The Rangitāiki Floodway is a multi-stage project designed to take pressure off the Rangitāiki River in a flood event, by diverting some of its flow, via a Spillway, into near-by farmland between stopbanks (known as the Floodway) and out the Rangitāiki River mouth at Thornton.
The Bay of Plenty’s most frequent natural hazard is flooding. As we have seen throughout history, the results of a significant flood event can be catastrophic to the lives and livelihoods of those in flood-affected areas.
The Rangitāiki River has a long history of flooding. Between the 1960s and 1980s, the Rangitāiki Floodway was created by the Bay of Plenty Catchments Commission to provide flood protection to the community in and around Edgecumbe.
Over time, the level of flood protection that the Floodway offers has decreased, for reasons such as ground settlement. As technology has advanced, we can also better predict what future flood events may look like and how our flood defences need to be constructed.
In 2009, Bay of Plenty Regional Council was granted resource consent to increase the amount of water that could be diverted into the Floodway (190 cubic metres per second) and upgrade the existing Spillway to better control how the water gets into the Floodway. Upgrades to the Floodway have been ongoing since then.
By diverting the consented amount of water during a flood event, in a controlled manner, through the Floodway, we can reduce the flood levels in the Rangitāiki River upstream of Edgecumbe, reducing pressure on the river near populated areas before it can cause disruption.
Construction to raise the bank heights (March 2022).
Construction to upgrade the Floodway began in 2011 and will be complete in 2023. To date, there have been seven stages of the project, each stage with its own engineering considerations.
Upgrades that have been undertaken on the Floodway include:
Here’s a quick video with our Project Lead Niroy Sumeran explaining the Floodway:
The Spillway and swing gates at McCracken and McLeans Road are the final defences to be constructed. In a flood event, the swing gates act as a barrier to close the roads and maintain the same stopbank height of the Floodway, to convey the water out to sea.
The Spillway is used to divert floodwater from the Rangitāiki River into the Floodway. The Rangitāiki Floodway upgrade is scheduled to be completed in 2023.
These new flood defences will form part of a network of protection along the Rangitāiki River. This includes the Rangitāiki Floodwalls and future work along the lower catchment. In a flood event, these defences will work together to help protect communities along the awa, by managing the increased water levels and reducing pressure on other flood defences.
Bay of Plenty Regional Council received funding for Stage 6 and the spillway from Central Government’s Crown Infrastructure Funding for this project as part of the Climate Resilience Programme ($10.275M). This funding was granted as part of the Covid-19 Response and Recovery Fund, and was one of six projects Bay of Plenty Regional Council received funding for.
In October 2022, Bay of Plenty Regional Council publicly notified the variation to the resource consent application, for the construction and operation of the Spillway (located at 266 Hydro Road, Edgecumbe).
While consent was first granted in 2009, we reapplied for consent as the design of the Spillway has changed to enable greater certainty of its operation in a flood event.
The publicly notified period closed on 3 November 2022.
The purpose of the Spillway is to alleviate pressure on the Rangitāiki River during flood events by diverting floodwater away from the main river and into the Floodway.
When the river flow increases to a certain level in a flood event, the Spillway allows water to pass over a section of lowered stopbank and into an area of paddock near Hydro Road – we call this ‘activating the Spillway’.
When there is enough flow, this water is then channelled into the Floodway and out to the Rangitāiki river mouth.
The resource consent that was granted in 2009 and was for a different type of Spillway design and operation.
The original set-up was utilising a reinforced earth stopbank (fixed crest weir) and an inflatable rubber dam (a rubber, cylinder-shaped balloon that can be inflated and deflated to control the water flow into the Spillway).
Since obtaining that original consent, we have determined that the consented Spillway design would not be the most suitable or reliable option.
There are a few reasons why we publicly notified the community about our reapplication:
After the resource consent was granted in 2009, further investigations and updated modelling technology showed that the planned design was not the most suitable or reliable option.
The original Spillway design carried a risk that it would not start to ‘activate’ unless the river flow was greater than 550 cubic metres per second, potentially putting the downstream community and other flood defences on the river in harm’s way.
The new, proposed Spillway design has been designed to start ‘activating’ for a lesser river flow (440 cubic metres per second). Therefore, it will activate more frequently, but provide greater certainty around its ‘activation’.
