Certain installations are devoted to risky activities such as nuclear facilities (power plants, waste repositories), sanitary landfills or some chemical industries. Placing such plants into the land, deserve specific geological, geotechnical and hydrogeological studies. Preferential flowpaths such as fractures or material boundaries deserve special attention on the geological mapping. An accurate borehole drilling is essential for the proper characterisation activities. Hydrogeology plays a relevant role, since integrates data from different origins. Methods to properly characterise a specific site involves tests specially designed for low permeability media