The Terrace & Taranaki Street

The original BNZ building in Petone, NZ, required seismic strengthening. There are following issues before pilling

Geological Issues:


  • Presence of liquefiable strata, piles lengths are limited to avoid loss of foundation strength due to liquefaction.
  • Presence of artesian aquifer in the deeper depth, deep piles extending to this depth is not desirable caused by huge resource cost and increased difficulty of drilling into the aquifer.
  • The foundation of building may be effected by natural force, for example tidal influences
  • Liquefaction risk of some layers of ground during an Ultimate State Limit (USL) earthquake, such as the medium dense sand layers


Structural Issues:


  • Existing building means space limitation inside building, there are limited pile layout options
  • Access limitations into the existing building leads to large equipment and machinery may not be possible
  • It may difficult control return grout due to existing foundations for instance there is a gap between floor level and ground level.

The CCS JETPILEs were identified as the only suitable choice based on performance, constructability, and cost.


  • 19 piles overall
  • Diameter 450mm with a diameter 323mm Reinforcing Tube to 5m BGL
  • 7.5m typical depth – above the Waiwhetu Aquifer and liquefaction layers
  • All access through standard double door and stairs
  • All piles installed and tested through diameter 500mm core holes through existing slab
Piling & Anchoring