The rubber dam was a back-up in case the Spillway did not ‘activate’. This may have been used if the river level rose significantly, but there was not enough flow to spill over the fixed crest weir. In that case, the rubber dam could have been deflated to allow water to pass into the Spillway.
In a report prepared for Regional Council, it was identified that the rubber dam had several shortcomings, including significant capital and operating costs, and the added risk of vandalism.
Using this report and through community consultation, it was decided a more robust Spillway structure, with added contingency gates, would be a better long-term option. The gates can be controlled to discharge water into the Floodway should the Spillway not ‘activate’ or if there is less water flow than anticipated.
The new, proposed Spillway design will ‘activate’ at a lower river level (a more frequent flood event).
However, the volume of water sitting in the Floodway during a smaller event will be less – for example, there may be localised ponding or increased water levels in Reid Central Canal only (amount of water subject to size of flood event).
The gates are designed to be a back-up, in case the Spillway does not achieve its consented flow (190 cubic metres per second).
The amount of water that the gates can release is minor when compared to the Spillway (about 20% of the Spillway’s capacity), but if the Spillway does not achieve its consented targeted, this will be an important tool to ensure the Spillway (and therefore the Floodway) functions as required.
Prior to reaching Te Teko, the Rangitāiki River passes through Lake Aniwaniwa, then into Matahina Dam. Both used for hydroelectric power generation.
For Matahina Dam, the role of dam management is to lower the lake level before a flood peak so that, at peak flows, the outflow from the dam can be kept significantly lower than the inflow for as long as possible that is consistent with the safety of the dam.
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Bay of Plenty Regional Council will begin construction for the final stage of the Rangitāiki Floodway in March 2023.
The Rangitāiki Floodway is a key piece of flood defence infrastructure to help protect the lives and livelihoods of the community.
Bay of Plenty Regional Council will begin construction for the final stage of the Rangitāiki Floodway in February 2023.
The Rangitāiki Floodway is a key piece of flood defence infrastructure to help protect the lives and livelihoods of the community.
In a flood event, the Rangitāiki Floodway is designed to take pressure off the Rangitāiki River by diverting some of its flow (via a Spillway) into near-by farmland between stopbanks and out the Rangitāiki River mouth at Thornton.
What’s happening?
The construction process involves installing swing gates (heavy duty steel flood barriers) at two sites along the Rangitāiki Floodway:
When the Floodway is activated, these swing gates will have two functions: They will act as a barrier on the road, keeping the community from entering a flood zone, and maintain the stopbank height of the Floodway, creating a channel that helps send water out to the Rangitāiki River mouth.
When not in use, the gates are locked open, allowing uninterrupted traffic flow.
How might this impact you?
Construction is due to begin in March 2023 and each site is expected to take approximately seven weeks.
During construction, road closures will be in place around the swing gate site and there will be no through traffic. Residents will be able to access their homes, however detours will be in place to travel to and from McLean and McCracken Roads.
We will keep you updated on construction and road closures via this project page.
If you have any questions or concerns, please contact Project Lead Niroy Sumeran on engineering@boprc.govt.nz or 0800 884 880.
Thank you for your patience during this time.
Bay of Plenty Regional Council have made the commitment to publicly notify the variation to the resource consent application, for the construction and operation of the Spillway (located at 266 Hydro Road, Edgecumbe).
While consent was first granted in 2009, we are reapplying for consent as the design of the Spillway has changed to enable greater certainty of its operation in a flood event.
Bay of Plenty Regional Council have made the commitment to publicly notify the variation to the resource consent application, for the construction and operation of the Spillway (located at 266 Hydro Road, Edgecumbe).
While consent was first granted in 2009, we are reapplying for consent as the design of the Spillway has changed to enable greater certainty of its operation in a flood event.
The original Spillway design was utilising a reinforced earth stopbank (fixed crest weir) and an inflatable rubber dam (a rubber, cylinder-shaped balloon that can be inflated and deflated to control the water flow into the Spillway).
Since obtaining that original consent, we have determined that the consented Spillway design would not be the most suitable or reliable option.
There are a few reasons why we are publicly notifying the community about our reapplication:
Access the full consent document and make a submission.
We’re two thirds of the way through the floodwall replacements with the Greig Road and East Bank Road walls now complete.
