Northland flooding: Mangamuka community 'cut in half' as road closure drags on

Tuesday, 25 August 2020

The slips that will close State Highway 1 at Mangamuka Gorge for at least 12 weeks have cut a small community in half and added an hour to some people’s daily commute.

The slips occurred during the Northland floods on July 17, when a record amount of rainfall fell on the previously drought-damaged region.

Waka Kotahi NZ Transport Agency hopes to have the highway open to one lane for light vehicles by mid-October, but the deadline is weather-dependent, as the hillside continues to slip in ongoing heavy rain.

Waka Kotahi NZ Transport Agency says underslips in the Mangamuka Gorge continue to move, making repairs difficult.

The opening cannot come fast enough for the small Mangamuka community, which is cut off from surrounding areas. For those south of the gorge, the trip to Kaitaia now takes an hour each way, instead of 30 minutes.

**READ MORE:

The small Mangamuka community is now cut-off from surrounding areas and more than an hour from Kaitaia. (File photo)

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The closure is impacting everyone in the community, said Maungataniwha Te Kohanga Reo kaiako [teacher] Millie, who did not want her last name used.

Rock under State Highway 1 in the Mangamuka Gorge fell 300m to the river below, leaving the road hanging unsupported.

“It’s a major impact for us; we’re literally blocked off. It’s really a hassle for us, not only for the kohanga reo but for the parents too.”

The trip to Kaitaia is not only twice as long, it is also a difficult drive on a metal road with logging trucks.

With the community cut in half, two of the kohanga reo’s six children cannot attend, impacting their early education, Millie said.

Older students also cannot attend kura kaupapa Māori in Kaitaia, she said.

Mangamuka Diary has seen a significant drop in business, not just because of the road closure but also due to the Covid-19 lockdown restrictions in Auckland, which has meant a drop in Kiwi tourists.

Normally the store and takeaways would serve truckers, tourists, hikers and locals, but customers have been greatly reduced, said owner Eliza Kete.

“It’s been a huge dent in business.”

Kete is also having trouble getting deliveries, with both truck drivers and NZTA favouring State Highway 10 through Doubtless Bay, rather than the west coast road through Herekino, she said.

NZTA Northland system manager Jacqui Hori-Hoult acknowledged the disruption to the local community and the extra time and cost of detouring.

“We thank motorists for their patience and understanding. We’re working as quickly as possible in difficult conditions to repair and reopen the road.”

In the worst slip, the ground under the road fell about 300 metres to the river below, leaving the road surface unsupported to the centreline, she said.

The surrounding rock is also very unstable and an ancient slip above the road is also a significant safety risk.

“[Engineers] found the ground was unstable both under and above the road and the concern remains that any repair work could reactivate old landslips.”

Hori-Hoult said a wall of 20m concrete piles will be built to support the road. This will take six to eight weeks, and allow the road to be open to one lane for light vehicles, potentially with convoys.

For now, SH1 through the Mangamuka Gorge is closed between Victoria Valley and Makene roads.

Hori-Hoult said the detour is State Highway 10, which NZTA has put time and effort into, to build its resilience as an alternate route.

That work includes replacing a one-lane bridge at Taipa with a new two-lane bridge, which opened December 2019.