Navigating the Challenge:

Along with an ageing water network, Wellington Water have the ever-present risk of seismic activity to consider. Mitigating the risk of water disruption is front of mind as Wellington Water develop and roll out a sustainable strategic plan, including seismic resilient pipelines.

Wellington Water resolved to improve the flexibility of a critical DN900 bulk water steel main situated along the Esplanade in Petone. The pipeline connections on either side of a valve chamber presented an increased risk of failure in the aftermath of an earthquake event.

Forging a Resilient Path

United under the Hynds Group - Hynds Pipes, Hynds Water, and Hygrade Water collaborated seamlessly with Wellington Water to orchestrate a dual-pronged solution: Seismic Resilient Ductile Iron pipe (SRDiP) in conjunction with Flex-Tend® Flexible Expansion Joint connections.

The Wellington Water Bulk Water Team subsequently installed two substantial Flex-Tend® joints either side of the valve chamber, each weighing 4.5 tonnes. The operation was supported by a custom-built cradle to help steady the devices as they were positioned in place.

In an area considered at higher risk of liquefaction along the shoreline, the ripple effect of this intervention to the security of the city water supply is significant.


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The New Wellington Children’s Hospital: Pioneering Seismic Resilience and Engineering Excellence:

Situated with an Importance Level 3 classification, the new Wellington Children's Hospital stands as a testament to cutting-edge seismic resilience. With a robust rating capable of enduring a once-in-a-2,500-year seismic event, the hospital not only safeguards patients and staff but also ensures swift recovery and operational continuity after a significant earthquake.

At its core lies a ground-breaking foundation: Triple Pendulum Base Isolators, meticulously designed and manufactured in San Francisco. These specially engineered isolators grant the building the ability to sway up to an impressive 1.5 meters in two directions. This ingenious design pre-empts potential risks to critical sanitary sewer and stormwater infrastructure, strategically mitigating large displacements during seismic events across the base isolation plane.

Aurecon Hydraulic Building Services Engineers collaborated with the Hynds Group to orchestrate the specific engineering design of the Hynds proprietary Flex-Tend® Flexible Expansion Joint. In synergy with the main contractor's BIM team, each connection was developed in Revit, ensuring seamless integration within the digital realm, before submitting as shop drawings for procurement with EBAA USA.

Senior Project Engineer Ray Yee commented that: "From concept, construction and hand-over to Te Whatu Ora late 2022, Hynds have been exemplary in the development of this critical component for this world-class medical facility. Aurecon New Zealand highly recommend Hynds for their commitment, innovation, and expertise in seismic engineering design."

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Enhancing Resilience and Future Growth: The Te Maunga WWTP Outfall Pipeline

Tauranga City sets its sights on the future with the introduction of a new outfall pipeline from the Te Maunga Wastewater Treatment Plant. This ambitious project not only strengthens the city's resilience but also paves the way for anticipated growth.

The accomplished team at HEB Construction completed the installation of 1200mm and 710mm diameter SDR17 HDPE outfall pipeline on behalf of the Tauranga City Council.

At various segments, the 1200 OD PE pipe required precise installation between fixed points. Overcoming this hurdle entailed creating a gap to insert sealing gaskets, followed by securing flanges through electrofusion or mechanical couplings to establish 'closure joints.'

A series of challenges emerged.

  1. PIPA Guidelines: A maximum gap of 20 mm between pipe ends is required for electrofusion couplers d400 and over.
  2. Precision Installation Amidst Change: These joints, however, had to contend with the dynamic nature of thermal expansion and contraction, leading to up to 100mm fluctuations throughout the day.
  3. Meticulous Alignment Amidst Flow: Certain connections relied on the closure of existing valves; a task complicated when small quantities of water continued to flow.
  4. Narrow Window of Completion: The final two connections had to be executed within a restricted shutdown timeframe, adding a layer of urgency to the equation.

Enter the Nova Siria MultiGrip Couplers and Flange Adaptors, carefully chosen for their exceptional attributes, which proved instrumental in surmounting the challenges:

  • Adaptable Design for Changing Conditions: The Multigrip fittings exhibit a remarkable range of tolerance in pipe insertion depths, effortlessly accommodating the expansion and contraction of PE pipes, a testament to their flexibility.
  • Unwavering Seal Performance: With a sealing tolerance of 30mm on the pipe's outer diameter, the fittings showcased the ability to counteract pipe ovality and flat spots, ensuring an unyielding seal.
  • Seamless Alignment Flexibility: Boasting a 3° angular deflection for flange adaptors and 6° for couplers, these components effortlessly navigated variances in pipe alignment, safeguarding structural integrity.
  • All-Weather Installation: Equipped to be installed under any weather conditions, these fittings required only basic tools, with the added convenience of accommodating running water during installation.

The installation process ranged from approximately three to six hours for each fitting. Following installation, a comprehensive four-part Denso corrosion protection system was meticulously applied to safeguard these critical connections.

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