To transfer the sand, nine kilometres of pipeline has been installed in two sections of Adelaide’s coast. There are also two main pump stations, three booster pump stations, 16 discharge stations and a relocatable sand collection unit.
Sand is scraped from the beach surface using a land plane and brought to the sand collection unit where it is mixed with seawater to form a sand-slurry (70% water, 30% sand).
The sand slurry is pumped southwards through the pipeline to discharge stations at southern beaches where it is discharged on to the back of the beach at the toe of the dune or base of seawalls. The sand settles out from the slurry forming a low, wide stable mound and the excess water returns to the sea.
When sand has built up at one discharge location, the sand slurry discharge can be redirected to another discharge location. At the end of each pumping session, the pipeline is flushed with plain seawater to remove remaining sand.
Waves then gradually spread out the discharged sand and move it northwards along the beach (known as littoral or longshore drift) providing coast protection to the foreshore.
Where seagrass has built-up on the donor beach, it is removed or set aside to ensure that mainly sand is collected and brought to the sand collection unit.
When does pumping take place?
Sand pumping operates at similar times to the past sand carting program, ie mainly in spring and autumn. Pumping may occur any time between 7:00am and 7:00pm from Monday to Saturday.
As with sand carting, pumping is scheduled to avoid work in summer and school holidays due to high beach usage. Winter work is also avoided where possible due to high tides and the frequency of storm events.
The duration of each sand pumping depends on the amount of sand required to be pumped. This is determined by DEWNR surveys of beach heights and calculations of beach volumes in relation to the minimum beach and dune buffer requirements. Sand pumping will continue over a 20 year period.