Ridgewood Lake Liner

City of Wanneroo

Perth, WA

November 2020

Scope of Work

Dowsing was contracted to undertake civil works for the replacement of the leaking Ridgewood lake liner used for irrigation and stormwater collection in a local park. Our civil services team worked closely with the council to dewater the existing lake and prepare earthworks for the installation of a new concrete liner.

Plastic membrane, mesh and concrete was installed with concrete poured at to a depth of 150mm thick for the base and ramp, and 100mm thick for the sides. The mix used for the project included a special additive to ensure the concrete was water proof.


The design of the new lake liner will allow ease of maintenance in the future to eliminate sediment build up in the lake and provide a more pleasant feature for the public space.

  • The lake was dewatered via three 100mm bore pumps over the course of a five-day period. Due to the time of the year and the inclement and unpredictable nature of the weather, this process proved challenging. The solution was to keep a small 50mm bore pump on site at all times and bund the inlets to the lake.
  • Access restrictions required the use of WA’s biggest concrete pump to be used for the construction of the liner.
  • The additive used in the mix proved to be a challenge to achieve the correct finish on the concrete. This was overcome by reducing the size of the pours and placing extra skilled labour on the project.
  • The works were completed ahead of schedule.