Pile-driving hammer built for difficult work

It is 3.9m long and weighs 14 tonnes. It is made of a steel tube filled with lead. It will be...
It is 3.9m long and weighs 14 tonnes. It is made of a steel tube filled with lead. It will be used for driving steel piles for the duration of the piling works at the new Dunedin hospital. The hammer will be attached to a Liebherr HS8100 Heavy Duty crawler crane. PHOTOS: SUPPLIED
Difficult soil conditions on the site of the new Dunedin Hospital have demanded a customised solution.

Auckland firm Hornell Industries built a brand new 14-tonne hammer specifically for use on the construction project, due to arrive on site this week.

The hammer, a steel tube filled with lead, will be used by Christchurch engineering firm March Construction to drive piles for both hospital buildings.

It will be hoisted into position using a Liebherr heavy duty crawler crane.

"It is probably the biggest hammer of its kind in New Zealand, given these will be the largest bottom driven steel tubes ever done here," March Construction operations manager Andrew March said.

"The hammer has been manufactured solely for use at the new Dunedin Hospital, which is a pretty unique job in terms of the size of the bottom driven steel tubes and the size of the hammer."

Consent documents for the hospital groundworks reveal how challenging the site, which is largely on reclaimed land, will be.

Five different layers of materials have been identified, including clay, silt, gravel and, at the bottom, volcanic rock.

There will also be tidal groundwater on site, as close as half a metre to the surface, and there are also expected to be patches of contaminated soil due to the numerous former industrial uses of the site.

Some piles are likely to have to be drilled as deep as 20m, and engineers expect boulders could cause obstructions in some areas.

Piling work was given fast-track consent last year and is expected to begin soon.

Conditions imposed by the independent panel which assessed the application included mitigation for noise and vibration.

mike.houlahan@odt.co.nz

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