The project
ASDP Stage 1 will initially supply 50 gigalitres (GL) of desalinated seawater annually to Perth’s Integrated Water Supply Scheme (IWSS) from 2028, with future expansion potential up to 100 GL per year under a second stage. Additionally, Stage 1 will treat 4.9 GL of groundwater annually.
GRP risers
The GRP risers each have a length ranging from 12 to 14 metres and an internal diameter of 1.8 metres. They are installed into pre-drilled holes offshore in water depths between 12 metres and 20 metres. Risers 1 and 2 connect to the intake tunnel, while the third riser is linked to the outfall tunnel from the shore, safely returning concentrated seawater to the ocean.
To facilitate internal pressure testing, each GRP riser has been equipped with GRP flanges at both the top and bottom, allowing for the attachment of temporary caps to act as sealing systems.
Pre-spooling of GRP above ground piping
Working with the Alkimos Seawater Alliance (ASWA), RPC was awarded the prefabrication of approximately 1,100 GRP spools incorporating around 4,000 butt strap and branch joints, with pipe sizes ranging from DN25 to DN1600. The project is delivered over a five-month program, supporting six priority work packages and multiple milestone dates.
OneRPC in action
The risers were made by our Batam team, with the Seven Hills Engineering and Project Team.
