Wednesday, 24 February 2010

Ynysbwllog Aqueduct, Neath and Tennant Canal

Ynysbwllog Aqueduct
Neath and Tennant Canal
12th December 2009

The isolated Neath and Tennant Canal system extends about 21 miles, following the Neath Valley north east from Swansea in South Wales. The canal has been abandoned since the 1920's and subject to on and off restoration attempts since 1974.

The navigation has a number of distinct engineering obstacles, including three significant aqueducts.

I am indebted to Martin Ludgate of Canal Boat (Jan 2010) for highlighting the restoration of the .
Ynysbwllog Aqueduct in 2008. This aqueduct used to be a multi arched stone structure, which ultimately failed but as the waterway still serves a function in delivering fresh water to the area, it was replaced with two large iron pipes spanning the gap.

Ynysbwllog Aqueduct in its piped state (Photo:

This water delivery function has been the Neath and Tennant's salvation and when the pipes were replaced it was with a new steel trough built to navigable dimensions.

Ynysbwllog Aqueduct 2009 (Photo: Canal Boat Jan 2010)

Low level river crossings like this represent a problem for drainage. In normal conditions the water capacity beneath their arches is adequate, but in times of exceptional flooding, water can be ponded back and threaten the integrity of the aqueduct, and represent a danger to the area beneath it in the event of a catastrophic failure.

The new slimline trough overcomes this problem by maximising the flow capacity beneath its single wide span and, in times of emergency, it should be robust enough to survive floodwaters running over the top as well.

And another old photo of this site in its unreconstructed days provided by Jim of nb Starcross taken in the 1970's:

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