| The compound area was established to LAWS ‘Safety First Standard’ with Heras fencing to the perimeter. A haul road consisting of approximately 200m was introduced which included layby passing areas around the site to protect historic landscape.
Temporary dam systems were established at the upstream and downstream ends of the cascade apron to assist with the lowering of the Great Lake to 1m below crest conducted to facilitate the works. Inspection of the existing apron structures then took place. Cleaning commenced using pressure washers and the joints were inspected. The wing walls were carefully dismantled both by hand and careful mechanical means by using an experienced LAWS operator in a long reach excavator. Stone was retained for re-use by the client. Stone samples for inclusion in the permanent works were then sourced for approval. Breakout, removal and disposal of the existing apron slab, weir wall and wall foundations was achieved using an 8t long reach excavator fitted with a hydraulic breaker positioned to the side of the weir and working in the apron field. Material was removed using dumpers with all concrete being removed from site. Voids identified at inspection beneath the apron were filled with foamed concrete. A resin injection cut off wall, the largest undertaken in the UK to date, was then installed running the full width of the dam. This was followed by the construction of a new reinforced concrete apron slab, including weir upstand containing 375m3 of concrete in total. Repairs to the upper section of the apron could then take place. Once the concrete walls were complete they were faced with a natural stone cladding approved by the client. Backfilling to the rear of the wing walls and replacement of the ‘Armourloc® was then undertaken with repairs to the existing wave wall using previously won site material (cleaned and prepared) before removal of temporary works and reinstatement of the grounds including footpaths, landscaping and demobilisation. This project was completed during the COVID-19 pandemic requiring safety measures to be in place. |