Geotechnical investigation, basement design and supervision

Galliford Try engaged CGL to value engineer the three-storey basement construction for the new Radisson Hotel in Guildford.

The project was originally conceived by others as a secant wall construction with piled foundations. This did not take advantage of the ability of chalk to withstand steep excavation in the temporary condition or recognise the water levels identified by the original investigation.

CGL worked closely with the structural engineer to simplify the construction approach as well as reduce the cost. We identified the potential for open cut excavation supported by adoption of the observational method for slope monitoring.

CGL set out inspection regimes for site staff, briefing documents and a call out service for identified issues using the traditional traffic light graded risk response of the CIRIA Observational Method.

Localised defensive ditches and a prolonged, cold winter tested the Observational Method principles from the start.

This project was voted Best Geotechnical and Geoenvironmental UK Project over £1M at the GE Awards Ceremony and was a finalist in the 2018 GE Awards for Project of the Decade. The geotechnical engineering made the vital difference in the economic viability of this project in the teeth of the recession. Our value engineering design saved £1m on the basement construction, leading to a shortened construction programme and a more sustainable use of resources.