Written by Hynds Pipe Systems
Asset owners rarely choose trenchless construction simply to avoid digging a trench. More often, they are trying to solve a different problem. Whether that’s improving resilience, extending asset performance, reducing disruption or lowering embodied carbon. As a result, many engineering decisions are being made much earlier in the project lifecycle.
The Lower Khyber Pass Stormwater Separation Project in Auckland illustrates this shift, requiring a new stormwater pipeline beneath Newmarket’s busy commercial precinct through native soils, basalt and East Coast Bays Formation ground conditions.
Working alongside March Cato, we helped optimise the 1500mm GRP jacking pipe solution around the selected construction methodology. Reducing the pipe wall thickness lowered both weight and outside diameter, improving constructability while reducing spoil volumes and tunnelling resistance. The result was an 80m pipeline installed in a single drive through challenging ground conditions.
Increasingly, trenchless methods are influencing decisions earlier in the design process, affecting everything from alignment selection and resilience through to carbon reduction and construction logistics.
“We’re seeing more projects where the discussion starts with the outcome the client is trying to achieve, not the product being installed” said Todd Randell, Hynds Trenchless and Specialist Pipelines Advisor. “Whether the driver is resilience, constructability or reducing project risk, bringing suppliers into this conversation early gives the project team more options for getting the best outcome from the project.“
The project also included a 24m-deep segmental caisson shaft. We worked with the project team to simplify the design and improve installation efficiency, while Hynds LC® lower carbon concrete segments reduced embodied carbon.
“People often think manufacturing starts once the design is finished, but in reality, the two go hand in hand. Early engagement gives project teams more opportunities to simplify designs, streamline installation and improve outcomes across programme, constructability and embodied carbon,” says Josh Siataga, Precast Project Manager at Hynds.
The same principle can be seen on the Barber Grove to Seaview Wastewater Treatment Plant Pipe Duplication project in Lower Hutt. Serving around 90 per cent of the Hutt Valley population, the wastewater main was aligned through more geotechnically stable ground while minimising disruption along a key transport corridor. In a seismically active region, the result was improved network resilience and reduced construction impacts.
The Greville Road Stormwater Culvert Upgrade presented a different challenge. The project team needed to restore network resilience while meeting growing sustainability expectations. Rather than treating material selection as a procurement decision, Hynds was involved early alongside the client and contractor to assess low-carbon alternatives against jacking loads, programme requirements and constructability considerations. The outcome was New Zealand’s first installation of Hynds LC® low-carbon concrete jacking pipes, demonstrating how early collaboration can create opportunities to improve project outcomes long before installation begins.
Across these projects, the priorities were different: constructability, seismic resilience and carbon reduction. In each case, the greatest opportunities came from involving the right people early enough to influence design, not just delivery.