Watch this video to see all the progress we’ve made this year:
We are recommencing work on the Rangitāiki Floodway project on the outskirts of Edgecumbe in the section located between SH2 and Mclean’s Road.
Please take extra care on the roads around the site, we’ll be taking extra care too.
We're doing this work to improve how water travels down the floodway which will reduce the pressure on the Rangitāiki River stopbanks during large flood events.
Construction of Stage 6c of the Rangitāiki Floodway is underway after resource consent was granted.
This stage will see 3km of the right stopbank raised and has been split into two sections.
Construction of Stage 6c of the Rangitāiki Floodway is underway after resource consent was granted.
This stage will see 3km of the right stopbank raised and has been split into two sections.
For the initial section, stockpiled construction earthfill will be transported from our storage site at the State Highway 2 end to halfway down the stopbank for construction. Contractors will then work back towards State Highway 2.
There is a temporary speed restriction of 50km/h (as identified on the map above) on State Highway 2 as trucks will be turning onto site.
We are hoping to complete to this section before July 2021, weather permitting.
We will then have to stop the project over winter, and will begin raising the second half of the right stopbank later in the year.
We’re doing this work to improve how water travels down the Rangitāiki Floodway (Reids Central Canal), which will in turn reduce the pressure on the Rangitāiki River stopbanks during large flood events.
Detailed modelling is continuing to feed into the final design of the spillway.
The summer construction season is in full swing with steady progress being made on raising the stopbanks as part of the Rangitāiki Floodway Project.
Earthworks for Stage 6a involved raising the left stopbank of the floodway north of McLean Road. Fencing and grass reinstatement will see this stage completed by the end of March.
The summer construction season is in full swing with steady progress being made on raising the stopbanks as part of the Rangitāiki Floodway Project.
Earthworks for Stage 6a involved raising the left stopbank of the floodway north of McLean Road. Fencing and grass reinstatement will see this stage completed by the end of March.
Work continues on Stage 6b with the raising of the left stopbank from McLean Road to State Highway 2. This stage has a likely completion timeframe of May/June.
Preparation works on the opposite right stopbank (6c) started in early February, while the earthworks resource consent for this stage is still pending.
Two thirds of the work on raising the stopbank for Stage 7 (between Hydro Road and SH2) was completed last year with the final section to be finished by June.
Meanwhile, detailed modelling is continuing to feed into the final design of the spillway.
Bay of Plenty Regional Council has received funding from Central Government’s Crown Infrastructure Funding for the Rangitāiki Floodway and Spillway.
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 75% of:
This was one of six projects Bay of Plenty Regional council received funding for. Find out about the other projects.
Thank you to those who were able to take part in the recent online consultation about the next stages of the Rangitāiki Floodway Project.
Thank you to those who were able to take part in the recent online consultation about the next stages of the Rangitāiki Floodway Project.
Now that COVID-19 alert levels have eased, Council is inviting anyone with an interest in the Rangitāiki Floodway to another opportunity to learn more, and tell us what you think, about Stage 6 and the preferred spillway design.
Some aspects of the these stages have changed, so this consultation will explain the reasons; the relating cost increases and the potential rating impacts.
If you live within the Rangitāiki-Tarawera catchment, it’s important to find out more, and have your say.
Rangitāiki Cosmopolitan Club, 9 Bridge St, Edgecumbe
13 June 2020 - 10.00am
Previously a ponding option downstream of Fonterra was being looked at to reduce the overall project costs. This option has now been abandoned.
This is because detailed design showed that this option was in fact going to be a more expensive option and the benefits were not as great as originally assessed.
Previously a ponding option downstream of Fonterra was being looked at to reduce the overall project costs. This option has now been abandoned.
This is because detailed design showed that this option was in fact going to be a more expensive option and the benefits were not as great as originally assessed.
Consequently the stopbank raising option is now the preferred option. The detailed design also showed that for all options the scale of work required had been under represented in previous modelling results.
Due to the above, Stage 7 of the Rangitāiki Floodway was brought forward to be completed before Stage 6.
The reason for this is that Stage 6 is a far more complex stage and more time was needed to complete the detailed design and geotechnical testing to inform the final design.
