ABSTRACT
If you want to understand how injected reagents and contaminants behave in an aquifer, inject some reagent and pay close attention. Tracer studies are the most powerful tool we have to unmask the heterogeneous structure of groundwater fl ow and we now view tracer studies as a standard element for all reactive zone remedial designs. In the past three years, we have harvested a rich base of tracer study data, often with stunning results — three, four, possibly fi ve discernable tracer peaks passing a series of 1.5-meter long well screens following a single tracer injection pulse, representing a fi ve-fold range of groundwater velocities, all of them exceeding the average groundwater velocity determined by hydraulic testing at the site. The analysis of these tracer studies is causing us to rethink much of our sense of fi ne-scale aquifer structure and groundwater and contaminant velocities, and is one of the main motivations for developing Remediation Hydraulics.
