Pinehaven Stream Improvements
On behalf of Greater Wellington and Upper Hutt City Council we are undertaking a phased programme of works to upgrade and increase the capacity of the Pinehaven Stream to reduce flood risk to the surrounding area.
If you have any questions about this work, please contact:
Wellington Water, 04 912 4400
Latest Updates
Work is now underway to construct a new timber boardwalk through the reserve.
Our programme of work to reduce flooding stood up to the test of recent deluges, protecting homes at a time of widespread flooding in the Wellington region.
Stage 2 works are in the process of being completed.
Current Status
Phase 1 works were completed in October 2023.
Phase 2 stream improvements commenced September 2023 in the Willow Park area immediately downstream of the Phase 1 works and are expected to be completed at the end of October 2024.
Greater Wellington Regional Council and Upper Hutt City Council are working to resolve issues around future works.
The goal
The project works will be focused on key flooding areas around Blue Mountains Road, Sunbrae Drive, Whitemans Road, Pinehaven Road, Birch Grove, Pinehaven Reserve, Upper Hutt.
By making the stream wider and deeper, the goal is to provide capacity in the stream for a 1 in 25-year return period flood event.
Background
Pinehaven has a long history of regular flooding events, with 1976 being the largest; Whitemans Road bore the brunt of the floodwaters.
The following year, GWRC and UHCC agreed to jointly administer the Pinehaven Stream with the Watercourses Agreement. However, it became apparent that the flooding issues were closely integrated with the piped stormwater reticulation system. The catchment is also quite contained in nature, within a built environment.
GWRC expressed a desire to transfer responsibility for the Pinehaven Stream to UHCC. The trouble was that the District Plan objectives, policies and rules did not recognise the identified Flood Hazard Extent and associated risk to development for either the Mangaroa River or the Pinehaven Stream. Quite clearly, there was a need to sort out structures that were impeding the flow of water during heavy rain events and improve the capacity of the Pinehaven Stream.
In 2012, GWRC and UHCC worked towards this with Plan Change 15 – Mangaroa River Flood Hazard Assessment. But, there was some discomfort with the flooding modelling results and Plan Change 15 expired over an extended review period. Next, with the Pinehaven Floodplain Management Plan (PFMP) in hand, both councils committed to Plan Change 42 and splitting the Pinehaven Stream Structural Improvements project cost 50/50.
On 27 March 2018, the Upper Hutt City Council (UHCC) unanimously approved Plan Change 42 (PC42). This moment was the culmination of decades of work by Greater Wellington Regional Council (GWRC) and UHCC to address the vexing issue of flood management for Pinehaven community. Two appeals were then lodged with the Environment Court; one relating to matters not affecting the project and the second by Save Our Hills – appealing the entirety of PC42. Experts’ conferencing was completed on 8 April and 9 April 2019. At the May mediation session, Save Our Hills advised that they had withdrawn their appeal. Other parties who joined the appeal continue to work with GWRC.
Phase 2
Phase 2 stream improvements, funded for $5 million, commenced in September 2023 in the Willow Park area immediately downstream of the Phase 1 works and include:
- Widening the section of stream through Willow Park from Sunbrae Drive to Blue Mountains Road.
- Building new retaining walls immediately downstream of the Sunbrae culvert.
- Widening the stream banks (without retaining walls) further downstream, where there is more space available.
- Removing the existing pedestrian bridge over Pinehaven Stream at Willow Park and replacing it with a new pedestrian and cycle bridge linking to 4 Sunbrae Drive.
- Improving the pedestrian path through Willow Park.
- New and replacement planting of native trees and plants.
Managing flood risk in the community
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| 915 metres of channel | 5 domestic bridges, 2 road culverts | 860 metres of retaining wall | Reinstatement of landscaping in approximately 41 private properties |
There will be significant improvements in flood protection for over 50 vulnerable properties and improvements for 179 properties affected by secondary stormwater flow paths. To achieve this, the open channel will need to be widened and deepened, there will be some roading changes, new retaining structures, new residential access bridges and quite a lot of reinstatement of private property.
There will be less vegetative debris in the stream after the project
Plan Change 42:
Addresses-the risk from flooding within the Mangaroa and Pinehaven stream catchments for the 1:100 year flood event. The proposed provisions seek to avoid development in the high hazard area and avoid and mitigate the risk of flooding in the lower hazard areas. A range of structural and non-structural measures are to be put in place, to reduce flood risk to the community.
Complements- the physical stream improvements works by seeking to reduce stormwater generation and the exposure of third parties to flood risk. It also includes some elements that enable the stream improvement works to be carried out.
Introduces- new objectives, policies, rules and other methods to address flooding risks associated with the Pinehaven Stream and Mangaroa River catchments. These new tools provide for certain developments and activities to be avoided with specified (high-risk) areas, and require mitigation and avoidance within other (lower risk) specified areas.
All Updates
Our team started work on the new timber boardwalk through the reserve on Monday, 9 September with some successful test piles. They will now continue to install piles over the next few weeks. We expect piling to be completed by 20 September.
There will be some noise from this during work hours between 8am and 5pm weekdays. It will be monitored to ensure it remains within permitted and acceptable ranges.
Meanwhile we are continuing to monitor the ecology in the area, mindful not to harm the geese and ducks that have stated moving back into the reserve.
Once piling is completed, over the next four weeks works will include constructing the timber boardwalk and concrete pathway, earthworks to place the excavated topsoil in the reserve and general landscaping.
The construction will be finished late October. But stay posted for the reserve opening date, we will confirm this once the grass is established.
On August 26, more than 75mm of rain fell within six hours (most of it between 5am and 7am).
