Media release

16 April 2013

Innovation and recycling reduce bridge costs

Keeping an eye out for opportunities to be innovative during the construction of the Lower Hatea River Crossing has paid dividends, with the recycling of discarded pontoons from Tutukaka Marina.

The 130 pontoons, large polystyrene blocks encased in concrete, were stockpiled at Pohe Island and Kioreroa Road about two years ago when new, wider pontoons were installed during an upgrade of the Marina.

“We were in the early stages of planning for the bridge when the marina upgrade was happening and we realised the pontoons and some of the piles at Tutukaka might come in handy so we held onto them,” said WDC Group Manager Infrastructure and Services Simon Weston.

“The pontoons turned out to be ideal to retain the sloping sides of the road on Pohe Island as it rises above the surrounding land to the bridge.

“They are large, uniform in shape, strong and very light for their size which was important as we didn’t want to use heavy materials which could have caused settlement problems on the new road due to the soft marine soils under the landfill. Being recycled, we did not have to purchase new materials for this job.

“The other option would have been to build a retaining wall, but it would have been more expensive and placed a heavier load on the land in this area.”

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