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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2008–5169

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Abstract

Sediments are believed to comprise as much as 50 percent of the Snake River Plain aquifer thickness in some locations within the Idaho National Laboratory. However, the hydraulic properties of these deep sediments have not been well characterized and they are not represented explicitly in the current conceptual model of subregional scale ground-water flow. The purpose of this study is to evaluate the nature of the sedimentary material within the aquifer and to test the applicability of a site-specific property-transfer model developed for the sedimentary interbeds of the unsaturated zone. Saturated hydraulic conductivity (K_sat) was measured for 10 core samples from sedimentary interbeds within the Snake River Plain aquifer and also estimated using the property-transfer model. The property-transfer model for predicting K_sat was previously developed using a multiple linear-regression technique with bulk physical-property measurements (bulk density [ρ_bulk], the median particle diameter, and the uniformity coefficient) as the explanatory variables. The model systematically underestimates K_sat,typically by about a factor of 10, which likely is due to higher bulk-density values for the aquifer samples compared to the samples from the unsaturated zone upon which the model was developed. Linear relations between the logarithm of K_sat and ρ_bulk also were explored for comparison.

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