Take a journey in time - water supply 1778 to now
Take a journey in time - water supply 1778 to now
The British settled Australia in January 1788. Some 859 convicts, soldiers, and administrators set up camp around the stream that emptied into Sydney Cove. Coming from a place where rivers always flowed and it rained all year round, they knew little about conserving or storing water.
The few local Aboriginal people to survive the smallpox epidemic brought by the British retreated inland to find shelter, food and water.
The drought that year
Governor Arthur Phillip had tanks carved into the sandstone banks of a stream to store water during the dry summer of 1789-90. It became known as the Tank Stream. This was the start of the search for a reliable and permanent water supply for Sydney.
As Sydney grew, the meagre fresh water supply from the Tank Stream was threatened by pollution, despite a 16-metre wide greenbelt reserve on both sides. A reward was offered to anyone who could find a new source of fresh water.
After three days exploring, two adventurers located a creek at Rushcutters Bay to supplement the colony's water supply along with various new wells.
The Tank Stream became so polluted it was abandoned as a water supply. Settlers relied on wells and water carted from the Lachlan Swamps (now Centennial Park).
John Busby supervised convicts to build a 3.4 kilometre bore (tunnel) from Lachlan Swamps to the city racecourse (now Hyde Park). Water was then piped to a valve at the corner of Park and Elizabeth Streets where water carts were filled.
An 18-month drought reduced the water supply through Busby's Bore to a trickle. At the height of the drought a bucket of water from the bore cost sixpence (five cents), half the average weekly wage.
The first reticulation pipes connected about 70 houses directly to Busby's Bore for 10 shillings (one dollar) a year. People could also buy water at new public fountains around Sydney.
The deep and narrow gorge of the Warragamba River, at the exit to Burragorang Valley, was identified as an ideal place for a dam by Polish explorer Count Paul Strzelecki. Two decades later, in 1869, a member of the Commission on the Water Supply of Sydney, Lieutenant T Woore RN, recommended a 50-metre high rock wall dam across the Warragamba River. It would still take nearly a century to overcome the limitations of engineering and economics before a dam could be built across the gorge.
A special committee of inquiry was set up to 'report on the best means of procuring a permanent supply of water to the City of Sydney'. This led to the design of the Botany Swamps Water Supply Scheme.
A steam-powered pump was installed to draw more water from the Lachlan Swamp to supply Busbys' Bore. The bore supplied drinking water into the 1890's. Construction began on the Botany Swamps Water Supply Scheme.
The Botany Swamps Water Supply Scheme began operating. Water draining east from the city into swamps on Botany Bay was dammed and pumped to a storage reservoir at Crown Street and later at Paddington. The system was continually updated to meet the growing city's ever-increasing demand for water.
The Upper Nepean Scheme was built following a Royal Commission recommendation to develop the 1,000 square kilometre Upper Nepean catchment south of the city. It would capture the headwaters of the Nepean River by building a weir at Pheasants Nest below the junction of the Cordeaux and Avon Rivers, and connect by tunnel to a second weir at Broughtons Pass, across Cataract River. The water would be gravity fed through 64 kilometres of tunnels, canals and pipes (known collectively as the Upper Canal) into a huge reservoir at Prospect, then to the city and suburbs.
The first Special Area, the Metropolitan Special Area, was declared to protect the land of the Upper Nepean catchment. This large area of undisturbed bushland around the Upper Nepean water storages would act as a buffer to stop nutrients and other pollutants from entering the drinking water storages. Special Areas were later declared in the O'Hares Creek (1927), Woronora (1941), Warragamba (1942), Shoalhaven (1970), Fitzroy Falls (1973), Wingecarribee (1973), Blue Mountains (1991) and Prospect (2008) catchments.
Demand for water continued to outstrip supply until Sydney had only 10 days of storage in the Botany Swamps Scheme. The Upper Nepean Scheme was yet to be finished.
