This site is about the construction of the Manapouri Power Station, which is located in Fiordland New Zealand.
Why create a website for it?
In my opinion the Manapouri Power Station is an impressive feat of engineering. This is a power station built in a cavern, in a national park (Fiordland National Park), which is in a World Heritage Area (Te Wāhipounamu – South West New Zealand World Heritage Area). Did I mention that the cavern is man-made and 200 meters below the surface of Lake Manapouri? Yip 200 metres below a granite mountain in an underground cavern.
The cavern (machine hall) is about 111 metres long, 18 metres wide, and 39 metres high. The access tunnel down to the machine hall is 2 kilometres long and 9 metres wide. And there is the tailrace tunnel, which takes the water that flows out of the station into Deep Cove in Doubtful Sound. That is a massive 10 kilometres long and 10 metres wide. All of this was constructed in the 1960s using ‘drill and blast’ excavation methods to carve through the hard Fiordland rock (noting that a second tailrace tunnel was constructed between 1999-2002 using a tunnel-boring machine).That is impressive and definitely one of New Zealand’s greatest engineering achievements.
Because I have a bunch of photos from my late father, Ray Williams (Dip.Surv., M.N.Z.I.S.) from when he worked on the construction of the power station. I think the photos are impressive and as I said – the Manapouri Power Station is an impressive feat of engineering, so I thought I would share them.
Why the construction period, not whole life of the station?
Here is the long answer… There is a surge chamber which relieves the back pressure – but with greater than anticipated friction between the water and the walls of the original tailrace tunnel means greater back pressure, and therefore higher water level in the surge chamber. The surge chamber vents into the access tunnel and therefore into the powerhouse itself, so the station operators risked flooding the powerhouse if they ran the station at an output greater than 585 MW, which was well short of the designed peak capacity of 700 MW.
Work on the first tunnel began in early 1964 and breakthrough occurred four years later, in late 1968. It was actually built in two halves, one contractor starting from West Arm and the other from Deep Cove — when they finally met in October 1968, the two tunnels were only two inches (50.8mm) out of alignment.
In 1998, work began on the second tunnel using a 1000 tonne Tunnel Boring Machine (TBM). This was estimated to take only take 18 months but it broke through in 2001 because the contractor had difficulties with penetration rate and utilisation of the TBM due to unexpected rock conditions. So the modern machine took 3 years. Even taking into account the stricter environmental constraints and health & safety rules the second time around, that really is a true testament to the work building the thing in the first place.
That was the long answer. The short answer is just that – short: I only have photos on the construction.
I hope you get some value out of this site and the information it contains. Feel free to contact me if you do (by clicking here).