Elan Valley Reservoirs
Encyclopedia
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
s in the Elan Valley
Elan Valley
The Elan Valley is a river valley situated to the west of Rhayader, in Powys, Wales, sometimes known as the "Welsh Lake District". It covers of lake and countryside....
in Powys
Powys
Powys is a local-government county and preserved county in Wales.-Geography:Powys covers the historic counties of Montgomeryshire and Radnorshire, most of Brecknockshire , and a small part of Denbighshire — an area of 5,179 km², making it the largest county in Wales by land area.It is...
, Mid Wales
Mid Wales
Mid Wales is the name given to the central region of Wales. The Mid Wales Regional Committee of the National Assembly for Wales covered the counties of Ceredigion and Powys and the area of Gwynedd that had previously been the district of Meirionydd. A similar definition is used by the BBC...
(also known as the "Welsh Lake District"), using the river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s Elan and Claerwen
Claerwen
The Claerwen reservoir and dam in Powys, Wales, were the last additions to the Elan Valley Reservoirs system built to provide water for the increasingly demanding city of Birmingham, in neighbouring England. Built mainly of concrete, the exterior of the dam face is dressed stone. The dam itself is...
. The reservoirs are Claerwen
Claerwen
The Claerwen reservoir and dam in Powys, Wales, were the last additions to the Elan Valley Reservoirs system built to provide water for the increasingly demanding city of Birmingham, in neighbouring England. Built mainly of concrete, the exterior of the dam face is dressed stone. The dam itself is...
, Craig Goch, Pen-y-Garreg, Garreg Ddu, and Caban Coch.
The work carried out over a hundred years ago to build the Elan Valley dams and reservoirs was only part of the huge undertaking. Almost as impressive was the challenge of delivering the enormous quantities of water by gravity alone, across very hilly country and over many river valleys, to the new Frankley Reservoir
Frankley Reservoir
Frankley Reservoir is a semi-circular reservoir for drinking water in Birmingham, England. Its construction was authorised by the Birmingham Corporation Water Act of 1892...
on the outskirts of Birmingham
Birmingham
Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...
in the West Midlands
West Midlands (region)
The West Midlands is an official region of England, covering the western half of the area traditionally known as the Midlands. It contains the second most populous British city, Birmingham, and the larger West Midlands conurbation, which includes the city of Wolverhampton and large towns of Dudley,...
of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. This involved building the 73 mile long Elan aqueduct
Elan aqueduct
The Elan aqueduct, crosses Wales and the Midlands of England, running eastwards from the Elan Valley Reservoirs in Powys to Birmingham's Frankley Reservoir, carrying drinking water for Birmingham....
, down which the water travels at less than 2 miles per hour, taking one and a half days to get to Birmingham.
The Elan aqueduct drops only 52m over a length of 118 km – a gradient of 1:2300. It runs from the Elan Valley to Frankley
Frankley
Frankley is a village and civil parish in the Bromsgrove district of Worcestershire, near the border with Birmingham. The modern Frankley estate is part of the New Frankley civil parish in Birmingham, and has been part of the city since 1995. The parish has a population of 122.-St Leonards...
in Birmingham. There are several signs of the aqueduct between these points, in the form of brick aqueducts, exposed pipelines and red brick valve houses on hillsides.http://www.geograph.org.uk/photo/619851
Birmingham's tap water is noted for being exceptionally soft, with a low percentage of dissolved minerals
Mineral water
Mineral water is water containing minerals or other dissolved substances that alter its taste or give it therapeutic value, generally obtained from a naturally occurring mineral spring or source. Dissolved substances in the water may include various salts and sulfur compounds...
.
Description
- Caban Coch with Garreg Ddu – 35,530 megalitre capacity
- Pen-y-garreg – 6,055 megalitre capacity
- Craig Goch – 9,222 megalitre capacity
- Claerwen – 48,300 megalitre capacity.
In addition to the four main dams, there are three other dams at the site:
- The Dol y Mynach dam – the masonry foundations and the base of this dam were laid in the Claerwen Valley at the time that the Elan Valley dams were being constructed. It was to be one of a series of three dams which were to hold back the waters of the Afon Claerwen making even more water available to the city of Birmingham in future times. The project was never completed but the base was laid in advance because the water level of the Caban Coch would have submerged the site once the reservoir was full. The project became completely redundant when newer materials and superior engineering led to the construction of the Claerwen dam higher up the valley.
- The Nant-y-Gro dam – this small dam was constructed in the early stages of the project to supply water to the navvies village at the site; it was most famously used during the Second World War by Sir Barnes Wallis during trials of the explosive charges he intended to use in the bouncing bombsBouncing bombA bouncing bomb is a bomb designed specifically to bounce to a target across water in a calculated manner, in order to avoid obstacles such as torpedo nets, and to allow both the bomb's speed on arrival at the target and the timing of its detonation to be pre-determined...
which later targeted the Ruhr dams. - The Garreg Ddu dam – although often referred to as a viaduct, the archways of this structure are built on a submerged dam; this hidden dam maintains the level of the reservoir behind it in times of extreme drought, and guarantees water can be extracted at the Foel Tower at sufficient height to enter the gravity driven aqueduct to the FrankleyFrankleyFrankley is a village and civil parish in the Bromsgrove district of Worcestershire, near the border with Birmingham. The modern Frankley estate is part of the New Frankley civil parish in Birmingham, and has been part of the city since 1995. The parish has a population of 122.-St Leonards...
reservoir in Birmingham.
