Swallownest GI

Central Alliance complete successful project, on programme and within budget for Colas Rail

Central Alliance was commissioned by Colas Rail, on behalf of Network Rail, to complete ground investigations at Swallownest, near Sheffield, South Yorkshire.


The investigation works  were instructed to ascertain whether the cause of track deterioration and subsidence was related to shallow underground mine-workings. The investigation was designed to intercept these underground workings in order to establish their nature and provide information for design of remedial mitigation measures, if deemed necessary.


The original scope of works comprised the completion of seven boreholes, to be completed on track, using rotary open hole methods and water flush to 20m bgl with a further two boreholes to be completed under a high street environment conditions using rotary coring techniques. The recovered cores were logged in accordance with BS5930:2015, by the Central Alliance supervising engineer.


Through early contractor involvement and a collaborative approach with all stakeholders, Central Alliance were able to deliver the works successfully, on programme and within budget. Increased efficiencies identified by Central Alliance and Colas Rail during the works enabled the completion of an additional three boreholes within the planned programme, providing the client with vital additional information for geotechnical design.


It was a pleasure working with Central Alliance who delivered the project early and achieved more than the original scope of works”.  Nathan Jones, Geotechnical Engineer, Colas Rail.