The site consisted mainly of low-density pumice sands and gravels from Taupō eruption deposits. These soils presented challenges due to their lightweight, porous, and highly abrasive nature. To address this, GSI modified its approach by incorporating steel facings onto the mixing arm, ensuring durability and reducing abrasion during soil mixing operations. Additional complexity came from the need to verify mixing uniformity and performance while meeting strict UCS strength criteria under tight timeframes.

GSI applied a cement binder based on successful pre-works trial results achieving >2.1 MPa UCS. A cement-to-water grout mix was batched on-site and delivered via low-pressure worm-drive pump. The treatment area extended 1m beyond the platform boundary to ensure full coverage. On board GPS unit allowed operator to mix in precise locations while recording as-built data.

Each treatment area was pre-dug daily using a 20T excavator to loosen soils for improved mixing uniformity. We employed a 36T IMS rig with onboard GPS for precise mixing depth control and cell overlap verification. Daily wet grab sampling was conducted for UCS testing at 7, 14, and 28 days via an IANZ-accredited lab. GSI managed and supported core sampling operations, adapting from sonic to rotary drilling to retrieve high-quality undisturbed cores.

All IMS cell locations and depths were logged using GPS, with full as-built plans and tabulated coordinates provided. Works were completed safely, ahead of schedule, and in accordance with project specifications. Core sampling and strength testing confirmed the uniformity and performance of the stabilised ground.