Trenchless technologies enable the installation and rehabilitation of underground utility infrastructure with little to no excavation, minimising the impact on the environment and reducing community disruption. Water Corporation, the principal supplier of water, wastewater and drainage services to over two million people throughout Western Australia, is utilising trenchless technology to deliver improved water and wastewater services to its customers.
Wastewater refurbishment program
Water Corporation continues its ongoing program of work to refurbish wastewater pipes across Western Australia to extend the life of this important infrastructure by at least 50 years.
The latest areas to be refurbished through the program include 12.5km of wastewater mains in Northam, 750m in Wagin and 950m in Gnowangerup.
Where practicable, Water Corporation uses trenchless technology to reline wastewater pipes, minimising the disturbance to the community and the environment.
Unlike traditional pipe replacement, relining involves accessing the wastewater mains via access chambers instead of open trenches.
The technology works by inserting a plastic strip liner inside an existing wastewater pipe via access chambers that is then wound down the length of the pipe route.
The wound plastic liner is then expanded to fit tightly within the walls of the existing pipe to provide a smooth finish.
Work began in Northam in December 2019, progressing to Wagin then Gnowangerup, with the project expected to be finished by late 2020.
Relining wastewater pipes is important as it not only helps prevent corrosion and reduce blockages, but it also helps protect the local wastewater systems and the health of the community and environment.
Since 2015, Water Corporation has refurbished around 65km of wastewater mains through the program, to ensure a reliable wastewater service into the future.
Wastewater is 99.97 per cent water, as it comes mostly from showers, baths and washing machines. Water Corporation manages more than 17,000km of wastewater mains across Western Australia and collected 165 billion litres of wastewater in 2018-19.
A total of 1,178 pump stations transport wastewater to 122 treatment plants across the state, where wastewater is treated and safely returned to the environment.
Water Corporation also operates 75 recycled water schemes across Western Australia, which not only reduce reliance on precious drinking water for irrigation, but also provide an environmentally-friendly way of disposing of the community’s wastewater.
Pipes for Perth
Sections of Perth’s water main network are over 100 years old and, like anything of that age, they’re starting to show some wear and tear.
Through Pipes for Perth, Water Corporation is renewing these aging water mains to reduce the likelihood of future breaks and leaks, and the disruption this may cause to commuters, residents and businesses.
Water Corporation undertook a comprehensive study of its water main network to see which streets needed to be renewed.
As the older pipes tend to have the highest priority for renewal, most of the work over the past few years has taken place in Perth’s oldest and most established suburbs, but it has also included other areas where pipes have been assessed as needing replacement.
While the original water mains in the late 1800s and early 1900s would have been laid by digging trenches by hand, and transporting sections of main using a horse and cart, it is a little different today.
The pipes are made of PVC (polyvinyl chloride) or PE (polyethylene) materials used worldwide for water mains for their strength, flexibility, durability and ease of installation.
PE water pipes in particular are often installed using trenchless construction techniques such as ‘microtunnelling’ and ‘horizontal directional drilling’, due to their capacity to be joined together in long ‘pipe strings’ for insertion under railway lines, major roads, rivers, and other locations where trenching is not appropriate.
An innovative relining technology can sometimes be used to renew the water mains. Pits are excavated every few hundred metres and a new PE pipe is then ‘pulled’ into the existing main from one pit to the next, breaking apart the old pipe and forming a new water main in the same location as the old.
Pit locations for trenchless and relining techniques are selected to minimise disruption to road users, businesses and residents, with traffic maintained in both directions where possible.
Since July 2016, Water Corporation has renewed over 120km of water mains across the Perth metropolitan area.