MONTE-CARLO SIMULATION OF CONTAMINANT TRANSPORT - I - LONG-RANGE CORRELATIONS IN FRACTURE CONDUCTIVITY

We develop a network model of fractures, and use the model to study tr ansport of contaminants by groundwater through natural geological medi a. The fractures are narrow rectangular channels between large flat pa rallel plates, which are embedded in the surrounding rock matrix. The fracture-permeabilities and the fracture-widths are obtained from both uniform and fBm distributions. The pressure distribution in the netwo rk, and subsequently the velocity of groundwater in each channel, is o btained. The transport problem in an individual fracture is solved in Laplace space using the realized groundwater velocities and network ma ss conservation. The transform space solutions are then inverted to re al time using a fast and efficient inversion algorithm. Monte Carlo si mulations are then carried out by repeating the above procedure for a large number of realizations. The main focus of this study is to explo re the effects correlated fracture-permeabilities and fracture-widths have on the transport of contaminants. While the primary transport mec hanism is convection, we also study such processes as adsorption onto the fracture surface, and radioactive decay. We show how these phenome na, individually and in combination with one another, affect the overa ll transport process. In addition, we investigate the nature of the mi xing zone, and discuss how these results can be helpful in developing remediation techniques for a contaminated site.