Hydrogeological modelling in support of site characterisation. Project phase disposal category A waste

The site characterisation campaign for the project phase should provide additional information in order to help reducing the uncertainty of the groundwater model and verify its validity and robustness. The most recent report on hydrogeological modelling in the framework of the category A waste disposal project (Gedeon and Mallants, 2004) recommended, among others, to perform a regional investigation regarding the geometry of the local model hydrostratigraphy and the thickness of the Kasterlee Diest Transition Layer (Kasterlee Clay). To provide recommendations for the site characterisation campaign, sensitivity analyses were performed with the steady-state groundwater models. Results of these analyses were augmented with information on existing boreholes, locations where previously information was obtained, etc. These comparisons resulted in delineation of zones where the collection of new data would result in a maximal reduction in model uncertainty. The new data will also contribute to confirm and/or improve the overall conceptual hydrogeological model. Recommendations are also made on the type and spatial density of hydrogeological parameters that would need to be determined to yield a significant reduction in conceptual model and parameter uncertainty.