Determination of the location of fractures in metamorphic rock with in-hole tracers

A detailed investigation of the geohydrology of slightly fractured metamorphic rock by means of exploratory boreholes involves three steps; first, determining the exact location and character of the fractures penetrated by exploratory boreholes; second, determinating the nature and connectivity of fractures between boreholes; third, determining the hydraulic parameters. This paper describes methods of determining the first of these, including core inspection, geophysical logs, packer tests, in-hole tracer tests, and dry drilling. Emphasis is given to the in-hole tacer tests by using an example from an investigation of slightly fractured metamorphic rock at the Savannah River Plant near Aiken, South Carolina, U.S.A