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The pours ran from 3.30am to about 9.30am. About 300 cubic metres of concrete, weighing 720 tonnes, was used to encapsulate the reinforced steel. About 60 truckloads were required.
Port Otago civil engineer Andy Pullar said a ''major milestone'' was achieved in late April by contractors HEB Construction, when the final large diameter tubular steel pile, which holds up the concrete deck, was driven to depth, about eight weeks ahead of schedule.
The cost for the wharf extension had risen from an estimated $15million in 2016, before tenders went out. A contract was struck at $21million.
Port Otago chief executive Kevin Winders said as HEB Construction was ahead of time, it was decided to do extra wharf sheet piling now instead of next year, meaning the full cost was now $23million.
Mr Pullar said a specialist concrete mix was required for the wharf slab, given the wharf's 750mm depth, which generated a lot of heat, and the need for a higher strength concrete.
The 138 piles averaged about 32m each in length, and were driven into the bedrock through a combination of vibration and impact hammer, before being filled with concrete.
''There's still some pile driving to be completed on the public fishing jetty and sheet piling of the existing wharf. However, these are driven by the vibrating hammer with the noise generated not expected to be noticeable beyond the site,'' Mr Pullar said.
The project to extend the wharf by 140m was advancing ahead of schedule, and was on target for completion in October, he said.
''The public fishing jetty is in the final stages of design with a slight change in position proposed from the earlier consented position,'' Mr Pullar said.
For safety reasons, it would be realigned back from the wharf face to the end of the Boiler Point walkway, with a ''T head'' to provide more fishing space, to access a water depth of about 5m.