Impreg’s UV CIPP liner system has helped to deliver almost 600m of sewer rehabilitation on a project in New Zealand.
In the heart of New Zealand’s Upper Hutt, where traffic flows thick along State Highway 2, an unseen crisis was quietly unfolding beneath the asphalt. A crucial section of the city’s main sewer trunk line, which carries a dry weather flow of 300 litres per second, had reached a critical point of deterioration. Urgent CCTV inspections confirmed what engineers feared: without intervention, the pipe was on the brink of collapse.
But the problem wasn’t just the failing pipe, but also its location. The compromised section sat directly beneath one of the region’s busiest transport corridors, making traditional repair methods virtually impossible without major disruption.
Faced with this high-stakes challenge, the team at PipeWorks stepped in with an innovative and minimally invasive solution. Their goal: to complete the entire rehabilitation within a strict two-week window, strategically timed during the school holidays to minimise impact on traffic and the local community.
Open trenching was ruled out early, as digging through the highway would not only have caused significant traffic chaos, but would also have been expensive, time-consuming and fraught with logistical hurdles. Instead, the answer lay in trenchless technology.
PipeWorks, in partnership with supplier Impreg, deployed an advanced ultraviolet cured-in-place pipe (UV CIPP) liner system. This cutting-edge technique offered what many in the industry now describe as a silver bullet solution: quick, efficient, and virtually invisible to the public eye.
By curing the liner in place using UV light, the team was able to restore the structural integrity of the pipe from the inside.
Over the two-week period, approximately 589m of sewer main was successfully rehabilitated using Impreg’s UV CIPP liner system. This included 144m of 825mm diameter pipe and another 445m of 675mm diameter pipe. The results were not only structurally sound but delivered with surgical precision.
The benefits extended beyond the pipeline itself. By avoiding conventional open trenching, PipeWorks was able to implement a far more agile traffic management plan, maintaining traffic flow on State Highway 2. This included both single and double lane closures, meticulously coordinated alongside a 24/7 work program to ensure the project was delivered safely, efficiently, and with minimal impact on road users and the surrounding community.
In the end, what could have become a major failure instead became a glowing success story. At the time of writing, the project is nominated as a finalist for the Water NZ Project Excellence Award.
hanks to the combined might of Impreg and PipeWorks, the critical section of Upper Hutt’s wastewater network was restored without ever lifting a shovel. And for the thousands of drivers who cruised above it all, it was just another normal day on the road.
For more information, visit impreg-australia.com