Characterization of Heterogeneities Controlling Transport and Fate of Pollutantsin Unconsolidated Sand and Gravel Aquifers: Third Year Report

摘要

The purpose of this project is to evaluate promising methodologies forcharacterization of heterogeneities in hydraulic conductivity. The major thrusts of this year's work were an assessment of well tests in heterogeneous formations and preparation for a series of induced-gradient tracer tests. The theoretical components of this effort included development of a general model for slug tests in partially penetrating wells, an assessment of the viability of conventional slug-test methods, modeling investigations of pulse tests in heterogeneous formations, and an analysis of appropriate designs for a tracer-test monitoring well array. The field component of this work emphasized slug tests. Practical guidelines for the design, performance, and analysis of slug tests, which should considerably improve the quality of resulting parameter estimates, have been proposed. A unified slug-test model incorporating the effects of nonlinearities, inertia, viscosity, changing casing radii, and velocity distributions has been developed to explain anomalous data from wells in formations of high hydraulic conductivity. Additional field work included drilling and sampling activities; laboratory analysis of sampled cores; an aqueous geochemistry study; construction and installation of multilevel sampling wells; and experimentation with a new single-well tracer test method. Overall, the research of year three reduced results of considerable practical significance. Heterogeneities, Alluvial aquifers, Slug tests, Site characterization, Pollutant transport, Pulse testing.