Yearly safety improvement on SH6 for NZTA – Nevis Bluff near Queenstown

 In association with Downer Edi Works and Opus International, we have scaled and blasted 2 rock features from the  230m high face: Epsilon VI and the Lower West Column for a total amount of 35 cubic meters.
These features that are regularly monitored by Opus, were highly fractured and threatened the road and traffic below.

Epsilon VI direct access on rigging
    
Setting up one of the three blast wirings at Epsilon VI.                          Click to enlarge

After the rock removal, we have drilled, installed, grouted and tested 10 rocks bolts (between 4.5 and 9 meters deep) at 100 meters high  on the West column. 

Also for reinforcement purpose, we then carried out a complete installation of a mesh on the Lower West Column, in a very overhanging zone. The location of anchors is carefully chosen to make sure the mesh fits well.

Click to enlarge

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We want to thank the road users for their patience that allowed the State Highway 6 to be safer between Cromwell and Queenstown.

Glenorchy Landslide Testing

In an emergency response to the rockslide on the Glenorchy-Queenstown road in May 2010, we intervened during the week-end to test the rock stability so that it reopened the following Monday (read the Otago Daily time article).

The helicopter dropped us off above the cliff, we scaled all the loose rocks. Then, we anchored the large rock of concern, so that a digger could tug it from the road with a cable. When no movement was observed, it was deemed safe enough to reopen the road, once cleared.

Nevis Bluff: successful and in due time!

Access and safety 

Climbing up to the workplace,credit J Barbour (c) DAS
Climbing up to the workplace, credit J Barbour (c) DAS

Installing the antirockfall barrier before start (c) DAS
Installing the antirockfall barrier before start (c) DAS

With our previous references on the same cliff, we succeeded on that tender. A team of four of us equipped in two weeks an access on that remote part of the Nevis Bluff. From the top first. Then with Heliworks delivery, we were able to built a rock fall barrier above the area to be worked on. The installation of 120m of ladders and steps bridges allowed Fulton Hogan team and ours to gain access every morning, using a double fixed line system. For the following 5 weeks: hand drilling, blasting, hand scaling and helicopter watersluicing composed the program. Thanks to our ability and abseiling  skills, Drilling & Abseil Services has been a successful part of the operations involving helicopters, heavy traffic management and work at height. 

 Rock Bolting

Rock bolting after rock removal,credit Dave McKinney (c) DAS
Rock bolting after rock removal, credit Dave McKinney (c) DAS
Nevis Bluff, Queenstown side (c) DAS
Nevis Bluff, Queenstown side (c) DAS