History
Birmingham Corporation Water Department
The Birmingham Corporation Water Department was responsible for the supply of water to Birmingham from 1876 to 1974. It was also known as Birmingham Corporation Waterworks Department.-Early History 1808 - 1876:...
to supply clean water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
to the Birmingham
Birmingham
Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...
area, by gravity feed along an aqueduct
Aqueduct
An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....
with a gradient
Gradient
In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....
of 1 in 2,300. the engineer in charge was James Mansergh.
Before the construction of the dams, the standard gauge
Standard gauge
The standard gauge is a widely-used track gauge . Approximately 60% of the world's existing railway lines are built to this gauge...
Elan Valley Railway
Elan Valley Railway
The Elan Valley Railway was a Welsh industrial railway built to assist in the construction of the Elan Valley Reservoirs in mid Wales. It was in operation from 1896 up until about 1912/1916.- History :...
was built to all dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
sites from a junction of the Mid Wales Railway, at Rhayader
Rhayader
Rhayader is a market town and community in Powys, Mid Wales. It has a population of 2,075, and is the first town on the banks of the River Wye, from its source on the Plynlimon range of the Cambrian Mountains....
. The railway was also built along the dams themselves at varying heights, on wooden scaffolding supported by concrete parapets. The railway itself went as far as the never-completed Dolymynach dam (lower down the valley from the later Claerwen
Claerwen
The Claerwen reservoir and dam in Powys, Wales, were the last additions to the Elan Valley Reservoirs system built to provide water for the increasingly demanding city of Birmingham, in neighbouring England. Built mainly of concrete, the exterior of the dam face is dressed stone. The dam itself is...
dam), which had to be built concurrently with the Elan dams as the Caban Coch reservoir would otherwise have flooded this construction site. However, this railway was never subsequently needed, and road transport only was used for construction of the Claerwen dam over 40 years later.
The navvies
Navvy
Navvy is a shorter form of navigator or navigational engineer and is particularly applied to describe the manual labourers working on major civil engineering projects...
(construction workers) lived in a village of wooden huts, which had a guard to prevent the illegal importing of liquor. This later became the permanent Elan Village (see Elan Valley
Elan Valley
The Elan Valley is a river valley situated to the west of Rhayader, in Powys, Wales, sometimes known as the "Welsh Lake District". It covers of lake and countryside....
). When construction of the dams was complete, most of the navvies moved on to the Derwent Valley
Upper Derwent Valley
The Upper Derwent Valley is an area of the Peak District National Park in England. It largely lies in Derbyshire, but its north eastern area lies in Sheffield, South Yorkshire...
in Derbyshire
Derbyshire
Derbyshire is a county in the East Midlands of England. A substantial portion of the Peak District National Park lies within Derbyshire. The northern part of Derbyshire overlaps with the Pennines, a famous chain of hills and mountains. The county contains within its boundary of approx...
.
The scheme was opened by King Edward VII and Queen Alexandra on 21 July 1904.
World War II
They played an important role in World War IIWorld War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
when the 35 foot (11 m) high Nant-y-Gro dam was used by Barnes Wallis
Barnes Wallis
Sir Barnes Neville Wallis, CBE FRS, RDI, FRAeS , was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the RAF in Operation Chastise to attack the dams of the Ruhr Valley during World War II...
to test his idea of detonating explosives against a dam wall in order to breach it. These experiments culminated in the Dambusters
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...
breaching of the dams in the Ruhr Valley. The remains of the breached Nant-y-Gro dam can still be seen today in the same state as it was left in 1942. The dam is now partially obscured by trees, but its location is marked by an interpretative plaque. The Derwent Dam was also used by the Dambusters for practice, though it was not breached.
After the Dambuster Raid steel cables were placed across Caban Coch reservoir to prevent enemy seaplanes landing on the lake.
Aborted expansion scheme
In the early 1970s it was proposed that the Craig Goch reservoir should be substantially increased in size with a new and higher downstream dam together with another dam to the north-west, impounding water that would otherwise have flowed down the YstwythRiver Ystwyth
The River Ystwyth is a river in the county of Ceredigion, Wales. Its source is a number of streams that include the Afon Diliw, located on the border of Ceredigion and Powys in the Cambrian Mountains....
valley. This scheme would have created a huge reservoir dwarfing all others in Mid Wales, and flooding miles of wild upland valleys. The proposals were eventually abandoned in the face of reducing projections for industrial
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...
water demand and an increasing awareness of the environmental issues that such an expansion might create.
The reservoirs today
The reservoirs are now owned by Dŵr Cymru Welsh WaterWelsh Water
Dŵr Cymru Welsh Water is a company which supplies drinking water and wastewater services to most of Wales and parts of western England.It is regulated under the Water Industry Act 1991.-History:...
.
Although the filtration works further down the valley is run by Severn Trent Water.
A scale model of the reservoir network, in the form of ornamental ponds, is in Cannon Hill Park
Cannon Hill Park
Cannon Hill Park is a park located in south Birmingham, England. It is the most popular park in the city, covering consisting of formal, conservation, woodland and sports areas...
in Birmingham.
In popular culture
- Elizabeth Clarke wrote The Valley (published by Faber & Faber, 1969) an account of Welsh hill farming life in the valley between the two main periods of construction. Many references are made to the dams, as well as an account of the later enquiry from the hill farmers' point of view.
- Francis Brett Young researched the Elan Valley as the basis for his novel The House under the Water [Heinemann, 1932] imagining how the scene may have appeared in 1887.