To avert disaster, Hudson Brothers of Clyde was commissioned to build a temporary scheme of elevated pipelines, canals and flumes to deliver water from the unfinished Upper Nepean Scheme to the city's supply system at Botany.
The first stage of the Upper Nepean Scheme was completed.
Prospect Reservoir, the first earthfill embankment dam in Australia, was completed. It stored water fed by gravity from the Upper Nepean Scheme via the Upper Canal. From Prospect Reservoir, the Lower Canal led to a basin at Guildford, where water was piped to several service reservoirs around the city. Hudsons' Temporary Scheme was dismantled.
The Board of Water Supply and Sewerage (later the Metropolitan Water Sewerage and Drainage Board) was created to manage all water supply and sewerage infrastructure owned by the government or city councils.
Severe drought in the Upper Nepean catchment. The level of Prospect Reservoir dropped so low that water could no longer be fed by gravity to Sydney and a pumping station was built.
Another Royal Commission recommended augmenting the Upper Nepean Scheme with four new dams to be built above the two existing weirs.
Rigorous water restrictions in Sydney. Garden hoses, watering cans and buckets were banned.
Cataract Dam, above Broughtons Pass Weir on the Cataract River, was the first of the four new dams built to support the Upper Nepean Scheme. All Upper Nepean Scheme dams were mass gravity dams - the enormous mass of the walls kept them in place. Cataract Dam wall was built using 2- 4.5 tonne sandstone blocks quarried on site. The castle-like sandstone structures on top of the wall and fanciful outlet tower evoke a sense of the importance of the structure. It was the biggest engineering project in Australia and the fourth biggest in the world at the time.
Cottages for men with families, and barracks for single men, were built to house the workers for each of the new dams on the Upper Nepean. The towns had a school, amusement hall, medical clinic and ambulance. As each dam was completed, much of the town was dismantled and moved to the next site along with most of the workers.
Lake Medlow Dam on Adams Creek near Blackheath was completed in 1907, the first of the Blue Mountains dams. It was also the first thin arch high stress concrete dam built in NSW, and one of the thinnest dam walls in the world.
The following year, the concrete arch Middle Cascade Dam near Katoomba was completed in 1908. It was supplemented by the Lower Cascade (1926) and Upper Cascade (1938) dams which were both earth embankment dams with concrete cores.
Cordeaux Dam, across the Cordeaux River upstream of the Pheasants Nest Weir, was the second Upper Nepean Scheme dam to be completed. It was similar to Cataract Dam, but with arched pylons at each end of the wall featuring stylised Egyptian motifs in the Art Deco style.
Avon Dam across the Avon River was the next Upper Nepean dam to be completed. It was similar to the Cataract and Cordeaux dams, though its curved wall and outlet towers were very simple in design.
Building the Nepean Dam, the smallest and last dam in the Upper Nepean Scheme, stopped for two years during the Great Depression.
Woronora Dam was built across a 100 metre deep sandstone gorge on the Woronora River to supply the southern suburbs of Sydney. Construction of the curved wall began using cyclopean blockwork, like the Upper Nepean dams, but the dam was finished in mass concrete. Many workers were laid off during the Great Depression. Their families were allowed to stay in the temporary Woronora township while workers travelled to find jobs elsewhere and waited for the project to restart.
In the Blue Mountains, NSW Railways began building Woodford Creek Dam in 1927 to supply water for its steam locomotives. During construction, the dam was adapted for domestic water supply before its completion in 1928.
Strict water restrictions were introduced in Sydney during a record eight year drought.
In 1938, Samuel T Farnsworth, Engineer-in-Chief of the Metropolitan Water Sewerage and Drainage Board, proposed developing the full water supply potential of the Warragamba River by building Warragamba Dam. Preparations began in 1942 but Farnsworth did not live to see his creation completed. He died in 1948.
The Warragamba Emergency Scheme began in response to the record eight-year drought. A 15-metre high overshot weir and pumping station were built on the Warragamba River and a 1.2 metre diameter pipeline was laid to Prospect Reservoir. The scheme started supplying water in May 1940.
