Site Record

Disused reservoir 400m E-W x 100m, surrounded by derelict chain link fence on 1.7m high concrete posts with access road and track on the south side. Reservoir dam is at the eastern end, 160m long x 24m wide at the base, and 3m wide at the top x 9m high faced on the inside with stone blocks, upper third cemented together, the outside is grassed.
The outfall is a 6 sided concrete plinth 6m x 3m high with an outlet at the base, currently open to drain the reservoir. This is surmounted by a circular tower 4.5m dia 4m high, with an outlet 2m below the top.
To the east of the reservoir is an area marked as filter beds on the OS map, All structures are underground and marked with bolted down covers, there are further adjacent underground structures of vaulted brick construction with vent pipes and evidence of demolished above ground structures.
Originally constructed to supply Brynmawr with domestic water, it was taken over by Welsh Water and designated the Cairn Mound Impounding Reservoir.

N. Tinkley, John Winterburn Archaeological Services, August 2005