Compacted fine-grained geologic materials are widely used to restrain leachate generated at waste containment facilities. The predictions of analytical contaminant transport models have been widely evaluated using laboratory column tests because data from field-scale compacted soil liners is extremely limited. This project will provide field-scale data on chemical transport through compacted soil liners, a comparison between contaminant transport model predictions and field-scale data, and recommendations for conducting chemical transport analyses for waste containment facilities.
This project will utilize the long-term field-scale study that the Illinois State Geological Survey (ISGS) started in 1985. The ISGS constructed and heavily instrumented a compacted soil liner, with plan dimensions of 8 m x 15 m and a thickness of 0.9 m. The ISGS liner has been monitored for approximately ten years, and the resulting data provides a unique opportunity to study the long-term chemical transport through a compacted soil liner and the performance of existing contaminant transport models. The main components of the research are: (a) sampling and excavation of the compacted soil liner, (b) chemical analysis of the soil samples to determine the variation of chemical concentration versus depth, (c) geostatistical analysis to quantify the spatial variability of chemical transport through the liner, (d) measurement of diffusion coefficient, saturated hydraulic conductivity, effective porosity, and other parameters required by existing chemical transport models using the original soil liner material, (e) state-of-the-art contaminant transport analyses and comparison of the results to field-scale measurements to investigate the performance/accuracy of existing transport models, (f) quantify the importance of advection and diffusion on contaminant migration through the compacted soil liner, and (g) develop recommendations for conducting chemical transport analyses for waste containment facilities. The Illinois Office of Solid Waste Research has provided matching funds for the proposed research.
