Drainage work costing up to $200,000 will be carried out on Manawahe Road in the Bay of Plenty to help protect the area against flooding.

Whakatāne District Council’s infrastructure and planning committee approved funding for the resilience work at a recent meeting.

Extremely high rainfall in 2022 and 2023 caused sustained flooding of surrounding properties and closure of the road from May 12 until June 12 in 2023.

Two homes on the road became uninhabitable, and the owners received total loss insurance settlements. More than six hectares of land between 1757 and 1849 Manawahe Road was affected for several months as the flooded area is a ponding basin with no natural drainage outlet.

The committee adopted the cheapest of several options provided by consultants to relieve future flooding of the road.

This option involves installing a culvert across the road connected to a manhole into which suction hoses can be fed, combined with legal agreements with affected landowners to discharge pumped water onto their land when required.

Other options had costs of between $1 million and $2 million.

A report to the committee described the rainfall levels to have an annual exceedance probability of 2.2 per cent - or a recurrence level of once every 46 years.

In another report, the committee heard that repairs to damaged roads caused by storms across the Whakatāne district in 2022 and 2023 had cost more than $1.4 million.

New Zealand Transport Agency Waka Kotahi will cover a large part of that cost, leaving just over $450,000 needing to be retrospectively approved from the council’s roading storm reserves.

Work on the culvert replacement and under slip on Braemar Road and one of two under slips on Stanley Road continues, while work has finished on other under slips across the district, including the second section of Stanley Road, another on Galatea Road and two on Herepuru Road.

A truck makes its way through flood waters on Manawahe Road in May last year.

Transport manager Ann-Elise Reynolds says while the repair work will leave a small deficit in the roading storm reserves, as it was close to the end of the financial year, it’s due to be replenished. It shows the amount allocated to the reserve fund is “about the right amount”.

Rangitaiki ward councillor Gavin Dennis questioned if whether anything could’ve been done to prevent the culvert damage on Braemar Road in May last year if the council had responded more quickly to residents’ reports that it was blocked.

“I was approached by a number of people concerned that they had warned us a month beforehand that the culvert was blocking up and that they notified council a couple of times. In their words, they were ‘ignored and as a result of that there was a massive blow-out'.”

Ann-Elise says in May last year, the council had to attend several events due to the high rainfall, including under slips on Herepuru Road, and staff responded to calls as quickly as possible.

“When resources are stretched that’s not always as quickly as some people may like. At the time that the under slip occurred, we had been onsite for about three days trying to unblock that culvert. It appears that culvert had some damage inside it, so water tried to get around it and that is what caused the slip.”

LDR is local body journalism co-funded by RNZ and NZ On Air.