Geotechnical engineering designs are often predefined before construction commences, in an attempt to eliminate uncertainty. Such predefined design can lead to poor value, either due to waste of resources from over design, when opportunities are missed for optimising the design during construction, or due to the delay and additional cost of dealing with unforeseen ground conditions. The Observational Method (OM) provides an alternative design approach, to proactively manage the uncertainty associated with ground conditions, using a flexible design that is able to be adapted to suit the actual conditions found during construction. Feedback from observations and monitoring allows the designer to maximise the opportunities and minimise the risks. Case studies of applications of this approach are presented to demonstrate the significant benefits that have been derived from managing geotechnical uncertainty in this way. The OM relies on the integration of construction processes and teams, best achieved through a collaborative style of management, rather than under the types of relationship formed under traditional fragmented procurement processes. A synopsis is given of the influence of procurement options on the implementation of the OM. A danger with collaborative approaches to project delivery is that responsibilities are not clearly defined. An example where failure in the management of the process led to a tunnel collapsing during construction is used to illustrate the importance of designing the process and clearly defining responsibilities in a project team that chooses to use an OM design. A process modelling methodology is described which facilitates the definition and mutual understanding of processes and responsibilities in a project team, thus ensuring robustness in the OM process. A further practical example is given of an application of this methodology within a project team using the OM for a deep basement construction.