SINGLE WELL TRACER TESTS IN AQUIFER CHARACTERIZATION

When the purpose of aquifer testing is to yield data for modeling aque ous mass transport, pumping tests and gradient measurement can only pa rtially satisfy characterization requirements. Effective porosity, gro und water flow velocity, and the vertical distribution of hydraulic co nductivity within the aquifer are left as unknowns. Single well tracer methods, when added to the testing program, can be used to estimate t hese parameters. A drift and pumpback test yields porosity and velocit y, and point-dilution testing yields depth-discrete hydraulic informat ion. A single emplacement of tracer into a test well is sufficient to conduct both tests. The tracer tests are facilitated by a simple metho d for injecting and evenly distributing the tracer solution into a wel lbore, and by new ion-selective electrode instrumentation, specificall y designed for submersible service, for monitoring the concentration o f tracers such as bromide.