A 'dummy' pumping station was built near the Ryde Pumping Station to draw attention away from this piece of infrastructure in the event of air attack. The Lower Canal was camouflaged and torpedo nets were placed in Upper Nepean dams to protect them from air attacks.
Choosing the site for Warragamba Dam involved drilling and reassembling 1,700 metres of 75 millimetre diameter rock cores. These were cut from a three-kilometre section of the river gorge. Findings of these geographical investigations informed geologists where to locate the dam. The final site was selected in 1946.
In 1942, Greaves Creek Dam was built on Greaves Creek, between Blackheath and Katoomba, in the Blue Mountains catchment.
At its peak, Warragamba township had 3,500 residents including 1,000 children, more than 500 cottages, single men's and women's barracks, a 'wet canteen' (pub), 15 kilometres of roads, a telephone exchange, post office, medical clinic, school, pre-school, two churches, town hall, police station and 14 shops.
Trees were cleared from the Burragorang Valley to be flooded by the lake that would form behind Warragamba Dam. The government compulsorily acquired properties – buildings were demolished or moved, residents evicted, and known graves relocated according to the wishes of relatives.
The Warragamba River was diverted so excavation for the dam could start. Two coffer dams, or temporary dams, were built across the river – one upstream and one downstream – to isolate the site and keep it dry. A 540-metre diversion tunnel was cut through the east side of the gorge to redirect the river around the site.
The technology of two centuries met in the River Control Office, perched high up on the edge of the gorge overlooking the site. Operators read the river level gauge through a 19th century telescope. People upstream of the site reported any local rainfall over 25 millimetres, and river levels were monitored and communicated back to the River Control Office by radio signal. When a flood was expected, equipment and workers were driven or lifted out of the site. After a flood, thousands of tonnes of silt and debris had to be cleared before work could begin again.
From 1948 until 1960, about 1,800 people (mostly men) of 30 nationalities worked three shifts a day, seven days a week, to build Warragamba Dam. Single men lived in pre-fabricated cottages in the new Warragamba township built for the project. There were 35 resident engineers and other professional and salaried staff. Senior staff lived in houses overlooking the site, and single female staff stayed in segregated barracks or with families in the town. Two pedestrian suspension bridges linked the town and barracks to the construction site.
Workers began to excavate the foundations of Warragamba Dam. Five years later 2,300,000 tonnes of sandstone had been removed. As this tremendous mass of rock was removed the underlying rock strata expanded upwards as predicted by the dam engineers.
By 1953 the river bed had been excavated down to a consistent sandstone foundation. Cracks and fissures in the bedrock were injected with high pressure grout and a geological fault zone on the western side was removed and stabilised with concrete. The upstream coffer dam is visible in the photo above.
The dam construction involved extensive tunnelling works. Warragamba Dam was built as a series of interlocking 15 by 15 metre concrete blocks staggered in 1.5 metre 'lifts'. Concrete for each block was poured into formwork and compacted by gangs of men using pneumatic vibrators. Copper sheets and bitumen seals were put between the blocks to minimise water seepage. The completed dam wall has a mass of 3 million tonnes.
Walking draglines with a five cubic yard (3.8 cubic metre) bucket dredged river gravel and sand from McCann's Island on the Nepean River near Penrith. It was delivered to a nearby washing, crushing and grading plant. Two and a half million tonnes of aggregate (graded river stone and sand) travelled 22 kilometres overland to Warragamba in buckets on an aerial ropeway.
Twenty-five separate floods inundated the site, dumping tonnes of debris and silt.
A continuous concrete production line ran 24 hours a day, seven days a week, for seven years. Block 21, where the wall meets the rock on the western side of the gorge, was the first concrete poured.
