1. Part of the Rheidol hydro-electric scheme (nprn 91572), the surge shaft is on the pressure tunnel from Nant-y-moch reservoir (nprn 268169) to Dinas power station (nprn 307999).
B.A.Malaws, RCAHMW, 28 February 2003.

2. Large circular structure, approx. 20m in diameter. constructed from brick with caged windows. Stands approx. 2.5m high. R.S. Jones, Cambrian ARchaeological Projects, 2004.