Between 2017 and 2019, PDP was engaged by Bay of Plenty Regional Council (BOPRC) to address the erosion of a critical section of Waitangi Stream, which links Lake Ōkāreka to Lake Tarawera in Rotorua. Our team conducted comprehensive geotechnical investigations to build a detailed ground model, which was crucial in shaping the design solution. Key elements of this project included:
- Raising the streambed with rockfill: This approach was key in reducing sedimentation and preventing further erosion of the riverbed.
- Regrading the stream banks and installing gabion baskets: These measures were implemented to stabilise the banks and protect them from future erosion.
- Constructed an energy dissipation rock structure with a plunge pool.
During construction, our team worked closely with BOPRC, providing ongoing construction review, site inspection, and monitoring services to ensure the project’s success. Given the ecological sensitivity of the area, especially during trout spawning season, we devised a meticulous construction methodology. This included diverting the stream through a bypass pipe beneath the new stream bed to prevent sediment-laden water from contaminating Lake Tarawera.
The project also involved slope stability analysis of the stream banks, the design of robust gabion walls, and continuous site monitoring to ensure the successful implementation of our design. Our collaboration with other contractors, including MAP Projects Limited, was integral to the project’s success. Further details and images of the completed project can be found through their summary.
URL – www.mappro.co.nz/uncategorized/waitangi-streamremediation-and-erosion-protection/
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