Daniels Mill Slope Stabilisation
The historic Daniels Mill to the South of Bridgnorth in Shropshire was hit by the twin disasters of flooding and landslip during the extreme rainfall in the area in the summer of 2007. These problems were intimately associated with those of the adjacent Severn Valley Railway which passes to the west of the site on a viaduct over the valley of the stream which serves the mill.
The landslip impacted on one of the outbuildings and stabilisation works were required to address both the slope behind the building and the slopes and buttress associated with the viaduct. Remediation needed to recognise the historic environment, access constraints, sustainability issues and the maintenance of stability to the viaduct throughout the construction. Reinforced soil was seen as providing the optimum solution.
Site investigation, analysis and conceptual design was undertaken by Geotechnics, detailed reinforced soil design by P&S Consulting Engineers and the construction by WM Longreach.
The scope of the works included:
- Removal of failed material from the slope and formation of a temporary batter.
- A drainage layer below and behind a reinforced soil wall comprising 16 layers of Huesker geogrid interleaved with imported compacted granular material and excavated soil to a height of 8 metres.
- An upper slope grading into the natural ground some 13 metres above the driveway level.
- A wall feature in Wenlock stone to the lower section of reinforced wall to blend with the character of the mill.
Critical to the success of the project was the use of specialist long reach plant both for excavation and construction on a very constricted site. Maintenance of close working relationships between all parties concerned including the mill owners, Severn Valley Railway, the designers, the contractor and the client was also essential to minimise disruption and to maintain access for visitors wherever possible.
The project was recognised for its outstanding innovation and achievement by winning the regional Institution of Civil Engineers (ICE) Geotechnical Award in 2010.