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Cyclone Gabrielle and unprecedented rainfall a fortnight earlier have left Auckland’s water infrastructure in a fragile state, officials from the city’s infrastructure authorities told Auckland councillors on Thursday.
“We have services restored but the system is very fragile,” Andrew Chin, who is head of Healthy Waters strategy at Auckland Council and an executive director at Watercare, told the council’s transport and infrastructure committee.
Chin said the entirety of damage to Watercare’s wastewater network was yet to be pinpointed, while landslides and erosion had damaged water pipelines.
“At the moment production is meeting demand, but we will probably need to ask Aucklanders to use water cautiously,” Chin told the committee which oversees the city’s major transport and infrastructure matters.
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Siltation was causing problems at dams, reservoirs and water treatment plants across the region, he said.
One example was the Huia water treatment plant, which as well as problems with siltation, had lost supply from key pipelines. That plant was operating at 50% capacity, he said, while Cylcone Gabrielle had also heavily impacted the Waitākere water treatment plant.
Abigail Dougherty/Stuff
Slips from recent storms have damaged roads and broken water pipes in Titirangi where water supplies have been diverted.
Water supplies had been diverted in Titirangi where pipes were broken and the Ardmore pumping station was supplying water to west Auckland via the New Lynn pumping station. However, he said the New Lynn pumping station was at a critical point.
Chin described further issues across the region, including that a tanker was supplying water to residents in Muriwai where the water treatment plant had been red stickered, while at Helensville a fleet of tankers was filling the water reservoir where there had been problems with high turbidity.
As for the wastewater network, Chin said damage to pipes on private land in small gullies and at the back of people’s sections was yet to be identified.
“We encourage people to let us know about it. There will be quite some time before we establish all the issues in the network,” Chin said.
Flooding in Wairau on January 27 had damaged the wastewater pump station there, he said, with new pumps sourced from Christchurch.
North Shore councillor Richard Hills asked what it would take to prevent the sort of tsunami-like event that happened there in January.
“We wouldn’t be able to build a pipe big enough to take the water away,” Chin said.
“It’s not so much trying to build a flood defence, it’s trying to adapt and being used to that kind of water on more occasions. We couldn’t contain that kind of water in constructed assets in an economically feasible way.”
Amberleigh Jack/Stuff
Water tankers set up in west Auckland on January 28 as Titirangi and nearby residents were told to expect low or no water pressure for 48 hours.
Also reporting on impacts from the extreme weather was Auckland Council’s head of engineering resilience, Ross Roberts, who said the weather caused several thousand landslides in the region with hundreds of houses affected.
Roberts said long term considerations needed to be made when thinking about rebuilding structures.
”There will be plenty of unknowns, we’re still very much at the beginning of this,” Roberts said.
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