Probuild contracted Delta Group to design a complex demolition works programme for the 24 storey Suncorp building, before Multiplex engaged us to deliver civil construction works for the $1.25b Collins Arch development

The scope of works included:

  • Site set up, including amenities, materials hoist, gantries and full height perimeter scaffold.
  • Demolition of existing 24 storey building down to plaza level, including an adjoining 8 storey structure, the retention of 2-3 levels of basement car park and internal soft strip out.
  • Restraining frame protection of marble facades.
  • Favello Favco tower crane installation and operation.
  • Emission, noise and vibration controls.
  • Transport logistics, including traffic management and supervision.
  • Recycling of construction waste materials.

As a pioneer of highly complex, floor-by-floor demolition techniques in high rise CBD structures, we mobilised a 35 strong project team and more than 20 plant ranging from 0.8t to 4.5t excavators and skid steers to systemically deconstruct each floor. We used oxy-sets to cut concrete encased steel columns and beams, before loading waste into commercial waste and craning them off site for materials to be recycled at our own waste transfer and concrete crushing facilities.

As part of mandatory protection works we set up perimeter scaffold which was split from the 12th floor off steel beam (needles) to the full height of the building at 102m. Fifty-six 10.5m steel beams were installed on stub columns to overhang from the structure and rise over the balconies. Our tower crane was established inside the adjoining 8 storey low rise structure and involved a grillage set up on a suspended slab with columns mounted into the existing footings.

We used the existing lift core as our demolition chute and introduced structural back-propping to the existing loading dock so we could increase load-out and transport efficiencies. However, in doing so we identified asbestos (friable and non-friable) in the lift door headers and immediately halted demolition works. We completed asbestos removal and make-safe works which involved more than 20 personnel over 5 weeks. Upon resuming demolition works we achieved our target of one floor every five days to complete the project on time and on budget.

Delta Group was also engaged to complete civil construction works on behalf of principal contractor Multiplex and to kick-start the exciting Collins Arch development.

The use of highly specialised plant and equipment overcame challenges posed by a basement level 7 metres below the water table and VHS rock, allowing us to maintain export rates at the level required to fulfil our programme. We also applied proven logistical techniques to manage vehicle movements to avoid interrupting busy CBD tram services on three sides of the project. Other key achievements included:

  • Excavation of 82,000 cubic metres of siltstone, including VHS rock.
  • Removal of 25,000t of contaminated material (odorous fill).
  • 300 lineal metres of capping beam to retention piles.
  • 3,800 sqm of shotcrete in-fill panels for retention works.
  • Diversion and relocation of existing stormwater and sewer infrastructure.
  • Detailed excavation and FRP of more than 1,000 cubic metres of footings/foundations in VHS rock.