Safeguarding our Stopbanks

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Welcome to spring and the official start of our construction season. This means the return of our regular SOS newsletter and, as we prepare to start Stage 3, we’re returning to our six-weekly distribution.

This issue outlines some of the work that’s due to begin and minor ‘finishing’ work that needs to be done to complete Stage 2. We’ve also included a reminder on bylaw property maps and the next Community Reference Group meeting.

If you’d like to have a chat about the project or have any questions about this update, you are welcome to contact us by email at riversanddrains@boprc.govt.nz or phone 0800 884 880.

Read the latest issue.

2023-06-15 - June 2023 update

Winter marks the traditional end of the construction season, so our teams are now making finishing touches to Stage 2, which primarily involves hydroseeding repaired areas of the stopbank and completing fencing work. The ongoing wet weather has made this work challenging so we’re keeping our fingers crossed for a decent run of sunshine to get things tidied up.

Over the next few months, the team will focus on gearing up for Stage 3. Physical works are planned to kick off in October. While the Stage 3 planning and preparation work is being done, we’ll reduce the frequency of these newsletters, with the next one planned for August. We’ll get back to our regular six-weekly distribution in September.

Keen to join your community reference group?

A community reference group, which includes residents impacted by the Safeguarding our Stopbanks work, was established late last year. The reference group provides a forum for sharing information, input on Council communications to residents, and feedback to the project team on what’s working well and opportunities for improvement. If you’d like to learn about the reference group or get involved, please contact Kirsty Brown, Rivers and Drainage Asset Manager via email riversanddrains@boprc.govt.nz

Please don’t dump rubbish and greenwaste on or near stopbanks

Illegally dumped greenwaste is expensive to remove and can cause damage to the gear our contracting teams use to maintain stopbanks – tree branches, flax leaves and mowers don’t mix.  Thanks!

Geotechnical inspections testing on public land

Over the next month or two you may notice some testing activity on the stopbank and berm area adjacent to the Riverside Drive stopbank. This work is part of preparation for Stage 3 of the project. The testing involves a hand auger that bores a small hole to sampling depths (the holes are filled once the sampling is complete). The analysis of the sampling information helps the team make decisions on what specific engineering work is required to remediate areas of the stopbank. You can expect to see a number of geotechnical specialists and engineers in the area from July onwards.

Sign up to your River Scheme

The schemes are areas of land where we maintain and upgrade flood defences, manage riverbank erosion risks and do drain maintenance. The Safeguarding our Stopbanks project is just one piece of work that we’re doing in the Whakatāne-Tauranga Rivers Scheme. To find out more on what’s happening across the scheme you can keep up to date via our website by subscribing to boprc.govt.nz/whakatane-tauranga-rivers-scheme Another way to see how this project relates to Council’s other work maintaining $442m worth of flood defences (floodgates, floodway and spillways) and the bylaws in place to protect them is to check out boprc.govt.nz/flood-defences

About your river scheme - Whakatāne-Tauranga

The Whakatāne-Tauranga Rivers Scheme covers the Tauranga River (previously known as the Waimana River), which has a 440km2 catchment and the Whakatāne River with a 1100km2 catchment. It stretches from Whakatāne town, Tāneatua and Waimana, south to Ruatāhuna and the Huiarau Ranges, and includes the Te Rahu, Waioho and Wairere tributaries. It is one of five major River and Drainage Schemes that were established in the 1970s by Regional Council (then known as the Catchment Commission) to effectively manage and maintain flood defences.

Why does the Matahina Dam ‘spill’ in heavy weather?

While relating to the Rangitāiki-Tarawera Rivers Scheme, our team is often asked “why does the Matahina Dam spill when it pours?” Here’s a quick rundown on the what, why, and how this happens.

In anticipation of, or during, heavy rain in the Rangitāiki River catchment, we will instruct Manawa Energy to ‘spill’ from Matahina Dam. This means they are required to release a controlled amount of water to lower the dam level in readiness of increasing river flows into the dam.

We do this to reduce the risk on communities below the dam by using the storage created in the dam to reduce peak river flows. This ensures downstream river levels are reduced from what they could be if this was not undertaken. In turn, this takes pressure off the flood defences and ensures everything is working together to help protect the community. During this time, water levels in the Rangitāiki River will remain higher than normal for a few days but will reduce slowly as the inflow into the dam reduces.

The river levels are closely monitored by our Duty Flood Manager during a heavy rain event until spilling is no longer required from the dam.

It’s a no go for trail and quad bikes on parks and reserves

Whakatāne District Council bylaws prohibit the riding of motorbikes and quad bikes on park and reserve areas. These vehicles can cause serious damage and are potentially dangerous to other users. If you see trail or quad bikes on or accessing the River Trail or riverside reserve, we encourage you to please contact Whakatāne District Council on 07 306 0500. Photographs are very helpful for enforcement purposes.

