Type:  Gravity (Masonary)
Length:  54.9m (180 feet)
Height:  9.1m (30 feet)
Nant-y-Gro Dam, Wales, 1942
The Nant-y-Gro dam was a small masonary dam built across the Nant-y-Gro stream during the construction of the dams and reservoirs in the Elan Valley, Wales.
The dam created a million gallon reservoir which was used to provide water to the navvies village below. It also supplied water to storage tanks used by locomotives, steam cranes and other steam driven machinery.
Once the water works were complete, the Nant-y-Gro dam was no longer needed because the Elan village obtained water from the new water works scheme.
The dam was still standing during the war and Wallis used it as a secret testing venue for the development of Upkeep.
On July 24th 1942, 280lbs of explosives were detonated against the wall of the dam at a depth of 10 feet. The blast blew a hole 60 feet wide and 25 feet deep in the dam wall.
Test detonation at the Nant-y-Gro Dam
Nant-y-Gro Dam destroyed after test detonation
VIDEO: Test detonation at the Nant-y-Gro Dam
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Nant-y-Gro Dam: Present Day
Remains of the Nant-y-Gro Dam
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