Massive flood protection boost for Whangarei’s Commerce St

A newly-completed 113-metre long flood wall is expected to massively increase the level of flood protection in a key part of Whangarei’s Central Business District (CBD).

The Woods Rd flood wall is part of a wider flood reduction/mitigation programme the Northland Regional Council is rolling out under its Long-term Plan 2018-2028 and will help protect flood-prone Commerce St in particular.

Newly-elected regional councillor Jack Craw, left, and Rivers and Natural Hazards Manager Joseph Camuso, atop the Woods Rd bridge. Councillor Craw is holding a photo of floods 20 years ago in the same spot where a new flood wall has now been built.

The regional council’s Natural Hazards Manager Joseph Camuso says the flood wall took contractors Barfoote Construction about 10 weeks to complete and cost about $360,000.

“Now it’s finished, we’ve effectively given Commerce St one-in-50-year flood protection, a big improvement on the previous one-in-10-year protection,” he says. “This is the first place in the city that the Raumanga Stream overflows during a flood.”

Floodwaters typically flow down Commerce St, flooding low-lying properties before flowing back into the river before Okara Dr. Following ex-tropical Cyclone Wilma in January 2011, some cars parked along Woods Rd were inundated with floodwaters that reached as high as their rear vision mirrors.

Councillor Jack Craw, recently appointed chair of the Whangārei Urban Rivers Flood Working Group, says the works should offer protection to a ‘one in 50-year flood’ design level.

“The amount of rain that actually falls in any given year can vary tremendously and no one has any control over that, but in theory, these works should cope with the sort of rainfall you’d normally expect to occur up to once only every 50 years,” he says.

The recently completed project is a small part of the Whangarei Urban Rivers Flood Mitigation Project which started in 2009. The recent LTP targets about $1M in flood mitigation works during the next three years.

As proposed, 70 percent of that work would be funded by ratepayers Northland-wide via the council’s regional flood infrastructure rate, with the balance funded locally through a targeted river management rate.