Roading

Kaikoura slips – the work so far

The eventual clearance of $2 billion worth of slips blocking SH1 north of Blenheim could take until Christmas. By HUGH DE LACY.

LIKE SH1, KIWIRAIL’S main trunk line between Christchurch and Blenheim remains blocked by multiple huge slips north and south of Kaikoura, and the best estimates of when those will be cleared range from “a year to god-knows-when”, as one local put it.

Clearing the railway line is expected to be a bigger job than building it in the first place – and that took from 1872 until 1945.

From the north the line has been cleared through to Lake Ellesmere, but 150 kilometres of it remains impassable.

Inevitably the response to the Kaikoura quakes has been compared to that of the 2010-2011 Canterbury quakes which killed 185 people.

The Kaikoura disaster repairs will probably cost about a 10th of the $40 billion it’s taking to get Canterbury back on its feet, and the two disasters are notably different in other respects, according to Steve Mutton, the NZTA’s earthquake recovery manager.

“The Kaikoura event was really different – different risks, different stakeholder needs, different complications, and it had to be considered in its own right,” he told Contractor.

“The principles are the same as SCIRT [the Stronger Canterbury Infrastructure Rebuild Team] where you have strong collaboration between stakeholder parties and very strong stakeholder engagement, but with Kaikoura they had to come up with a different response.”

Apart from Wellington, which caught the edge of the mighty upheaval and will lose a couple of dozen high-rise buildings, the Kaikoura series affected mainly rural populations, with the greatest damage being to the transport infrastructure.

This prompted the establishment of SCIRT’s little brother, the North Canterbury Transport Infrastructure Recovery organisation (NCTIR, which the locals pronounce as the ironic acronym ‘nectar’), comprising NZTA, KiwiRail and the major construction companies.

Initially NCTIR put the recovery cost at between $1.4 billion and $2 billion, but a more recent assessment has a $2 billion price-tag for clearing the slips and repairing the road north of Kaikoura alone.

It’s the slips that present the biggest problem.

“There are nine of them and they are massive: one in particular is 300 metres high and contains enough material to fill 300 Olympic-size swimming pools,” Steve says.

After canvassing a range of options on how to approach the task, and with the southern access restored, NCTIR launched into the northern biggies back in mid-February.

There are four local excavating companies in Kaikoura, and a large chunk of their resources has been committed to building access around each of the slips for heavy machinery, and also to provide footpath access to local residents cut off from the highway.

NCTIR has about 100 staff on the job, including designers and a crew based in Kaikoura, and there are other crews still working on upgrading the southern access routes.

Until the recent switch in focus last month to the northern access, the biggest concentration of work parties was along the coastal strip between Goose Bay – where SH1 descends from the Hunderlee Hills – and Kaikoura.

“We knew how critical it was to get that route open.

“It’s still very fragile and we’re using a lot of aerial gear to clear slips,” says Steve.

As many as six helicopters at a time have been used in sluicing operations to make the job safer for ground-based machinery.

Steve won’t speculate on how much spoil was shifted from the Goose Bay-Kaikoura section, but getting rid of the spoil has presented its own problems, with the shoreline a protected area where simply dumping the stuff into the sea is not a feasible option.

Instead the spoil has been stockpiled in the short term.

North of Kaikoura the government made an Order In Council allowing NCTIR to dump spoil within the coastal marine area, and the NZTA has developed what Steve calls, “a very robust environmental management plan” to implement it.

The same Order In Council established a Restoration Liaison Group which began meeting in mid-January to establish its terms of reference.

In Kaikoura itself the biggest challenge is getting the whale-watch dock facilities dug back out after the quakes raised the sea-floor there by more than a metre, restricting access for tour boats to just a couple of hours either side of high tide.

To local businesses dependent on the tourist trade, no less than to the Ngai Tahu-owned whale-watch fleet, this is almost as important as road access.

Work on the harbour began in late December 2016 and was expected to take six months.

This article first appeared in Contractor‘s April issue.

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