Three concrete floodwalls on the Rangitāiki River are being replaced to ensure they continue to help protect our communities from flooding in the coming decades.
During the 2017 flooding event, excessive seepage (the slow escape of water through porous material) was observed at three floodwalls downstream of the College Road breach site. While controlled seepage is good for relieving pressure within the stopbanks, excessive seepage can lead to stopbanks collapsing putting people and properties at risk.
Investigations into the excessive seepage, along with a recommendation from the Rangitāiki River Scheme Review, has led to the need to upgrade the existing floodwalls adjacent to Greig Road, Thornton School and College Road with new flood defences.
The new flood defences are a combination of sheet piles (big sections of sheet steel that have interlocking edges that are driven into the ground) that are then covered by an earth stopbank. This combination ensures that any seepage is controlled and will not undermine the stopbank.
This project will involve the following at each of the sites:
- Excavation and removal of the concrete floodwall.
- Installation of a sheetpile wall, at the location of the concrete floodwall.
- Placing of selected earthfill against the sheetpile walls and at each end of the sheetpile walls to control seepage.
Greig Road: These works were completed in April 2021.
Thornton School:These works got underway in early July 2021 and are expected to be completed by October 2021.
College Road: These works are expected to commence in January 2022 and be completed by May 2022.
Crown Infrastructure Partners funding
Bay of Plenty Regional Council has received funding from Central Government’s Crown Infrastructure Funding for the floodwalls.
Toi Moana put the project up as a shovel ready project after Central Government announced it wanted to help with economic recovery after Covid 19.
The funding covers $2.25 million of the $5.0 million project.
This was one of six projects Bay of Plenty Regional council received funding for.