Part of a trans-Wales Liquified Natural Gas (LNG) pipeline (see NPRN 412593 for main record). This section runs between Llandovery and Brecon, and includes the depot and road-crossing point at Defynnog.
See also record for temporary construction depot at Llyswen (NPRN 406448).

T. Driver, RCAHMW, 4th July 2008.