INFLUENCE OF FRACTURE TRUNCATION ON DISPERSION - A DUAL PERMEABILITY MODEL

Simulations with a dual permeability model show that a few discrete fr actures can have a major influence on plume geometry. A limited number of truncated fractures (1-4) within a permeable matrix can create nea rly circular plumes, with about the same degree of spreading in the di rection transverse to the average hydraulic gradient as in the longitu dinal direction. By comparison, continuous fractures in the direction of flow tend to produce elongated plumes, similar to those typically s een in granular materials. Both types of plumes have been observed in tracer experiments in fractured porous media on the Oak Ridge Reservat ion. Understanding the influence of fracture geometry is important in planning field characterization and subsequent remediation in fracture d porous media. (C) 1998 Elsevier Science B.V.