2023-04-11 - April 2023 update

Despite a wet start to the year, we’ve been making good progress on finalising Stage 2. We’ve included details in this update, what’s planned for Stage 3 and when this work is expected to be underway. We’ve provided an update on what’s happening with the inanga (whitebait) ponds near Stages 1 and 2.

Please don’t dump rubbish and greenwaste on or near stopbanks

Illegally dumped rubbish and greenwaste is expensive to remove and can cause damage to gear our contracting teams use to maintain stopbanks – tree branches and mowers don’t mix.

Stage 2 almost complete

This stage is divided into two parts, A and B. Stage 2 involves 20 properties, from 48 Henderson Street to 80 Landing Road and 2 – 6 Mananui Avenue. Due to consistently bad weather, Stage 2A progressed more slowly than expected, however it’s now complete, with repairs to the stopbank done and some finishing touches being made to grass cover and fencing.

Stage 2B involves work to the section of the stopbank where the floodwall is also located. Two teams have been working, with one removing vegetation and the other focusing on repairs to the stopbank. The teams are working with Whakatāne District Council to reduce the cumulative impact for residents beside the Hinemoa Stream, where a stormwater upgrade project is planned. We appreciate the ongoing support of residents and the positive feedback – thank you!

Stages 3 and 4 involve the stopbank behind Riverside Drive and this work is scheduled for the 2023/24 and 2024/25 constructions seasons (spring, summer and early autumn).

Why aren’t some trees allowed in certain areas on or near a stopbank?

Tree roots can grow through a stopbank and leave holes allowing water (seepage) to flow through it and cause the stopbank to fail. Tree roots can also get underneath floodwalls, lifting wall sections and breaking joints.

Stumps can also cause problems as they rot, leaving holes in the ground and potentially allowing water from sand layers beneath the ground to come up around the stump and impact the integrity of the stopbank.

Here are some photos from Stage 2 highlighting the risk of some trees and tree roots close to the stopbank and floodwall.

Members of the team checking out soil characteristics following removal of a large puriri tree.

Tree roots impacting the base of the floodwall and top of the stopbank.

Whakatāne Project Future Proof: What is it?

You may have heard that further upgrades to flood defences in the Whakatāne area are planned: Whakatāne Project Future Proof. This project will happen over multiple stages and involves upgrading the stopbanks and floodwalls along the town centre stretches of the river (from McAllister St Pump Station through to the Whakatāne Boat Ramp).

In April 2017, the Whakatāne district experienced widespread damage to homes, property, businesses, as a result of the events generated by ex-Tropical Cyclone Debbie. As the climate changes, communities across New Zealand are adapting to meet the challenges of a rising sea level and more frequent, more significant rain events that may cause flooding.

Using data gathered from historical events, as well as what we understand about the changing climate, we know town flood defences need to be upgraded. We have been working closely with the Whakatāne District Council and Te Rūnanga o Ngāti Awa and will be having conversations with the community in the future, to keep you informed about work that is planned.

Bylaw Authority records

The team has had some queries about prior Bylaw Authorities issued for work on a property that may not have been passed on as part of information when the property has been sold.

Any property owner in a Bylaw applicable area can contact the Regional Council to find out if a Bylaw Authority has been issued for the property previously. Council has records for all Authorities that have been issued since the original Flood Property and Drainage Bylaws came into effect in 2002.

It’s worth noting that the Safeguarding our Stopbanks work is being undertaken on public land to remove structures and plantings that present a risk to the stopbanks integrity. This work is being undertaken under a project specific issued Bylaw management plan.

The bylaws aren’t in place to stop people from doing any work on their land, but instead ensure any work carried out doesn’t inadvertently affect the integrity of Council’s flood protection assets.

Helping safeguard native fish species

Where and when it’s practical the Council team tries to include habitat restoration as part of river and drainage maintenance work. The inanga ponds at Ferry Road are a good example of this. Inanga are the most common native fish species caught as whitebait.

The other species that make up the whitebait catch are banded kokopu, giant kokopu, kōaro and shortjaw kokopu.

The work in the Henderson Street area requires fill material to strengthen and repair the stopbanks. Excavation of the inanga ponds along the river edge is a very cost-effective source of fill material which also avoids the need to ‘truck in’ fill through residential streets in close proximity to schools.

The ponds provide important refuge for native fish species that are otherwise vulnerable to predatory fish in the main river channel.

Ongoing planting of native plants around the ponds is being supported by Halo Whakatāne and Trees for Survival, who are working with local schools to assist students to grow native plant seedlings and learn about native fish life cycles and conservation values.

2023-02-21 - February 2023 update

It’s a big year ahead as our team progresses Stage 2 and works on planning for Stage 3, which they expect to get underway in October. This is to coincide with the construction ‘season’ over the warmer (and hopefully drier) months from October to April.

