Predicting Water Quality at Hardrock Mines - Methods and Models, Uncertainties, and State-of-the-Art
This report lays out a framework for evaluating the methods and models used to predict water quality at hardrock mine sites and makes recommendations for their improvement. It is intended to be used by regulators, the interested public, and mine operators and managers.
In order to determine if a given hardrock mine project will be protective of water resources during and after mining, regulators at state and federal agencies review Environmental Impact Statements or other types of environmental assessment documents submitted by mine proponents. In these assessments, the potential of the mined materials to generate acid and contaminants and to affect water resources is evaluated using a number of laboratory and field techniques and a variety of predictive modeling approaches. The regulator’s job is to evaluate, sometimes with incomplete information, whether the tests and modeling that were conducted were appropriate for the site-specific conditions at the mine and whether the predictions and the mining approach are reliable enough to guarantee that future environmental liability is adequately addressed.
In this study, we review the methods and models used to predict water quality at hardrock mine sites, with an emphasis on the state of the art and on advantages and limitations of these techniques. Because water quantity and quality are interrelated, methods and models used to predict water quantity will also be discussed, but the emphasis will be on how these methods relate to water quality. This study brings together technical information on water-quality predictions at mine sites in a single report, and attempts to present a straight forward approach to using and evaluating the results of the methods and models used to predict water quality at mine sites. Approaches developed primarily in the United States, Canada, and Australia and applied in these countries and in other parts of the world, especially in the last 10 years, are discussed, and the format of the study is geared toward use by regulators of
hardrock mines. The approach and results of this study could also be used by environmental managers at mine sites and community groups, and allows for the creation of a checklist for prediction methodology used at mine sites. Recommendations are made for improvements in water quality prediction methods and models