History in Structure

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Reservoir of former Llantrisant Colliery

A Grade II Listed Building in Llanharan, Rhondda Cynon Taff

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Latitude: 51.5471 / 51°32'49"N

Longitude: -3.3983 / 3°23'53"W

OS Eastings: 303137

OS Northings: 184055

OS Grid: ST031840

Mapcode National: GBR HM.FRYJ

Mapcode Global: VH6DX.1CTW

Plus Code: 9C3RGJW2+RM

Entry Name: Reservoir of former Llantrisant Colliery

Listing Date: 7 October 1994

Last Amended: 14 November 2000

Grade: II

Source: Cadw

Source ID: 15842

Building Class: Industrial

Location: Located in the wood to the W of the former colliery engine hall.

County: Rhondda Cynon Taff

Community: Llanharan

Community: Llanharan

Locality: Ynysmaerdy Farm

Traditional County: Glamorgan

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Llantrisant or Ynysmaerdy Colliery was established by the Powell Duffryn Steam Coal Company after World War I. It closed in 1942 following an underground explosion. It was constructed on the efficient modern model developed by the Powell Duffryn Company, with a single engine hall containing the main power equipment needed on the surface. The site is a particularly complete and impressive colliery complex, containing the engine hall, workshops and stores, ruined offices, a separate winding engine house, railway lines, tips, a long revetment wall, a reservoir, and an explosives store. It was associated with the planned housing estate at Ynysmaerdy.


The reservoir is a perfectly circular structure approximately 30m in diameter and 9m high, erected between the rock faces of a former quarry on the line of a small stream. It is constructed as a thin reinforced concrete shell with straight vertical sides topped with a narrow lip, and a dished bottom. The use of concrete in such a structural form was unusual at this date, and this example demonstrates some virtuosity of design.

Reasons for Listing

Listed for its advanced use of reinforced concrete, and for group value in this unusually complete and impressive colliery complex.

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