In this update you’ll find a quick guide on the process we’ve developed to progress this work alongside property owners.

We’ve also provided an update on what’s been happening, where things are at and how to stay informed.

If you would like to have a chat about the project or have any questions about this update you are welcome to contact us by email at riversanddrains@boprc.govt.nz or phone 0800 884 880.

The Safeguarding our Stopbanks project team

How the team works with you

We often get asked how the ‘process’ works when it comes to liaising with property owners to get the work done. As a reminder, the vegetation and structures being removed as part of the Safeguarding our Stopbanks work are on public land and present a risk to the stopbank’s integrity.

While there are unique characteristics and circumstances associated with each property, our team typically uses the following approach when working with owners.

STEP 1: Information gathering

It’s important to gather as much information about a property and the surrounding area as possible, so this step involves examining property files, District Council permits, data from our GIS (Geographic Information System) mapping to identify any issues. Anyone can access our GIS system – just search ‘Maps’

STEP 2: Contact with owner

The team then contacts the property owner, by phone (or email if phone details are not available) to provide background to the work, overview of the current work and arrange a time that suits to visit the property.

STEP 3: Onsite visit

We then meet with the property owner on site – this can take up to an hour. Here we discuss proposed work on council-owned land and what it will likely involve e.g. tree removal, contouring of the stopbank, the impact of that work on private land and how we’ll remediate the work area, e.g. fencing, grass. We will also identify anything that needs specific geotechnical investigation (e.g. rotten tree stumps or structures close to the boundary).

STEP 4: Plan developed

Following the site visit, a member of our survey team will place markers to clearly highlight property boundaries. Any further geotechnical investigation and inspections are carried out, plus any arborist inspections needed to assess the health of trees close to the stopbank. The team reviews everything and develops a plan.

STEP 5: Plan finalised and work starts

Once the plan is finalised we discuss this with the owner, including fencing options and when the work will start. We also go over any last requirements the property owner has, for example ensuring temporary fencing is in place. We also give the owner plenty of time to organise the shifting of any items from the public land

STEP 6: Keeping in touch

While the work is underway, we stay in touch with the owner and advise any updates or answer any queries they may have.

Geotechnical testing on public land

You may have recently noticed some testing activity on the stopbank and berm area adjacent to the Riverside Drive stopbank. The testing involves a hand auger that bores a small hole to sampling depths (the holes are filled once the sampling is complete). The analysis of the sampling information helps the engineering team make decisions on remediation work.

Is this work connected to the Flood Protection and Drainage Bylaws?

The vegetation and structures being removed as part of the Safeguarding our Stopbanks work are on public land and present a risk to the stopbank’s integrity. This work is not dependent on the Flood Protection and Drainage Bylaws. It’s important to note the bylaws aren’t in place to stop people from doing any work on their land, but instead ensure any work carried out doesn’t inadvertently affect the reliability of Council’s flood protection assets.

Trail and quad bikes

Whakatāne District Council bylaws prohibit the riding of motorbikes and quad bikes on park and reserve areas. These vehicles can cause serious damage and are potentially dangerous to other users. If you see trail or quad bikes on or accessing the River Trail or riverside reserve, please contact Whakatāne District Council on 07 306 0500.

Did you know

This work is one part of ensuring 104km of stopbanks, including 14km of urban stopbanks in the Whakatāne-Tauranga River Scheme area, are fit for purpose.

Regional Council flood defences operate across four major river schemes and one drainage scheme in the Bay of Plenty.

The schemes are designated areas of land where we maintain and upgrade flood defences, manage riverbank erosion risks and do drain maintenance.

• The Rangitāiki-Tarawera Rivers Scheme covers 3005km² of the Rangitāiki catchment and 984km² of the Tarawera catchment. The Rangitāiki River is the region’s longest river at 155km, while the Tarawera River is 65km.
• The Kaituna Catchment Control Scheme includes Lake Rotorua and Rotoiti, as well as the Kaituna River. The whole catchment area covers 1,250km².
• The Waioeka-Otara Rivers Scheme covers the Waioeka River with a 825km² catchment and the Otara River with a 350km² catchment.
• The Rangitāiki Drainage Scheme provides drainage to much of the Rangitāiki Plains. The Rangitāiki Plains covers an area of 29,000ha across Matatā and Whakatāne, extending from the coast to Kawerau, and covers the lower flood plains of the Rangitāiki, Tarawera and Whakatāne Rivers.
• Your scheme, the Whakatāne-Tauranga Rivers Scheme, covers the Tauranga River (previously known as the Waimana River) with a 440km² area and the Whakatāne River with a 1100km² catchment.

All ratepayers across the region contribute to river and drain management.