DEFINING CONTROLS ON IN SITU BIODEGRADATION VIA CONTROLLED FIELD EXPERIMENTS

In several long-term injection experiments, we've evaluated heterogeneity of flow and reaction in a shallow aquifer at Vandenberg Air Force Base, California. Transects of closely spaced monitoring wells, oriented perpendicular to the mean groundwater flow direction, were sampled to yield insights into controls on solute distribution, solute migration rate, mixing of injected plumes with surrounding groundwater, and in situ biodegradation. While the monitoring methods used in our work are often used in research and thus are not innovative, per se, they are rarely applied in practice despite improvements in recent years in monitoring approaches. Our research results provide graphic reminders of some key issues that we've known for years warrant much more attention in practice, whether by development of completely new tools or by innovative use of currently available technologies.