In 2016, we’ve fulfilled our commitment to Treble Cone and Geosolve (abseil inspections and assessments) and did some scaling and geotextile installation at Queenstown Hilton Site for Civil Construction Ltd.
But mostly, we’ve been sailing and chartering yachts between NZ and the Pacific Islands…
And also we have:
done a lot of maintenance,
purchased a hydraulic drill to reduce compressor costs for our clients to increase our drilling capacity,
We wish to present here the very efficient rock fall solution by the Company Elite, with whom we are in close contact. We have been working for them 15 years ago on one of their trial test and we regularly meet their sale representative, in NZ and in France recently.
They have specialized for 20 years on designing, conceiving, installing and testing rock fall barriers and screens in parallel with any other rock stabilization works. We suggest you have a look on their site www.elitegts.com, especially on their Elite 5,000kJ product.
These products are more specialized than any other worldwide renowned barriers retailers for the following reasons:
requiring less anchors,
with their own patented retaining mesh easy to install,
the net positioned above poles, though preventing them to be hit,
posts are not anchored: the post can be installed where needs to be, the best rock can be used to anchor cables as these can be extended
all absorption capacity relies on dissipators to dynamize the potential impact. Active rock catch is the key, as in rope access safety in general.
The Elite system is made up to be installed by abseil drilling means, closer to the potential instability, reducing cinematic and uncertainty on blocks travel.
Not exactly the same approach as those steel retailers who try to sell you bigger barriers built down the slope, close to the highways and involving lots of anchoring…
With kilometers already installed in Europe, this product has made its way. There is surely a scope for them on the Milford and the West Coast roads. We are ready to import and install them (only mesh, brakes and patent need to be brought in; the rest can all be done here: posts, cables and anchor systems).
Twice in the last two years, we were booked to come and stabilize cliffs around Christchurch when another earthquake brought more damage and obliged to reassess the plans.
At last, we were called by a large local abseiling company, who has been granted the contract by Fulton Hogan despite no previous experience in drilling. At McCormick reservoirs in Sumner, the initial design, a self-drilling system, didn’t work for 2 weeks until I managed to convince everybody that an open hole strategy had to be deployed.
We’ve seen in Christchurch recovery other occurrences of drilling companies called on abseiling works and abseiling companies specialized in cleaning windows attempting geotechnical jobs. What a waste of time and ratepayer money…
Conclusion: Always ask the experts and experienced first!
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.
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.
We want to thank the road users for their patience that allowed the State Highway 6 to be safer between Cromwell and Queenstown.
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.
Access: Even with a fragile barrier at the top of the slope, we are still able to find a way to rig safely.
Drillability: The presence of clay at different depths has obliged us to alternate the use of a down hole hammer and drag bits, to drill top anchors 4m deep embedded in 90mm holes, whereas on most jobs of that kind just a hand-drill and 2m holes should do.
Lindis Pass road is exposed to some rocks from bluffs near Camp Creek.
Lindis oct 09 (DAS)
Once again, helicopter sluicing and scaling by abseiling means have successfully permitted us to get rid of a few truck loads of rocks overhanging SH4 near Lindis Pass.
We made in five days the work planned for ten, to the satisfaction of Opus consultants . Thanks to NZTA maintenance manager from Downer EDI Works and the road management team who did a very professional work.