Unitywater crews are relining four wastewater pipes a day as part of a $400 million replacements and renewals program to improve water and wastewater assets over the next five years.
In the past two years, the utility has relined 53 kilometres of wastewater pipeline and 317 maintenance holes across Moreton Bay, the Sunshine Coast and Noosa to reduce odour, improve network efficiency and operability and avoid overflows and impacts to residents.
In the Sunshine Coast and Noosa regions, 25km of pipes – the equivalent distance from Peregian Beach to Maroochydore – have been relined and 219 maintenance holes renewed.
One of the jobs was in Buderim, where 60 metres of pipe was relined, and another in Noosa Heads, where 81 metres was relined.
Unitywater Executive Manager Sustainable Infrastructure Solutions Mike Basterfield said two innovative methods were used to reline the assets which delivered customer and cost benefits.
“Wastewater mains on average are about two metres deep and some are as deep as four metres below ground, 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,” he said.
“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.
“Our Network Programs team has a comprehensive, proactive program to identify which of our assets need to be renewed, including cleaning programs and jet blasting to clear debris build-up and blockages, CCTV to clearly see any issues inside our pipes and removal of tree roots – one of the biggest culprits causing blockages and subsequent overflows,” he said.
“They assess the age of the asset, the material it’s constructed with and the current condition. Some maintenance holes are located on private properties and we work with our customers to rectify any issues.”
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. If we didn’t carry out these important works, overflows would occur inside private properties and in the environment,” he said.
