Revived falls station's keeping Kaimai cosy

An engineering marvel in a beautiful corner of the Western Bay of Plenty is keeping Kaimai homes lit and cosy following a remarkable restoration.
The 95-year-old Omanawa Falls Power Station, hewn out of a bush-clad ravine on the doorstep of Tauranga, is humming again thanks to the vision of Te Kuiti hydro-electric entrepreneur Michael Davis.
Built to supply electricity to the 400 homes that comprised Tauranga in 1915, it was the Southern Hemisphere's first underground power station.
But this testament to the fortitude and vision of the Bay's early engineers fell into neglect after it was shut down by TrustPower 12 years ago and gifted to the Tauranga City Council.
Ravaged by vandals, its future looked bleak until Mr Davis stepped in.
"The main issue for me was the preservation of the site - it is very significant both for New Zealand and the world. Everything about that scheme was amazing."
With a 35-year lease from the council in his back pocket, he plunged $300,000 into a project that many felt was doomed to failure. No one counted on Mr Davis' faith in the 108-year-old Swiss-made Escher Wyss turbine. The turbine and generator originally powered a gold quartz crushing plant in the Karangahake Gorge.
While the generator was unsalvageable, the turbine was a different story.
Thanks to the perseverance of Bay engineer Jim Berryman, the turbine was restored and has operated without a hitch since the old station began generating power again in November, 2008.
"It says something for the old turbine. It's been going for 100 years and it will go for another 100 years."
Water from the Omanawa River drives the turbine via a superb feat of Edwardian engineering involving a 180m tunnel from the inlet to a surge chamber carved out of rock and then a further 33m tunnel to the powerhouse.
Mr Davis regards the restoration as an unqualified success: "It has given us no problems - it is nice to be poking energy back into the grid again."
Power from the old station is hooked into PowerCo's Kaimai feeder, supplying power to households on Omanawa Rd and further up the Kaimais.
The spring-fed river's constant flow meant that power output was also constant, without the usual seasonal fluctuations which he encounters with his other small hydro-electric stations dotted around the North Island.
Output was 200 kilowatts, producing 1.5 million units of electricity a year.
His consent to take water from the river ensured there would always be a good flow over the scenic Omanawa Falls - the power station is carved into the ravine off to one side of the falls.
Mr Davis said the reduction in the volume of water going over the falls has not affected its beauty. Less turbulence in the pool at the bottom meant people could now see into the pool and watch the fish.
"This scheme has no impact on the environment."
The track down to the steep final descent to the powerhouse through a gated tunnel has been upgraded by the council.
 Guided tours of the powerhouse by McLaren Falls Park rangers can be arranged through the council by contacting the rangers.