Kaymac were commissioned by Cardiff City council to carry out concrete repairs to Llandaff Weir located on the River Taff.
Llandaff Weir is situated on the River Taff 2.2miles to the northwest of Cardiff City Centre. It spans 150m in length from east to west and measures approximately 7.5m from the crest to the toe. Kaymac operatives carried out a detailed conditional survey of Llandaff Weir to establish the level of deterioration on the structure since the previous survey carried out by Kaymac in 2014. It was evident from the survey that the level of scour to the downstream toe of the weir had increased substantially since the original survey and that remedial works were required to stabilise the structure to prevent further deterioration and possible failure.
During summer of 2018, Kaymac were awarded the contract to carry out the mass concrete repairs to stabilise the toe of the weir and after a short period of planning, Kaymac received National Resources Consent in July to commence the works without delay.
Kaymac mobilised to site and began the repair works which in general included the following:
- Assembly of a 15m x 8m pontoon platform within the river to provide access to the weir for a long reach excavator and the Kaymac personnel.
- Installation of a temporary sand bag bund to divert the water flow away from the working area.
- Removal of mobile bed material from within the scoured areas and installation of temporary formwork.
- Installation of environmental protection and mitigation measures.
- Installation of 240m³ of mass underwater concrete to the scoured areas using a concrete boom pump.
- Removal of the existing steel baffle which was originally installed by Natural Resource Wales.