Aggregate (crushed river stone and sand) was stockpiled on site to keep concrete production going. Buckets arrived every 30 seconds, delivering 172 tonnes an hour continuously for seven years. The buckets were either emptied straight into service bins to be mixed with cement, or onto a stockpile.
A convoy of trucks brought 271,000 tonnes of cement from Berrima to be mixed with the aggregate in one of two concrete batching plants. The largest refrigeration plant in Australia manufactured ice to add to the mix, controlling the thermal reaction and preventing the concrete from cracks.
Over 640 kilometres of steel tube were laid in the formwork to circulate chilled water from the refrigeration plant through the setting concrete. This cooled the concrete to its final stabilised temperature in months instead of an estimated century at normal cooling rates. When cool, the concrete blocks shrank away from each other, leaving open joints. The joints were filled under pressure with cement grout to help to seal the dam together.
Pre-measured batches of concrete were loaded into buckets on rail locomotives that travelled along a terrace cut into the side of the gorge. The buckets were hooked up onto overhead cableways, moved over the site, and lowered to place the concrete where it was needed.
An 18 ton (18.2 tonne) cableway across the gorge did the heavy lifting on the project. It was used to remove excavated rock, deliver and move heavy equipment, place concrete, evacuate the site before a flood, and to clean it up afterwards. A 10-tonne cableway served the downstream section or apron of the dam.
Critical operational components were built into Warragamba Dam. Four 84-inch (1200 millimetre) diameter needle valves were installed, connecting the water supply outlets to a steel pipeline that ran from the dam to Prospect Reservoir.
A pair of automatically operated 40-foot (12 metre) long radial flood gates were installed at the top of the Warragamba Dam wall, either side of a 90-foot (28 metre) long central drum gate.
A 50 megawatt hydro-electric power station was built in the dam, to operate only when excess water was available in the lake.
When the dam opened, Syndeysiders arrived in droves to marvel at the engineering triumph. At the time, it was one of the biggest dams in the world and the world's largest domestic water supply dam.
The opening of Warragamba Dam on 14 October 1960 allowed Sydney to catch its breath in the race to secure a water supply, but not for long.
The Shoalhaven Scheme was designed as a dual-purpose water supply and hydro-electric power generation scheme. Water from Fitzroy Falls (1974) and Wingecarribee (1974) reservoirs, and Lake Yarrunga behind Tallowa Dam (1976), supplies local communities and can supplement other Sydney storages. Water can be pumped from Lake Yarrunga to Fiztroy Falls and then onto Wingecarribee Reservoir in the Southern Highlands. It can then be released down the Wollondilly River to Warragamba Dam, or sent via canals and pipelines to the Nepean and Avon Dams which supply the Illawarra Region.
A traditional Australian way to save water in a drought was to put a house brick into the toilet cistern to reduce the amount of water in it. In 1980, Bruce Thompson of Caroma developed a cistern with two buttons and flush volumes (11 litres and 5.5 litres). The cistern saved 32,000 litres of water a year per household when it was trialled in a small South Australian town. In 1994 the company designed a six and three litre dual flush cistern.
When rain and flood event studies showed that Warragamba Dam could experience floods much larger than it was originally designed for, the height of the dam wall was increased by five metres. This was the first of two steps to ensure the dam met modern international dam safety standards. The wall was raised and strengthened using post-tensioned steel cables to tie the upper wall to its base. In 1988, Cataract Dam was also strengthened using post-tensioned anchors, Cordeaux Dam was upgraded with a system of drains in the wall and foundations, and Woronora Dam was upgraded with wall and foundation drains.
Responsibility for the Blue Mountains dams (Cascades Dams, Lake Medlow Dam, Greaves Creek Dam and Woodford Creek Dam) and water supply was transferred from Blue Mountains City Council to the Sydney Water Board.
Nepean Dam was upgraded and strengthened by post-tensioned anchors, a downstream rock-fill embankment and a concrete-lined spillway on the right abutment.
