CONTAMINANT ADVECTION AND SPREADING IN A FRACTURED PERMEABLE FORMATION .1. PARAMETRIC EVALUATION AND ANALYTICAL SOLUTION

This paper concerns contaminant transport phenomena in aquifers comprising fractured permeable formations. In contrast to deep rock formations with tight, almost impermeable matrix rock, we consider fractures embedded in permeable rock blocks. It is shown that in many cases (e.g. in sandstone formations) the advective transport of contaminants in permeable blocks can be identified as the major process leading to contaminant exchange between fractures and blocks. In the framework of the present study, a simplified conceptual model of the fractured formation is adopted. The conceptual model is formulated by sets of space linear differential equations subject to time-dependent boundary conditions. A closed form analytical solution of these sets of differential equations is developed. Calculations of the contaminant distribution along the fracture network are utilized to obtain breakthrough curves concerning the time variation of the average contaminant concentration in certain cross-sections of the fractured permeable medium. Characteristics of the contaminant transport phenomena originating from the contaminant advection and the mixing between the fracture flow and the permeable block flow are determined, and possibilities of considering the fractured permeable formation as a continuum are discussed.