Last Modified: 27 June 2012
Planning
Pinehaven Stream Study
Floodplain Management Investigations
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In conjunction with Greater Wellington Regional Council (GWRC), Upper
Hutt City Council (UHCC) has commissioned a three stage study into the
management of the Pinehaven Stream Floodplain. Stages 1 and 2 of the
study have been completed and we are about to commence stage 3.
In brief, stages 1 and 2 collected data allowing us to model the
catchment for various flood scenarios e.g. 10 year, 25 year, 100 year
including climate change and basic costing to achieve flood protection
for 10 and 25 year protection. The 25 year protection cost has been
included in the councils long term plan (LTP) being released for public
consultation. Stage 3 will refine the protection options which after
consultation with affected residents will determine the preferred
option.
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The consultation will cover such things as access, construction
impact on property etc. Currently the LTP allows for construction over a
10 year period commencing 2015/16 but this is subject to consultation
with residents on the options as noted above.
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| Scroll down or click on a link below for more information |
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Latest developments
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Update as at 26 June 2012
Click here to download this update in pdf format (79Kb)
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- Options have now been prepared for flood mitigation which will be presented to Council on Wednesday 27 June.
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- Following the presentation to Council an open workshop for residents in
the area will be held. There is a tentative date of 9 July but this will
be confirmed within the near future.
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- Following this workshop the Officer Steering Group will meet and agree a preferred option.
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- The preferred option will be presented to the community.
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- The preferred option will be developed in detail.
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- Implementation funding has
been allowed within the Upper Hutt City Council and Greater Wellington
Regional Council LTPs commencing 2015.
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Phase 1 and 2 Conclusions:
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Phase 1 investigations found that
much of the Pinehaven Stream channel has less than a five year flow
capacity. The numerous bridges and culverts further constrain the
stream and are significant contributors to flooding.
Furthermore there
is a high potential for blockages in the narrow vegetated stream channel
or the intakes of culverts or bridges. Analysis of both hydraulic
modelling and flooding history identified the areas of highest flood
risk in the Pinehaven catchment are Birch Grove, Blue Mountains Road,
Sunbrae Drive and the properties downstream of the piped sections of the
Pinehaven Stream under Whiteman’s Road.
Phase 2 investigations sought to identify the available flood mitigation
options for the Pinehaven Stream catchment. This resulted in the
consolidation of four flood mitigation philosophies for the Pinehaven
catchment, along with potential upgrades that would be required in to
implement each of the four philosophies. The four philosophies are:
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An integrated long-term upgrade option to meet the UHCC target level of service for streams.
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An integrated upgrade option to provide a minimum 10 year channel
capacity, including the predicted mid-range impacts of climate change.
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A ‘do minimum’ option that focusses on preventing blockages and introducing planning controls.
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The implementation of source control in the catchment.
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Phase 3 Investigations:
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The third phase of investigations committed to by
GWRC and UHCC will result in an agreed action plan to manage the risks
of flooding from the Pinehaven Stream. Success for this phase will be
the endorsement of this action plan by the community and by the two
council partners. To achieve this will require robust technical
analysis of the range of options including their costs, benefits and
risks and a comprehensive consultation strategy.
A methodology
for Phase 3 has been agreed by GWRC and UHCC. The methodology builds on
the four flood mitigation philosophies and includes:
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- Refinement of upgrades required to implement each of the four flood mitigation philosophies
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- Development of an evaluation criteria and assessment tool
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- Analysis of risks, flood damages and impacts of upgrades on stormwater networks connecting into the stream
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- A comparison of philosophies
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- Consultation with the Pinehaven community
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