Glennies Creek Dam is a 67 metres high, concrete faced, rock fill embankment dam

Embankment dam

An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...

 located on Glennies Creek near Singleton, New South Wales

Singleton, New South Wales

-Industry & Commerce:Major industries near Singleton include coal mining, energy generation, light industry, vineyards, horse breeding and cattle production. Dairying was once a mainstay in the area, but has declined....

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Glennies Creek is a tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Hunter River

Hunter River

The Hunter River is a major river in New South Wales, Australia. The Hunter River rises in the Liverpool Range and flows generally south and then east, reaching the Pacific Ocean at Newcastle, the second largest city in New South Wales and a major port....

 in the foothills of the Barrington Tops National Park

Barrington Tops National Park

Barrington Tops is a National Park in the Hunter Valley, approximately north of Sydney in New South Wales, Australia. The nearest towns are Scone, Singleton, Dungog, Gloucester and East Gresford....

. The lake is up to 16 kilometres long, and has a capacity of 283 000 megalitres.

The dam was built primarily to replace water withdrawn from the upper Hunter River for electricity generation. Geotechnical problems included weathered, non-welded tuff in the dam foundation and toppling slope failures in welded tuff in the unlined spillway

Spillway

A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...

 cutting. The dam was constructed by the New South Wales Department of Water Resources and was completed in 1983. The lake impounded by the dam is now known as Lake St Clair.

Glennies Creek Dam spillway is an unlined cutting in welded ash flow tuff which supplied the entire rock fill requirement for the construction of the dam embankment. The spillway excavation

Earthworks (engineering)

Earthworks are engineering works created through the moving or processing of quantities of soil or unformed rock.- Civil engineering use :Typical earthworks include roads, railway beds, causeways, dams, levees, canals, and berms...

 was designed to be located entirely in welded tuff and not to encroach on either the underlying non-welded tuff or the overlying sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

, both of these rock types being much inferior to the welded tuff as a rock fill construction material.

Links

Water Storage Report:
Glennies Creek Dam: http://waterinfo.nsw.gov.au/sr/glenniescreek.shtml

Hunter Valley storage: http://waterinfo.nsw.gov.au/sr/valley-hunter.shtml