Significant trunk main replacement project nears completion

The majority of the project to replace the trunk main from the water reservoir to Westport has been completed this week. 

The goal of the project is to bring a safe and reliable supply of drinking water to Westport and Carters Beach. The trunk main is the pipeline that makes that happen.  

As part of the project, new polyethylene (PE) pipe is replacing Westport’s 100-year-old 14” steel pipes. The new PE pipe that is thick and virtually indestructible. It is welded together in sections. 

The replacement project was divided into three stages, with the first two stages complete. 

• the terrace section pipeline (downhill from the treated water reservoir) – this was completed in late 2022. 

• the flat section to Westport (to McKenna Road) – completed September 2023*. 
• a final section from McKenna Road to Queen Street in Westport is in the planning stages and will be considered by Council as part of the 2024-34 Long Term Plan (LTP) investment. 

*The work also incorporates a Pressure Reduction Valve (PRV) assembly for improved network pressure management helping to further reduce network losses. 

Prior to this pipeline replacement work, the existing supply lines were losing around 40% of the water being carried down the terrace and to Westport through leaks. 

Manager Infrastructure Delivery Eric de Boer says: “We have already seen good results in terms of water savings. Before the switchover, Westport’s median daily water usage was 5,478m3. The township is now using 4,500m3. The drop in usage is most likely attributable to a reduction in water loss/leakages through the system due to the new pipeline being installed. 

“This has been a major project for council. We’ve seen 700 metres of terrace pipeline completed by WestReef Services Ltd as part of the initial stage coming down the terrace, followed by the currently completed 2-kilometre section through to Scotts Bridge and onto McKenna Road. This was delivered by Hadlee & Brunton Ltd supported by Westreef Ltd. To date, almost 3 kilometres of trunk main pipe replacement is a huge undertaking for any council, especially in the challenging terrain we have sometimes faced.” 

The $4M terrace replacement phase was funded by the Department of Internal Affairs, whilst the pipeline to Kew/McKenna Road was part of Council’s $1.6M investment into Westport’s water infrastructure. 

“We are conscious that this work has sometimes resulted in low water pressure and/or complete outages in Westport and Carters Beach and we thank those communities for bearing with us. They were an unavoidable component of the work, but we appreciate they were challenging for the community.  

“We are still investigating the leaks that have occurred this week. It was unexpected as the new water line underwent pressure testing to much higher levels than it would be expected to face (1500 KPA) so it is currently unclear what is leaking at present. 

“The contractor will excavate the site today to prepare for the repairs. Leak will be repaired along with flow meter install 13/09/2023 as advertised 8am-4pm. This will result in low water pressure again,” says Mr de Boer. 

The final stage in Westport, from McKenna Road to Queen Street is subject to the Long-Term Plan 2024 – 2034 process that will seek to endorse further funding. 

See here for more information.

-ENDS- 

For further information please contact: 
Manager Infrastructure Delivery 
Eric de Boer 
eric.deboer@bdc.govt.nz