Mammoths Prepare Raft for Sinking

Construction at the new Christchurch Central Police Station site has marked a major step forward with the completion of the concrete raft foundation. The 400mm-thick raft is the primary ground stabilisation foundation for the new building, which ensures it meets IL4 earthquake rating requirements. It covers 8300 square metres of the 1.5 hectare site at the corner of St Asaph and Antigua Streets.

The raft was completed in two mammoth concrete pours, the second taking place earlier this week. Both pours were major logistical exercises with trucks from three different concrete suppliers making multiple trips over several hours to deliver to the site. The first stage saw 1200 cubic metres of concrete poured - about a third of the total raft.

The second stage pour is believed to have been the biggest single concrete pour on a conventional building site in the South Island. Over a 10-hour period, starting at 1.40am, a total of 348 truck loads of concrete were delivered to the site, pouring a total of 2096  cubic metres of concrete. At times dozens of trucks were lined up on surrounding streets waiting to enter the site. Up to five concrete pumps were operating around the site, with 28 contractors working on pumping, placing and levelling the concrete.

The weather remained perfect for the operation and the pour went completely according to plan.

The raft foundation is now destined to be buried, while the main concrete slab foundation for the building will be poured next month.

The construction project remains on track for completion in November, with police staff expected to be fully relocated by the end of the year.