Infrastructure fails Hobbs Road residents

Infrastructure fails Hobbs Road residents

From left, residents say the collapse of this power pole on Hobbs Road is a prime example of infrastructure that is not coping with development. Jane Comber saw her back garden swept away by a torrent of water after recent rain. All that remains is weed matting.
A power pole that has been carried down a bank by a major slip provides dramatic evidence of infrastructure problems on Hobbs Road in Gulf Harbour.

Residents are also facing severe flooding that they say is due to poor stormwater provision.

The power pole came down when the edge of the road and bank collapsed during heavy rain at the end of last month. That rain also worsened several long-standing slips along the road and one resident, Jane Comber, had her back garden destroyed by an overnight flood.

At 4am on the stormy night of March 26, Jane was up to her thighs in water trying to stop the railway sleepers that had formed an edge to her garden from being washed down Hobbs Stream. The stream flows through her land and frequently overflows its banks, causing a large amount of erosion.

Again, as the remnants of tropical cyclone Debbie hit Whangaparaoa on April 4, brown water overflowed the banks of the stream.

Jane acknowledges that recent rainfall has been exceptional, however she says residents have been complaining to Auckland Council for years about stormwater issues on the flat part of Hobbs Road.

Another Hobbs Road resident, Bruce Lindsay, says that when Council approved an increase to two culverts on a subdivision behind his property it directed “double barreled shotguns” of water directly onto Jane’s land.

That water had been retained in ponds, which were reclaimed. “As a result the stream redirects its heaviest flows directly at Jane’s property unhindered,” Bruce says. “It doesn’t affect us apart from a little debris but it is very destructive for Jane. We told council this would happen but their engineers said their calculations were infallible. Well, twice in the last week those calculations were proven wrong.”

In addition several formerly single house sections are being subdivided in the area. Trees have been felled and new driveways concreted. Jane, who has lived on her property for 16 years, says that the cumulative impact of those developments on an already stretched stormwater system has left her house vulnerable. The drains and stream cannot cope and burst their banks.

“We clear the stream, plant to absorb water and do whatever we can,” Jane says. “Meanwhile the ground is whipped away from under my feet and Council says it has no money to make my property safe.”

“Auckland Regional Council prepared a 20-year plan which included culverts along each side of Hobbs Road, to be built at developers’ expense,” Jane says. “This was not acted on by Auckland Council and they are in denial about the need for proper drainage.”

Auckland Transport spokesman Mark Hannan says works are underway to clear the slips on Hobbs Road. He says a geotechnical engineer has assessed the site and is working with Auckland Transport on the design of a permanent fix for this section of road including a retaining wall and a bund (a low wall used to divert water).

Council’s Healthy Waters general manager, Craig Mcilroy, says that stormwater engineers have been to several properties in the Hobbs Road area over the last four years and spoken to owners about maintaining their private watercourse, however some sections of the downstream drainage channel have been modified which constricts the flow.

“Council is currently focusing on ensuring upstream developments do not have adverse effects on downstream flooding which involves encouraging developers to install stormwater mitigation measures,” Mr Mcilroy says. “We will investigate any potential restrictions along the main drainage channel.”

“Following recent severe rainfall, the council, in good faith, will undertake free minor maintenance of the main drainage channel, which will contain road grit and debris. The Healthy Waters department will also be doing stream walks assessments and have added Hobbs Road to this list.”
Record rainfall
Metservice figures for Whangaparaoa station show that last month was the wettest March since records began, in 1946. A total of 354mm fell – the average for March is 78mm.

March was almost Whangaparaoa’s wettest month ever, falling just short of the 356mm of rain recorded in August 1965.

The tail end of Cyclone Debbie dumped 172mm of rain on Whangaparaoa between 9am on April 4 and 9am the following day – this is 2.4 times the normal April rainfall in 24 hours.

The peninsula is off to the wettest start on record by 206mm.


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