Genesis Energy : Old $26.5m Tekapo Intake Gate Project completed, will protect from alpine fault earthquakes

22 February 2021

After nearly two years of construction, the $26.5m Tekapo Intake Gate Project is complete on time and under budget, protecting one of the South Island's key hydro power stations from alpine fault earthquake risks.

The 50-tonne gate is designed to stop inflows from Lake Tekapo in the advent of a serious emergency, such as a 1 in 10,000-year earthquake (Richter scale 7+) that would potentially send up to 680 million tonnes of water surging around Lake Tekapo.

Five years from planning to completion, the project had to overcome a number of unique engineering challenges, including how to integrate modern gate technology into infrastructure and tunnels originally designed and built in the 1940s. This included digging 22m down to the original underground tunnel, and cutting a 20m hole in its roof to construct the new gate housing.

While the gate can be manually triggered, it is also designed to automatically close when its earthquake monitors hit a certain threshold, acting as a 'dead man's switch'. The gate can shut completely under its own weight and does not require any electronics or hydraulic systems. This is vital in an emergency where power may not be available, or the station's operators are incapacitated.

Genesis Chief Operations Officer, Nigel Clark, said the key to the project's success was coordinated teamwork amongst numerous partners under lead engineering contractor, Downer Engineering.

'The scale of the challenge was significant especially when we needed to continue operating the Tekapo Power Scheme during construction. As Government-classified Essential Services provider, construction also had to continue throughout the COVID-19 lockdown to hit deadlines. I am proud to say our teams have performed admirably under strict health and safety guidelines to get this done on time, and under budget.'

Genesis also used this opportunity to perform maintenance and upgrades to both Tekapo A and Tekapo B power stations. This included replacing the Tekapo B turbine runner, providing an efficiency gain of 2.5% and further enhancing the Tekapo Power Scheme's long-term reliability and performance. The Tekapo Power Scheme is now back to running at its full 190MW capacity, providing power to more than 100,000 Kiwi homes and businesses.

The final stage of the project is to beautify the former construction site with more than 400 native grasses and plants.

Special thanks to Genesis' key partners: Downer New Zealand, Parfitt Construction, Farra Engineering, Hyspecs, Queensland Hydraulics, ABB, JLE, Coolair, G&H Comms, Aorangi Electrical.

Key facts about the Intake Gate project:

• The main shaft housing the new intake gate is 22m deep
• The tunnel the gate sits in has a diameter of 6m, and is 1.4km long
• The intake gate itself weighs 50 tonnes
• Up to 130-cumecs of water flow through the tunnel - that is equivalent to 130 tonnes of water passing per second, or equivalent to the weight of 65 cars per second
• More than 4,100 cubic metres of dirt removed (9000 tonnes) during construction
• More than 4,000 tonnes of concrete poured
• 22 months of construction, 5 years in the planning
• Up to 35 people worked on site, with a further 25 providing support, design and management

About Tekapo Power Scheme:

• Tekapo A power station opened in 1951. Tekapo B opened in 1977 (and is New Zealand's only power station completed surrounded by water)
• The canal between Tekapo A (sitting on Lake Tekapo) and Tekapo B (sitting on Lake Pukaki) is 25.5km long
• The Tekapo Power Scheme (Tekapo A + B) produces 190MW of zero emissions, 100% renewable electricity
• Powers nearly 100,000 Kiwi homes
• You can read more here

Media Contact:
Allan Swann
External Communications Manager
Genesis Energy
PH: 027 211 4874
[email protected]