Walker Corporate engaged Delta Group to undertake one of the biggest earthworks contracts in South Australian history and to construct a five storey basement as part of their $500m redevelopment of Adelaide Festival Plaza.

Our scope of works included:

  • Retention Piling
  • Capping beam construction
  • Temporary anchors and walers installation
  • Bulk excavation
  • Foundation piling
  • Pile caps / core rafts / shear wall construction
  • Dewatering
  • Group slab prep (potential scope)
  • Civil & Hydraulic works (potential scope)

Unique project attributes included a very deep and large basement – 13,000m2 in area; up to 14m in depth; and 270,000t of material to take out. The secant pile wall retention system scope involved 948 retention piles and 700+ temporary anchors over 4 rows. Meanwhile, the site was located on the busiest street in Adelaide; surrounded by SA Parliament house, Adelaide Festival Centre, Adelaide Casino and Adelaide Railway Station. Effective stakeholder management has been key to the project’s success to date, together with our ability to manage high traffic flows in a congested/restricted site footprint. Environmental measures and controls to minimise and suppress vibrations, dust and noise have also proven effective with the SA Parliament directly adjacent to the site. Similarly, geotechnical conditions have presented challenges for anchoring works as a result of highly variable ground conditions.

Key project statistics include:

  • Bulk excavations: >340,000t, including contaminated spoil
  • 570 lineal meters of Guide Wall and Capping Beam
  • 8,500m2 retention wall hardstand
  • 14,500m2 foundation pile hardstand
  • 948 (750dia) secant piles
  • 500(1200dia/750dia) foundation piles
  • 50 pile caps, strip footings, cores
  • 750 anchors
  • 480 walers
  • 17,000+ construction vehicle movements

The project won the Civil Contractors Federation (SA) Earth Awards for $30-70m.