Investigation of Potential Saltwater Intrusion Pathways in a Fractured Aquifer using an Integrated Geophysical, Geological and Geochemical Approach

Borehole geophysics and horizontal loop electromagnetic profiling (Max-Min) were integrated with regional and site-scale geological and geochemical data to investigate the occurrence of, and possible pathways for, saltwater intrusion near fracture zones on a small island in British Columbia, Canada. An island-wide geochemical study identified a number of coastal wells that are contaminated by seawater; however, the occurrence of high salinity groundwater is spatially irregular due to variable fracturing of the bedrock. To investigate the influence of fracturing on the presence of high salinity groundwaters, geophysical investigations were undertaken at several sites. The nature of the bedrock permeability at these sites, with respect to lithology and fracture zone proximity, is described from geologic and hydrogeologic investigations and supported using surface EM profiling. Fractures and bedding contacts within boreholes, which were suspected to dominate bedrock permeability on the basis of outcrop studi...