Non-sorbing tracer migration experiments in fractured rock at the KamaishiMine, Northeast Japan

This paper describes the design, implementation, and analysis of in situ tr acer migration experiments in fractured granite, The research highlights th e importance of gee-hydraulic investigations prior to performing tracer mig ration experiments. The authors conducted a detailed but simple investigati on in order to understand the spatial distribution of conductive fractures and the pressure field. Seven boreholes were drilled in the test area, reve aling hydraulic compartmentalization and a heterogeneous distribution of co nductive features. After identifying several suitable conductive fractures, three sets of dipole tracer migration experiments were conducted with Vari ous combinations of injection and withdrawal hole and dipole ratios. The tr acer breakthrough curves were analyzed using a streamline, analytical solut ion and numerical analysis of mass transport. Best-fit calculations of the experimental breakthrough curves were obtained by assigning apertures withi n the range of one to ten times the square root of transmissivity and a dis persion coefficient equal to one-tenth of the migration length. (C) 2000 El sevier Science B.V. All rights reserved.