Crotty Dam

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Crotty Dam
Mount Jukes and burbury.JPG
Crotty Dam at right, above King River gorge, Mount Jukes at left
Crotty Dam is located in Tasmania
Crotty Dam
Location of the Crotty Dam in Tasmania
CountryAustralia
LocationWest Coast Tasmania
Coordinates42°09′35″S 145°37′00″E / 42.15972°S 145.61667°E / -42.15972; 145.61667Coordinates: 42°09′35″S 145°37′00″E / 42.15972°S 145.61667°E / -42.15972; 145.61667
PurposePower
StatusOperational
Opening date1991 (1991)
Owner(s)Hydro Tasmania
Dam and spillways
Type of damEmbankment dam
ImpoundsKing River
Height83 metres (272 ft)
Length245 metres (804 ft)
Width (crest)300 millimetres (12 in)
Dam volume770×10^3 m3 (27×10^6 cu ft)
Spillways1
Spillway typeControlled and uncontrolled
Spillway capacity
  • 245 m3/s (8,700 cu ft/s) chute on dam face
  • 190 m3/s (6,700 cu ft/s) valve in tunnel
Reservoir
CreatesLake Burbury
Total capacity1,081,420 ML (38,190×10^6 cu ft)
Active capacity1,065,000 ML (37,600×10^6 cu ft)
Catchment area559 km2 (216 sq mi)
Surface area53,250×10^3 m2 (573.2×10^6 sq ft)
John Butters Power Station
Coordinates42°09′21″S 145°32′04″E / 42.15583°S 145.53444°E / -42.15583; 145.53444
Operator(s)Hydro Tasmania
Commission date1992 (1992)
TypeConventional
Hydraulic head184 metres (604 ft)
Turbines1 x 144 MW (193,000 hp)
Fuji Francis turbine
Installed capacity144 megawatts (193,000 hp)
Capacity factor0.9
Annual generation576 gigawatt-hours (2,070 TJ)
Website
hydro.com.au/energy/our-power-stations/king-yolande

The Crotty Dam, also known during construction as the King Dam,[1] or the King River Dam on initial approval,[2] is a rockfill embankment dam with a controlled and uncontrolled spillway across the King River, between Mount Jukes and Mount Huxley, located in Western Tasmania, Australia.

The impounded reservoir is called Lake Burbury.

The dam was constructed in 1991 as part of the King River Power Development Scheme, by the Hydro Electric Corporation (TAS) for the purpose of generating hydro-electric power via the John Butters Power Station located 8 kilometres (5.0 mi) below the dam wall.[3]

Features and location[edit]

Looking up King River gorge and Crotty Dam between Mount Jukes and Mount Huxley

The Crotty Dam, together with the Darwin Dam, are two major dams that form the headwaters for the King River Hydroelectric Power Development; the dam is located in the upper reaches of the King River gorge where the river breaks through the West Coast Range. It captures the high rainfall in the catchment of the King River and allows diversion of water through a tunnel to the John Butters Power Station downstream of the dam.

The Crotty Dam wall, constructed with 770 thousand cubic metres (27×10^6 cu ft) of concrete faced rock and gravel fill core, is 83 metres (272 ft) high and 245 metres (804 ft) long. At 100% capacity the dam wall holds back 1,081,420 megalitres (38,190×10^6 cu ft) (43,000×106 cu ft) of water. The surface area of Lake Burbury is 53,250 hectares (131,600 acres) and the catchment area is 559 square kilometres (216 sq mi); the single uncontrolled and controlled spillway is capable of discharging 435 cubic metres per second (15,400 cu ft/s).[4]

Spillway[edit]

A unique feature of the dam is its spillway; the spillway is located on the embankment, rather than on one of the rock abutments. This had never been successfully attempted before in the design of dams of any significant height, due to problems in making allowance for embankment settlements. In the case of Crotty Dam, the embankment was partly composed of well graded gravels, and thus a very high modulus of embankment deformation was achieved; the high modulus limits embankment settlements. Additionally, the spillway was designed to articulate in order to accommodate any settlement that did occur.

The spillway is designed to allow sufficient time for a large jet flow valve located in the diversion tunnel to be opened so that larger floods can be safely handled.

The spillway designers, Sergio Giudici, also the chief engineer on the Gordon Dam, Frank Kinstler, Steven Li, Tony Morse and Graeme Maher were acknowledged within the engineering community because the spillway was the first known to provide for articulation of the spillway structure so that movements in its foundations could occur without damage to the overlying structure.[5]

Power station[edit]

The water from Lake Burbury is conveyed through a 7-kilometre (4.3 mi) long unlined tunnel that runs through Mount Jukes to the John Butters Power Station, which is located on the King River downstream of the dam and King River gorge, near the confluence with the Queen River.[6]

History[edit]

The dam was constructed in the 1980s following the abandonment of the Gordon-below-Franklin power development scheme, part of the Franklin Dam; the Crotty Dam was commissioned in 1991, with the King River Power development being completed by 1992.[7]

The dam is named in honour of James Crotty who founded the North Mount Lyell Copper Mine at the turn of the 20th century. A ghost town site of the same name Crotty was submerged by the waters of Lake Burbury.

In the 1910s the Mount Lyell Mining and Railway Company had investigated and surveyed a site very close to this dam for a proposed hydro electric scheme. Charles Whitham also wrote of the inevitability of the dam in 1927 and even proposed "Lake Dorothy" as a name for the reservoir.

In 2001, Engineers Australia selected Crotty Dam as one of the 25 dams with the greatest Australian heritage value.[5]

See also[edit]

References[edit]

  1. ^ HEC (1983) King River Power Development, HEC Public Relations, December 1983
  2. ^ "Anthony and King Power Developments approved". Cross Currents. Hydro-Electric Commission (70). 1983. ISSN 0811-4803.
  3. ^ "King - Yolande". Energy: Our power stations. Hydro Tasmania. Retrieved 21 June 2015.
  4. ^ "Register of Large Dams in Australia" (Excel (requires download)). Dams information. Australian National Committee on Large Dams. 2012. Retrieved 28 June 2015.
  5. ^ a b "Crotty Dam, Tasmania" (PDF). Submission for historic engineering marker. Engineers Australia. September 2000.
  6. ^ page 10 and 11 of Tasmania. Hydro-Electric Commission (1992), King River power development, The Commission, retrieved 9 June 2018
  7. ^ Felton, Heather; Hydro Tasmania (2008). Ticklebelly tales and other stories from the people of the Hydro. Hydro Tasmania. pp. 482, 465–472. ISBN 978-0-646-47724-4.

Further reading[edit]

External links[edit]