Observational Method
CGL has experience of applying the Observational Method to assist clients and allow value engineering of bulk excavations for basements as well as tailoring retaining wall support solutions to control movements in the most advantageous ways both to construction programmes and third party requirements. CGL has also applied the methodology to protect sources of drinking water abstraction from the impact of nearby piling operations in response to concerns expressed by the Environment Agency.
Using a familiar traffic light solution we have set criteria for the successful excavation of a number of bulk basement dig operations in chalk, using face mapping to inform construction staff of what to expect. The observational method approach involved continuous monitoring by informed staff to achieve safe excavations and has made considerable cost savings over alternative solutions.
CGL is also familiar with ground movement analyses of various complexities to develop the wall and building movement criteria to be monitored for during construction, as well as setting interventions at the various thresholds embodied within the methodology.
CGL applied these principles to monitor abstracted water with the inclusion of turbidity criteria to safeguard supplies during piling operations in chalk in East London. The approach allowed the successful construction of deep foundations in a sensitive location without which the development would have not progressed.
