HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Healy, R. W. Articles by Mills, P. C. Search for Related Content PubMed Articles by Healy, R. W. Articles by Mills, P. C. Agricola Articles by Healy, R. W. Articles by Mills, P. C.

Variability of an Unsaturated Sand Unit Underlying a Radioactive-Waste Trench

U.S. Geological Survey, Water Resources Division, M.S. 413, P.O. Box 25046, Denver Federal Center, Denver, CO 80225-0046

Patrick C. Mills

U.S. Geological Survey, Water Resources Division, 102 E. Main, 4th Floor, Urbana, IL 61801

*Corresponding author.

ABSTRACT

Properties of soils vary considerably within any field. This study was conducted to investigate the variability in properties of an unsaturated sand unit that lies at a depth of 13 m below land surface. Four-hundred-forty soil core samples, obtained from a 1.75 by 18-m horizontal plane within a sand unit underlying a waste trench, were used to describe the variability of moisture content, tritium concentration, and several physical properties. A simple model based on unit-gradient theory was used to calculate fluxes of water and tritium through the study plane. The effects of including spatial variability of properties in model calculations were examined. The sand was uniform in terms of median particle size, bulk density, and proposity, but several variables, including saturated hydraulic conductivity (K_s) and tritium concentration, showed considerable variability. In general, correlation coefficients calculated between variables were low. Spatial correlation structures were identified for moisture content, tritium concentration, and a few particle-size variables, but were absent for K_s and most other variables. Variances of K_s and field-measured volumetric moisture content () were lower than published values for soils. Model-calculated fluxes of water and tritium that accounted for spatial variability of properties were considerably higher than those that did not account for the variability. Model results were more sensitive to changes in and residual moisture content (each parameters of the relative hydraulic conductivity function) than to changes in K_s.

Received for publication October 16, 1989.