Characterization of Dye Tracer Plumes: In Situ Field Experiments

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Abstract
The second ground‐water dye tracer experiment at Sand Ridge State Forest, Illinois, was conducted during the Spring of 1983. Slugs of three different fluorescent dyes (Rhodamine WT, Amino G Acid, and Lissamine FF) were allowed to migrate under natural hydraulic gradient conditions through a water‐table aquifer composed of wind‐blown sand overlaying glacial outwash sand and gravel. The plumes in the outwash deposit and in the dune sand were monitored first by a line of sand point wells placed perpendicular to flow at a distance of 10 ft and 5 ft, respectively, from the source wells. A trilevel nest of sand points was then placed in the path of each plume at a greater distance (50 feet from the sources of the deep plumes). The field data suggest that the plume geometry varied with distance from the source. A solute transport model, calibrated to the field data, provided estimates of longitudinal dispersivity (0.10 ft and 0.17 ft for the plumes in the lower unit) and average linear velocity (approximately 1.5 and 1.7 ft/day in the lower unit and 0.21 ft/day in the upper unit). The model was then used as a mass accounting system to relate the tracer concentrations detected in monitoring wells to the mass within the plumes.