Bowen State

Four x 25m deep new 1500dia board piles with 3.6m wide bells were required to hold and anchor two new 10-storey shear walls that give the building stability. In a technique untested before in Wellington on this scale, the four belled piles were linked as two sets by two massive 220m³ transfer beams.

It was critical to correctly sequence the three main elements: cutting the two existing central core walls into three disjointed sections and installing 36 new bearing plates; building the two new shear walls; and adding the annex wings.

The southern shear wall provides both structural integrity and an architectural feature. A fibreglass mould made specifically to match the contour of the façade also resulted in exceptional high-finish concrete. BSB’s new lobby and ground-floor retail and hospitality spaces look out on Parliament’s sculpture garden.

It was a huge job, involving the pouring of 2631m³ of concrete, the largest ever undertaken by LT McGuinness. One single pour was 220m³. At the job’s peak, 300 staff and subcontractors were on site.

For much of the three-year project, LT McGuinness was also working on the adjacent Charles Fergusson Tower (CFT) as part of a wider Bowen campus development. Two new office blocks in Bowen Street, in addition to the BSB and CFT rebuilds, will complete a complex worth $350 million in total. Ultimately around 5000 office workers will occupy the campus.