Introduction
A temporary cofferdam was installed to divert the water flow around the working area, and an excavator was used to dig down behind the wing wall to a depth below the existing leak. The landward side of the excavation was then battered down to a slope of 45 degrees.
The back of the wingwall was then cleaned, inspected and repaired. Bentonite powder was used to dress the back of the wingwall and sides of the excavation, and imported clay was used to rebuild the bank and backfill the void.
Upstream, a section of the bank was faced with concrete-filled sandbags and reinforced with steel pins, to provide erosion control.
The gauge board was also replaced and fixed to a galvanised mild steel post driven into the stream bed. The new gauge board was levelled into a stored datum to avoid the need for recalibration of the monitoring equipment.
To complete the works, the cofferdam was removed, the bank was reinstated, and the area was seeded with a suitable grass mix.
Project gallery
