Engineering projects often run into "difficult" ground donditions which cause delays, failures, hugely increased costs or even abandonment with consequent disputes and claims. Pertinent questions are "what constitute difficult conditions\ulcorner" and "how might they be foreseen\ulcorner" and these questions provide the focus for this paper. Geological, geotechnical and hydrogeological models for engineering projects(simplified representations of the ground) need to be developed in a systematic manner. Within these models, the potential hazards associated with material (small) and mass (large) scale attributes of the geology, the environmental setting and the influence of the engineering works themselves need to be considered individually and in a progressive, systematic manner. This paper introduces the concept of a Geotechnical Hazard Review with reference to examples from various engineering works.