Chaffey Dam

Chaffey Dam is a minor ungated rock fill with clay core embankment dam with an uncontrolled morning glory spillway across the Peel River, located upstream of the city of Tamworth, in the New England region of New South Wales, Australia. The dam's purpose includes flood mitigation, irrigation, water supply, and water conservation.

Chaffey Dam
Chaffey Dam (pre upgrade) at 77% capacity, in 2008.
Location of Chaffey Dam in
New South Wales
LocationTamworth, New South Wales, Australia
Coordinates31°20′45″S 151°08′19″E
PurposeFlood mitigation, irrigation, water supply, and water conservation
StatusOperational
Construction beganAugust 1976 (1976-08)
Opening dateSeptember 1979 (1979-09)
Owner(s)State Water Corporation, William Wordsworth Chaffey
Dam and spillways
Type of damEmbankment dam
ImpoundsPeel River
Height55.8 metres (183 ft)
Length430 metres (1,410 ft)
Width (crest)8 metres (26 ft)
Width (base)195 metres (640 ft)
Dam volume1,413 cubic metres (49,900 cu ft)
Spillways1
Spillway typeMorning glory
Spillway capacity903 cubic metres per second (31,900 cu ft/s)
Reservoir
Total capacity100,000 megalitres (3,500×10^6 cu ft)
Catchment area420 square kilometres (160 sq mi)
Surface area542 hectares (1,340 acres)
Maximum water depth30 metres (98 ft)
Normal elevation518 metres (1,699 ft) AHD
Website
Chaffey Dam at www.statewater.com.au

Location and features

Commenced in August 1976 and completed in September 1979, the Chaffey Dam is a minor dam on the Peel River, a tributary of the Namoi River, approximately 16 kilometres (9.9 mi) north of Nundle and 44 kilometres (27 mi) south-east of Tawmorth.[1] Water from the dam is released directly into the Peel River which is used by irrigators downstream of the dam, and for water supply of the city of Tamworth.[2]

The dam wall comprises 1,413 cubic metres (49,900 cu ft) of rock fill is 55.8 metres (183 ft) high and is 430 metres (1,410 ft) long. The maximum water depth is 30 metres (98 ft) and at 100% capacity the dam wall holds back 62,830 megalitres (2,219×10^6 cu ft) of water at 518 metres (1,699 ft) AHD. The surface area of the reservoir is 542 hectares (1,340 acres) and the catchment area is 420 square kilometres (160 sq mi).

The dam uses an unusual concrete morning glory bell-shaped uncontrolled spillway which is capable of discharging 903 cubic metres per second (31,900 cu ft/s).[2][3][4] The spillway measures 25.81 metres (84.7 ft) in diameter and tapers down to 7.72 metres (25.3 ft). The spillway tower is 35.1 metres (115 ft) high.

Chaffey Dam provides valuable public recreation including swimming, sailing, boating and fishing.[2]

Upgrade of facilities

An A$13 million upgrade of Chaffey Dam commenced during 2010 that involved the construction of a 35 metres (115 ft) auxiliary spillway with release plug, funded by the Government of New South Wales and was completed in early 2011.[5] A second stage A$43.33 million augmentation commenced in 2013, funded by the Australian Government, the NSW Government and Tamworth Regional Council. This augmentation is expected to be completed during 2014 and involves raising the dam wall by 8 metres (26 ft) and subsequent works to raise the morning glory spillway and bridge deck. These works will increase the full supply level of the dam by 6.5 metres (21 ft), the dam's capacity from 62 gigalitres (2.2×109 cu ft) to 100 gigalitres (3.5×109 cu ft) and ensure it can withstand the maximum possible flood. The project also involves a realignment of roads on the western foreshore; the Tamworth-Nundle Road, and River Road.[6]

Etymology

The dam is named in honour of Frank Chaffey,[1] who represented Tamworth in the New South Wales Legislative Assembly between 1913 and 1940, and his son, Bill,[1] who represented the same seat between 1940 and 1973.

  • Chaffey Dam as viewed from lookout on Nundle Road, 2008.
  • Lower section of wall, April 2018.
  • Spillway post upgrade, April 2018.

See also

References
  1. "Chaffey Dam". Geographical Names Register (GNR) of NSW. Geographical Names Board of New South Wales. Retrieved 14 April 2013.
  2. "Chaffey Dam" (PDF). State Water Corporation. 2009. Archived from the original (PDF brochure) on 20 March 2012. Retrieved 14 April 2013.
  3. "Chaffey Dam". Water delivery: Dams. State Water Corporation. Archived from the original on 10 April 2013. Retrieved 14 April 2013.
  4. "Register of Large Dams in Australia" (Excel (requires download)). Dams information. The Australian National Committee on Large Dams Incorporated. 2010. Retrieved 22 April 2013.
  5. "Chaffey upgrade". Projects: Dam safety upgrades. State Water Corporation. Archived from the original on 10 April 2013. Retrieved 14 April 2013.
  6. "Chaffey Dam augmentation". Projects: Dam safety upgrades. State Water Corporation. Archived from the original on 10 April 2013. Retrieved 14 April 2013.
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