The final estimate for Stage 6 has now been produced and is shown in table 1 below:
|
Stage |
LTP Cost Estimate (000) |
Updated Estimate (000) |
Difference (000) |
|
6 |
$ 2,428 |
$ 10,915 |
$8,497 |
During 2018 consultation was undertaken within the local community on options for the spillway design. The proposed option was for a lower fixed crest weir with contingency radial gates and was generally supported at the culmination of the consultation on 24th November 2018.
The option that had been prepared prior to this consultation taking place in the Long Term Plan (LTP) was for a lower fixed crest weir with no contingency allowance.
Table 2 below shows the increase in cost for the Spillway.
|
Stage |
LTP Cost Estimate – Lower Fixed Crest Weir (000) |
Lower Fixed Crest Weir with contingency gates (000) |
|
Spillway |
$ 0.360 |
$ 2,800 |
Central Government announced that it wants to help with economic recovery once we are out of the Covid 19 restrictions. We have put the Rangitāiki Floodway project up as a “spade ready” project that Central Government could help fund. If successful, the increased costs outlined above could be off-set by the CIP funding.
Key links:
We’re about to begin Stage 7 of the Rangitāiki Floodway Upgrade Project – the section from Hydro Road to State Highway 2.
We’re about to begin Stage 7 of the Rangitāiki Floodway Upgrade Project – the section from Hydro Road to State Highway 2.
We’re doing this work to improve how water travels down the Rangitāiki Floodway (Reids Central Canal), which will in turn reduce the pressure on the Rangitāiki River stopbanks during large flood events. Construction works will begin in January 2020 and are expected to be completed in June 2020 but are weather dependant. We’ll keep you informed if these dates change or work goes longer than expected.
If you have further questions, please call 0800 884 880 to speak to a staff member about the project.
Stage 5 of the Rangitāiki Floodway Project has reached a significant milestone with bridge construction nearing completion on Thornton Hall Road near Whakatāne.
Stage 5 of the Rangitāiki Floodway Project has reached a significant milestone with bridge construction nearing completion on Thornton Hall Road near Whakatāne.
The Rangitāiki Floodway Project is being built in stages to take pressure off the flood-prone Rangitāiki River. The current work, which started in late February this year, has seen the construction of a bifurcation channel and the upgrading of Thornton Hall Road, including the new bridge.
Project Manager for Stage 5, Bay of Plenty Regional Council’s Civil Construction Engineer, Jordan Mandery says local residents will see a few final works in the area before the current stage is complete.
“Getting the bridge in place is a significant milestone. We have the bridge beams on, so now we can complete the abutments and bridge approach. We expect the subbase layers of the road construction to get underway shortly and be completed by the end of October. At that point we can divert traffic across the bridge and remove the final piece of land and open the bifurcation channel,” Mr Mandery explains.
Activity around Thornton Hall Road has bound together several other improvements including upgrading the powerlines in conjunction with Horizon Energy and working with Whakatāne District Council to widen the road.
At the same time, a wetland has been created in the area where Reid’s Central Canal will meet the Rangitaiki River. Regional Council’s Land Management team has overseen initial plantings, with more scheduled once the bifurcation is open.
“I’d like to thank the residents and motorists for their cooperation and patience while these critical works are undertaken. Please continue to be considerate and follow the direction of the temporary traffic management while driving past the site as it is important for the safety of our contractors.”
“We are also looking to raise the section of stopbank alongside Thornton Road which is set out in our Long Term Plan, but we’ve decided to bring that forward while we are working in the area, so people will see that work taking place in coming weeks,” Mr Mandery said.
Check out this short video of a recent drone flight over the completed Stage 4 works and the Stage 5 works currently in progress.
Check out this short video of a recent drone flight over the completed Stage 4 works and the Stage 5 works currently in progress.
Stage 5 involves creating a bifurcation cut to connect the Rangitāiki Floodway with the Rangitāiki River, as well as building a bridge over the new bifurcation and undertaking stopbank overlay works along Thornton Hall Road. A wetland is also being created to help encourage wildlife into the area. These works are expected to be completed in September 2019 and we hope you will share the journey with us as we post regular updates of the works progress.
The Bay of Plenty Regional Council will be undertaking a drone survey of sections of the Rangitāiki Floodway during the week of 13 – 17 May to provide council engineers with a Digital Elevation Model (DEM) which will feed into the design for Stage 7 of the Floodway Project.
