Understanding Solute Transport in Extremely Heterogeneous Subsurface Media: A Field Perspective

Dr.Chunmiao Zheng- Department of Geological Sciences, University of AlabamaField studies at well-instrumented sites have played a preeminent role in our efforts to better understand and characterize solute transport processes in geologic media. In particular, several field tracer tests conducted at well-known sites such as those in Borden, Canada (MacKay et al., 1986), Mobile, Alabama (Molz et al., 1986), Twin Lake, Minnesota (Killey and Moltyaner, 1988), Cape Cod, Massachusetts (LeBlanc et al., 1991) and Columbus, Mississippi (Boggs et al., 1992) have provided new insights and extensive data sets for development and testing of transport theories and mathematical models. This presentation focuses on the Columbus, Mississippi site, more commonly known as the Macrodispersion Experiment (MADE) site.
Since the 1980s, three large-scale natural-gradient tracer tests and other types of field studies have been conducted at the MADE site located inside the Columbus Air Force Base in Mississippi, southeastern United States. The field data from the MADE site have been used extensively by researchers around the world to investigate and understand contaminant transport processes in highly heterogeneous aquifers. The MADE site has directly or indirectly inspired the development of a number of new and improved theories and computer models aimed at more accurate representation and prediction of contaminant transport affected by extreme aquifer heterogeneity. A great deal of recent and on-going research on contaminant transport in heterogeneous media has been motivated by the findings from the MADE site that suggest the existence of preferential flow paths resulting from small-scale heterogeneities. Since the 1980s, three large-scale natural-gradient tracer tests and other types of field studies have been conducted at the MADE site located inside the Columbus Air Force Base in Mississippi, southeastern United States. The field data from the MADE site have been used extensively by researchers around the world to investigate and understand contaminant transport processes in highly heterogeneous aquifers. The MADE site has directly or indirectly inspired the development of a number of new and improved theories and computer models aimed at more accurate representation and prediction of contaminant transport affected by extreme aquifer heterogeneity. A great deal of recent and on-going research on contaminant transport in heterogeneous media has been motivated by the findings from the MADE site that suggest the existence of preferential flow paths resulting from small-scale heterogeneities. This presentation will provide an overview of the research activities at the MADE site over the past 25 years and discuss how the findings from field studies have motivated various theories and models purported to accommodate so-called non-ideal transport behavior observed at the MADE site. Of particular interest are our recent field campaigns to further test the hypothesis that solute transport at the MADE site is dominated by small-scale preferential flow paths. These field campaigns include forced-gradient tracer tests, soil coring, direct-push hydraulic profiling, and high-resolution resistivity and GPR surveys. The on-going efforts are aimed at building stronger theoretical underpinnings and useful practical tools for modeling solute transport and for designing remedial measures in extremely heterogeneous aquifers such as that encountered at the MADE site.

Location: Kaprielian Hall (KAP) - 209

Audiences: Everyone Is Invited

Contact: Evangeline Reyes