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  1. Ā mātou mahi I What we're doing »
  2. New fish-friendly pumps of megalodon proportions

The fish-friendly Archimedes screw pumps are each about the size of the pre-historic megalodon shark.

Waikato Regional Council’s latest fish-friendly Archimedes screw pumps for the Churchill East drainage area, Hampton Downs, are each about the size of the pre-historic megalodon shark.

The two new pumps, each measuring 18 metres in length and 3 metres in diameter, are over six times the size of the one installed in the Aka Aka drainage area near Waiuku in late 2021, which then project manager Richard Dodera had laughed could pass a small shark.

"These pumps are next level," says project manager Stephen Wilson.

"They’re twice the diameter and almost twice as long as the Mangawhero pump in Aka Aka so that means they’re around six times the size."

Image of the screw inside the pump

Each pump is three metres in diameter.

"I wouldn’t go so far to say they could pass a large shark, but they themselves are of megalodon proportions. They were certainly too big to put into a shipping container and required some special attention to get them here."

The pumps are currently being shipped to New Zealand after being built in the Netherlands by FishFlow Innovations, a worldwide leader in fish-friendly pumps and fish protection solutions.

The FishFlow Archimedes screw pump put in at Aka Aka was the first of its kind in New Zealand, although other regional councils have since replaced older pumps with FishFlow screw pumps.

To allow fish to pass through the pumps completely unharmed, the fin blades do not stretch across the full width at the tip of the pump and the screw is enclosed and fixed within a pipe. The entire pump – inner shaft, fin blades and outer casing – all rotate as one unit so there are no fast-moving parts or shear hazards.

Image of the large screw pumps being loaded onto a shipping ship

The pumps were too big to fit into a shipping container.

The pumps are also incredibly efficient, meaning they have a lower cost of life.

Stephen says the pumps are due to arrive in New Zealand the day before Christmas and will be installed as part of the fish passage upgrade to the Churchill East pump station, which pumps water from the Ngariohe Stream into the Waikato River, this summer.

They will replace the four current non-fish friendly pumps that are past their used by date – one of which has permanently failed.

"Each can pump a maximum flow of 2.25 cubic metres per second, so the two of them together will meet the level of service requirements of the pump station, which is up to 4.3 cubic metres per second."

Image of an aerial view looking down at a river site

The site of the Churchill East pump station, where the pumps will be installed as part of the fish passage upgrade.

eDNA testing has revealed the presence of shortfin eel in the Ngariohe Stream, and the upgrade is expected to create safe downstream passage for them into the Waikato River.

The regional council has about 124 pump stations in the Waikato which help protect communities' lives and livelihoods.

It is developing a regional infrastructure fish passage strategy that will identify and prioritise pumped catchments to allow fish passage and the appropriate measures to do so, such as fish-friendly pumps.

The council received $4.48 million from the Climate Resilience COVID-19 Response and Recovery Fund, which is administered by Kānoa Regional Economic Development and Investment, for the fish-friendly upgrades of the pump stations in the Aka Aka and Churchill East drainage areas and to scope out three other sites.

The council has also been working with MacEwans Pumping Systems and Callaghan Innovation to develop a fish-friendly pump to replace the existing MacEwans PPF axial pumps found widely in New Zealand, without the need to make any civil structure modifications to pump stations.