EVALUATION OF THE RELATIONSHIP BETWEEN SATURATED HYDRAULIC CONDUCTIVITY AND GRAIN-SIZE DISTRIBUTION OF GLACIAL-FLUVIAL DEPOSITS, PUGET LOWLAND, WASHINGTON

Geologists have explored the relationship between saturated hydraulic conductivity (Ks) measured from laboratory permeameters and grain-size distributions for over a century. However, results from this study show that data comprising in-situ material properties is needed to better correlate Ks and grain-size distribution. Therefore, a relationship between Ks and grain-size distribution was analyzed for sites underlain by glacial-fluvial deposits in the Puget Lowland in Washington State. Using linear regression, comprising pairs of pilot infiltration tests and grain-size analyses, Ks predictions showed a significant reduction in uncertainty and a strong correlation between Ks and grain-size distribution, in contrast to a widely applied analysis in western Washington (Ecology, 2012). The method developed in this study distinguishes between glacially over consolidated and normally consolidated material for determination of Ks for glacial-fluvial deposits in the Puget Lowland.