Elan aqueduct
The Elan aqueduct crosses Wales and the Midlands of England, running eastwards from the Elan Valley Reservoirs in Mid Wales to Birmingham's Frankley Reservoir, carrying drinking water for Birmingham.
It delivers enormous quantities of water by gravity across the mid-Wales countryside, through north Herefordshire, south Shropshire and into the West Midlands through eleven major river valleys. The aqueduct is 73 miles (117 km) long, down which the water travels at less than two miles per hour, taking one-and-a-half days to get to Birmingham.
Work on the first 13 miles (21 km) of the route from the Elan Valley was started in June 1896 by Birmingham Corporation Water Department. The aqueduct was built in sections by outside contractors, using three types of construction depending on the nature of the terrain it had to cross. "Cut and cover" was essentially a brick lined channel which was manually dug as a trench, then roofed over and concealed underground. Where the route of the aqueduct encountered high ground above the gradient needed to maintain the downward slope, a certain amount of tunnelling was required, using the same type of channel as above. This totalled around 12 miles (19 km), with the longest single length being just over 4 miles (6.4 km). The third construction type was the use of pipelines to cross valleys and rivers where the ground level dropped too steeply for the required hydraulic gradient. The pipeline was continued at the other side of the valley at the same height as the delivery pipe, as the water naturally fills the pipe due to the head of water travelling along behind.
The initial scheme opened in 1906 with two 42in-diameter pipes. Two more pipes of 60in diameter were added between 1919 and 1961.
The engineer for the Elan aqueduct scheme was James Mansergh.
The route is Caban Coch (52°15′51″N 3°35′52″W / 52.264032°N 3.597665°W) via Elan Valley, Rhayader, Dolau, Knighton, Leintwardine, Downton on the Rock, Ludlow, Knowbury, Cleobury Mortimer, Bewdley and Hagley to Frankley (52°25′21″N 2°00′05″W / 52.422451°N 2.001329°W).
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