Location:

Trehafod, Lower Rhondda Valley

Sunk:

1850

Closed:

1983

This colliery comprised of the Coedcae, Hafod, Bertie, Trevor and Lady Margaret Pits and on 22 November 1956 an explosion at the Trevor pit killed nine men - two outright and seven later from their injuries. Two years the Lewis Merthyr Colliery wound up its production operations when it was merged with Ty Mawr Colliery, its coal diverted via an underground roadway.

The Ty Mawr / Lewis Merthyr was closed by the National Coal Board in March 1983 following the failure by the South Wales branch of the National Union of Mineworkers to gain strike support from other NUM areas.