Pipe program tops 50km

Unitywater is relining four wastewater pipes a day as part of a $400 million replacements and renewals program over the next five years.

In the last two years, the utility has relined 53km of wastewater pipeline and 317 maintenance holes across Moreton Bay, the Sunshine Coast and Noosa.

The replacement and renewal is to reduce odour, improve network efficiency and operability and avoid overflows and impacts to residents.

Across the Moreton Bay region, 26km of pipes – the equivalent distance from Morayfield to Redcliffe – have been relined and 91 maintenance holes renewed.

One of the jobs was in Deception Bay, where 74.3 metres of pipe was relined and another in Eatons Hill, where 29.8 metres was relined.

“Wastewater mains on average are about two metres deep and some are as deep as four metres below ground,” Executive Manager Sustainable Infrastructure Solutions Mike Basterfield said.

“So, to be able to line the inside of existing pipes and not excavate and replace the entire pipe is much more cost-effective and less disruptive to the community.

“Our teams use spiral relining with a PVC plastic and a ‘cured-in-place’ solution which is a polymer UV liner that is cured and sealed to the inside of the existing pipe.”

Mr Basterfield said hydrogen sulphide, the gas produced in wastewater, could be corrosive and over time deteriorated infrastructure.

The Network Programs team identifies which assets need renewing, cleaning and jet blasting to clear debris build-up and blockages.

CCTV is used to see any issues inside pipes and remove tree roots – one of the biggest culprits causing blockages and subsequent overflows, Mr Basterfield said.

Mr Basterfield said as part of the program, maintenance holes may be identified to be raised to avoid infiltration during large rain events.

“Stormwater and wastewater are two separate systems that shouldn’t mix and when large volumes of stormwater enter the wastewater network, it is inundated,” he said.

“If we didn’t carry out these important works, overflows would occur inside private properties and in the environment.”