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SUMMIT ROAD RETAINING WALL CONSTRUCTION - CHCH 

DURATION 

Feb 2024 – Current

CLIENT

Christchurch City Council 

CONSULTANT/DESIGNER

Beca

VALUE

$920,000.00

Hunter Civil is currently undertaking the construction of two retaining walls along Summit Rd, in Christchurch's Teddington area. The construction takes a staged approach, with excavation and soil nail installation being completed using our 14T excavator & excavator mounted drill rig positioned at the top of the slope. Following excavation and trimming of the slope face, the soil nails are setout, each nail is referenced with a unique identification number as part of our soil nail quality assurance process.  Anchor testing will be completed following the grout's attainment of strength.

Following verification of the soil nails, a dedicated construction crew will transition to wall construction. This phase includes subgrade testing, reinforced footing beams, and erecting scaffolding for access. Shotcrete application will occur in layers, with the initial layer serving as a robust slope protection layer. Special measures will be taken to protect soil nails from bonding with shotcrete.

The walls have been designed using a lightweight construction method to minimise the completed weight on the slip. To achieve this, polystyrene blocks were to be cut and placed to fill the core of the retaining wall, which creates significant waste. Hunter Civil proposed an alternate light weight method, using spray foam, similar to residential & commercial spray insulation. This achieved the desired outcome the designers were after and as this is a sprayed product there is zero waste. Additional testing had to be completed on this product to ensure it met the engineering requirements.

Following the lightweight void filling, reinforcing steel installation will take place, followed by a final shotcreting layer, to complete the retaining wall face and to allow the securing of soil nail anchor heads. The project will conclude with road reinstatement and installation of site railings.

During the recent fire emergencies, the team had to act swiftly to reinstate access for emergency vehicles and vacate site. Despite this delay, the team are ahead of programme and in the completion stages of the first wall.  

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