Abseilers enjoy a labour of love
Against the backdrop of the Pacific Ocean, abseilers working on the biggest rockfall drape in New Zealand lower themselves down the unstable bluff at the top of Ohau Point, north of Kaikoura.
A helicopter carrying a 50-square metre panel of ring net flies in from the south, lowering the steel down to the abseilers who shackle it together like chain mail over the rock face.
From the air, the shattered highway on both sides of the point is swarming with activity; excavators, cranes, and the barely visible dots of workers hurrying to open it by Christmas.
But the road below Ohau is still buried. During the 7.8-magnitude earthquake last November, more than 100,000 cubic metres of rock and debris tumbled down the cliff face.
It is the biggest and most technically challenging slip facing the alliance charged with rebuilding the road and rail corridor, and the abseilers on the bluff are playing a crucial role.
Perched on the ridge above the bluff is base camp: a winding series of pathways and clearings cut from the bush using chainsaws and a 1.5-tonne excavator flown in by helicopter.
From there, the abseilers gear up, strapping into full body harnesses and securing their lines, before descending the steep, and in places vertical, rock face to attach the ring net.
Mat Avery, of Hiway Geostabilization, says the 12 abseilers love heights, and when base camp is 180 metres above sea level, it helps.
The scenery helps, too. The expansive views take in the mountains, construction sites and the ocean, where abseilers have spotted dolphins, and even a baby humpback whale.
‘‘It’s spectacular. It’s got to be one of the best workplaces in the country,’’ Avery says.
Avery is the man leading the mesh project, which he says is the largest rockfall drape to be installed in New Zealand, covering 4500sqm at the top of the bluff.
To account for overlap and wastage, the North Canterbury Transport Infrastructure Recovery alliance bought 5600sqm of the 9-millimetre thick, high tensile steel ring net. This exhausted the global supply of the product.
Abseilers have been working at Ohau since January, using crow bars and air bags to dislodge loose rocks with assistance from helicopters trailing monsoon buckets to sluice the bluff.
‘‘Once we’ve got the ring net installed we have to remove all the loose rocks down to road level, which is, at a guess, 10,000 to 12,000sqm of rock face that needs to be made safe,’’ Avery said.
‘‘When we’ve done that they’ll have construction access to the road underneath us to build the sea wall and the new road.’’
All of this happens at the mercy of the weather. There have been times where the team has had to scramble to get a helicopter before low cloud enveloped the site, making it too dangerous to fly.