A NOVEL solution to prevent failure of a rapidly deteriorating excavated slope averted serious delays to a recent project in the centre of Bolton and provided protection for an archaeological dig.
Shoring supplier Groundforce came up with a quicker and cheaper alternative to a conventional retaining wall, using trench boxes for support and to act as shuttering for the concrete pour.
And instead of the estimated two or three days to build the wall by conventional methods, the alternative operation was completed in just eight hours.
Excavating the cellar for a new public house on the site of a demolished building in Bolton's Churchgate area, main contractor Quinn Construction unearthed the remains of an historic brick built cellar.
Work was immediately stopped to allow an archaeological investigation. But during this time, torrential rain hit the site for two weeks, putting the already weak ground on one side of the excavation at risk of failure and threatening surrounding buildings.
Quinn Construction decided to build a further wall outside the cellar structure to support the poor ground. But as time and cost were at a premium, a faster solution was needed.
Groundforce, which had already supplied its Mega Brace system and mechanical props to provide support for the excavation, suggested placing a line of trench boxes parallel to the line of the new wall, with the gap between the boxes and the cellar wall filled halfway with spoil. Steel reinforcement was then dropped in between the panels and the excavation face and mass concrete poured, with the trench boxes acting as shutters.