15 April 2024:
Fulton Hogan’s Civil division and the Southland team have combined to install ’Archimedes’ screw pumps to protect migratory fish and the people of Invercargill.
Turning at 16 rpm and pumping 1.5m3 of water per second each, the two Finnish-built screws have no impellers, making it safer for fish like shortfin and longfin eels (tuna) and galaxiids (whitebait). The fish can travel both ways – a by-pass passage enables them to swim upstream.
From a human perspective, Invercargill is low lying and relies on significant drainage, stop banks and pumps. The Southland floods of 1984 severely affected the Invercargill Airport and, in 2016, a storm surge from the estuary flooded Stead Street – the main road to the airport, the Otatara community and where the new pump station is situated.
Civil Division Project Manager, Luke Hazlett, says it’s inspiring to help protect humans and the natural world, together, using this sort of technology.
“It’s about considering the needs of living creatures as widely as possible, and it certainly adds something special to this project,” Luke says.
Among fish life, tuna are likely to be a key beneficiary. Living in streams, drains and other freshwater habitats, they – like other migratory fish – are susceptible to injury or death in traditional pumping systems as they leave for their spawning grounds in Pacific deep-sea trenches. Newly hatched tuna larvae make their way back to New Zealand river mouths on ocean currents before moving inland on flood tides as glass eels.
The project on behalf of Environment Southland is due for completion in July. The team plans to work with Environment Southland to hold a public open day on World Fish Migration Day (25 May).
