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The utility is expected to undertake rehabilitation works on more than 2,700m of sewer main. 

The $2 million project involves relining pipes beneath several of the city’s roads, such as Booth Street, Cudmore Terrace, Nicolson Avenue and Playford Avenue. 

Relining pipes is a modern technique adopted by water utilities to extend the life of sewer mains, where a PVC liner is fed inside a pipe to create a new internal surface and restore its structural integrity.

SA Water’s Senior Manager of Infrastructure Planning and Strategy, Dr Daniel Hoefel, said that the project’s primary goal is to reduce saline groundwater infiltration in order to improve the quality of Whyalla’s Recycled water. 

“Every day, our wastewater treatment plant turns Whyalla’s number ones and twos into a sustainable supply of recycled water, with around 2.5 million litres delivered to help irrigate the local golf course, ovals and parks,” Dr Hoefel said. 

“Recycled water is an incredibly valuable source of water given the city’s warmer climate and reduced rainfall, and one of the characteristics we monitor to ensure its quality is salinity levels.

“One of the challenges faced by our sewer network in Whyalla is the proximity of highly-saline groundwater. In some areas, the groundwater is only a metre from the surface – which is several metres higher than the depth of our sewer mains – and as a result, it makes its way in through small cracks or gaps between joints.

“Conventional treatment plants, like ours in Whyalla, aren’t able to remove this amount of salt from within the wastewater, so that’s why we’re tackling the issue at the source.” 

Dr Hoefel said that after investigating sources of this infiltration across the network and undertaking CCTV monitoring of high-risk areas where data indicated high salinity levels, SA Water identified several pipes to be relined.

“Relining pipes is a far more cost-effective and less invasive approach when compared to replacing a pipe, which is especially beneficial in this location due to the surrounding marine environment.

“Our crews will clean each sewer main to ensure they’re clear of blockages before deploying a specialised winding machine into the pipes’ access chambers.

“A strip of PVC is then fed into the machine from an above ground spool and is wound by locking the edges together to form a continuous helix with a diameter slightly less than the host pipe.

“The diameter of the liner is expanded to ensure it fits tightly against the wall of the pipe, creating an entirely new section of pipe inside to restore its structural integrity and serviceability.

“By rehabilitating these sewer mains, we’re confident we’ll see an improvement in the quality of recycled water for our customers and secure the reliability of this important supply for years to come.”

Work is expected to be complete by mid-2024 and includes a combination of day and night work, with local businesses and residents informed ahead of work taking place in their area.

Elsewhere in Whyalla on Billing Street, SA Water’s new odour control unit is beginning to take shape.

“Pleasingly, our crews have achieved a number of milestones recently including the installation of the above ground odour pipework, vent stack, extraction fans and filters,” Dr Hoefel said.

“We’ve also reviewed our dust suppression strategy on-site in response to feedback from local residents and have since laid gravel in the access driveway to further minimise dust movement.

“During earlier stages of construction, we ensured all areas where we were working were always watered down as part of the compaction process, along with using sprinklers to help combat the effect of wind.”

Featured image: PVC strip being fed into a pipeline during the relining process. Image credit: SA Water. 

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