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Hynds manufacturing has empowered customers across New Zealand to succeed by delivering high-quality products and innovative solutions, designed with the specific challenges of each new project in mind.

Over 49 years of partnership with New Zealand’s infrastructure industries has equipped Hynds with the local knowledge and expertise to deliver on many projects in New Zealand. Sections of water infrastructure across the country are nearing the end of their service life, prompting a series of upgrade projects to ensure the safety of their water and wastewater networks for years to come.

Unique and sometimes challenging conditions beneath the ground have pushed Hynds to innovate and adapt, enabling clients to succeed.

Success under pressure

Hūnua 4 is Auckland’s biggest water project. Completed in 2022, it includes a new 31 km watermain that connects Watercare’s reservoirs to water storage in the city centre.

Section 11 of the project consisted of three drives and a total of 961 lengths of 2550 mm ID, 3000 mm OD Jacking pipe, with a total length of 2.8 km under major arterial roads, and well-established residential and commercial suburbs. This section provided a temporary works tunnel that allowed teams to install the 1600 mm OD CLS watermain.

The second drive for the Hūnua Section 11 set the record for the longest single pipejacking drive in the southern hemisphere by a tunnel boring machine (TBM). The drive was 1216 m, and the record was broken straight after, with the third drive hitting 1263 m. The drives included multiple compound curves, highly fractured and variable basalt and lava caves presenting the contractor McConnell Dowell with many challenges.

In addition to the jacking pipe the length of the drives meant that McConnell Dowell required five to six intermediate jacking (inter-jack) stations for each drive.

Throughout the project, Hynds supported McConnell Dowell to deliver the project and set the bar for future works. The success of the project created a resilient water supply, safeguarding the future of the city’s water supply from Auckland’s southern reservoirs.

Adapting and delivering

More recently, Hynds has been supporting McConnell Dowell in Wellington who have Section 11 of the project consisting of three drives and a total of 961 lengths of 2550 mm partnered with Wellington Water on the Barber Grove to Seaview Wastewater Pipe Duplication project.

The project requires a new 1200 m long, 1000 OD PE pipeline. It will connect the Barber Grove wastewater pump station to the Seaview treatment plant. The existing 50-year-old concrete pipe is vulnerable to earthquakes and will be supported by the new pipe. The pipes carry 90 per cent of the Hutt Valley’s wastewater.

Over half of the total length being installed for the project (55 per cent) runs down the centre of Randwick Road, a main arterial route. With housing on either side of the road, as well as a school and a golf course, the decision has been made to use micro tunnelling to install a concrete conduit jacking pipe which will carry a slip-lined DN1000 PE100 wastewater pressure pipe along this stretch of the project.

Hynds supplied the contractors with its 1200JACZ marine grade pipes manufactured in the Hynds Christchurch Factory. The pipes were fabricated to a class 4 loading with increased concrete cover as required for marine environments. The 1080 mm ID and 1310 mm OD – perfectly matched McConnell Dowell’s tunnel boring machine. The 1000 OD PE pipe fits snuggly into the concrete conduit pipe with minimal packing required. Installation of the concrete pipe along the road has been split into three portions, or drives, at 160 m, 200 m, and 230 m. To further minimise disruption, there are two launch shafts and two retrieval shafts — limiting the disruption caused by moving equipment as work progresses.

Three grout ports have been included on every third pipe length — so that bentonite can be pumped in during jacking and allow for grout to be installed, fully sealing the void between the outer wall and the surrounding earth.

Two inter-jack pipe sets have also been supplied, with the goal of recovering and re-using the first set after drive 1 is complete. The inter-jacks provided a unique challenge, as each pipe has a 32 mm thrust plate cast into each end with threaded holes to allow the inter-jack station to be secured to the leading pipe.

The mould had to be modified to hold the plate in place while it was centrifugally spun. Hynds Pipe Systems completed the design of the steel CAN pipe required by the inter-jacks thus supplying the customer with a full concrete jacking pipe package including MDF timber packers used as cushions between the pipe faces to transfer jacking forces evenly.

Products Featured
Jacking Pipe

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