Lake Vyrnwy, Powys (Llanwyddyn) - RP postcard by T Sergeant c.1950s

• Postcard

   

• Picture / Image:  Lake Vyrnwy, Llanwyddyn - real photo postcard - photo by T. Sergeant - shows the straining tower
• Publisher:  Friths LWDN.24
• Postally used:  no
• Stamp:  n/a
• Postmark(s): n/a
• Sent to:  n/a
• Notes / condition: 

Please ask if you need any other information and I will do the best I can to answer.

Image may be low res for illustrative purposes - if you need a higher definition image then please contact me and I may be able to send one. No cards have been trimmed (unless stated).

------------------------------------------------

Postage & Packing:

Postage and packing charge should be showing for your location (contact if not sure).

No additional charges for more than one postcard. You can buy as many postcards from me as you like and you will just pay the fee above once. Please wait for combined invoice. (If buying postcards with other things such as books, please contact or wait for invoice before paying).

Payment Methods:

UK - PayPal, Cheque (from UK bank) or postal order

Outside UK: PayPal ONLY (unless otherwise stated) please.   NO non-UK currency checks or money orders (sorry).

NOTE: All postcards are sent in brand new stiffened envelopes which I have bought for the task. These are specially made to protect postcards and you may be able to re-use them. In addition there are other costs to sending so the above charge is not just for the stamp!

I will give a full refund if you are not fully satisfied with the postcard.

----------------------------------------------

Text from the free encyclopedia WIKIPEDIA may appear below to give a little background information (internal links may not  work) :

*************

Lake Vyrnwy (Welsh: Llyn Efyrnwy, pronounced [ɛˈvərnʊɨ] or Llyn Llanwddyn) is a reservoir in Powys, Wales. Its stone-built dam, built in the 1880s, was the first of its kind in the world. It was built for the purpose of supplying Liverpool and the districts later designated as Merseyside with fresh water. It flooded the head of the Vyrnwy valley and submerged the small village of Llanwddyn. The Lake Vyrnwy Nature Reserve and Estate that surrounds the lake is jointly managed by the Royal Society for the Protection of Birds (RSPB) and Severn Trent Water, and is a popular destination for days out, and for ornithologists, cyclists and hikers. The reserve is designated as a national nature reserve, a Site of Special Scientific Interest, a Special Protection Area, and a Special Area of Conservation.

Dr George Deacon (1843–1909) began the design of the Vyrnwy Dam in 1879 at the age of 36. In 1890, following Vyrnwy, he founded an engineering practice in London which subsequently became Sir Alexander Binnie Son & Deacon, then Mr Binnie and Partners. Its present-day successor is Black & Veatch.

Dr Deacon was instructed to prepare the parliamentary plans for the scheme in 1879. The dam construction started in 1881 and was completed in 1888. It was the first large stone-built dam in the United Kingdom, and is built partly out of great blocks of Welsh slate. When built it cost £620,000, equivalent to £62,000,000 in 2015.^[1] The dam is 45 metres (146 ft) high from the bottom of the valley, and 37 metres (120 ft) thick at the base; it is 355 metres (1,165 ft) long and has a road bridge running along the top. It is decorated with over 25 arches and two small towers (each with four corner turrets) rising 4.3 metres (14 ft) above the road surface.

Vyrnwy was the first dam to carry water over its crest instead of in a channel at the side. At the bottom of the dam is a body of water known as a Stilling Basin, this is necessary to absorb the energy when the water flows over the crest and into the valley, and to stop the water eroding the foundations of the dam.

A power house located under the west tower contains an electrical generator driven by water leaving the reservoir. Before mains electricity arrived in the 1960s this was the area's only source of power.

The west and east Towers release compensation water by huge valves, which are controlled by Severn Trent Water. This water flows into for the River Vyrnwy, which would otherwise dry out unless in flood. Depending on the water levels downstream the reservoir can release anything from 25 to 45 megalitres (5,500,000 to 9,900,000 imp gal) of compensation water per day. This flow is measured by the Environment Agency at a weir few hundred metres downstream.

