Eastern Interceptor relining work underway

Eastern Interceptor relining work

Work is underway to reline the Eastern Interceptor – a 19km reinforced concrete trunk sewer that carries roughly 60% of Auckland’s wastewater from Okahu Bay to Māngere Wastewater Treatment Plant.

The relining of the Eastern Interceptor is a significant project within our $8 million a year Wastewater Targeted Asset Renewal Programme – a five-year programme of work to upgrade and rehabilitate Auckland’s wastewater network.

By partnering with civil engineering construction firm March Cato, we will reline sections of Auckland’s Eastern Interceptor over the next five years – with work currently being carried out in Mt Wellington’s industrial heart.

Our project manager Frank Lin says relining parts of the Eastern Interceptor network will add resilience to the wastewater pipes and reduce overflows.

"The project will ensure that our existing wastewater pipes continue to transfer wastewater safely and consistently through our network to treatment plants for the next 50 years.

"Relining sections of the Eastern Interceptor will help to reduce overflows in much of Auckland including the Waitematā Harbour, Hobsonville Point, Manukau Harbour and the Māngere inlet."

As we reline the pipeline in Mt Wellington, we’ll also be rehabilitating some of the manholes along the Eastern Interceptor network.

"To reline the pipe, the project team has constructed a 3.2m-diameter access chamber to allow them to lower trenchless technology to help fix the biogenic deterioration caused by bacteria commonly found in a wastewater system.

"Doing this allows us to easily crane in and out high-pressured industrial equipment needed to remove the eroded concrete, repair corroded surfaces with reinforced steel and reline it using the concrete solution SewperCoat, which is sprayed over reinforced steel.

"SewperCoat is a 100% calcium aluminate mortar solution that bonds very well to moist surfaces. It does not include pin holes and provides rock-solid structural rehabilitation within an hour."

The trolley used to transport the equipment in and out of the tunnel is custom made.

Lin says every effort is being made to minimise any disturbance to Mt Wellington businesses by using trenchless technology, avoiding open excavation in roads and by carrying out much of the work at night.

"We’re carrying out much of the remedial work at night, when we can restrict the flow of wastewater coming into the Eastern Interceptor as there’s much less pressure on our network at that time – so it’s safer for our team doing the work.

"We’ve also installed a ventilation system to maintain good quality airflow in the areas where our team is working.

"Our crew is making good progress. Although there may be some localised traffic disruption, noise, and odour in the immediate vicinity – we are making good traction.  We thank the community for their patience as we carry out this critical infrastructure work."