Ground Engineering
Marine Parade — CFA Piling & Retaining Wall
Three rows of 600 mm CFA piles and a GCS wall — road corridor ground improvement in Auckland.
- Location
- Marine Parade, Auckland
- Client
- Auckland Transport
- Designer
- Andy O'Sullivan Geotechnical Engineering
- Timeline
- December 2022 — January 2023
- Scope
- CFA piling, subsoil drainage and GCS wall
Design
Stabilising the Road Edge
Marine Parade in Auckland, required ground improvement works to remediate an underslip that had reduced the road to one lane. GSI was engaged by Fulton Hogan as a specialist subcontractor, with design by Andy O'Sullivan & Associates.
The works involved undercutting the low-strength slip debris and constructing two counterfort drains and a subsoil drain along the base of the cut batter. Three rows of 600 mm diameter CFA piles were specified to a depth with 1.0 m embedment into the underlying weathered rock, followed by construction of a Geosynthetically Confined Soil (GCS) wall to road level. The CFA piling approach offered a non-disruptive installation method which allowed the road to remain open throughout construction with minimal vibration and noise impact on adjacent properties.
Build
CFA Piling and GCS Wall in Constrained Conditions
Works commenced with road edge excavation and access ramp construction to establish a working platform. CFA columns were then constructed using GSI's FD45 CFA piling rig, spaced at 1.8 m centres and installed at depths between 6.2 m and 11 m depending on the depth to weathered rock. Embedment of 1.0 m into weathered rock was verified by monitoring drilling torque pressure and visually assessing drilling spoil.
The GCS wall was constructed with Cirtex Duramesh facing panels, with AP65 placed in 200 mm compacted layers and Stratagrid SGU80 geogrid repeated at each lift.
Deliver
Road Edge Secured, January 2023
The Marine Parade project was completed in January 2023, delivering a permanent, engineered solution to the road edge instability. The combination of CFA piles and the GCS retaining wall provides long-term structural support with a finished appearance suited to the coastal residential context.
GSI provides specialist CFA piling, ground improvement, and retaining wall construction across Auckland and New Zealand-wide — delivering technically detailed solutions to constrained suburban and coastal sites under single design-build contracts.
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Coastal or Waterfront
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Coastal and waterfront geohazard work demands specialist knowledge of tide, wave action, and marine access. Our team has delivered across New Zealand's coastline.
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