Clyde Dam

The Clyde Dam, New Zealand's third-largest hydroelectric dam,[Note 1] is built on the Clutha River / Mata-Au near the town of Clyde. It is owned and operated by Contact Energy.

Clyde Dam
Clyde Dam from the east, looking west
Clyde Dam is located in New Zealand
Clyde Dam
Location of Clyde Dam in New Zealand
LocationClyde, Otago, New Zealand
Coordinates45.179314°S 169.306955°E / -45.179314; 169.306955
Dam and spillways
Type of damConcrete gravity dam
ImpoundsClutha River
Height100 m (330 ft)
Length490 m (1,610 ft)
Width (crest)10 m (33 ft)
Width (base)70 m (230 ft)
Reservoir
CreatesLake Dunstan
Surface area26 km2 (10 sq mi)
Power Station
Operator(s)Contact Energy
Commission date1992
Turbines4× 108 MW (145,000 hp) Francis turbines
Installed capacity464 MW[1]
Annual generation2,100 GWh

History
Clyde Dam under construction circa 1986

There was considerable controversy when the dam was planned because it would flood many houses and orchards upstream at Cromwell,[2] as well as the scenic Cromwell Gorge, which was a highlight of the then young but growing New Zealand tourism industry. Construction also required replacement of a stretch of highway[3] and the closure of the Otago Central Railway beyond Clyde, though materials for the dam would provide significant traffic for the rest of the line which was experiencing a drop in freight tonnage. To mitigate these problems, the Kirk Labour government decided a low dam should be built at Clyde. This decision was overturned by the following National government, who preferred a high dam.[4]

There was also debate about whether the dam was needed. National's support for a controversial aluminium smelter at Aramoana, another of Prime Minister Sir Robert Muldoon's Think Big projects of the late 1970s and early 1980s, was one justification propounded for the dam.[4] An initial grant of water rights for the dam was overturned by the High Court following an appeal by landowners. National overturned this decision, after bargaining for the support of Social Credit (who had initially opposed a high dam), in the Clutha Development (Clyde Dam) Empowering Act 1982.[2][4] The Act was later repealed by the following National government on 1 October 1991, when it was superseded by the Resource Management Act 1991.[5]

Expansion joint

The dam was constructed between 1982 and 1993. Filling it was done in four controlled stages beginning in April 1992, and completed the following year, creating Lake Dunstan.[2] The power station has a capacity of four 120 MVA (116 MW) Francis turbines (for a total of 464 MW), but was only allowed to run 432 MW due to resource consent conditions. The dam was built with two additional penstocks, allowing additional turbines to be installed in future.[6] The resource consent was changed in 2005 to allow the full 464 MW to be produced.

During construction, the adjacent rock was discovered to be microfractured, because of an earthquake fault running underneath the dam site. The dam was redesigned, losing a sluice channel and cutting its generation capacity from 612 MW to 464 MW. A slip joint was built into the dam to accommodate 1–2 metres of potential ground movement,[7][8] and a large amount of slurry cement was pumped into the rock to stop water leaks. This additional work was one reason for a major project cost overrun, which made the dam the most expensive in New Zealand. The other areas of overrun were due to stabilisation of landslides in the Cromwell Gorge.[9][10] There are over 18 km of tunnels throughout the gorge for draining purposes. Because of all this extra work it overran the budget by nearly an extra 50% and delayed the filling of Lake Dunstan by a few years.

Maintenance workers accidentally activated fire alarms in the dam on 15 December 2008. The alarms triggered the release of a large bank of CO2 cylinders at the generators, flooding the equipment with the gas. Extractor fans to clear the CO2 then activated, and firefighters with breathing apparatus and gas detectors checked through the dam to ensure it had cleared.[11]

Trivia

The Clyde Dam, while still under construction, was used for on-location filming in the 1985 movie Shaker Run.[12]

See also

Notes
  1. List of power stations in New Zealand

References
  1. Hydroelectricity: turning water into power Archived 2010-05-24 at the Wayback Machine, Contact Energy.
  2. Gilchrist, Shane (31 January 2009). "Reflections on Lake Dunstan". Otago Daily Times. Retrieved 2009-03-18.
  3. Dai Redshaw (1997). Sustainable Energy Archived 2008-10-16 at the Wayback Machine, New Zealand Science Monthly, March 1997.
  4. Aynsley John Kellow (1996). Transforming power: the politics of electricity planning. Cambridge University Press. ISBN 978-0-521-47122-0.
  5. "Resource Management Act 1991 No 69 - New Zealand Legislation". Archived from the original on 4 April 2012. Retrieved 30 December 2010.
  6. "Clyde Dam factsheet" (PDF). Contact Energy. Archived from the original (PDF) on 27 January 2018. Retrieved 26 November 2021.
  7. Fault Provisioned Design Examples Archived 2011-07-22 at the Wayback Machine, Chapter 7 in Key Points for Rational Design for Civil-Infrastructures near Seismic Faults Reflecting Soil-Structure Interaction Features Archived 2011-07-22 at the Wayback Machine, Japan Society for Promoting Science, 2007.
  8. Eileen McSaveney. Earthquakes - Building for earthquake resistance Archived 2011-03-10 at the Wayback Machine, Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009.
  9. Michael J. Crozier. Landslides - People and landslides, Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009.
  10. Vicki Hyde (1990). Slip Sliding Away, New Zealand Science Monthly, November 1990 (Via Archive.org).
  11. Brown, Diane (16 December 2008). "Gas cylinders inadvertently activated at Clyde dam". Otago Daily Times. Retrieved 2008-12-15.
  12. "Shaker Run". IMDB.

Further reading
  • Bagge, Michael (2002). Dams or Democracy? The Clyde Dam Controversy 1968-1982 (MA). Dunedin: University of Otago.
  • Findlay, Angela (2004). 'Vive Aramoana': the Save Aramoana Campaign, 1974-1983 (PDF) (MA). Dunedin: University of Otago.
  • Martin, John E. (1991). People, Politics and Power Stations. Wellington: Bridget Williams Books Ltd and Electricity Corporation of New Zealand. ISBN 0-908912-16-1.
  • Ministry of Works and Development. (1987). Clyde dam : Clutha power.
  • Reeves, Trevor; Wolfe, Judith (1994). An Abuse of Power: The Story of the Clyde Dam. Dunedin: Square One Press. ISBN 0-908562-12-8.
  • Sheridan, Marion (1995). Dam Dwellers – End of an Era. Twizel: Sheridan Press. ISBN 0-473-03402-6.
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