Posiva, the nuclear waste management organization in Finland, is currently constructing an underground research facility at the Olkiluoto site. The Olkiluoto Modelling Task Force (OMTF) has been established for planning and integrating the results and the modelling work in the different supporting disciplines. The main duty of the OMTF is to develop site descriptive models of the Olkiluoto site, as well as predicting and evaluating the disturbance created by construction of the ONKALO ramp and characterization tunnels. Various approaches are utilised including crossdiscipline workshops to ensure a common basis for modelling; prediction/outcome studies; and carrying out an overall confidence assessment are key synthesizing and integrating tools. The resulting geosynthesis is reported in a series of Site Reports. Future updates of the Site Report will be part of the Safety Case portfolio supporting a licence application for constructing a final repository for Finland’s spent nuclear fuel at the site.