A new bridge designed to prevent flooding in Moerewa and Ōtiria has taken a big step forward with the first of 15 25-tonne beams craned into place.

The Ōtiria and Moerewa flood scheme has reached a significant milestone with the successful placement of bridge beams on the new 60-metre span bridge.

The Pokapu Rd bridge, which is a central component of the flood mitigation project, is poised to better protect the communities of Ōtiria and Moerewa from the adverse effects of flooding.

Moerewa and Ōtiria have been repeatedly affected by floods in recent years, with the townships inundated with floodwaters that have washed through homes and even Ōtiria Marae.

Stage one of the Northland Regional Council’s Ōtiria-Moerewa flood mitigation spillway project, the construction of an 80m-long downstream section of spillway, was completed last year.

The present stage involves building a 60m bridge at Pokapu Rd to replace the 20m bridge blamed for diverting floodwaters from Ōtiria Stream and Waiharakeke River into the two townships. Stage three involves excavating another 800m of spillway upstream from the bridge.

Construction of the bridge – under way on whānau land with the blessing of its shareholders – began in January after a dawn blessing ceremony late last year.

Northland Regional Councillor Geoff Crawford said an important turning point in the project was craning the first of the 15 sturdy beams, weighing around 25 tonnes each, into place.

Crawford, who chairs the area’s Taumarere Flood Mitigation Working Group, said the beams, meticulously positioned with a 10-millimetre tolerance between each one, form an integral part of the new bridge. Traversing three spans, the beams have been arranged in five rows, showcasing the emerging structure to the community.

He said the overarching aim of this project is to restore the Ōtiria Stream to its natural flow, which was impeded decades ago by the construction of Ngapipito and Pokapu Rds and Ōtiria’s railroad embankment.

The unique geographical characteristics of the area, with ancient lava flows beneath Ōtiria and Waiharakeke, have presented an unusual scenario. In a one-in-100-year flood, approximately 70 per cent of the Ōtiria Stream’s flow and 80 per cent of the Waiharakeke River’s flow would traverse the associated floodplain, unlike the usual scenario where most of a river’s floodwaters would be contained within its banks.

‘’The Waiharakeke River falls off the lava flow at Pokapu Rd into a series of waterfalls and over the years has carved out a massive canyon increasing the cross-sectional area from just 36 square metres at Pokapu Rd to more than 600 square metres at Ōtiria Marae.”

‘’The successful placement of the bridge beams signifies a remarkable step forward in the Ōtiria and Moerewa flood scheme. The emerging bridge structure serves as a testament to the collaborative efforts of various stakeholders and provides the community with a tangible glimpse of what the new bridge will look like,’’ Crawford said.

Stage two, due for completion before Christmas, will effectively triple the flow of floodwaters that can pass beneath it. The works mean that in a flood, most water will be sent down the new spillway and into the Waiharakeke River past the lava flow, where the river is considerably wider and deeper.

While floods will still occur, parts of the area subjected to potentially damaging and life-threatening half-metre deep floodwaters should get just ankle-height water instead.