PHYSICAL AND CHEMICAL HETEROGENEITY IN THE SUBSURFACE: SPATIAL DISTRIBUTION OF TRANSPORT PARAMETERS AND THEIR RELATION TO DEPOSITIONAL PROCESSES

Authors

Dana Divine, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

5-2002

Citation

D. Divine, 2002. Physical and chemical heterogeneity in the subsurface: Spatial distribution of transport parameters and their relation to depositional processes. MS Thesis, Washington State University.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN GEOLOGY, WASHINGTON STATE UNIVERSITY, Department of Geology, May 2002.

Copyright (c) 2002 DANA PACKARD DIVINE.

Abstract

This thesis consists of two parts. The goal of first section is to better understand the influence of heterogeneity on contaminant transport. This objective is approached by quantifying the heterogeneity that may have affected transport of the Stanford-Waterloo tetrachloroethene (PCE) plume. Specifically, I determine the statistical distribution of the PCE sorption distribution coefficient (K_d) at Canadian Forces Base Borden, identify the spatial distribution of K_d, and determine the cross-correlation structure between PCE Kd and permeability (k). The results show that K_d is not lognormally distributed, and that variance is insufficient to fully describe heterogeneity. Skewness may be an important aspect of the ln K_d distribution because the samples constituting the high K_d tail are clustered spatially into predominantly one lens. The cross-correlation in this section of the aquifer is both very weak positive and negative, the sign depending on the spatial location of the samples. The primary goal of the second section is to determine if geologic processes separate sediment into distinct zones of chemical reactivity. If such a correlation exists, the sedimentology of site may be used to constrain the prediction of subsurface chemical heterogeneity. An intermediate step to achieving this goal is to determine if characteristic K_d values can be assigned to lithofacies; qualitative lithofacies information may be used to generate quantitative model input if such a relationship exists. The results suggest that distinct K_d distributions can be linked to lithofacies and that chemical reactivity does correlate to depositional processes. The observation that sorption and permeability are related to different aspects of facies, coupled with the observation that cross-correlation between sorption and permeability varies spatially, suggests that synthetic sorption and permeability fields should be generated independently and be constrained by sedimentology of the site.