A flood alleviation scheme on the behalf of National Resources Wales in the Swansea area, involving the construction of an earth embankment, approximately 120m in width and 7.5m in height, to form a flood storage reservoir.
The total embankment volume will be approximately 35,000m3, containing a core of approximately 9,000m3. The shoulders of the embankment will be formed using materials selected from the borrow area approximately 200m away, whilst the core will be formed using imported clay.
The embankment will have a pre-cast culvert passing through it (2m by 1.8m), with graduated trash screens at the entrance. A flow control mechanism on the upstream side will be provided in the form of a sluice gate installed within the reinforced concrete inlet structure to the pre-cast culverts. A weir structure will be formed at the dam outlet to further control flows, with a subsequent 60m wide spillway covered with grasscrete and contained using concrete training walls.
Local traffic flows will be maintained via a temporary bailey bridge whilst the reinforced concrete structure is constructed in the location of the existing highway. The road will then be reinstated to its permanent position atop the new embankment.
The whole area, including the borrow area will require seeding and making good following construction.
Natural Resources Wales