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Subiaco WWTP

Project data

Location: Perth, Australia

The Subiaco wastewater treatment plant is the third largest of its kind in WA. This upgrade project will boost the plant capacity to up to 67 million litres a day and includes upgrades to existing treatment facilities, including new inlet works, replacement of secondary treatment components and modifications to the plant’s power supply. 

Monford Group Pty Ltd engaged PERI to design the formwork for the new inlet works structures. This connects to the new main sewer line for the Western suburbs of Perth.
Integrated with the old sewer line, it leads down to clarifiers and outflows on towards the main treatment ponds through a series of covered channels. 
The integration of four different types of PERI Wall formwork systems was seamless, switching between both straight and curved formwork. 


  • The highest standard for water retaining structures
  • Exacting dimensions to incorporate into existing structure
  • Geometrically complex shapes
  • Demanding concrete placement and waterproofing
  • The retardants and plasticizers in the concrete demanded a very high pour rate
  • As the entire structure is on a gentle fall, below ground level and adjacent to existing sensitive structures, requiring piling to be very close to the form face 


Monford Group Pty Ltd

Customer's benefit

  • Cost-effective
  • Saving time
  • Reduced patching
  • Less tie points


Peter O'Grady
Project Manager

PERI, as a system, in my opinion, was the best option for this project. From the product itself through to the drawing design, sales team and competitive rates, they were a pleasure to work with.

The proprietary SK tie system along with the decreased number of tie points on the Maximo form system meant there was less potential for leaks and thus limiting Monford Groups liability for reworks.
All different PERI systems used on the project works effortlessly together reducing the need for conventional make-up pieces and it was easy to switch from one system to the other. The RUNDFLEX system makes curves consistent and without imperfections.

I would highly recommend the entire PERI range of products as being user-friendly, quick to assemble and value for money and will continue to use PERI for future projects.

PERI solution

  • The proven waterproof SK tie system was supplemented with DK Concrete Cones, providing a simple and quick patching solution, while also being a waterproof system in its own right. 
  • MAXIMO's slim profile was ideal where worker access was limited and geometrically complex shapes were required. 
  • The integration of 4 different types of PERI Wall formwork systems