Background

Kennecott Eagle Minerals Company retained Foth to complete permit applications for the refurbishment and recommissioning of an ore processing mill in Marquette County, Michigan. Foth also needed to complete a set of applications consistent with the sister project permit applications of the Eagle Mine and the rigorous standards of mining permits under Michigan’s new mining rules.

Approach

Environmental conditions were documented for past mining activities associated with open pit iron mining and milling operations for both iron and sulfide ore. A detailed hydrogeologic and limnologic study was completed on the water-filled iron pit historically used for disposing sulfide tailings, and a hydrologic and geochemical mass balance model of the iron pit was completed. The model incorporated thermodynamic mixing because of the future placement of tailings and redox-based geochemical processes that attenuate metal concentrations. Studies were conducted to document the hydraulic integrity of the surrounding bedrock and stability of the chemocline and thermocline. The model also examined water quality conditions in the hypolimnion and epilimnion. The results of the analysis were used as the basis for the development of a mine permit application, environmental impact assessment, a NPDES permit application for the facility, and an air permit that included dispersion and depositional analysis.

Results

Foth successfully obtained the second set of approved permits under Michigan’s new nonferrous mining rules by developing and implementing a data collection, analysis and documentation system that served as the foundation for defining baseline conditions at the site. Our comprehensive documents enabled the regulatory agencies to grant permits, maintain environmental protection and defend decisions in a high-scrutiny public arena. Foth substantiated the predictions and engineering controls that protect the environment and minimized the effects of facility operations. And we successfully evaluated and documented the hydrogeological and geochemical conditions of a complex sub-aqueous tailings disposal facility, and predicted the effects of additional tailings placement—a pivotal issue in the permit approval evaluation.