Natural gases are a potential hazard in construction of underground excavations. Encountering with gases usually result in costly delays. Gases occur in a wide variety of geological conditions, so predict the occurrence of potentially hazardous concentrations of gases needs a good understanding of geological conditions. Understanding gas grounds will enable investigators to assess the risk associated with gas prior to excavation. This article outlines the findings of post inundation desk study and specialized geological investigations carried out to verify the gas ground risks. Some practical mitigation measures and recommendations for gas ground investigation are also presented.