An advanced academic style desk study is critically important as one of the first tasks to be undertaken. bit.ly/3KUBVHC
The study typically looks at the macro to micro picture and includes an understanding of the regional and site specific geological features. The fundamental principle that helps anticipate and plan to mitigate ground risks for pumped hydro projects is the early development of a predictive ground model that is called a conceptual engineering geology model (EGM).  The output is typically a 3D digital model that can be used for early design, but also as a communication tool to stakeholders to explain the construction process. 
The ongoing refinement of the expected geological and geotechnical conditions, which may include a number of phases of investigation, provides greater certainty of the actual conditions and therefore reduces project risk.