The Prospect Water Filtration Plant was commissioned. Raw water from Warragamba and the Upper Nepean dams could now go directly to the treatment plant, bypassing Prospect Reservoir. The filtration plant can also draw from the reservoir in times of high demand.
The new millennium began in drought. A number of strategies to secure Sydney's water supply were investigated and implemented through the NSW Government's Metropolitan Water Plan. Climate change and the environment became topics of increased public discussion.
Warragamba Dam was closed to the public in 1998 to allow a $240 million program of important upgrades to take place. These key mechanical, electrical and operational upgrades were designed to allow the dam to withstand a one-in-100,000 year flood and improve dam operations.
The Warragamba Dam upgrades included:
- $111 million auxiliary spillway to withstand a worst-case scenario flood
- $62 million deep water pumping station and other works to allow access to deep water in the dam during drought
- $23 million upgrade of the dam's entire electrical network
- $20 million operations building, visitor centre and new precinct works
- $15 million upgrade of the valve house lifts, crest cranes and stoplog rails
- $9 million replacement of pipeline valves, spares and inspections as well as fencing and painting.
The construction of the Warragamba Dam Auxiliary Spillway, begun in 1998, was completed. The spillway is located on the east bank of the dam and is designed to operate in extreme floods by allowing floodwaters to pass safely around the dam, reducing the pressure on the dam wall. This protects the areas downstream of the dam from the devastating effects of a dambreak and safeguards Sydney's water supply. The auxiliary spillway would only come into effect in a flood that had one chance in 750 of happening in any given year (a 1:750 flood). The worst flood on record for the Hawkesbury-Nepean Valley is a 1:200 year flood, which happened in 1867. The auxiliary spillway is designed to protect the dam up to a 1:100,000 year flood.
Woronora Dam's outlets were modified to enable environmental releases.
In 2003, Sydney's water supply levels fall below 60% and level 1 water restrictions were introduced.
As the drought continued, 820,000 megalitres of water was transferred from Tallowa Dam on the Shoalhaven River to Sydney and the Illawarra. During this drought period, more than 30% of greater Sydney's water came from Tallowa Dam. Without the transfers from the Shoalhaven River, total dam storage would have dropped to around 13%.
In 2004, level 2 water restrictions were introduced when the total water supply storage levels fell below 50%. These restrictions further limited hand watering of gardens and the filling of new or renovated pools.
BASIX, the Building Sustainability Index, was introduced by the NSW Government to ensure new houses use less drinking water and produce fewer greenhouse gas emissions by setting energy and water reduction targets.
In 2005, level 3 water restrictions were introduced when the total water supply storage levels fell below 40%. At the same time, environmental flow releases from dams to the rivers downstream were halved to conserve water.
Deep water access projects at Nepean and Warragamba dams added about six months of water supply to the system and increased the amount of water that can be drawn out of the dams each year by about 40 billion litres. Deep water lies below the lowest outlet point in a dam where water can be extracted. To access the deep water at Warragamba Dam, a team of international saturation divers, or aquanauts, worked around the clock for two weeks to remove a 17 tonne block from the base of the dam wall. Working at a depth of 85 metres, the divers cut a two-metre hole through a section of the dam wall to allow water deep in the dam to be pumped into the Warragamba pipeline.
The NSW Government's Metropolitan Water Plans released in 2004 and 2006 included investigation of underground sources of water, major recycling projects and desalination to secure an ongoing supply of water.
Groundwater bore fields at Kangaloon in the Southern Highlands and Leonay and Wallacia in western Sydney were investigated as a possible future supplement to the drinking water supply system.
'Sustaining the Catchments - a regional plan for Sydney's drinking water catchments' released. The plan helped protect catchment health and the quality of water flowing to the dams.
The 235-metre long suspension bridge over the deep Warragamba River gorge was removed. Closed in 1987 due to termite damage, the bridge was irreparably damaged by the Christmas Day bushfires in 2001.
