The Cordeaux Dam is a gravity dam across the Cordeaux River, located in Cordeaux, in the Southern Highlands of New South Wales, Australia. Completed in 1926 under the supervision of Ernest Macartney de Burgh, the resultant reservoir was established to supply potable water to the Macarthur and Illawarra regions, the Wollondilly Shire, and metropolitan Sydney.
It is one of four dams and weirs in the catchment of the Upper Nepean Scheme, owned by Water NSW, a NSW Government agency.
The dam was added to the New South Wales State Heritage Register in 1999.
Structural details The heritage-listed gravity dam is s high and long. Construction began in 1918 and was completed in 1926 at a cost of A£945,000. When full, the resultant reservoir has capacity of . The dam wall consists of large sandstone blocks, quarried onsite and cemented together, faced with a combination of bluestone and sandstone concrete. The dam featured a number of improvements in design and construction on the earlier-completed Cataract Dam. These included contraction joints between units of construction placed at intervals of ; inspection galleries at upper and lower levels, together with piping for registering any ground water pressure. The blue metal used in the construction of the dam was supplied from the Government Quarries at Kiama and brought by rail to Douglas Park. From here it was conveyed by aerial ropeway across the Nepean Gorge to an interchange on the eastern side where the material was transferred to a gauge steam tramway to a point adjacent to the dam site. The spillway has an unlined side on the left abutment.
History The Upper Nepean Scheme was commenced in 1880 after it was realised that the Botany Swamps scheme was insufficient to meet Sydney's water supply needs. The Nepean project consisted of the construction of a weir across the Nepean River to divert of the rivers Cataract, Cordeaux, Avon and Nepean, to the Prospect Reservoir.
The design and construction of Cordeaux Dam was undertaken by the Water Supply and Sewerage Branch and Harbour and Rivers Branch of the New South Wales Public Works Department. The construction of the dam necessitated the knowledge and experience of a number of engineers employed in the branches at the time including Cecil Darley (NSW Inspecting Engineer in London), Leslie Wade (Principal Engineer, Water Supply and Sewerage Branch), Henry Dare and Ernest M. de Burgh (Supervising Engineers). The successful completion of the dam and its continuation of use as a water supply dam are a lasting testament to the professional capabilities of the late Victorian/Edwardian era generation of engineers of the Public Works Department.
Description Cordeaux Dam is a cyclopean masonry dam composed of sandstone blocks, weighing from two to four and a half tons, quarried at the site and bedded in a cement mortar. The roughly rectangular blocks were bedded on and packed with sandstone concrete, with cement mortar only being used where considered necessary. The concrete is made with crushed Hawkesbury sandstone. Concrete made of hard basaltic stone (instead of the softer sandstone) is used for the upstream face, thick, which merges into sandstone concrete thick at lower levels and thick at higher levels. The dam wall is curved in plan and has a bywash spillway as a continuation of its southern end. Each end of the dam wall is flanked by massive Egyptian style pylons complete with decorative lotus columns. These pylons differ from those at Avon Dam by having heavy fluting to the lotus columns. Two valve houses along the dam wall are square, flat-roofed concrete buildings with strong Egyptian stylisation in the tapered wall profiles, circular beading to corners and overhanging eaves. These contain discharge outlets, with the Upper Outlet consisting of two pipes with FCD valves and Ring Faulkner gate valves. The two lower valve houses at the downstream foot of the dam wall are very similar in appearance and which contain discharge pipes with Ring Faulkner gate valves and scour valves as outlets.
The dam featured a number of improvements in design and construction on the earlier-completed Cataract Dam. These included contraction joints between units of construction placed at intervals of ; inspection galleries at upper and lower levels, together with piping for registering any ground water pressure.
The Cordeaux Dam storage is discharged to the Cordeaux River downstream, flowing to Pheasants Nest Weir on the Nepean River where it is diverted through a tunnel long to the Cataract River at Broughton's Pass. From here it is diverted by another weir to the Cataract Tunnel, long, emerging into the Upper Canal by which it is conveyed to Prospect Reservoir.
There are three cottages associated with the Dam, two of brick and one of weatherboard. The brick cottages are both very similar single-storey brick bungalows with terracotta-tiled hipped-gable roofs, dating from the 1960s. The weatherboard cottage appears to date from the construction of the Dam and is reputed to have been the Resident Engineers residence. It is a single-storey, weatherboard clad building on sandstone piers with a hipped and gabled roof clad in corrugated-iron. The building features little decoration but has a front verandah which wraps around the building for half the length of the sides. This has chamfered square timber posts, a slatted timber balustrade and sandstone steps with sandstone masonry balustrades.
