FREMANTLE’S Port Beach Sand Nourishment Project will see up to 150,000 cubic metres of sand dredged from Fremantle Port’s Deep Water Channel and rainbowed onto the beach.
Rainbowing involves the pumping of a mixture of dredged sand and water through a hose with a nozzle, into a high arc through the air and onto the nearshore area.
The project is being delivered as a partnership project by the City of Fremantle, Fremantle Ports and the Department of Transport using $3.25 million in WA Recovery Plan funding from the state government.
Fremantle Ports CEO Michael Parker said while protection of the beach for the public was paramount, the sand renourishment had operational advantages as well in terms of maintenance of the shipping channel’s depth and ensuring a buffer for the critical Port Beach Road access to Rous Head.
The present pattern is for eroded sand from Port Beach to be transported to the north and deposited near Leighton Beach. In a bad year, Port Beach can lose up to 40,000 cubic metres of sand; however, the average annual loss is around 15,000 cubic metres.
The works are intended to provide protection for up to 10 years, although the actual life of the works will ultimately depend on the weather conditions experienced over the next decade.
Some of the placed sand is expected to migrate northwards over time. A shoreline monitoring program will be implemented to track the movement of the placed sand, and if significant movement occurs additional maintenance or nourishment works may be required.
Sand nourishment via dredging was selected over other potential coastal erosion adaptation options based on the investigations and recommendations of coastal engineering experts in 2019.
The sand nourishment project will address the current extreme erosion risk level while allowing time for a longer-term planning process to enable the implementation of a managed retreat strategy, that includes the establishment of a broader foreshore reserve to retain a beach and amenities for the community.
