The geochemical speciation model MINTEQA2 was applied to study the movement of highly acidic contaminants through a carbonate-bearing aquifer underlying a mine waste site at Globe, Arizona. The MINTEQA2 code was modified to allow the aquifer to be represented as a column through which a finite amount of contaminated water was allowed to pass. The distribution of contaminants among dissolved, adsorbed, and precipitated phases was tracked as a function of distance and the volume of acidic water that passed through the column. This type of modeling allows for an estimation of total contaminant loading within the column and forecasting of breakthrough events. This approach and its computer code may have further applications in the evaluation of in-situ remediation options.