This project is the home of an international beverage producer, in Nelson, Lancashire. Since new proprietors took ownership of the site in 2019, it was noted that significant ground movement had occurred within the staff car park, located adjacent to Pendle Water.
The new site owner was keen to remedy the situation; to restore the staff car park and to safeguard the factory, prior to additional investment. A 900mm diameter foul sewer, which passed through the site, had shown signs of distortion as it had moved with the ground.Ground Conditions
When designing stabilisation schemes, ground investigations and their results play a very important part. Quality site and ground investigations allow the designers to give accurate and detailed design information to the contractor prior to commencement of work.
The ground conditions at this project comprised of ~15m of notoriously weak Glacial Laminated Clay, over more competent cohesive Glacial till with Pennine Coal Measures at ~30m depth. Additionally, artesian groundwater pressures more than 5m above the ground level were recorded within the bedrock strata which resulted in a greater than hydrostatic groundwater pressure profile. When combined with relic shear surfaces and low strength Laminated Clays, this presented the designer with a unique combination of ground conditions to overcome.
The solution was an embedded sheet pile wall along the site boundary adjacent to Pendle Water. This was subsequently backfilled to provide a working platform enabling construction of passive tension micropiles providing restraint to the top of the wall via a reinforced concrete capping beam, which encased the two elements.