Western Hills Sewer Main Rehabilitation
On behalf of Hutt City Council and Upper Hutt City Council, we are working on a project to rehabilitate the wastewater pipeline on State Highway 2 crossing north of Melling to strengthen the resilience of the network.
If you have any questions about this work, please contact:
Wellington Water, 04 912 4400
Latest Updates
Planning is underway to prepare for the works to commence in the second quarter of 2025.
The project team are making great progress with the design phase.
The project is in its design phase. We also have a live operational contingency plan in place to mitigate any risks should the pipe fail in the interim.
In November 2023, Wellington Water recommended to Hutt City Council that a condition assessment of the wastewater pipeline on State Highway 2 (SH2) crossing North of Melling be carried out.
When we became aware that Riverlink Alliance was going to be in the area and excavating the road, we recommended that the pipe assessment was conducted in conjunction with the Riverlink Alliance work.
Following this, the poor condition of the wastewater pipe was uncovered as part of the RiverLink project mid-March 2024. The pipe’s poor condition was later confirmed following a comprehensive investigation.
In response, Wellington Water’s Urgent Capital Works team been deployed for further investigations to fully understand and assess any immediate risk to the wastewater network and the potential environmental and transportation impacts.
An emergency response plan is being developed. At this stage, there is no imminent risk of failure, but it is important to ensure processes are in place should an emergency occur.
Frequently Asked Questions
What’s the scope for this project?
At this stage, the scope of this project is for the urgent renewal of a 590m wastewater pipeline which is jointly owned by Hutt City Council and Upper Hutt City Council that is in poor condition.
This is the main pipeline serving approximately 50,000 people including Western Hills in Lower Hutt and Upper Hutt.
- Primary objective: Providing reliable services to customers.
- Secondary goal: Minimising public health risks associated with wastewater and stormwater.
What will the impact be if the pipe critically fails?
There are no indications of imminent failure with the pipe and we’re regularly monitoring its condition.
- In the short term, we have a contingency plan in place to ensure we’re keeping the disruptions to a minimum if a pipe failure occurs prior to the repair.
- And in the longer term, we have a preferred option to rehabilitate the pipeline that will minimise transportation disruption on SH2.
If a pipe failure occurs before the repair, there may be some environmental and transportational impacts depending on the failure and the effectiveness of our operational response.
We’ll be working closely with Hutt City Council, Upper Hutt City Council, Greater Wellington Regional Council and NZTA to determine the best approach. We will communicate with the public to ensure they are aware of the approach, timelines, and any impacts of the work.
What's the likely cost for this work?
We have funding for the initial investigations and options assessment which is now underway. Further funding for the next phases of works will be informed by the initial assessment and worked through with our council owners in due course.
What's the timeframe for getting this renewal project completed?
The project is currently in the design phase, and we expect to carry out the rehabilitation work in 2025.
Does this point to a bigger problem with the wastewater network?
This finding further highlights the ageing infrastructure in the Wellington region and the importance of our existing programme of work for condition assessment our council owners fund us to do which support the prioritisation of pipe repairs and renewals throughout the region.
In this case, the condition assessment has identified that the pipe is in worse condition than anticipated, so has enabled repairs to be developed prior to the assets failing.
All Updates
Planning is underway to prepare for the works to commence in the second quarter of 2025. We're also working hard to ensure the potential impacts on SH2 are minimal.
The condition of the two upstream lengths of pipe has been confirmed as poor (condition grade 4). Corrosion is significant so they will be included in the works. The completed options report has confirmed CIPP as the option. Tenders were issued for the works last week and closed on 8 November.
The project team are making great progress with the design phase.
We’ve identified CIPP (Cast-in-place pipe) pipelining to be the most viable option to remediate the wastewater pipeline. Our contractors are now working through finalising the concept design and developing a budget estimate. We have a live operational contingency plan in place
We’ll keep you updated as this work progresses.