Over 100 years since its inception, Brisbane’s S1 Main Sewer underwent an ambitious seven-year upgrade. By harnessing the power of innovation, Urban Utilities and its delivery partner, Interflow, have given new life to a hidden but essential piece of infrastructure.

Deep under Brisbane’s bustling CBD lies the city’s oldest and largest sewer pipeline. Averaging 1.5m in diameter, the S1 Main Sewer runs a total of 12km, stretching from Toowong to the Eagle Farm pump station, and is buried eight stories beneath the ground.

Completed back in 1924, the S1 serves well over 750,000 people, carrying 60 per cent of the city’s sewage. To put that in perspective, more than 60 Olympic-sized swimming pools of wastewater travel through the system daily. A lot has changed in Brisbane over the last 100 years, so it’s no surprise that the S1 would eventually need an upgrade to meet the needs of the growing city.

An asset seven years in the making

The works involved rehabilitating a section of the pipeline between James Street in Fortitude Valley to the Eagle Farm pump station, spanning a 5.7km distance. Owner of the asset, Urban Utilities, first awarded the rehabilitation works to leading pipeline infrastructure company, Interflow, back in 2015.

Since then, Interflow has relined 40 individual sections (averaging 160m) of pipeline using a spiral-wound lining system. Fast forward seven years and the S1 Main Sewer upgrade is now complete, with Brisbane’s largest sewer asset ready to serve its community for generations to come.

Operating underneath a bustling CBD

To reduce community disruption and minimise traffic impacts on the busy road, the works took place at night. This meant all traffic lanes could operate undisrupted during peak travel periods. It also meant crews needed to move on and off the busy road each night to allow full lane access in the morning.

Interflow’s Project Manager during the program’s early phases, John Adamo, said, “We developed a portable set up that could be quickly assembled and removed, giving us more time to make progress on relining the S1 within our small nighttime working window from 8pm to 5am.

“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. We imported a special trailer and built a mobile grout plant on it.”

By making their set up portable, Interflow was able to work in the peak of the night within a small working window, allowing little disruption to Brisbane’s traffic network.

Going deeper underground

On projects of this scale, it is not unusual for conditions to change along the way, and in this case it led the delivery team to seek new solutions in order to adapt.

Interflow’s Development Manager, Boris Graljuk, said, “As we moved further through the sewer, the pipelines were getting deeper. This meant there was an increase in the external forces on the pipeline.”

Working closely with technology partner, Sekisui Rib Loc Australia, Interflow identified an innovative way of reinforcing a spiral-wound liner with steel.

“Spiral lining is performed by winding an interlocking strip of PVC into an existing pipe to form a smooth, continuous pipe,” Mr Graljuk said.

“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.”

With the last line now complete, the S1 Main Sewer is ready for its next chapter, and the impressive, yet hidden, piece of infrastructure will go on to serve the Brisbane community for generations to come.

This sponsored editorial is brought to you by Interflow. To learn more about Interflow and the work it does in Brisbane and across Australia and New Zealand, visit

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