The work we have completed so far on behalf of Upper Hutt City Council and Greater Wellington Regional Council to reduce flood risk in Pinehaven performed successfully, protecting multiple properties that would otherwise have faced significant risk of being flooded. Check out the images below.
So far we have completed Stage 1 and are in the final phases of Stage 2 works in this multi-phase programme of works.
Stage 1 as included enlarging two culverts and constructing retaining walls to taper into the existing stream. Stage 2 work has focused on making Pinehaven Stream wider and deeper in the Willow Park area – in some areas increasing from just 2m wide to 9.5m - building retaining walls and creating more capacity in Willow Park to cope with flood waters.
The goal is to provide capacity in the stream for a four percent annual exceedance probability (AEP) flood event, so property owners can expect the capacity of the stream to be five times greater than now.
Images demonstrate culverts, widened stream and retaining walls during 26 August flooding
Stage 1 and 2 works have also enhanced the area including installing a new pedestrian and cycle bridge over Pinehaven Stream at Willow Park, improving the pedestrian path through Willow Park, new and replacement planting of native trees and plants and upgrading the junction where Pinehaven Stream joins Hulls Creek to make it easier for fish and eels to travel between the two watercourses.
Meanwhile, upstream in areas where no work has been done, properties suffered.
With Stage 2 due for completion in September, Greater Wellington Regional Council and Upper Hutt City Council are working to resolve issues around future stages of the programme of works.
With Stage 2 works nearly finished, Greater Wellington Regional Council and Upper Hutt City Council are now working to resolve issues around future works.
We will provide an update once these issues have been resolved and what this means for the programme of works.
Pinehaven residents now have a new pedestrian bridge over Pinehaven Stream at Willow Park, linking to Sunbrae Drive.
The new bridge replaces the old pedestrian-only bridge as part of the wider programme of work to increase the capacity of the stream and reduce flood risk to the surrounding area.
We are also improving the pedestrian path through Willow Park and planting new native trees and plants in the area.
Here are some shots of the crew installing the bridge blessed by a rainbow.
Planning for the next phases of the work programme are now underway.
This will include a survey of the stream involving ecological, photographic and topographic surveys and general field visits. This will be carried out between March and September during normal working hours. The works will be confined within the stream banks and not beyond any property fence lines.
To enable construction to proceed safely, the 28 Blue Mountains Road was purchased. The house on this property was badly damaged in a fire, and is being demolished to make the site safe.
Laboratory tests by a licensed asbestos assessor have identified asbestos in some parts of the house. Licensed asbestos removal specialists have been involved throughout the demolition process in accordance with strict procedures, including air quality monitoring.
The soil will also be tested and if any contamination is found, the topsoil will be removed. The property will continue to be securely fenced throughout.
Some additional construction traffic will access the property during the works, and this may result in brief delays to traffic to allow vehicles to safely turn. However, this is not expected to lead to any disruption to access to driveways or detours.
Stream study surveys are being undertaken, investigating for future phases of the project - you may see people in and around the stream until these are completed.
We are making good progress on Phase 2 of the work upgrading Pinehaven Stream at Willow Park to reduce flood risk in the area.
Since staring work on Phase 2 in September last year, we built one of the two new retaining walls immediately downstream of the Sunbrae culvert and will be starting work building the second wall on the other side of the stream in February.
Retaining wall
Retaining wall and stream divider
The existing pedestrian bridge over Pinehaven Stream at Willow Park has been removed and over the next few months we will be replacing it with a new pedestrian and cycle bridge. The new bridge will link to 4 Sunbrae Drive, which will be landscaped as an extension to Willow Park.
This is all part of the wider programme of work to increase the capacity of Pinehaven Stream to accommodate the 1 in 25 year flood event and make significant improvements in flood protection to over 50 vulnerable properties and improvements for 179 properties affected by secondary stormwater flow paths.
Meanwhile, preparatory work for Phase 3,4 and 5 is underway and planning ongoing for future the phases of the programme.
We're no experts in geese, but with work now underway, we want to do the right thing to protect their welfare. That's why the GHD project team recently met with representatives from the Wellington Bird Rehabilitation Trust (WBRT) and the project contractor HEB Construction to assess the situation.
What was observed was that, at present, the geese naturally prefer the habitat available immediately downstream of the construction site. Having reviewed the site conditions, WBRT advised us that this familiar habitat could not be recreated if the geese were relocated. So, the best approach is to continue to monitor the geese where they are.
WBRT is preparing some further options if things change. Meanwhile we'll continue, with HEB, to monitor and regularly reassess the situation.
HEB is also briefing all team members working on the site as well as sub-contractors about the geese so they are aware to look out for their safety if seen approaching the construction site.
Wellington Water, on behalf of Upper Hutt City Council and Greater Wellington, is soon to start on the next stage of work upgrading Pinehaven Stream at Willow Park to reduce flood risk in the area,
Works will commence 25 August and take around 12 months to complete, with hours of work generally 7am to 5pm Monday to Saturday. No works are scheduled for public holidays.
The works include:
- Widening the section of stream through Willow Park from Sunbrae Drive to Blue Mountains Road
- Building new retaining walls immediately downstream of the Sunbrae culvert
- Widening the stream banks (without retaining walls) further downstream, where there is more space available
- Removing the existing pedestrian bridge over Pinehaven Stream at Willow Park and replacing it with a new pedestrian and cycle bridge linking to 4 Sunbrae Drive
- Improving the pedestrian path through Willow Park and new and replacement planting of native trees and shrubs.
To allow us to undertake the works safely and efficiently, Willow Park will be closed during the construction period. Accessways through Willow Park via Blue Mountains Road and the Tapestry Grove walkway will also be closed. At times temporary traffic management will be in place for large vehicle movements delivering materials to site.