When conducting hydrogeologic investigations, it is commonly assumed that once bedrock is encountered, it acts as an “impermeable barrier” to groundwater flow and contaminant migration. Yet, current research and experience shows that all types of bedrock are fractured to some degree, and fractures can be the primary conveyer of groundwater and contaminants. This talk will focus on a case study highlighting how groundwater and petroleum hydrocarbon contamination in fractured volcanic rock were investigated, to allow the development of a conceptual site model that describes the complex physical and contaminant hydrogeology at the Site.