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Resilient Westport programme updates – January 2024 – WCRC, BDC

The West Coast Regional Council (WCRC) and Buller District Council (BDC) are focussed on delivering initial flood protection works to provide immediate relief from flood risks this financial year.

The multi-tool Resilient Westport business case works under the PARA (Protect, Avoid, Retreat, Accommodate) framework for adaptation. Budget allowances and key responsibilities have been allocated under this framework approach.

Both councils play a key role in, and have specific responsibilities towards enabling the business case, although there are also areas specific to each council.

Under the Protect function, WCRC’s overall aim is to have structural mitigation works to prevent most direct threats from the Buller River and some from the Orowaiti River completed by June 2025.

Most of the remaining works will be completed by June 2026, aiming for 90% completion by that date.

Key areas of BDC responsibility fall within the Avoid, Retreat and Accommodate functions. The Crown also works collaboratively on all projects via the Joint Steering Group for Resilient Westport.

What has happened in the past three months?

Protect – Stage One programme

A significant amount of progress has been made on the implementation of the Stage One programme (previously called ‘quick wins’), under the Protect function – the focus is on immediate flood mitigation works led by WCRC.

A draft engineering design report has been completed by Davis Ogilvie & Partners Ltd. Together with this report, preliminary design plans have been completed for all four of the Stage One works.

Initial geotechnical designs have been received for all four works. Quotations have been received and a company, Prodrill Ltd., commissioned for the borehole drilling for the detailed geotechnical investigations.

The environmental assessment of the proposed Stage One works at McKenna and Cats Creeks have commenced. This involves consultation with tangata whenua and assessments of the landscape and other environmental factors. This is being managed by consultants Chris J Coll Surveying.

An assessment has commenced into the quantum of impacts on properties outside the stopbanks. The design’s flood levels at these locations, with and without the proposed scheme have been assessed for both the 1% annual exceedance probability (AEP) (1 in 100 year) current climate and 1% AEP future climate in 2120 under RCP 6.0, a greenhouse gas concentration trajectory used in climate modelling. Council has decided that for the Stage One Avery’s stopbank, the design should be to the 1% AEP level with 600 mm freeboard and an allowance of 200 mm for climate change.

This will retain the 1% AEP level of service for about 30 years and give the community the opportunity to consider adaptation strategies for the impacts of climate change in this area – where both groundwater levels and rainfall intensities will increase, creating risks separate to those from direct river flooding.

A construction engineer, Mr Jordan Mandery has been appointed. Jordan brings a good set of experience in construction of flood mitigation works.

Retreat/Relocate

The primary area of focus for our team in the BDC has been the establishment of the Master Planning work programme as identified and funded in the multi-tool business case. This project looks to take a holistic approach to planning Westport’s future.

A significant area of focus is how Westport can adapt to its multi-hazard profiles. This not only takes account of the obvious hazards and location issues but will also address and reflect the community’s economic, cultural, and social aspirations for the greater Westport area. This Master Planning process will ultimately guide the development of areas of land for future use, creating greater choice for the community around lower-risk areas.

This is the first instance of a planning exercise of this scale taking place in the Buller District. A specialist firm, Isthmus, has been engaged to develop the Master Plan and has been working closely with the BDC project team to get this work underway.

What is planned for the next three months?

Protect

After assessing the information available, the two Stage One projects, the McKenna and Cats Creek- Abattoir drains are likely achievable this financial year (June 2024). Part of the Avery’s stopbank project is possible, but the Floating Basin work requires some further consultation to solve.

The final design and consents will be sought for the two proposed Stage One works. Final plans and construction documents will be completed, and tenders called for these two proposed Stage One works. Preliminary design will also continue on the other two proposed Stage One works – Avery’s stopbank and the Floating Basin.

In parallel, the detailed initial and final designs for the remainder of the scheme are progressing. The geotechnical design is well underway and is a very important part of the investigations in order to provide a secure flood protection scheme.

Central government did not include funding for the Carters Beach flood mitigation in its approval. This is being investigated further to determine the most expedient path forward. Options will also be investigated for individual flood mitigation solutions in the Snodgrass area. Design preparation for the overall scheme will continue. Floor levels of those properties outside the stopbanks will be surveyed and the flood risk to these properties assessed. The borehole drilling will be significantly advanced, enabling the detailed geotechnical design to be conducted.

Avoid

Isthmus will complete the first stage of the Master Planning work programme by the end of March/April with a high-level vision concept. At this point we will then begin the significant and extensive engagement with the community for their feedback on the vision before commencing stage two. This engagement will coincide with the opening of the Resilient Westport Community Engagement Hub in Palmerston Street – a shared space between WCRC and BDC.

Engagement activity to support the creation of the Master Plan is a crucial step for Westport – this will be the plan for the town’s future, looking at our responses to multiple hazards over time, as well as where, and most importantly how Westport may grow.

Challenges and breakthroughs

Protect

The biggest challenges have been calling quotations and assessing and engaging the borehole drilling. We are extremely satisfied with the engagement of Prodrill Ltd. for this work. Good progress has been made on formulating the plan for the assessment of environmental effects and obtaining the necessary resource consents, with particularly beneficial liaison between the two councils.

Avoid, Retreat/relocate

The appointment of Isthmus, a high-calibre team to support this work within the Westport community is a big milestone, along with gaining the support of the various Crown partners who will assist the local community as it responds to the challenges and opportunities the district faces.

Other areas of progress

Accommodate

The wave buoy to be located a short distance offshore from Westport has been purchased. This will measure wave size, wave period and other important parameters. It will give real-time online data that will be invaluable for commercial shipping, recreational boaties and scientists alike.

We are meeting with NIWA shortly to facilitate the real-time operation of the flood-forecasting model for the Buller River. This work is progressing well.

Avoid, Retreat/relocate

It is interesting to note that it has been a long time since the greater Westport area has had the opportunity and the funding available to carry out a detailed, holistic plan for adaptation and growth. A Master Plan looks to ensure that the community, public and private sectors have a road map for the future – one that looks to spatial planning but importantly also considers the key well beings for the community (economic, social, cultural, and environmental). Planning exercises of this type are intergenerational and ensure that the whole community can plan for the future, together.

 

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