Integrated Lecture and Laboratory Modules for Contaminant Transport Studies in Undergraduate Geotechnical Engineering

Abstract

The engineering concepts necessary for fully describing contaminant transport processes in soil and groundwater have been largely neglected by traditional civil engineering curricula in the United States. New lecture and laboratory modules have been developed and integrated into the undergraduate soil mechanics course for civil engineering students at the Colorado School of Mines. The lecture module includes theoretical development of the advection-dispersion equation and a set of practical example problems designed to clarify the relative importance of advection, dispersion, and molecular diffusion in realistic contaminant transport scenarios. The laboratory experiment is developed using relatively inexpensive soil permeability testing equipment common to most academic and industrial geotechnical engineering laboratories. Unlike conventional chemical transport testing, which requires relatively complicated, time consuming, and expensive analytical instrumentation, the new laboratory exercise relies on the use of simple colored dye for simulating the movement of a contaminant through a one-dimensional soil column. The key soil parameters governing the transport of the dye, including the diffusion coefficient, hydraulic conductivity, dispersion coefficient, and retardation coefficient, are quantified by observing the location and color intensity of the dye as it moves through the column. Emphasis is placed on maximizing the simplicity and visual impact of the experimental exercise. The effectiveness of the lecture and laboratory modules is assessed through a student survey.