Preparation for pumping sand onto Te Rauone Beach – the final step of the Port Otago 10-year-long community project – is progressing well.
While the three impressive breakwater groynes were finished in February, global shipping delays held up delivery of the pumping equipment needed for the job. Now, the equipment which was recently commissioned is finally ready for use.
The Port Otago hopper dredge New Era will collect sand from the maintenance dredge area located on the edge of the harbour channel.
The port also announced that specialist contractors DivePro have laid about 400 metres of 200mm-diameter pipe from the beach, out into the harbour. To ensure public safety, the pipeline is marked with a row of floating buoys.
Two 21-metre long piles have been driven into the harbour (away from the channel), providing a stable platform for pumping works.
Next, the backhoe dredge Takutai will moor alongside these piles, retrieve the flexible end of the discharge pipe (tied to the piles) and connect it to the specially-sourced 120kw submersible pump.
The 1360kg pump will be manoeuvred by the hi-ab on the Takutai deck and powered off the vessel’s Liebherr excavator. The set up is capable of pumping up to 800m3/hour of a sand and water mix (approx. 20% sand to 80% water) – from the New Era hopper, through the new pipe and onto the beach.
Meanwhile, on the beach, the sand will settle out and be distributed across the length of the beach by SouthRoads. The pipe will be moved by DivePro two or three times through the course of the renourishment.