BOUNDARY-ELEMENT ANALYSIS OF CONTAMINANT TRANSPORT IN FRACTURED POROUS-MEDIA

A two-dimensional boundary integral method to analyse the flow of cont aminant in fractured media having a two- or three-dimensional orthogon al fracture network is presented. The method assumes that the fracture s provide the paths of least resistance for transport of contaminants while the matrix, because of its low permeability, acts as 'storage bl ocks' into which the contaminant diffuses. Laplace transform is used t o eliminate the time variable in the governing equation in order to fa cilitate the formulation of a boundary integral equation in the Laplac e transform space. Conventional boundary element techniques are applie d to solve for the contaminant concentrations at specified locations i n the spatial domain. The concentration in the time domain is then obt ained by using an efficient inversion technique developed by Talbot. T he method is able to analyse the behaviour of waste repositories which have diminishing concentration due to the mass transport of the conta minant into the surrounding fractured media.