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Comprehensive Process Secures Permits While Maintaining Environmental Protection

Background

Foth was retained to complete permit applications for the refurbishment and recommissioning of an ore processing mill in Marquette County, Michigan. The applications needed to be consistent with the sister project permit applications of the Eagle Mine, and the rigorous standards of mining permits under Michigan’s new nonferrous mining rules. The Humboldt Mill is the processing site for ore from Rio Tinto’s Eagle Mine.

Approach

As lead environmental consultant for the Humboldt Mill, Foth managed all hydrologic and geochemical studies related to the deposition of tailings in the retrofitted pit lake formed from the historic iron mine. We completed the technical reports related to site environmental engineering, hydrology, wetlands, biological resources, and all permit applications. Foth led the completion of studies related to legacy impacts at this old ferrous and gold processing site.  Our studies conformed to state regulatory standards for identification of necessary site remediation for legacy environmental impacts from old historic mining operations.

We successfully obtained the second set of approved permits under Michigan’s new rules by developing and implementing a data collection, analysis and documentation system that served as the foundation for defining baseline conditions at the site. 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. A hydrologic and geochemical mass balance model of the iron pit was also completed, which included an examination of water quality conditions. The results of the analyses were used as the basis for the development of a mine permit application, environmental impact assessment, NPDES permit application for the facility, wastewater treatment plant design, and an air permit that included dispersion and depositional analysis.

Results

Our comprehensive documents enabled the regulatory agencies to grant permits within 14 months. Foth substantiated the predictions and engineering controls that protect the environment and minimized the effects of facility operations. 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.

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