Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/9/2000
Publication Date: 7/9/2000
Citation: Cristy, A.D., Fausey, N.R., Allred, B.J., Hall, G.F., Bigham, J.M. 2000. Hydraulic, physical, and chemical properties of fractured glacial till. ASAE Annual International Meeting. Interpretive Summary:
Technical Abstract: For years, glacial till was considered to be moderately slowly, slowly, or very slowly permeable. It is now known that joints and fractures are caused by regional glaciotectonic stress, desiccation, thermal expansion and contraction and are common in unconsolidated glacial drift. These features can extend from the soil into the subsurface geologic strata, acting as conduits for water and contaminant flow. Fluid can flow through fractures much faster than laboratory hydraulic conductivity measurements on matrix samples would indicate. A study was conducted in Madison County, Ohio, to illustrate the extensive presence of fractures in the till and to quantify the differences in hydraulic conductivity and physical and chemical properties between the fracture-affected zones and the till matrix. Hydraulic conductivity measured in small boreholes intersecting fractures was 0.018 in/hr (1.25x10-5 cm/sec), one order of magnitude greater than in matrix boreholes. Particle size distribution and total cla content did not vary between the fracture faces and the matrix. There was a slight increase in expandable clay, calcite content was 62% greater, dolomite content was 6% lower and iron content was 73% lower on the fracture faces as compared to the matrix. The fractures affected approximately 7% of the total soil volume.