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Interflow finishes night works in Brisbane

Interflow - S1 sewer rehab

Interflow have completed a seven-year upgrade project on Brisbane’s oldest and largest sewer pipeline, working nights to meet the unique challenges of the project.

The S1 main sewer, built in 1924, averages a 1.5 m diameter and runs for 12 km to serve over 750,500 of Brisbane’s residents and carrying 60 per cent of the city’s wastewater.

It runs beneath one of the city’s main road corridors, Kingsford Smith Drive – a primary freight route that connects the CBD to the Port of Brisbane and Brisbane Airport, among other important locations.

Awarded the rehabilitation work in 2015, Interflow’s teams knew that minimising disruption would be paramount and ultimately decided that works would need to be conducted at night.

Project Manager John Adamo said that the company developed a portable set up, one that could be assembled and removed with speed, allowing full lane access for traffic during the day.

“Once we had sewer access, we would mobilise a gantry set up straight over the access chamber using a small crane, which could easily take it on and off the worksite daily. We did something similar for our grouting team, too,” he said.

The grouting crew operated as a separate team, working from a mobile grouting plant built on a special trailer.

Boris Graljuk, Interflows Development Manager, said that the increasing depth of the sewer meant that there was also increasing external forces on the pipe.

By working with technology partner Sekisui Rib Loc Australia, Interflow identified a new innovation that allowed teams to reinforce spiral wound liner with steel.

“The new solution, called RibSteel, involved clipping stainless steel strips into the outside of the PVC strip in the lined pipe, which makes it exceptionally strong,” said Graljuk.

Interflow Spiral Lining
Image: Interflow

The product was rigorously tested to meet the exacting standards of Interflow and its client, Urban Utilities. Graljuk said that, once RibSteel was given the tick of approval, all the work needed to utilise it was done on site.

“The steel arrived flat and was formed to shaped using a roll former, before being coiled into the same diameter as the liner. Once it was formed, we could pass it down to the winder and insert it into the profile,” he said.

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