Carpark hole plumbs new depths

Greg Pritchard, left), Andrew Rolfe and Peter Dufaur, right, at the Fonterra construction site.

Fletcher excavates below seabed level for second of two commercial buildings being built near waterfront.

The deepest hole dug near the waterfront is now below the level of the seabed.

Andrew Rolfe, Fletcher Construction project manager, said a 16m hole on the corner of Halsey St and Gaunt St in the Wynyard Quarter had now been completed.

That was deep enough for four levels of basement for 247 carparks beneath a new commercial building, VXV3, about to start rising, he said.

"But the foundation walls actually go down 22m into the bed rock," Rolfe said of the Halsey St hole next to Fonterra's new world headquarters, now up to level four.

He also worked on the ASB North Wharf nearby where a 3m hole was dug.

No other new building near the water's edge had such extensive carparking as the new VXV3 building, he said.

Digging that deep on reclaimed land required the special D-wall construction technique, creating a vertical trench which was then filled with a viscous liquid, Bentonite, which keeps the sides from collapsing. Anchors also go down 22m "and they hold the bottom slab down because of the water pressure".

VXV3 and Fonterra are expected to be worth about $135 million on completion.

Peter Dufaur, Goodman's development general manager, said the new seven-level Fonterra headquarters was expected to be worth about $93 million and the neighbouring six-level VXV3 would be worth about $42 million.

VXV3 is yet to be named and leasing announced.

Five new blocks worth about $300 million will eventually rise on the Gaunt/Halsey/Fanshawe St block in the joint venture between Goodman and Fletcher.

Yet from the surrounding streets, building work is only apparent on Fonterra while VXV3 is yet to emerge from the ground due to such extensive subterranean work. Fonterra's block has only one basement carparking level and 69 spaces whereas VXV3 has four levels with 247 carparks. Fonterra staff will park beneath both, allotted 193 carparks across the two buildings, Dufaur said.

"It was most economic to put most of the carparking under VXV3 due to the shape of the building. It was cheaper to go down deeper on a smaller footprint," he said.

Rolfe said the groundworks were by far the biggest challenge.

The 16m hole for the VXV3 building is now below the seabed.

"There was contamination and ground water. We've done a lot of work with Tonkin and Taylor and Auckland Council to mitigate that. It was a timber processing and fuel storage site, so there was leaching down to 6m and when we got to 6m to 7m, we came across clean fill. Land was reclaimed, used for coal, oil and timber, and developed in 1912."

The workforce is about to increase from about 110 on both blocks now, up to 500 people in around April to May. One floor, each 2600sq m, is being built each month in the 16,000sq m Fonterra block, Rolfe said.

Dufaur said rents of $450/sq m to $475/sq m were expected at VXV3 where floors are 1300-1400sq m.

Two new builds

Fonterra headquarters (left)
*Corner Fanshawe St/Halsey St.
*New 7-level block, now up to 4th level.
*$93m projected value.
*Completion due January 2016.

VXV3 (above)
*16m hole now formed for four-level carpark.
*Corner Halsey St/Gaunt St.
*$42m projected value.
*Completion due March 2016.