Ground-Water solute-transport simulation modeling is an important tool that aids in the analysis of ground-water contamination problems, both actual and potential. Accidental spills, leakage, and waste disposal operations can lead to ground-water contamination. The ability to analyze and predict the movement of solutes in ground-water systems is necessary to assess the effects of a contamination situation or properly design a waste-disposal operation. Laboratory experiments are essential to understanding geochemical reactions in the field and for obtaining the necessary reaction coefficients and rate constants used in transport models. Simulation modeling also is used to compare alternative strategies for aquifer reclamation. In some cases, the transported component of interest is thermal energy. Heat transport simulation is useful in the analysis of geothermal systems, waste heat storage systems, and some deep aquifer systems. Project objectives are to develop and apply new analytical, quasi-analytical, and numerical techniques to the field of saturated ground-water solute-transport simulation modeling; develop mathematical representations of solute-porous medium interactions and chemical reactions and develop and apply efficient algorithms for numerical calculation; apply analytical and numerical simulation modeling to laboratory and field-scale situations, both actual and experimental; and evaluate accuracy of laboratory experiments for predicting geochemical behavior of solutes in the field.