Keen-eyed observers of the Oamaru Harbour will have noticed some heavy machinery at work on the breakwater last week. 

About 2000 tonnes of rock have been placed on the sea-ward side, as part of maintaining the revetment (sloping structure to absorb wave energy and reduce erosion) and protecting the breakwater, Waitaki District Council property manager Grant Rhodes said.

The rock was supplied and placed by Road Metals, using a 30-tonne excavator and 35-tonne loader. 

Three quarters of the rocks used weighed between seven and 26 tonne, and contractors also removed unsightly concrete on the Macandrew Wharf, which runs parallel to the breakwater.

The cost of this necessary coastal erosion prevention was $130,000, Grant said. 

Rock revetment work took place on the harbour wall near the sheds opposite Sumpter Wharf in 2022, and the breakwater itself was last added to in 2021.

“Regular rock revetment is important for the physical wellbeing of the Harbour, and with the winter weather now easing, it is important for us to check the breakwater and add to the existing rocks where necessary,” he said.

Later this year the council will be conducting a Lidar survey to monitor rock loss on the revetment walls that protect the Oamaru Harbour. Lidar surveying uses laser pulses that calculate distances and capture precise measurements.

The tool is a quick, simple, and accurate way to collect data.