FIELD-SCALE REACTIVE TRANSPORT SIMULATIONS OF MULTIPLE TERMINAL ELECTRON ACCEPTING PROCESSES

Field-scale simulations involving multiple terminal electron accepting processes (TEAPs) and abiotic processes are often limited by reaction parameterization and complexity associated with heterogeneous groundwater flow. We have constructed a 3D field-scale groundwater flow and multicomponent reactive transport model that incorporates multiple TEAPs obtained from a batch TEAP model which has been successfully formulated and used to simulate laboratory experimental observations. Field-scale simulation is conducted using the reaction system and parameters derived from the batch TEAP model and the conceptual model and hydrologic parameters estimated from the results of pumping tests and water level monitoring and model interpretation of a tracer test conducted in August 2004 for a highly heterogeneous surficial aquifer near Oak Ridge, TN. Preliminary simulations are used to understand field-scale processes and evaluate alternative experimental designs involving injection of ethanol to stimulate microbial reduction of uranium and precipitation of U(IV) minerals.