A decision by Christchurch Police, in December 2011, to move out of their 40-year-old Hereford St building due to concerns another major earthquake would cut essential services, prompted work to begin on a temporary central police station at the corner of St Asaph and Antigua Streets.

The $20 million project was to be completed by November 2012 but with potentially unstable/ liquefiable land a concrete raft foundation floor was designed and required before construction of the new single level building could begin.

The 400mm-thick raft would be the primary ground stabilisation foundation for the new building meeting earthquake rating requirements. It would cover 8,300m2 of the site and would be completed in two pours.

“Due to the amount of concrete required for these pours it was decided by Apollo Projects Ltd, Project Managers for the build, that they would use the three main players in the concrete market in Christchurch to get this foundation poured over two pours – Firth, Allied Concrete and Christchurch Readymix,” says Dominic Sutton, Chief Operating Officer (Southern) for Firth.

“With such a large footprint for this new temporary building and the tight programme of the project the pours were just too large for any one company to handle. So we approached the three main suppliers in Christchurch who were all happy to be involved,” says Steve Hastie, Project Manager for Apollo Projects Ltd.

Both pours were major logistical exercises for all involved, with trucks from the three suppliers making multiple trips over several hours to deliver to the site. The first stage of the pour, about a third of the raft foundation, was for 1200m3 but it was the second pour at the end of June that was a “first” in many ways.

“Where else would you see rival companies standing side by side in a common cause – the rebuild of our city,” adds Dominic. “As you can see by the photos it was an impressive sight and I am glad that Firth was a part of this historic day.”

The second stage pour was believed to be the biggest single concrete pour on a conventional building site in the South Island and was completed over 10 hours. Starting at 1:40am a total of 348 truckloads of concrete carrying 2,096m3 was delivered to the site.

“It was a remarkable couple of days and thanks to all involved it went exceptionally well,” adds Steve.

The raft foundation is now destined to be buried, while the main concrete slab foundation for the building will be poured in September. Police staff are expected to be fully relocated to the new building by the end of the year.

Taken from the October 2012 NZRMCA Newsletter

Images – Firth Industries