Christoph Wels, Sarah Loudon, Greg Newman, Robertson GeoConsultants Inc.
This paper provides information about the reclamation of the Zortman and Landusky gold and silver mines in the little Rocky Mountains of north-central Montana that is currently on-going under the direction of the Montana Department of Environmental Quality and the U.S. BLM. The paper describes the results of cover performance modeling carried out in support of this decision analysis. The cover performance model was calibrated against observed flows captured from a covered mine rock pile. One dimensional modeling results suggest that the rate of net infiltration is more influenced by the precipitation pattern, (i.e. wet versus dry year), than by the different cover materials. Two dimensional modeling of cover performance on a sloped surface suggested that placement of a fine layer on coarse waste rock would significantly reduce net infiltration due to the capillary break effect. The study concludes that source control could not eliminate the need for on-site water collection and treatment.