CHARACTERIZATION AND HYDROBIOGEOCHEMICAL MODELING AT A MULTIPLE-WELL IN-SITU URANIUM BIOREDUCTION SITE, AT OAK RIDGE, TN

Since 2001, a multiple injection-extraction well system has been operating at Oak Ridge National Laboratory (ORNL), TN, for in-situ reduction and immobilization of Uranium VI. The system has been used for chemical delivery and mixing for the purpose of creating biogeochemical conditions conducive to bioreduction. The in-situ reactor has been characterized principally through tracer tests. The results of conservative and reactive tracer tests have been processed to obtain transfer functions through parametric and non-parametric methods. The results of the tracer tests allow us to model reactive transport using a travel-time formalism. This approach does not require the characterization of the conductivity and velocity fields. The advective-dispersive mixing is represented through travel-time distribution functions between the injection and extraction well, obtained through tracer tests.