| A major subsurface environmental problem is the random release of immiscible organic fuels and solvents, which are often non-aqueous phase liquids (NAPLs), into the subsurface environment. Inherent in the investigation of subsurface contamination is understanding the pathway from the point of release. Knowing the preferential pathways of contaminants, the sites of sorption or entrapment, and the difficulty of remobilization also allows for a better assessment of the extent and rate of pollutant movement.; Small spills of hydrocarbon fuels generally occur at the ground surface of refueling areas, industrial parks or waste transfer stations. These spills enter a subsurface environment that generally consists of unsaturated, fine-grained soils, whose structure has been altered by construction and climatic weathering. To date, little work has been done to characterize the fate and transport of hydrocarbon fuels in this environment.; The areas addressed in this study include assessing how the structure and NAPL fate and transport of fine-grained compacted soils varies as a function of such parameters as water content, matric suction and desiccation. Specific issues are assessing the suction capabilities of the soil, estimating the conditions for the onset of microcracking and the resulting conductivity of compacted soils to a range of possible liquid formulations.; Research will yield two important results; where to look in the vadose zone to find contamination if a small spill/leak is detected and a realistic determination of mobilization risk and cleanup potential. |
