Hutt at Heart
Mainmark explaining the injection process and locations at the Seaview Plant to Lower Hutt Mayor Ray Wallace and Lower Hutt Deputy Mayor, and Wellington Water Committee Chairman, David Bassett
Mike Baker of Mainmark (right) explaining the injection process and locations at the Seaview Plant to Lower Hutt Mayor Ray Wallace (centre) and Lower Hutt Deputy Mayor, and Wellington Water Committee Chairman, David Bassett (left).

“Like botox for the ground” – new technique builds resilience

The infrastructure supporting our water network could be negatively impacted after a large earthquake, resulting in significant disruption to the management of drinking water and wastewater. Hutt City Council and Wellington Water are taking this risk seriously and working to improve resilience across our water network.

In early May, work began on ground improvement at the Seaview Wastewater Treatment Plant. New resin injection technology is being used to strengthen the ground underneath key buildings, improving the resilience of the plant overall.

Lower Hutt Mayor, Ray Wallace, and Lower Hutt Deputy Mayor, and Wellington Water Committee Chairman, David Bassett, recently visited the Seaview Wastewater Treatment Plant to check on progress of these ground improvement works.

Mayor Wallace says, “It’s incredibly important that key infrastructure such as the Seaview Wastewater Treatment Plant has the capability to operate as normal following a large quake. Wellington Water is working towards improving the resilience of these key plants, and it’s brilliant to see innovative technologies like this being used to keep normal operations going while the upgrade happens.”

Fran Wilde, chair of the Wellington Lifelines infrastructure group, shared her support for this work on earthquake resilience.

“This is a great example of how our region is now focussing on our essential lifeline infrastructure,” she said.

“Wellington’s earthquake risk is well known so all our lifeline providers are now stepping up with enhancement programmes.  But householders also need to plan to be on their own for a period after a big event. So as we mark this occasion we should also have a think about how we would manage those essentials of life such as wastewater disposal if the big one struck our region tomorrow”.

Ground Engineering experts, Mainmark, have developed a non-invasive ground improvement and liquefaction mitigation technique, Terefirm™ Resin Injection, which can be applied under existing structures. Wellington Water’s Seaview project team has likened the technique to “botox for the ground”.

Going as deep at 7m into the ground (at the Seaview location), the engineered resin is injected through thin tubes, and distributes in a veining pattern through the soil. It then crystallises and expands to three to four times its original size. The resin works to create stable ground underneath key buildings in the plant, so it can move as one rather than being pushed and pulled in different directions during an earthquake.

Improving resilience isn’t just about being prepared for a large earthquake or disaster, it’s about repairing and recovering quickly. With the goal of having the plant continue to operate following a large earthquake, it’s important that we create strong foundations underneath existing structures, which will allow for reduced re-build efforts and a quicker return to full operation.

Originally researched by Mainmark in the Christchurch red zone, and underneath an operational retail space, Terefirm™ Resin Injection is a practical solution for the treatment plants and other important infrastructure in the water network, as they can continue to operate as normal while ground improvement works are being completed.

Importance of resilient infrastructure to Lower Hutt Mayor Ray Wallace (and Lower Hutt Deputy Mayor, and Wellington Water Committee Chairman, David Bassett
Tristan Reynard, Project Director (right) explaining importance of resilient infrastructure to Lower Hutt Mayor Ray Wallace (left) and Lower Hutt Deputy Mayor, and Wellington Water Committee Chairman, David Bassett (centre left), with Nick Clendon, Associate Engineering Geologist, Coffey (centre right).
Point of injection in ground at Seaview Wastewater Treatment Plant
Point of injection in ground at Seaview Wastewater Treatment Plant
Mainmark contractors in the process of injecting resin through injection tubes 7m into the ground
Mainmark contractors in the process of injecting resin through injection tubes 7m into the ground

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