Ōamaru Harbour Rock Revetment Maintenance
Published on 30 September 2022
Waitaki District Council will continue regular rock revetment maintenance with the placement of 450 tonne of basalt rock on the Ōamaru Harbour foreshore opposite the sheds near Sumpter Wharf on 3 and 4 October.
The inner harbour doesn’t wear out quickly due to the protection provided by the breakwater however Council has identified some areas of subsidence and erosion which will eventually eat away at the popular foot path areas.
While this maintenance work is essential, Council recognises this is also an important area for many of our little blue friends who nest around the harbour.
Project and Assets Officer, Grant Rhodes said “While the rock revetment maintenance is important for the physical wellbeing of the harbour, we have also taken special consideration and planning to minimise any ecological impacts by working closely with the Ōamaru Blue Penguin Colony.”
Dr Philippa Agnew, Science and Environmental Manager from the Ōamaru Blue Penguin Colony said, “The penguins come and go from their nests year-round so no matter the time of year, there is always the possibility there will be penguins nearby which we need to look after.”
Dr Agnew has already surveyed the site and while there doesn’t appear to be breeding penguins present, she will be on site during the rock revetment maintenance work looking for non-breeding birds who may be visiting the area during the day. Dr Agnew has authority from the Department of Conservation to safely relocate any penguin day visitors during this work.
Contractors will also gently tip the trucks to minimise any noise or disturbance to all local wildlife including the noise sensitive shags on Sumpter Wharf.
Council has conducted aerial surveys with drones and an aerial 3D mesh LiDAR survey. LiDAR surveying uses laser pulses that calculates distances and captures precises measurements. While this is a sophisticated monitoring tool, it is also a quick, simple, and accurate way to collect data.
Previously Council has also used Bathymetric LiDAR surveying with this tool able to penetrate several metres below the sea level to detect submerged rocks. This technology is subject to calm seas, so its use is dependent on the conditions of the day.
A traffic management plan will be in place to divert pedestrians to walk alongside the edge of the buildings for two days while the work is carried out. A 14-tonne wheeled excavator and two tip trucks will be utilised for this project.
Council frequently maintains the harbour area with rock revetment maintenance near Friendly Bay Beach and the area outside the North Otago Yacht and Power Boat Club completed in 2021.
The breakwater will be the next part of the project and is scheduled in for around April 2023.
The Ōamaru Harbour Plan 2020 and Beyond takes a holistic view of the harbour and surrounding area and considers a range of options to ensure it remains a key community asset, both now and into the future.
Four investment objectives are outlined within the Ōamaru Harbour Plan 2020 and Beyond are:
- Enhance the harbour in sympathy with the town’s heritage, creating a unique experience that residents are proud of, attracting visitors
- Confidence – attracting increased investment in the harbour area
- Keep adding to the harbour area’s vitality in a planned way that complements and benefits the town centre where possible
- Protect wildlife and improve environmental outcomes, helping people enjoy and understand both
ENDS