>> Read more

>> Hide detail

Physical Description

The dam wall is curved in plan and has a spillway channel constructed as an open cut through a ridge between the Reservoir and a watercourse. It discharges into the Avon River approximately 0.8km below the dam. Each end of the dam wall is flanked by Egyptian style pylons of massive scale are adorned by lotus motif columns. The dam is fitted with outlet valves on two levels. The upper level serves as the water draw-off, with 0.9m diameter pipes each fitted with needle valves 76.2m wide. This is positioned 24.4m below the level of full supply. The lower level intake, originally for the purpose of eradicating the stream flow during construction, consists of two 1.2m diameter pipes fitted with 0.9m wide needle valves at the level of the river bed. , In 1971, work was commenced in order to alleviate uplift pressure and leakage through the foundations of the dam wall. This was carried out in accordance with modern design and engineering techniques, involving the support of the downstream face of the wall with an embankment of quarried sandstone blocks and sandstone fill, the latter being compacted by grid and vibratory rollers. The spillway was also modified from the original 1.2 m high mass concrete weir, and transformed into a sawtooth shape. The intent is to provide for a greater discharge of water which will accord with modern flood estimates, greater than those considered adequate at the time of original construction. The Dam currently serves the Wollongong area. An electrical pumping station located at Flying Fox Creek, facilitates the transfer of water over the Great Dividing Range to the Wollongong and Shell Harbour areas., The Dam site is a popular area for passive recreation and provides landscaped gardens, picturesque pathways, and shelter sheds (maintained and managed by Sydney Water Corporation), set within a natural bushland setting. These elements heighten the visual amenity of the dam wall area and enhance the visual catchment of the curtilage upstream of the dam.

Modifications

Although modifications to the structure of the dam were carried out in 1971, these were largely engineering modifications which occurred to the foundations and interior of the dam wall. They have not impinged upon the integrity of the dam. The decorative pylons are intact and in good condition.

History

In 1921, three years after the construction of the Cordeaux Dam and five years prior to its completion, the Public Works Department, under contract to the Government, commenced work on the Avon Dam. This was the third dam in the Upper Nepean Scheme, situated at a higher point than the Cataract and Cordeax Dams on the Avon River, a tributary of the upper Nepean River. It was designed and constructed under the supervision of the Public Works engineer, E. M. DeBurgh. Similar to the dams which preceded it, the Avon was built using the Cyclopean Masonry technique, renowned at the time for strength and durability. This involved quarrying sandstone blocks on site, which were fitted into an irregular pattern and packed with sandstone concrete. This dam is unique however, as it was necessary to take a large section of sandstone from a neighbouring creek for its use as the spillway. It shared with its predecessor the honour of having the upstream face sealed with a layer of basaltic concrete (0.6m thick), intended to protect it from the eroding forces of wave action and other forms of weathering. A road 9.6km long was constructed from Bargo Station for the transporting of materials to the site. The dam storage area was cleared of all timber and brush, and an extensive area of Coachwood timber (Ceratopetalum Apetalum) was harvested from the storage basin. Approximately 3,540cu.m of sawn and dressed timber was produced, used in the construction of buildings in the Nepean township. Avon dam was completed in 1927 and handed over to the Water Board in 1928.

Internet links

Webpage	Source
Avon Dam
Avon Dam	Attraction Homepage

Go back to search results