The final stage of the major flood protection works on the Wainui Te Whara Stream in Whakatāne is set to start early in November.

The work will see the stream channel through the urban area widened and deepened, increasing its flood flow capacity by at least 60 percent to an estimated 32 cubic metres per second. This will provide sufficient channel capacity to cope with a one-in-100-year rainfall event, based on current rainfall statistics.

 Whakatāne District Council Capital Projects Manager Jim Finlay says the first stage of the project involved work in the stream's upper catchment, installation of enlarged culverts at the King and Douglas Street stream-crossings, the replacement of five private bridges and the installation of 140-metres of channel retaining walls. "The scale of the excavations involved in stage two will be substantial, with an estimated 1600 truckloads – or 12,500 cubic metres – of material removed from the stream banks and bed," Mr Finlay adds.

Mayor Tony Bonne says that when completed, at a total cost of $3.9 million, the Wainui Te Whara work programme will greatly reduce the likelihood that the stream will overtop its banks during extreme weather events.

"We anticipate that stage two will take in the order of six months to complete, which should see the work finished before the worst of the autumn and winter weather sets in next year," he says. "It has taken longer than we would have liked to get this stage underway, due to the geotechnical complexity of the channel works, but this will give nearby residents much greater protection from future flood events.

"This a key element of our stormwater infrastructure, particularly in light of the predicted impacts of climate change on our weather patterns. If those predictions are borne-out in increased flood flow rates in the stream, future Councils will need to consider further channel works in the upper section of the catchment."

Resource consents for the channel work were issued by the Bay of Plenty Regional Council and Whakatāne District Council earlier this month. The contract for the work has been awarded to Waiotahi Contractors.

Residents in each work zone will be advised well ahead of excavations beginning and will have an opportunity to seek further information or express any concerns.