LESSONS LEARNED FROM LEGACY RESEARCH SITES IN CONTAMINANT TRANSPORT AND NEW CHALLENGES FOR FUTURE RESEARCH

Field studies at dedicated and well-instrumented tracer test sites, such as Cape Cod, Borden and MADE, have provided extensive datasets and insights essential to developing and testing fundamental theories and mathematical models for contaminant transport in the subsurface. This presentation provides an overview of the lessons learned from three decades of research at some of these legacy sites, and discusses how they have affected the evolution and progress of contaminant hydrogeology as we know it today. However, although we have made great strides over the past 30 years, our ability to predict contaminant transport in highly heterogeneous aquifers remains limited. New and innovative field methodologies are needed to characterize the connected preferential flow networks rapidly and cost-effectively; and existing transport models must be improved and advanced to represent the resulting non-ideal transport phenomena accurately and efficiently. These challenges will be discussed further in the context of a new field tracer test site being established in the Tongzhou district near Beijing, China. The design of the Tongzhou site will be presented, along with the site characterization and tracer tests performed to date. The new research site is intended to provide a new field observatory where the key lessons and insights from the previous legacy tracer test sites will be used to guide new research experiments aimed at understanding and predicting solute transport beyond what is possible today.