Buller District Council

Media Release- Westport Water Fit for Future

13th April, 2018

Council will consider a further option for the future of Westport’s water supply. A new gravity-flow overland pipe will be evaluated to replace the century-old tunnel network, which has been out of service since the No.1 Tunnel collapse in December 2016.

After completing the tender due diligence, Council’s project team concluded that an overland pipe out-matched tunnel repairs in key areas including safety, resilience and residual risk. A new gravity-flow overland pipe would convey water from the current Giles Creek intake directly to the reservoir ponds and by-pass the entire tunnel network, including inter-connecting races and open drains.

Group Manager Assets & Infrastructure Mike Duff says “The existing tunnel network has served Westport well over the years, but this is a ‘Fit for Future’ initiative based on detailed analysis and risk assessment to ensure we get the right outcome for ratepayers today, and for generations to come”.

The overland pipe eliminates the ongoing risk of collapse in any of the four tunnels. It also avoids substantial tunnel renewal costs for ratepayers in the future. The water intake system could incorporate the north branch of Giles Creek to supplement the existing south branch and improve reliability and security of supply.

The hydraulics design will ensure no pumping is required. Planning assessment for resource consents including consultation with affected parties still needs to progress, but preliminary investigations were promising.

Council had previously identified overland pipe as an alternative to tunnel repairs during a selection study almost a year ago. During the tender due diligence, the project team were able to establish a feasible overland pipe solution which ranked better than tunnel repairs in criteria and scoring for all key attributes.

Mike Duff says “Moving away from tunnels has obvious risk and safety advantages. With the ever-tightening regulatory environment, compliance for working underground is getting more complex and costly. We also need to consider operations and maintenance personnel and our duty of care. Going around the ‘hill’ instead of under it just makes more sense, and once we had a way, we had a will”.

All tunnel repair tenders were subsequently rejected so that a new procurement process for overland pipe could begin. Several tendering options will be presented to the Council meeting on 17th April to decide how procurement will proceed.

Due to the faster construction time of overland pipe versus tunnel repairs, original project completion by the end of the year may still be on track and potentially within budget. This will be confirmed during the new tender process.

Mike Duff says “There is more work to do but we have absolute confidence in this result. The project processes adopted and diligence of the entire team over several months has delivered this opportunity for added value and improved outcomes for our community. In terms of safe, adequate and reliable drinking water for Westport, this new option would make good on our promise to Fix the Water”.

 

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