New South Wales
|Location||Dungog, New South Wales|
|Owner(s)||Hunter Water Corporation|
|Dam and spillways|
|Type of dam||Gravity dam|
|Impounds||Chichester River, Wangat River|
|Height||43 metres (141 ft)|
|Length||254 metres (833 ft)|
|Dam volume||91 cubic metres (3,200 cu ft)|
|Spillway capacity||3,300 cubic metres per second (120,000 cu ft/s)|
|Total capacity||21,500 megalitres (760×106 cu ft)|
|Catchment area||197 square kilometres (76 sq mi)|
|Surface area||1.8 square kilometres (0.69 sq mi)|
|Max. length||4.22 kilometres (2.62 mi)|
|Max. width||580 metres (1,900 ft)|
|Normal elevation||156.2 metres (512 ft) AHD|
|Commission date||November 2001|
|Installed capacity||110 kilowatts (150 hp)|
|Annual generation||0.4 gigawatt-hours (1.4 TJ)|
Chichester Dam is a minor concrete gravity dam across the Chichester and Wangat rivers, upstream of Dungog, in the Hunter Region of New South Wales, Australia. The dam's main purpose is water supply for the Lower Hunter region. A mini hydro-electric power station operates at times of peak flow and is connected to the national grid. The impounded reservoir is Lake Chichester.
Location and features
Commenced in 1917 and completed in 1926, the Chichester Dam is a minor dam on the Chichester River, a tributary of the Williams River, approximately 21.6 kilometres (13.4 mi) north of Dungog. The dam contributes about thirty-five percent of the lower Hunter region's water supply.
The dam wall is 43 metres (141 ft) high and is 254 metres (833 ft) long and was constructed using a cyclopean system of interlocking concrete blocks and large boulders with a volume of 91 cubic metres (3,200 cu ft). The wall is anchored to the bedrock below it by 93 stressed tendons. At 100% capacity the dam wall holds back 21,500 megalitres (760×106 cu ft) of water at 156.2 metres (512 ft) AHD. The spillway is capable of discharging 3,300 cubic metres per second (120,000 cu ft/s). The surface area of the reservoir is 1.8 square kilometres (0.69 sq mi) and the catchment area, largely located within the Barrington Tops National Park, is 197 square kilometres (76 sq mi). The dam is connected to reservoirs in Maitland, Cessnock and Newcastle by an 80 kilometres (50 mi) long gravitation main.
Land for the water supply scheme was appropriated in the Gazette of 6 October 1916. To safeguard the purity of the water the populated part of the Wangat Valley, including the old goldmining town of Wangat, and the greater portion of the populated part of the Chichester Valley were resumed. The Act appropriated A£1,049,000 as the estimated cost of construction of the dam, with additional funds set aside for land resumption.
In 1965 the spillway was lowered by 2.75 metres (9 ft 0 in) to increase flood capacity. In 1985 the dam was post tensioned with cables and the spillway was relocated to the centre of the dam and returned to its original height. In 1995 the seepage potential was reduced under the northern abutment and in 2003 an improved drainage system for the dam's foundations was installed and the left parapet wall was raised to prevent overtopping in a major flood.
Following a report by the Health Rivers Commission, in 1998 the Minister for Urban Affairs and Planning, Craig Knowles, announced that a small hydro-electric power station would be installed in the Chichester Dam in order to generate electricity, reduce greenhouse emissions and allow surplus power to be sold back to the grid. Completed in 2001 and operated by Delta Electricity, the mini-power station generates up to 110 kilowatts (150 hp) of electricity at times of peak flow; with an average annual generation of 0.4 gigawatt-hours (1.4 TJ).
- "Chichester Dam". Hunter Water Corporation. Retrieved 8 November 2007.
- "Register of Large Dams in Australia" (Excel (requires download)). Dams information. The Australian National Committee on Large Dams Incorporated. 2010. Retrieved 22 April 2013.
- "Chichester Dam Approved". Hunter Water. 1916. Retrieved 14 April 2013.
- "Hunter Water Supply (Chichester Dam) Act" (PDF). NSW legislation. Government of New South Wales. 1916. Retrieved 14 April 2013.
- Knowles, Craig (2 June 1998). "Chichester Dam Electricity Generation". Hansard (transcript ). Parliament of New South Wales.
- "Chichester Dam Mini-Hydro". Case studies: Hydro. Clean Energy Council. 2013. Retrieved 14 April 2013.
- "Hunter River catchment". Office of Environment and Heritage (map). Government of New South Wales.
- "Chichester Dam: Public amentities (sic.) and access" (PDF). Hunter Water Corporation.