The NSW Government opened one of the biggest industrial water recycling schemes in Australia at Wollongong. Nowadays, the plant provides up to 20 million litres of high quality recycled water each day to BlueScope Steel at Port Kembla. This replaces up to 7.3 billion litres of drinking water each year that previously came from Avon Dam.
A $23 million electrical upgrade at Warragamba Dam replaced 170 kilometres of cables inside the dam wall, enough to stretch from Warragamba to Goulburn. A team of 25 electricians replaced or installed 233 light switches, 155 power outlets, 500 light fittings and 1,200 energy efficient fluorescent bulbs.
In February 2007, Sydney's total water supply fell to an historic low of 33.9%. Warragamba's storage capacity was at its lowest 32.5%.
In June 2007, the Warragamba catchment received 210 millimetres of rain. Warragamba storage increased from 33.5% to 50.1%. The total system storage increased from 36.9% to 55.0% in two weeks.
Construction ended in 2007 on a $56 million raw water pumping station at Prospect Reservoir. It provides an alternative raw water supply if supply from other dams is unexpectedly interrupted, and allows the Warragamba pipelines to be taken out of service for maintenance.
Important works at Tallowa Dam on the Shoalhaven River were completed to improve river health. The $30 million project included new infrastructure to allow for environmental releases from the dam that better mimic natural river flow. The amount of water released increased from up to 90 megalitres a day to peaks of more than 370 megalitres, providing significant environmental benefits for the whole system. A new state-of-the-art fishlift was also built to transport migrating fish up and over the dam wall. The mechanical fishlift was a first for NSW and the first of its kind to be fitted to an existing dam in Australia.
With dam levels holding above 65%, pre-drought environmental flow releases were restored from Cataract, Cordeaux, Nepean and Warragamba dams to benefit the health of the Hawkesbury-Nepean River. At the same time a new environmental flow was released from Avon Dam following a $9.6 million upgrade.
Water Wise Rules began on 22 June 2009 replacing the previous restrictions. These long term rules were introduced as dam storage levels remained at around 60% for 12 months.
In November 2009, Warragamba Dam was re-opened to the public after being closed for more than a decade for major upgrades. The community could enjoy new visitor and picnic facilities including viewing platforms overlooking the dam and Lake Burragorang.
Work began on a major upgrade to the drum and radial gates at Warragamba Dam, which was completed in 2012. The gates are a safety mechanism used to control the release of flood water from the dam. The upgrade involved installing locking systems to secure the gates in the fully open position. This mechanism will allow the radial gates to be moved out of the way in extreme floods in order to protect the gates. The gates were also strengthened and refurbished.
Sydney's desalination plant came online in January 2010. The plant can provide up to 15% of our drinking water. Desalination uses a technology called reverse osmosis to remove the salt from sea water. The plant is powered using 100% renewable energy from a purpose built wind farm.
The Healthy Catchments Strategy 2009-2012 is developed. The strategy outlines how to protect and improve the health of Sydney's drinking water catchments. The strategy included consultation with local councils, landholders, government agencies, industry and other community stakeholders. It describes how the best science and technical information, best management practices, and experience of landholders is used to identify the key priorities and activities for protecting water quality.
Warragamba Dam celebrates its 50th anniversary in October 2010. The community and former workers play a key part in the celebration of this significant milestone in the history of Sydney's water supply. The anniversary recognised the wonderful achievements of the dam builders and began with a special ceremony to commemorate their contribution and the unveiling of a permanent memorial to honour the men who were killed while working to build the dam.
Following high rainfall across Sydney's water supply catchments, Warragamba Dam spilled for the first time since 1998. The evening of Friday 2 March 2012 saw water spilling from the dam through its central drum gate.
Major works replacing and relining large pipelines that distribute water from Warragamba Dam to Prospect Water Filtration Plant were completed. It was the first time in 20 years that both pipelines had been closed at the same time. Over a period of two months the pipes received an overhaul including valves being replaced and repairs to the internal lining.