Work is underway to install more than 100 temporary piles at the currently impassable slip No 8. Photo / Peter de Graaf
Work is underway to install more than 100 temporary piles at the currently impassable slip No 8. Photo / Peter de Graaf
A key Far North highway badly damaged in the July storm will re-open to light traffic before Christmas.
The record-breaking downpour that hit Northland on July 17 flooded homes and roads around the region and devastated State Highway 1 where it crosses the Mangamuka Ranges south of Kaitaia.
The twisting stretch of highway was hit by eight major slips and has been closed to traffic since.
However, repairs at the worst landslide, an "underslip" which left a stretch of asphalt suspended in midair with no ground underneath it, are making progress.
Last week lead contractors Fulton Hogan started drilling holes for more than 100 temporary, 8m-long piles.
Those piles will support a platform to take the weight of a much bigger drilling rig, which will prepare the site for 47 reinforced concrete piles, each up to 30m long, to shore up the side of the gorge.
Work is underway to install more than 100 temporary piles at the currently impassable slip No 8. Photo / Peter de Graaf
The so-called slip number 8 drops about 150m to the river below and has hollowed out a cavern under the road extending about 1.5m from the edge of the seal into the hillside.
Part of the road consists of a 100mm thick layer of seal and about 200mm of compacted gravel with nothing but air under it.
NZ Transport Agency/Waka Kotahi Northland manager Jacqui Hori-Hoult said the highway would re-open to light traffic in mid-December in time for the holidays.
Cars and campervans would be allowed through, but not buses or trucks.
Only one lane would re-open around the two worst slips, both on the northern side of the summit, so traffic lights or stop-go traffic control would be installed.
Work is underway to install more than 100 temporary piles at the currently impassable slip No 8. Photo / Peter de Graaf
Contractors would work 20 hours a day to reopen the highway but much depended on weather and the stability of the hillside. The first phase of repairs would cost $3.8 million, she said.
The next phase would involve realigning a section of road further into the hillside around slip No 8 so the highway could be fully restored to two-way traffic.
That work had, however, been complicated by the discovery during geotechnical investigations of an "ancient" slip — possibly a few hundred years old — further up the hillside.
Fulton Hogan site supervisor Kevin George, of Taupo Bay, and NZTA Northland manager Jacqui Hori-Hoult inspect the troublesome slip No 8. Photo / Peter de Graaf
Slip No 6, which was just north of the summit and caused the initial closure, was described at the time as ''an entire forest sliding onto the road''.
That has been cleared and the hillside reinforced with large boulders brought down when the earth gave way.
A slump caused by slip No 7 continues to move every time it rains. Photo / Peter de Graaf
Repairs to slips No 5 and No 7 are still in the design phase.
Slip No 7 caused a slump about 1.5m deep and 25m long, taking out the entire northbound lane, and which continues to move any time it rains.
Hori-Hoult acknowledged the inconvenience to the local community and appreciated their patience.
Until all design work was complete it was not possible to give an estimate for the total cost of repairs or a final completion date.
The gorge closure adds about 20 minutes to travel times for people driving from, say, the Bay of Islands to Kaitaia because they can use SH10 around the east coast instead.
For people who live in Mangamuka and drive to Kaitaia, however, it has tripled travel times.
Mangamuka residents Dorothea Heke, left, and Te Rina Pihema say the gorge closure is tough for locals who work or go to school in Kaitaia. Photo / Peter de Graaf
Dorothea Heke, of Mangamuka, said people were now travelling to Kaikohe or Kerikeri to do their supermarket shopping.
Those who had to go to Kaitaia for work or schooling had to allow 90 minutes for the drive via Broadwood instead of 30-40 minutes via the gorge.
Driving around the east coast took even longer, almost two hours, and while Otangaroa Rd offered a shortcut to SH10 it was really only suitable for four-wheel drives.
"We've got people here who work at the hospital, at Pak 'n Save, at the dentist. They have to get up at 4am to get to work on time," she said.
Some of those workers were staying with relatives or had found temporary accommodation in Kaitaia, but it was a major disruption.
People were driving less frequently and planning ahead so they did all their chores in one trip.
"It's like we've slipped back 10 years," she said.
Kaitaia's Terry Anderson, of Safetrak Northland, makes sure only workers and a handful of residents enter the southern end of Mangamuka Gorge. Photo / Peter de Graaf
Te Rina Pihema, also of Mangamuka, said a young relative who had been attending Te Kura Kaupapa Māori o Pukemiro in Kaitaia had to change schools and was now going to the kura in Kaikohe.
The loss of through traffic had also affected Mangamuka Dairy, which was not only the settlement's only shop but also an important social hub and a vital supply point for walkers using the Te Araroa trail.
