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Flood protection – Hutt Central from just north of Ewen Bridge to Kennedy-Good Bridge

http://www.gw.govt.nz/protect-the-hutt-cbd-from-flooding

Flood protection – Hutt Central from just north of Ewen Bridge to Kennedy-Good Bridge

Updated 3 November 2016 1:57pm

Hutt CBD flood protection project enters new stage

The Hutt Valley community spoke loudly and clearly last year that it favours Option A flood protection in which we will move to building 1 in 400 year protection in one step within five years, a verdict that was agreed to by the Hutt Valley Flood Management Subcommittee and the GWRC late last year:

The focus of preliminary design now, therefore, is Option A – One Step where we provide 1 in 440 year return period flood protection that includes an allowance for climate change (by enlarging and moving stopbanks further west into Pharazyn and Marsden streets, which will require purchase and removal of property on those streets). Going straight to this option would cost about $143 million, including property purchase.

 

 

Over the next 18 months GWRC will work with Hutt City Council, NZ Transport Agency and a range of consultants to plan and design the project, culminating in a Preliminary Design Report to be published in August 2017 ahead of applications for resource consents in 2018.

The report will provide full details of the key phases of the project: costings, river channel design works, stopbanks design, transport linkages, urban and landscape design and civil works. Each of these areas will be covered in a separate plan and brought together in the final report.

The details of each key phase are as follows:

 

Design phase

What does this cover?

Release date

River channel design works

Charts the exact shape of the river channel between Kennedy Good Bridge to Ewen Bridge

Designs river edge protection

Sources construction materials

Feb 17

Stopbank design

Decides exact location (“footprint”)

Develops stopbank profiles for community viewing

Works out relocation of services and utilities (power lines etc)

Feb 17

Urban works and landscaping

Reviews the river corridor’s environment

Decides on matters such as environment and amenities (planting, recreation options etc)

Mar 17

Civil works

Identifies treatment of Daly St

Considers links with stopbanks

Decides cycle/way pedestrian bridge options

Reviews Melling Bridge options

Mar17

Transport design

Discovers impact of project on local transport network

Works out improvements to Daly St

Develops options for impact on Pharazyn St

Plan car parking

Reviews the layout of Melling Station and adjacent parking and bridge access

Mar 17

Melling intersection

Completes the first stage of the NZ Transport Agency business case to concept design stage.

June 17

Final Preliminary Design Report

Presents all phases

Aug 17

Construction begins   2018/2019

Community engagement on preliminary designs

In Stage One of the project we engaged with the community to explain the flood protection issue, outline flood protection options and identify its preferred approach. In Stage Two we will gather feedback on our approach to the detailed design of Option A. We’ll seek you’re your views on different elements of the design as they are produced, and on the full Preliminary Design in August 2017. We’ll also issue progress updates as we go.

Once the design is finalised and agreed by the Hutt Valley Flood Management Subcommittee and the full GWRC in 2018 it will be submitted for resource consents. The public will then have a formal opportunity to comment on the designs.

Lower Hutt CBD’s riverside city

One of the key elements of Option A is the ways its riverside promenade design will help link the CBD to the river and provide great opportunities for commercial, recreational and residential development. Precisely on how this will come together won’t be available until March 2017, even then making the plan a success will depend on the willingness of entrepreneurs and developers to get involved once the infrastructure is developed along the stopbanks and in the linking streets.

For more information on Hutt City Council’s approach to breathing more life into its CBD, click here.

Transport plans begin to take shape

The New Zealand Transport Agency’s review of the Melling intersection and bridge, both of which are integral to the flood protection and transport flow elements of the project, will begin in July 2016 with the development of an indicative business case. This will be completed by July next year. Detailed planning will then go ahead on final designs, which will take a further year to complete.

Property purchase programme

One of the consequences of the moving to Option A is that the stopbanks on the Hutt River’s western side will need to be heightened and pushed out into Melling, requiring some property to make way.

One hundred and seventeen properties will be affected on Marsden St and Pharazyn St. All owners and residents are aware of this and we have been involved in discussions with owners about their circumstances.

Also two properties on the eastern side of the river upstream of the Melling Bridge will need to be acquired to enable us to link the recently upgraded stopbank near the Boulcott Golf course to the Melling Bridge ans we have been in discussion with owners there, too.

We recently issued a property strategy which outlines the approach we will take to acquiring annd managing properties throughout the project and rfeinforces our primary goal of treating proprty owners fairly and with respect.

Given that we are years away from beginning construction there is no need for owners to make quick decisions on the sale of their property. We will continue to keep them fully informed of all matters that affect them. If there is a genuine need to sell soon we will be happy to negotiate with them.

About the chosen option

Based on a thorough analysis of 10 options, the followi9ng option was favoured by the community after extensive public consultation:

Option A – One Step where we provide 1 in 440 year return period flood protection that includes an allowance for climate change (by enlarging and moving stopbanks further west into Pharazyn and Marsden streets, which will require purchase and removal of property on those streets)

Going straight to this option would cost about $143 million, including property purchase.

Flooding on the Hutt River – a constant threat

Since settlement began, the Hutt River has had a history of floods which have caused emotional and financial damage to the people and businesses of the Hutt Valley.

Consistent flooding has occurred since recording began in 1855 and, with the onset of climate change and the likelihood of more volatile weather, it's sure to continue into the future.

The current stopbanks are mostly high enough to contain a 1-in-100 year flood but in some sections they are too weak to do so.

The Hutt Valley Floodplain Management Plan was agreed with the Hutt community in 2001 and aims to minimise the flood risk by progressively strengthening flood protection throughout the valley.

GWRC is continuing to follow the plan and is now collaborating with HCC on measures to better protect the Lower Hutt CBD and its surrounding neighbourhoods from flooding and better link the CBD to the Hutt River.

The New Zealand Transport Agency is also involved in the project and investigations are under way into the replacement of Melling Bridge and a new intersection serving the bridge and SH2.

Flood protection options

Option B – Two Steps where we take a staged approach (by building flood protection within the existing corridor to a slightly lower standard) which would initially require no property purchases then, in around 20 years, move to the higher Option A flood protection standards for completion in around 30 years to allow for increased river flows driven by climate change.

Going with this option would cost about $114 million but would increase by an additional $68 million to a total cost of $182 million.