Junction Reefs Dam is a heritage-listed former mining dam on the Belubula River at Lyndhurst, Blayney Shire, New South Wales, Australia. It was designed by Oscar Shulze and built by Schulze in 1896. It was the first multi-arch dam built in Australia. It is also known as Belubula Dam. The property is owned by Department of Planning and Infrastructure (State Government). It was added to the New South Wales State Heritage Register on 2 April 1999.
History
The Junction Reefs area on the Belubula River near Mandurama has been the site of intermittent gold production since 1870. Belubula Dam was built in 1896 in a deep narrow ravine at an altitude of about 61m above the crushing mill and was completed in nine months. It was built with day labour about 40 men strong under the personal supervision of the eminent civil engineer Oscar Schulze.
This arched dam was the first of its type constructed in Australia and Schulze was one of the few Australian visionaries. He advocated improved windmills and waterwheels for heavy industry and campaigned against the use of steam gas and petroleum engines when alternative energy was available. Junction Reefs Dam and its hydro system gave him the opportunity to demonstrate his theories and apply them to the mining industry.
After the dam was completed he delivered a paper to the Australian Institute of Mining Engineers at Melbourne in 1897. He elaborated on his theory and enunciated how the final design for the dam evolved. The brick buttress was the accepted design as it was the cheapest of the furable designed and was the quickest to build. Good brickmakers clay was on the northern bank adjacent to the dam site. Once built the water backed up the river 2 kilometres and impounded 2ml and would keep the machinery running for three months if the river ever stopped running, which seldom happened.
Description
The dimensions of the Belubula Dam are as follows: its total length along the crest, including bye-wash, is 431 feet, which is not curved but straight on plan; the greatest height of the structure at the deepest foundation is 60 feet; the height of the brickwork 36 feet 9 inches; the height of the rugged contour of the bed rock.
As has already been stated there are six buttresses, 28 feet apart from the centre to centre, each 40 feet long, 12 feet wide on top at the end where they outer end. The front wall of the foundations increase slightly in thickness downwards. On top of these foundations the buttresses were carried up as brick-masonry, each forming a sextant of a circle of 36 feet 2 inches radius and decreasing in thickness from the centre towards the circumference from 8 feet 6 inches to 4 feet.
These buttresses serve as piers for the support of five brick arches of elliptical shape which decrease in thickness upwards, from 4 feet thick at the foot to 1 foot 7 inches on top, and have a lean of 60 degree. The spandrils between these arches were faced flush with concrete which covers the crown of the arches were faced flush with concrete which covers the crown of the arches 12 inches thick, thus making the arches 2 feet 7 inches thick at the thinnest part. On each side of this central portion of the dam the ground rises, and the wall was continued about 100 feet long, up and into the hill sides to firm rock faces, as concrete masonry, with the same batter of 60 degree in front (that is on the water side) as the arches part, but almost vertical at the back, the width on top being 2 feet.