Powys Digital History Project

The Elan Valley aqueduct 3
The hidden waterway

 One of many
service buildings
along the route
of the aqueduct

'A very creditable result'
The sectionsAqueduct service building,1999 of the aqueduct carried in syphons are equipped with valves at the highest points to release trapped air, and with wash-out valves to remove sediment at the lowest points along the route.
The course of the aqueduct is recognisable at many points by the substantially constructed stone and redbrick buildings housing valves and maintenance equipment, often standing conspicuously in open country with no trace of the aqueduct beneath them.
This extract is from
"The Future Water
Supply of Birmingham"
by Thomas Barclay,
published in 1898.
A report on the construction of the aqueduct, published in 1898, commented admiringly on the work done by contractors on the longer tunnel sections of the route, involving tunneling inwards from two ends miles apart to meet in the middle:
"..the work was so skilfully carried out that when the time for joining up arrived, the centre lines from the two headings exactly coincided, a result very creditable alike to engineer and contractors. It should be explained, so as to give an idea of the skill and care required in carrying out this work, that the tunnels were started at the bottom of deep shafts at either end, and because of the gradient thence to Birmingham, the borings had thus to be commenced at different levels."  
The aqueduct
crossing a valley
near Nantmel (right)
and the River Severn
(far right)
Aqueduct valley crossing  River Severn crossing,1908
River Severn
aqueduct photograph
is from 'City of Birmingham
Elan Supply' by
E Antony Lees, 1908.
Powys County Archives.

The superbly engineered system incorporated automatic valves for diverting the flow in the event of burst pipes or leakages, detectable by an increase in the speed of the water along the aqueduct.
The first continuous flow of supply water from the Elan Valley was to travel down the new aqueduct on 28th July 1904, a week after the ceremonial opening of the system by King Edward VII.

There are 3 pages on the Elan Valley aqueduct. Use the box links below to view the other pages.

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