The Bay of Plenty Regional Council will be undertaking a drone survey of sections of the Rangitāiki Floodway during the week of 13 – 17 May to provide council engineers with a Digital Elevation Model (DEM) which will feed into the design for Stage 7 of the Floodway Project.
The data being collected is high resolution aerial photography used for photogrammetric modelling purposes and will be used for internal purposes only. The survey will be carried out by Regional Council engineers who will be wearing Hi-Vis clothing and will be in a branded Bay of Plenty Regional Council vehicle. Please feel free to approach them on the day should you have any questions.
Initial site preparation works started on Monday 25 February on the Reid’s Canal bifurcation which is Stage 5 of the multi-stage Rangitāiki Floodway Upgrade Project commenced in 2011.
Initial site preparation works started on Monday 25 February on the Reid’s Canal bifurcation which is Stage 5 of the multi-stage Rangitāiki Floodway Upgrade Project commenced in 2011.
The purpose of this stage is to create a bifurcation cut from the left bank of Reid’s Central Canal across Thornton Hall Road to provide a second outlet into the Rangitaiki River and out through the river mouth. These works, which are expected to be completed within six months, also include road alignment works and a new bridge to carry Thornton Hall Road over the new canal outlet.
Following selection of the successful tenderer for the Rangitāiki Floodway Stage 5 works, a karakia ceremony was held at the Reid’s Canal bifurcation with the Rangitāiki River on Monday 18 February, 2019.
Following selection of the successful tenderer for the Rangitāiki Floodway Stage 5 works, a karakia ceremony was held at the Reid’s Canal bifurcation with the Rangitāiki River on Monday 18 February with representatives of Ngāi Taiwhakaea, the works contractor, the project’s archaeology advisor and the Bay of Plenty Regional Council in attendance.
Around 40 interested community members, representing a number of stakeholder groups, turned out on Saturday to hear an update on the consultation process for the upgrade of the Rangitāiki Spillway.
Around 40 interested community members, representing a number of stakeholder groups, turned out on Saturday to hear an update on the consultation process for the upgrade of the Rangitāiki Spillway.
The spillway – the mechanism to divert floodwater from the river into the Floodway - is planned for upgrade in 2020/21 and in recent months Council’s engineering team has been engaging with directly affected landowners and the wider community around the options for the spillway design.
Thank you to those people who have been involved in finding out about the options for the design of the Rangitāiki Floodway spillway and potential ponding areas.
Thank you to those people who have been involved in finding out about the options for the design of the Rangitāiki Floodway spillway and potential ponding areas.
On Saturday, 24 November, starting at 10am there will be a further information session at the Rangitāiki Cosmopolitan Club to inform interested parties about the preferred option that will be put to Council in December.
We will be asking those attending to give an indication of their level of support for the proposed option.
For further information, please email engineering@boprc.govt.nz
Drier spring weather has allowed the work to start again on Stage 4 of the Rangitāiki Floodway Upgrade Project after it was put on hold over winter.
Drier spring weather has allowed the work to start again on Stage 4 of the Rangitāiki Floodway Upgrade Project after it was put on hold over winter.
Meanwhile, consultation with affected landowners and the wider community over the design options to upgrade the spillway section of the Floodway is in its final stages before a recommendation is made to Council on the preferred option (lower fixed crest weir or inflatable rubber dam). The spillway is the structure that diverts floodwater from the Rangitāiki River into the floodway and its construction and associated stopbank widening will be the final stage of the project. Keep an eye on this page for publication of an information session planned for mid-November 2018.
As part of the consultation underway on the Rangitāiki Spillway, a site visit was held in Edgecumbe on 11 August this year, with over 30 people attending, including residents of property adjoining the floodway and interested members of the community.
As part of the consultation underway on the Rangitāiki Spillway, a site visit was held in Edgecumbe on 11 August this year, with over 30 people attending, including residents of property adjoining the floodway and interested members of the community.
Those who came along on the bus trip out to the spillway off Hydro Road appreciated the chance to see the current spillway up close and hear about the options available. Once the preferred option is confirmed by Regional Council, it will go through a consent process. Construction is anticipated to start in 2020. The spillway construction will mark the final stage in this multi-stage project.
There are no events scheduled for this project.