Foreshore Beach-Cast Seagrass Wrack Relocation Project

STATUS: Complete

Throughout Monday 23 December 2024, council will be moving the beach-cast seagrass wrack (commonly referred to as ‘seaweed’) from the section of the foreshore between the disabled beach access point and the marina breakwater, where seagrass wrack naturally accumulates (see below map for the detailed area).

As a result, different sections of the foreshore will be closed throughout the day, with pedestrians requested to maintain safe distances from the worksite and operating machinery. Spotters will be present to manage pedestrian safety.

There will still be public access to the remainder foreshore that is outside of the project area during this period.

Project overview

This wrack will be collected and moved to sections of the foreshore closer to Robets Terrace, where there is significant cliffing occurring along the face of the foredune. This seagrass will be placed hard up against these sections of foredune, providing foredune protection and removing the risks posed by the cliffing foredunes. These new seagrass foredunes will also be far more robust against the actions of the tides than sand alone would otherwise be.

This project will help to minimise any nuisance sand from blowing up on to the promenade behind the seawall, with the wrack piles collecting the nuisance sand, locking it in place along the project area. This process will also help to create an erosion resistant foredune, providing ongoing protection for our beach side assets from the action of the tides and storm surges, while also improving dune fertility.

This project will also improve the swimming experience for beach users at high tide, as they won’t have to wade over large accumulations of seagrass wrack to get into the sea. There may be a ‘smell of the sea’ coming from the new piles of seagrass, however, any smell will quickly dissipate within a couple of days.

An example of a section of beach where cliffing is occurring is pictured below…

Section of the Foreshore frontal dune where cliffing is occurring

Works will be undertaken by local contractor Whyalla Earthworks. They will be prioritising their seagrass frontal dune construction along the high-risk cliffing areas in the first instance. Once the wrack is placed, it will be specifically shaped into a foredune and swale system. This method / technique has been successfully trialled along Adelaide's metropolitan coastline, to reduce sand leaving the beach. See picture below…

Beach wrack dumping and shaping plan.

For more context on the importance of sand management on our foreshore, watch this video: https://youtu.be/3niFHXCGCeU?si=oIOXN5IgCezXqqaw

Estimated timeframe:  COMPLETE