Earlier dams in Britain had been built using great earth embankments to hold back the water. This new type of stone dam would change the face of the Welsh landscape over the coming years. The next stone dams to be built in Wales on an even bigger scale than Vyrnwy were those built in the Elan Valley.^[2]

Approximately 1,200 metres (0.75 mi) from the dam is the reservoir's straining tower. Standing only 30 metres (98 ft) from the shore, its purpose is to filter or strain out material in the water with a fine metal mesh, before the water flows along the aqueduct to Liverpool. Its architecture represents Gothic revival, built at the same time as the dam. The tower as a whole is 47 metres (154 ft) tall, 32 metres (104 ft) of which is above water, and is topped with a pointed copper-clad roof, coloured light green.

The water from Lake Vyrnwy is carried 109 kilometres (68 mi) to Liverpool in the Vyrnwy Large Diameter Trunk Main (LDTM) aqueduct. This originally consisted of two pipelines, made largely of cast iron. To help maintenance work on the 2.7 metres (9 ft) diameter cast-iron tunnel which took the aqueduct under the Mersey, riveted steel piping was also used. This was an early use of the material which was to become the norm for trunk water-main piping.

The original aqueduct was constructed across the valley from the reservoir between 1881-92. It crosses the valley floor near Penybontfawr and then runs north of Llanrhaeadr-ym-Mochnant and Efail-rhyd on the north-east of the Tanat Valley. The aqueduct is largely hidden from view although there are some visible surface features including air valves, the Cileos valve house, the Parc-uchaf balancing reservoirs, and a deep cutting to the west of Llanrhaeadr-ym-Mochnant.

Brick and concrete-lined tunnels carried pipes at Hirnant, Cynynion and Llanforda, and a fourth later added at Aber so that the Hirnant tunnel could be made accessible for maintenance. The first section of a third pipeline was laid in 1926-38 using bituminous-coated steel. To increase capacity, a fourth pipeline was added in 1946.

Re-organisation of the pipe crossings beneath the Mersey and the Manchester Ship Canal was undertaken in 1978-81. The current provision relies on three pipes 1.1 metres (42 in) in diameter delivering up to 230,000 cubic metres (50×10⁶ imp gal) per day into reservoirs at Prescot, east of Liverpool. In 2013 United Utilities commenced a major refurbishment of the LDTM aqueduct, which was scheduled for completion in 2020.^[3]

The reservoir is Severn Trent Water's largest. When full, it is 26 metres (84 ft) deep, contains 59.7 gigalitres (13.125×10⁹ imp gal), and covers an area of 4.54 square kilometres (1,121 acres),^[4] the equivalent of around 600 football pitches. The lake has a circumference of 19 kilometres (12 mi) with a road that goes all the way around it. Its length is 7.64 kilometres (4.75 mi). On a clear day the lake, along with many others in North Wales, can be seen from space.

311 brooks, waterfalls and rivers flow into the lake and are named after the mountains or hillsides they flow from. Some are no more than a trickle, while others cascade down the mountains. The main ones, clockwise from the west side of the dam, are named Afon Hirddu, Eunant, Afon Eiddew, Afon Naedroedd, Afon Cedig and Afon Y Dolau Gwynionew.

On the northern edge of the lake is a small hamlet called Rhiwargor where the rivers Afon Eiddew and Afon Naedroedd meet. Up the valley of Afon Eiddew is an impressive waterfall, one of the largest surrounding the lake. Known locally as Pistyll Rhyd-y-meincau, it is commonly known as Rhiwargor waterfall.

In 1889, shortly after completion, the lake was stocked with 400,000 Loch Leven trout.

The lake continues to supply Liverpool with fresh water. It is the water source used in the manufacture of Bombay Sapphire gin.^{[citation needed}