State Highway 2 Waioeka Gorge 22nd Project Update

Over a week ago geologists were concerned about fractures high up on the slope on the Opotiki side (left side of the slope) and the possibility it could cause a small slip failure. 

After inspecting this area, they were confident that this area was relatively stable, but did agree that it needed to be removed to stabilise the slope. 
 
The excavator has all but completed removing the 30,000 cubic metres from the whale-back area.  The machine has been sitting on a 30m long and 5-8 metre wide platform area at the top of the whale-back area, benching in a downwards motion to remove this large volume of material.   
 
Our consultants Opus have provided us with a plan which outlines how to get State Highway 2 reopened through this area of the gorge.  As mentioned previously the short term plan will focus on stabilising the slip face so the diversion road can operate safely and securely without traffic controllers.  What this plan tells us in detail is how we can stabilise this challenging slope quickly and effectively.  The geologists have determined the most effective method of doing this is by benching the identified fractured areas of the slope.
 
The method currently being used by the excavator is to pull away at the base of the slip material above the excavator which causes a natural release, this has been effective so far, and the plan is to continue with this, but at a progressively faster rate by having a bulldozer work simultaneously with the digger to bench the remainder of the slip face. Once the excavator has dropped slip material down the chute (see photo) on to the ramp below, the bulldozer can push the material down the ramp to the waiting trucks.
 
The excavator will then bench across towards the Opotiki side and follow the same process as above to remove the fractured area on the left side of the slope. This area contains around 3,000 cubic metres of material, we plan to progress this stabilisation work over the next couple of weeks
 
The short term plan also involves maintaining security of the highway by constructing a rock fall barrier at the base of the slope.  The design and structure of this rock fall barrier is still to be confirmed, this barrier will help to stop slip material ending up on the highway. 
 
Long term plan is likely to take approximately 2-3 years, this plan focuses on getting the existing state highway fully reopened, this time-frame is required to enable the detailed design work to be undertaken, resource consents to be obtained, funding to be approved and for the contract to be successfully tendered.  The existing road is buried approximately 20 metres into the slope, the new road alignment is likely to start 4-5 metres from the current slope edge. To provide flooding protection from the Opato Stream, a retaining wall may be required to add further protection to the state highway once opened.
 
These short and long term plans will also ensure that the temporary diversion road remains largely unaffected by any work on the slip face.

ENDS

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