Outer Harbor Rock Revetment Remediation

Background

Key Function

The primary function of the breakwater is to serve as a protective barrier against strong waves, tides and storm surges, creating a more sheltered and safer area for ships and harbour operations.

It plays an important and critical role as the primary protective barrier for Outer Harbor where South Australia’s only container terminal is located. The structure is essential not only for safeguarding port operations but also for protecting the swing basin which is used by most vessels accessing Berths 1 to 8.

The breakwater is vital in ensuring operational integrity and safety for South Australia’s import and export trade.

Why was Remediation Required?

There was an approximately 70m section of the breakwater that had deteriorated over time.

Storm surges in May and June 2025 then caused a breach and erosion to the wall. Please see images below highlighting the condition of the breakwater prior to remediation:

In the below 3D images, storm surges comparing 2024 and 2025 clearly show the breach:

Without remediating the breakwater, the continual deterioration of the breach could have impacted operational integrity and safety for South Australia’s import and export trade.

Scope of Works

The works were undertaken by our Contractor Maritime Constructions and included:

• Removal and disposal of unsuitable material.
• Re-use of suitable material where appropriate.
• Ground improvement works, including re-levelling.
• Supply and placement of geotextile fabric and rocks.

The project footprint was not located on Bird Island, works only occurred at the rock revetment located south of Bird Island. The footprint did not overlap with Pelican breeding areas; these are located further north of the rock revetment.

Project Controls

Flinders Port Holdings (FPH) has a longstanding partnership with Green Adelaide, Birdlife Australia and volunteer groups. Through sponsorship and collaboration, FPH support colonial breeding bird monitoring on Bird Island, Fairy Tern breeding monitoring, shorebird counts and rubbish collection.

During the planning phase for the works, FPH engaged with these organisations, plus other stakeholder groups to identify a suitable window for the works to occur, and to use the knowledge and research shared to develop project controls to be implemented.

These controls included measures to manage habitat disturbance, noise and vibration, introduction of pests, dust generation, water runoff, marine traffic and spills. Examples of the project controls included:

• Surveying of vegetation for Australian Sea-Lions immediately before any vegetation disturbance to ensure no Sea-Lions were resting in the vegetation.
• Ensuring fresh water and waste were not left exposed while on site, as this can attract predators of the Australian Fairy Tern.
• Reducing impacts from the tender vessel such as disturbance and damage to the tidal flats and shorebird feeding habitat.
• Surveying shorebirds and any nests prior to any vehicle movements.

During construction, wildlife groups and Maritime Constructions undertook periodic inspections and reviewed project controls.

Assessments

An Environment Protection and Biodiversity Conservation (EPBC) self-assessment was completed by our consultant – JBS&G. This assessment included using findings from field surveys at the project site together with desktop reviews including:

• An ecological assessment undertaken by Ecosphere that included vegetation and bird surveys plus recording opportunistic observations.
  • The ecological assessment covered the project site, with particular focus on approximately 2km² of degraded vegetation required for the equipment laydown area. This laydown area was chosen as the highest point and closest to the project site, thereby minimising disturbance.
  • The assessment concluded the project was not likely to have a significant impact on any matter of national environmental significance. As a result, an EPBC Act referral was not required.

These findings combined with advice from stakeholders and wildlife groups, informed the timing, logistics and development of a Construction Environment Management Plan (CEMP) for our contractor.

Outcomes

Mobilisation commenced in November 2025, with works completed in early May 2026. The timing took into consideration bird nesting activity on the breakwater, particularly to minimise disturbance to Black-faced Cormorants.

The works involved placing 5,680 m³ of material to restore and reinforce the breakwater, including rock armour and filter layers, as well as material to reinstate the dune area. The works also included the removal of 446.5 tonnes of concrete waste and 20 tonnes of dilapidated timber piles from the revetment, with all waste transported to and managed at a licensed waste facility.

The project concluded with revegetation works undertaken by LCS Environmental Pty Ltd, including planting of Atriplex paludosa, Atriplex semibaccata, Carpobrotus rossii, Disphyma crassifolium and Threlkeldia diffusa.

The works helped preserve the breakwater, supporting safer shipping and harbour operations, including recreational boating, while maintaining habitat for local wildlife.

See an aerial image below highlighting the site post works.

Contact

If you have any questions regarding the Outer Harbor Rock Revetment Remediation, please email [email protected].