Buller District Council

Media Release – Westport Water Terrace Section Trunk Main Going Ahead

14th April, 2020

Council has selected WestReef Services Limited to complete the 700m Terrace Section Trunk Main pipe replacement for Westport’s water supply.

The $1M ‘design & build’ project is the continuation of a significant asset renewal program initiated by Council for the aging and problematic pipeline infrastructure.

The Terrace Section is the first part of a 5km treated water Trunk Main that is long overdue for capital investment. The supply currently experiences major leaks and service disruptions due to the poor asset condition and maintenance challenges.

Originally constructed over 100 years ago, the system conveys gravity‐flow water from the treatment plant on the terrace above Sergeants Hill into Westport where it connects with the town’s reticulation.

Group Manager Infrastructure Services, Mike Duff says, “Council promised to ‘fix the water’ and awarding this contract is another significant step forward. Renewal programs are essential for maintaining good asset condition and service levels for our community.”

“Continued investment ensures that we aren’t creating a backlog problem for future generations to deal with, especially something as essential as drinking water.”

On the untreated side, Council has recently completed the $7M, 2.5km Tunnel Pipeline project from Giles Creek to the reservoir ponds, and the $300k raw water feed from the reservoir ponds to the treatment plant.

These projects were important to guarantee adequate and reliable supply and reserves. Following treatment, the Trunk Main is then the critical lifeline that delivers safe drinking water into town.

The Terrace Section will be new SDR11 450mm diameter PE100 pipe. The pipeline will negotiate the 100m elevation drop from the top of the terrace down the steep escarpment to the river flats below.

The design requires careful consideration to hydraulics (water flow and pressure), slope stability and vertical profile to ensure a fully engineered solution.

The new PE pipe will then connect to the existing 8” cast iron and 14” steel pipes for the remaining journey to Westport. Future Council projects will progressively replace these old, leaking lines with new PE pipe to complete the entire Trunk Main system over time.

WestReef were confirmed as the successful tenderer following a detailed evaluation process and due diligence of critical issues and risks. This included geotechnical assessment and impact of Covid‐ 19 in terms of revised construction methodologies and supply chain logistics.

Through their tender responses, WestReef were able to demonstrate a clear understanding of the scope, site conditions and resilience factors required for a 100‐year asset life.

Council resolved at its February meeting to proceed with the work, and has already factored project costs into its draft annual plan budgets. Hence, there is no additional impact to ratepayers.

The overall project duration is estimated at 6 months and will commence after the current lockdown is lifted, and as soon as the national alert levels allow.

“Once it is safe to do so, we will pick up where we left off and ensure the long term planning for core infrastructure continues to be ‘fit for future’. We are very confident that WestReef are the right choice for this important project and they will deliver it successfully for our community”.


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