Contaminant transport in heterogeneous porous media: a case study. 1. Site characterisation and deterministic modelling

Abstract The aim of this study is to illustrate the contribution that geostatistical techniques can make to risk assessment for buried waste repositories. For a hypothetical repository site in Bedfordshire, UK, multiple realisations of the hydraulic properties of the principal aquifers are constructed. For each realisation a numerical model describing the groundwater flow regime at the site is used to predict a possible pattern of migration based on the available hydrogeological data. A statistical analysis of the results is carried out to provide quantitative measures of the uncertainty in the patterns of migration deriving from a lack of knowledge of the media properties. In the first part of this two-part paper, the formulation of the conceptual and numerical models describing the regional groundwater flow regime is presented. A detailed assessment of the site has been undertaken to determine the principal hydrogeological formations within which contaminant migration would occur and the principal controls governing regional groundwater flow and contaminant transport. From the resulting conceptual model a quasi-three-dimensional groundwater flow and transport model has been developed. Part 2 of the paper describes the simulation experiments carried out using this model and the analysis of the results.