area has environmental and recreational value, which are both important considerations. To inform any future action taken in this area we are carrying out a site analysis, reviewing existing studies and plans, engaging the community and stakeholders and undertaking a technical analysis.

Below: The current foreshore.

Based on the analysis, concept designs of five options to stabilise Northbank have been prepared.

Each option has advantages and disadvantages, you can explore them below and let us know your thoughts in the online survey below by 5pm Wednesday 6 June 2018.

This information and online survey is supported by a community information session. We recommend you consider attending before completing the survey. The session will be held Thursday 31 May 2018 between 5.30pm and 7.30pm, at North Fremantle Community Hall. There are two formal presentation sessions with question time being offered, one at 5.45pm and then repeating at 6.45pm.

Option 1A – Build a limestone wall along the river alignment

This option would have the least soil disturbed during construction as well as being a durable option with the smallest footprint and minimal impact on river processes. Using the river alignment would increase the useable land area above the riverwall and there is no need for ongoing beach replenishment.

The disadvantages of this option are that there is likely to be little or no sandy beach area and the wall would make access between land and water difficult.

Option 1B – Build a limestone retaining wall along the river alignment and place rocks along the water edge of shoreline (a ‘rock toe’)

This option is similar to option 1A but placing rocks and beach sand along the water edge of the shoreline would create some beach area.

The disadvantage of this option is an increase in beach replenishment requirements to maintain the beach area. The wall would make access between land and water difficult. It would require slightly more disturbance to the soil during construction and slightly increase the footprint.

Option 2A – Build a limestone wall along the land alignment

This is a durable option offering both land and some beach area, a footprint similar to 1A and minimal impact on river processes.

The disadvantages of this option are more soil disturbance during construction than option 1A or 1B and the wall making access between land and water more difficult. There would be ongoing sand replenishment costs to maintain a beach area as it likely to be subject to erosion.

Option 2B – Build a limestone wall along the land alignment and place rocks along the water edge of shoreline (a ‘rock toe’)

This option is similar to 2A (durable and minimal impact on river processes) however it would increase the stability of the beach area and slightly increase the footprint. The addition of a rock toe would reduce the sand replenishment costs of 2A because the beach is wider and further away from wave action. Because of the location of the wall this would require less sand replenishment than option 1B.

The disadvantages of this option are increased disturbance of soil during construction than for 1A or 1B and the wall making access between land and water more difficult. There would be ongoing beach replenishment costs to maintain a beach area as it is likely be subject to erosion but less so than 1B.

Option 3 – Build three rock groynes and use geotextile sand bags on the bank

This option also offers a land and beach area, with the stability of the beach comparable to 2B and allows easy access between land and water. It follows the land alignment above but offers less landscaped grassy area than any of the other options.

The disadvantages of this option are greatest soil disturbance during construction, the largest footprint, possible impact on natural river processes and the sand bags have a shorter design life than a wall. This option also has similar beach replenishment requirements to 2B, but adds complexity (and therefore cost) to the replenishment works by having to work around the groynes and sandbags.

Options at a glance

Please tell us your thoughts in the survey below.