Buller District Council

Media Release – Leaks fixed for Westport & Carters Beach Water Supply

9th October, 2017

Significant leaks discovered in the raw water line connecting the reservoir ponds to the Westport Water Treatment Plant were temporarily fixed over the weekend.

WestReef crews battled difficult circumstances on Saturday to “bandage” two sections of concrete pipe with special purpose wrapping to stem the water loss, at least for the short term. The work took around 6 hours to finish in heavy rain and trying site conditions.

The leaks were found after exposing sections of the 80 year old concrete pipe, which is the 700 metre lifeline between the reservoir ponds and the treatment plant. The pipe has deteriorated over time and is extremely fragile in sections. Additional leaks were detected on Saturday, and more temporary pipe wrapping is planned this week to arrest those breaches. Initial estimates of water leakage exceed 2,000m3 per day. Inspections yesterday confirmed the fixes were holding up after the first 24 hour period.

Council Group Manager, Mike Duff says, “Although this pipe is mostly buried and out of sight, suspicions grew when our reservoir levels plateaued at 80%, compared to steady growth over the previous weeks. We knew that the treated water leaving the plant averaged 5,000m3 per day, and we were supplying up to 9,000m3 raw water to the ponds, yet we weren’t seeing the gain in levels. It just wasn’t adding up, and so the culprit pretty much revealed itself.”

“Hats off to Dylan Taylor, Luke Hateley and the entire WestReef team, including their subcontractors who all played a key role in identifying the target areas and getting the job done so safely and quickly. Assuming the temporary fixes hold, we will be saving more of the precious water being pumped to the ponds, and will therefore see upward trend in our levels again.”

“Obviously our goal is to reach and maintain the conservation level for all consumers, and to stay well away from the danger zone (50%). We want to get up to 100% before the traditional dry period early next year.” says Mr Duff.

A failure of the existing concrete pipe could leave Westport without water in less than 24 hours – as soon as the 3,700m3 treated-side storage tank ran out. This latent risk has always been present, since the system design does not include any redundancy for raw water supply to the treatment plant.

An emergency works proposal will be submitted to Council this week seeking urgent approval to install a new polyethylene (PE) raw water pipe, which may take several weeks and hundreds of thousands of dollars to complete. A decision can then be made about the old concrete pipe in terms of its potential to remain as a contingency line, or whether a new back-up will also be required. This decision will be based on a full risk assessment.

“The entire Westport water supply is a massive exercise of risk management across many fronts simultaneously. The first challenge of pumping water during heavy rain is now resolved, with Ballarat Creek and other sources recently coming online. This new raw water pipe is now essential, given the likelihood and consequence of the concrete pipe failure. We also have our ongoing risk reduction strategies including water storage tanks and town bore supply in case the worst ever happens.”

“Then we’ve got the water tunnel reinstatement work, with local mining specialists developing a low-risk repair methodology with early WorkSafe engagement. And then the alternatives for Westport’s long term supply being assessed in the Selection Study due out in a few months. It’s all happening, and we’re throwing everything into it to minimise risk for our community.” says Mr Duff.

Council will monitor and report reservoir capacity on a daily basis and use this information to forecast trends in relation to potential status changes. Today’s level of 87% is a spike increase of 7% from Friday, and is directly attributable to the leaks fixed over the weekend.

Photo 1: Lateral crack in raw water concrete pipe

 

Photo 2: WestReef crew wrapping the leak

 

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