571 Ormiston Road Stages 1&2, Flatbush

Project Progress

Client: Whitford Investments Ltd

Location: Flatbush, Auckland

The site is 25.74ha in size and located at 571 Ormiston road, Flatbush. It was previously a farm lifestyle block and predominately covered in pasture with pockets of native bush mostly located in the gully areas.

The project required a subdivision of the land into 46 Lots ranging from 2000m2-8200m2 in Stage 1 and 8 Lots ranging from 2500m2-5000m2 in Stage 2.

The site topography ranged from rolling to steep, there are three steep gullies with ridgelines that provided access to the top and bottom. The underlying soil was more or less weathered mudstone/sandstone and the gullies were wet with isolated springs present.

The roads, accessways and lots were within close proximity to the identified headscapes and shallow seated slumping. A mix of palisade retaining walls, geotechnical underfill drainage (counterfont drains) and buttressed fill was required to ensure inherent stability for these components of the project to mitigate any potential risks.

Project Scope

  • Cut/fill on steep undulating terrain, 65,000m3
  • Counterfont drains, 535M 0 to 5M + deep
  • Pallisade walls, 2020m
  • Geotech benches, 14,000m2
  • 1 x 18M single lane bridge
  • 1800m2 of reinforced concrete accessway
  • 20 x Wetland swales incorporating weirs, spillway, rock baffles, scruffy dome discharge chamber and planting.