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Bridge approved to protect city's water supply

Friday 1 April, 2022

Additional budget to complete critical infrastructure to protect our city’s water supply was approved at a Council meeting yesterday.

The $515,000 is needed to complete a 24-metre bridge before winter that will allow water treatment operators to access the Bush Intake for operational maintenance.

A major landslide above the Te Arai River is only 1km above the water treatment plant at Waingake and our major water pipeline, this bridge ensures it remains accessible.

The land began to slip on 28 September 2021 and continued to move in October, November and again last week after the most recent heavy rain event.

Significant changes include a small lake that has gone, trees that were holding back one of the banks by the river also gone and an unstable bank on the other side.

Council’s principal scientist Dr Murry Cave says the landslide is expected to keep moving so a bridge is the only option.

The bridge can take a max load of 20 tonne. It will be placed where it can offer added protection to the water pipeline if the landslide got worse.

However, Dr Cave says he does not anticipate the landslide getting as far as the pipeline.

Chief executive Nedine Thatcher Swann says as our region encounters more of these adverse weather events there is likely to be more damage to our assets.

“This means we must act now while also think long-term to mitigate issues around these events and how to protect our assets.”

Longer-term access for heavy vehicles is critical for any repairs on the pipeline that supplies most of the Gisborne City’s water from its dams and gravity intakes,” she says.

Engineering advice was obtained and based on that advice, an estimate of $490,000 was established based on the construction of the bridge along with associated works, bridge access construction, ancillary monitoring, consenting, and engineering costs.

It is expected costs may be greater because of the present material supply uncertainties therefore a contingency of five per cent was added to bring the budget to $515,000.

Te Arai landslide