Power station will close to visitors

Waimarino Bulletin, Volume 5, Issue 23, 3 November 1987, Page 5

Power station will close to visitors

Tourists are unlikely to be able to visit Rangipo Underground Power Station after it goes automatic, probably before next year. At present the station, situated south east of Turangi, 250 metres underground in the Kaimanawa Forest Park, is manned round the clock by twoman teams. These staff have been available in the past, at times, to show tourists around the impressive project. When the station is automated it will be controlled from Tokaanu, leaving no personnel available to lead tours. Access to the massive powerhouse would also be a problem as only diesel powered vehicles are allowed in the 648 metre access tunnel. Electricorp's assistant information officer Elizabeth Murphy has said there is an enormous amount of interest from both New Zealanders and foreigners in the scheme. She said it was easy to see visits could be a draw card for the area and the tourist industry. She suggested that tours might be conducted at set times, which would mean hiring a guide. Another Electricorp representative has said while tours have not been considered yet, they could be in the near future. Water diverted The Rangipo Power Station is part of the Westem Diversion of the Tongariro Power Development Scheme, which diverts water from the Moawhango River and rivers on the Eastem flank of Mt Ruapehu.

A tunnel carries this water 19.2 kilometres to the headwaters of the Tongariro River. This tunnel is one of the longest hydro tunnels in the world, and took 10 years to complete. Rangipo Dam diverts water from the Tongariro headwaters to the Rangipo headrace tunnel, 8.3 kilometres long, to the penstocks, which drop about 240 metres to the turbines, located in the power house carved out of the rock. The power house is a cathedral sized cavern, 36 metres high, with the generator floor half way up the cavern.

Because of the surge effects caused by variations in the amount of water passing through the turbines two surge chambers have been excavated. The headrace surge chamber, above the penstocks, is circular, 15 metres in diameter and 80 metres high and is open to the atmosphere. The tailrace surge chamber is a cavern of similar size to the powerhouse and also carved out of solid rock: The 3 km tailrace tunnel takes the water back to the Tongariro River, just upstream of the Poutu intake, which in turn carries water

to the Poutu tunnel and canal, thence to Lake Rotoaira. A tunnel from * the lake carries water to « the Tokaanu power station. , The Rangipo Power Station produces 120 \ megawatts, which is enough power to supply , two towns the size of \ Taupo. Most travellers along the ( Desert Road, running roughly parallel to the ! tunnels of the Westem Di- ' version, would see little more evidence of the ( Rangipo power project than the AA sign showing the way to the entrance of the access tunnel.