The Paeroa flood control gates across State Highway 26 at the town’s Criterion Bridge. Photo / Waikato Regional Council
The Paeroa flood control gates across State Highway 26 at the town’s Criterion Bridge. Photo / Waikato Regional Council
While Paeroa’s community slept during the height of Cyclone Gabrielle, a small team was beavering away to dam the Ohinemuri River by putting the town’s floodgates to use - for the first time in five years.
The blue flood control gates across State Highway 26 at Paeroa’s Criterion Bridge, spanning 22 metres and weighing 5500 kilograms each, were installed in 2018.
In the very early hours of Tuesday, February 14, a river level recorder upstream triggered the alarm that high water was on its way, so Waikato Regional Council’s Hauraki operational staff closed the floodgates, which create a seal against encroaching floodwater.
Works supervisor Hayden McGregor says he has never experienced a weather event like that night.
Works supervisor Hayden McGregor. Photo / Waikato Regional Council
“It was absolutely wild out there ... I have no other words for it, it was just crazy,” McGregor says.
“We knew the river was going to spill, and it went really quickly. We were on-site in shifts from before the gate closure right until the river was down enough at 8pm the next day to open the gates, clean up the remaining water and mud; huge day, huge hours, huge effort.”
He says the river went up very quickly.
“The river came up far quicker than what was expected... It’s a huge pressure situation. I’m really proud of the level of preparedness of the crew and how smoothly it went, and the monitoring of the incoming storm, which allowed us to be ahead of the punch with closing the gates,” McGregor says.
“Once closed, the water kept rising... to peak at 400 millimetres below the top of the gates.”
The stop logs in Paeroa. Photo / Waikato Regional Council
On the other side of the bridge, wooden stop logs were erected to close the stopbank.
McGregor says: “A lot of people were standing on the other side of the river looking across and [saw] the river being contained; it really showed how awesome the gates were.”
Before the floodgates were installed, the town relied on stop logs which had to be pieced together like a jigsaw by operational staff. The regional council says with the stop logs, it was always touch-and-go as to whether they’d be erected in time before the river came through.
Meanwhile, the cyclone also put Paeroa’s recently upgraded Mill Road pump stations to the test.
Flooding in Paeroa after Cyclone Gabrielle - on the left side of the photo, the floodgates and stop logs can be seen.
McGregor says the “smartification” of the pumps was “worth its weight in gold”.
“The pumps can be controlled by a mobile phone, and slowed down, rather than needing to be started and stopped all the time.
“We [even] had farmers with an interest in the pump stations... The difference between the land riverside and land-side [was significant]. On the land side, you wouldn’t even know there had been rain, as it looked so dry.”
