Estimating the Hydraulic Conductivity of Glacial Tills From Soil Index Tests
Abstract
The most important parameter in any groundwater flow or contaminant transport problem is hydraulic conductivity (K). However, for fine-grained soils, the measurement of hydraulic conductivity (K) can be expensive and time-consuming. Previous attempts at estimating K for fine-grained soils have been marginally successful. In this study, 23 glacial till were sampled at seven sites in McLean County, Illinois. The samples were tested for saturated vertical K, grain-size distribution, porosity, plastic limit and plasticity index. Soil characteristics from the soil-index tests were mathematically manipulated into several variable forms and correlated to K by using the Statistical Program for the Social Sciences (SPSS). Variables that correlated significantly with K were then used to perform a step-wise multiple regression analysis, with K as the dependent variable. The resulting equation explained 75% of the variance in K. Plastic limit and clay content showed the strongest correlation to K. Plastic limit showed a positive correlation with K, along with clay contents above 23%. This is likely due to the effect that clay content and plasticity have on structure in shallow, unsaturated soils. Repeated expansion and contraction leads to fracturing in highly plastic soils, which increases K. This study shows the need for a closer examination into the importance of structure on the hydraulic conductivity of shallow, fine-grained soils.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2002
- Bibcode:
- 2002AGUSM.H42A..09B
- Keywords:
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- 1899 General or miscellaneous