SMITH, KEVIN H., University of Tennessee, Dept. of Geology, Knoxville, TN

ABSTRACT: Influence of Illuviated Clays and Soil Cements on Hydraulic Conductivity in Sedimentary Saprolite

The goal of this research is to use relatively inexpensive field and lab techniques to assess the variability of hydraulic conductivity from soil surface to bedrock in shale saprolite, and relate this to factors such as distribution of illuviated clays, FeMn-oxide cements and fracture density. The research site is near Oak Ridge, TN, and is located in a 40-60 mile wide stretch of folded and faulted rock known as the Valley and Ridge province. The investigation will be carried out in a stepped pit excavated to depths of up to 4 meters. At each of the steps down to bedrock studies will be done to evaluate the geologic and hydrologic characteristics of the saprolite. These studies will include: detailed geologic mapping of the pit walls and floor, including fracture density, spacing, and orientation, soil texture, bedding thickness, etc.; Measurement of hydraulic conductivity values on each step using a tension-disc infiltrometer for K(y) and a Compact Constant Head Permeameter for K_sat. Lastly a collection of undisturbed core samples will be gathered for later preparation of epoxy-impregnated thin sections, which will be examined under a microscope to determine the degree of micro-fracturing, pore size distribution, pore in-filling and their effects on the distribution of porosity throughout the pit. This research will enhance our understanding of groundwater flow through deeply weathered and fractured sedimentary saprolite in east Tennessee, and will have implications for agriculture, drainage and contaminant migration.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid