The Margam "Superpit" was a much cherished plan back in my dad's day (he helped project manage Betws New Mine near Ammanford) - they had a brilliant Area Director called Phil Weeks* who really pushed it hard , but the economy was so bad etc at the time , not much more than basic planning was done. There is some excellent coking coal there , so with a bit of luck some more good local jobs will turn up in due course.
(*Mr Weeks was a practical and human orientated manager with a strong sense of working with the Trade Unions , particularly in the strikes in the 70's when a tacit agreement was reached that no South Wales pit would be let to flood , and any geological etc damage in the strike period would be attended to. Some bureaucrat in Hobart House made the comment "not bad for a Grammar School boy" !!)