An inspection on the structure identified numerous defects that over time would have had a detrimental effect on the structural integrity and stability of the culvert.
The structure is 67.5m long and comprised of a combination of masonry, concrete and brickwork sections.
The concrete pipe sections downstream of the obstruction had severe scouring to the invert of up to 600mm in width, with open jointing throughout the length of the structure. There was severe scouring to the invert of the adjoining concrete pipe sections with penetration in excess of 500mm in the worst locations. This deterioration was typical throughout the entire length and ran for approximately 33m, with open construction joints of up to 100mm throughout.
The work was carried out by Kaymac’s confined space team. It was necessary to first over-pump the water running through the structure to ensure that the work could be carried out in dry conditions in accordance with the Licence agreement with the Environment Agency.
Once a reasonably dry working area had been created, shuttering was erected and fixed to the structure where required. Concrete with an underwater additive was then pumped into the voids via a concrete pump located on the surface. As the location of the works was near to a main road, traffic management was installed to allow minimum disruption to the road users.
Concrete was also pumped into the large voids that were identified behind the masonry arches and abutments. The areas of missing masonry were repaired to match the existing profile and all re-pointing works were completed using a proprietary marine based mortar.