Pirates fail to sink pump station upgrade

The pumps service the Churchill East drainage area at Hampton Downs.

Waikato Regional Council’s two biggest fish-friendly Archimedes screw pumps made it through the Suez Canal and across the Red Sea mere days before pirates forced ship operators to re-route, and have been installed on time and under budget near Te Kauwhata.

Project manager Stephen Wilson says the pumps, which were built in the Netherlands, were a bit late due to impacts still from COVID-19, and he’d been anxiously tracking the ship which was due to arrive in New Zealand the day before Christmas.

“There was a container ship that either got hit by a rocket or nearly, and then it happened again, and all the shipping companies diverted their routes after that point”, taking a lengthy detour of 3500 nautical miles (6500 kilometre) around Cape of Good Hope.

A coffer dam and six temporary pumps had to be installed as part of the project.

The two pumps, which replaced four non-fish friendly pumps that are past their used by date (one which had permanantly failed), have been pretty busy since they were installed in April, but not as busy as the old ones were during wet weather.

Stephen says of the old pumps, installed in 1965 by the Waikato County Council, one was almost constantly pumping water, with the second and third pump kicking in when required.

“Now, just one pump can keep on top of water levels by operating for an hour every six hours or so, on low speed.”

One of the pumps being loaded onto the container ship.

Stephen says he’s very impressed with the amount of water the pumps can handle. Each pump measures 18 metres in length and 3 metres in diameter, and can pump a maximum flow of 2.25 cubic metres per second.

The council had already installed the same kind of pump, albeit a much smaller version at 10 metres  by 1.6 metres, in Aka Aka near Waiuku.

When undertaking replacement of its old flood protection infrastructure, the council needs to comply with legislation, including fish passage requirements.

The enclosed Archimededs screw pump design means fish can pass through them unharmed.

The enclosed screw pump design means they allow tuna/eels to pass completely unharmed, giving them access to the Waikato River and out to sea to breed.

Stephen says a big part of the pump upgrade to the Churchill East pump station at Hampton Downs was creating a coffer dam around the existing pump station and requiring backup pumps in case of wet weather.

“It’s a huge job. Not only do we need to install temporary pumps, but we have to put a steel bridge in to carry the outlets to the other side of the pump station.

“We got in six temporary pumps on a Friday, and then that weekend we had a lot of rain where all six pumps had to run to keep on top of all the water. That was the only time they all had to go at once – they got a good thrashing.

“Overall, it was a really positive project. All the contractors worked well together. And while we had problems with getting the pumps from the Netherlands, we completed the project on time and under budget.”

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.