The Cordeaux Dam site is a popular tourist attraction. The public area is maintained with picnic grounds, landscaped gardens, shelter sheds and pathways. The grounds associated with the main public areas of the dam contain many intact landscape elements from the s (and possibly late 1920s). Remnant landscape features include stone retaining walls; gardens (layout and plantings); a robust and imaginative cement-sculpted grotto/picnic shelter sited between a large Monterey pine and a very large Eucalypt; a broad stone flagged surface drain in the upper picnic area; a lower picnic area with a series of grassed terraces accessible by a narrow crazy-paved path in stone; and a Monterey pine (Pinus radiata) avenue to the lower dam road with gums beyond. The upper park area is characterised by mature pines while an interwar cottage and nearby propagating structure include older plantings of Magnolia grandiflora and Lagerstroemia indica which are probably contemporary with the cottage. A distinctive feature of the site is stands of autochthonous Cypress Pine (Callitris sp.).
The Conservation Management Plan outlines the key elements and their individual significance assessments.
Condition
As at 21 January 2009, the condition of the dam was good. The fabric of Cordeaux Dam retains a high level of integrity.
Modifications and dates 1960's - Two brick cottages were built, probably as replacements for earlier weatherboard cottages. 1988 - Upgraded with a system of drains in the wall and foundations.
Further information
Cordeaux Dam is located in three Council areas: Wollondilly, Wingecarribee and Wollongong.
Heritage listing As at 21 January 2009, Cordeaux Dam was the second of the four water supply dams built as part of the development of the Upper Nepean Water Supply Scheme, one of the most important engineering works and items of public infrastructure in Australia, and still has the longest wall of all the NSW water supply dams. It was designed by the NSW Public Works Department under the direction of one of Australia's leading water supply engineers, E.M. De Burgh. The completion of the Cordeaux Dam was a significant step in the continuing process of providing a reliable water supply for Sydney and surrounding areas as part of the Upper Nepean Scheme. Even by the international standards of the time, Cordeaux was a large dam and was a significant work of engineering in its day. It continues to play an important role as a major source of supply for the Sydney region.
Cordeaux Dam is a handsome, well proportioned structure with strong Egyptian style architectural character which complements the monumental nature of the structure and its attractive natural surroundings. Cordeaux Dam includes a range of ancillary structures which form components of the overall site, including residential cottages of various ages for operational staff, one of which appears to date from the construction of the dam. This latter is associated with the Residential Engineer for construction and operation of the dam and is a fine example of a late Federation Bungalow style building. The other residences are representative of their age and type.
The public picnic grounds and gardens attached to the Cordeaux Dam contain a cultural landscape resource - including remnants of its interwar period plantings, layout and detailing, and extensive areas of bushland. There is evidence in the landscape design, particularly in the use of palms and tree ferns and battered stonework retaining walls, of an intention to continue the Egyptian Revival references apparent in the design of the main dam structures.
Cordeaux Dam was listed on the New South Wales State Heritage Register on 18 November 1999 having satisfied the following criteria.
The place is important in demonstrating the course, or pattern, of cultural or natural history in New South Wales.
Cordeaux Dam is constructed within the Upper Nepean catchment area which was developed with the completion of the Cataract and Nepean tunnels in 1888, as the fourth source of water supply for Sydney. The potential of the Upper Nepean Catchment Area to supply water was fully developed through the construction of four major dams between 1903 and 1936. Cordeaux Dam is the second of these dams to have been completed. The Upper Nepean Catchment Area continues to supply the regions of Sydney and Illawarra.
Cordeaux Dam was the fourth of the major water supply dams constructed in NSW during the first half of the twentieth century. The design and technologies used in the construction of the dam are representative of the methods developed by the Public Works Department of NSW at the time.
In conjunction with the completion of Avon Dam in 1927, the impounded water of the Cordeaux catchment area provided one of the major sources of water for domestic and industrial consumption in metropolitan Sydney, the largest city in New South Wales. In providing water for metropolitan Sydney during this era the dam, in ensuring security of supply, contributed to the extensive residential, commercial and industrial development of Sydney during the 1920s and 1930s.
The place has a strong or special association with a person, or group of persons, of importance of cultural or natural history of New South Wales's history.
The design and construction of Cordeaux Dam was undertaken by the Water Supply and Sewerage Branch of the NSW Public Works Department. The construction of the dam drew upon the knowledge and experience of a number of engineers employed in the Branch at the time, including Ernest M. de Burgh (Chief Engineer). The successful completion of the dam and its continuation of use as a water supply dam are a lasting testament to the professional capabilities of the Federation/Inner War era generation of engineers of the Public Works Department.
The tract of Eucalyptus bordering the encircling road of the upper picnic area was planted out by Board members of the former Water Board in 1928. The trees have particular memorial associations with past identities of the Board.
The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.
The wall of Cordeaux Dam is an engineering work imbued with a sense of aesthetic values expressed through the long curved wall set within the valley of the Cordeaux River.