The Rangitāiki Floodway project is a multi-stage project to take pressure off the flood-prone Rangitāiki River by diverting some of its flow.
Increasing the capacity of the Floodway reduces flood levels in the main Rangitāiki River from upstream of Edgecumbe to the river mouth. This will in turn reduce pressure on the Rangitāiki River stopbanks during large flood events.
Figure 1: Rangitāiki River & Reid's Canal during 2004 floods
The Project works are in several stages:
- Stage 1: Channel Widening. Physical works were completed in the 2011/12 construction season ($3.2million)
- Stage 2a: Channel Widening. Physical works were completed in the 2013/14 construction season ($2.7million)
Figure 2: Rangitāiki River as per Stage 2a.
- Stage 2b: Channel Widening. Physical works completed in the 2014/15 construction season ($2.5million).
- Stage 3: Stopbank Raising. Physical works completed in the 2015/16 construction season ($2.05million).
- Stage 3a: Stopbank wicks and widening. Physical works completed in the 2016/17 construction season ($2.4million).
- Stage 4: Channel widening. Works currently underway.
Figure 3: Stage 4 - Channel Widening
Stage 4 works are downstream of Thornton Road on the true left bank. This stage includes earthworks to relocate stopbanks, increase canal capacity through widening and works on internal drainage systems.
There is currently a variation to the consent being sought for the added works of a second canal outlet, known as a bifurcation. The bifurcation is necessary to reduce the amount of upstream floodway works to achieve the required capacity of the floodway.
- Stopbank raising in 2018/19 ($3.4million budgeted)
- Stopbank raising and the spillway ($2.6million budgeted). Read more on the Spillway below.
Figure 4: Stages in the Rangitāiki Floodway Project.
A crucial part of the Floodway project set for construction is the Spillway at the northern end of the Floodway. The Spillway is the mechanism used to divert floodwater from the Rangitāiki channel and into the Floodway.
Council has looked extensively at several designs: a lower crest weir, a collapsible tipping block or a rubber inflatable dam. There are significant differences in the costs, advantages and disadvantages of the different designs. These options are being worked through as part of the consent variation process.
In May 2018, Council held an information session for those living close to the floodway areas and presented different options and some of the details sitting behind those options.
Presentation to information session on 3 May 2018 (pdf, 1MB)
Bay of Plenty Regional Council (BOPRC) is currently consulting on two of these options, lower crest weir and rubber inflatable dam. The lower crest weir would require a change to the consent that was granted in 2008. We are currently at an early stage of the consultation and there are a number of opportunities for you to ensure your concerns and views are being received by BOPRC.
For more details around the Rangitāiki Floodway Project, please contact:
0800 884 881 x7497
021 687 300
0800 884 881 x9437
027 222 0298