environment faqs

A list of our most frequently asked environmental related questions are below.

There would not be an impact to the mine site. The floodplain was examined extensively as part of the MDEQ’s review of the environmental impact assessment (EIA). The analysis shows that the magnitude of a flood to negatively impact the mine would be a catastrophic event on the order of a 100,000-year surge. The likelihood of a 10,000-year flood over a 50 year period is less than 0.5%. The pit is not within the 100-year floodplain due to the high bluff on the east side of the river where the mine will operate. The west side of the river in Wisconsin features the more extensive floodplain and is ultimately where a surge in water would flow.

In the Environmental Impact Assessment (EIA) we submitted to the MDEQ for review, we addressed potential impacts on water. The analysis shows that the open pit will lower the water table in the area that is owned by Aquila. Groundwater levels in nearby domestic wells will not be impacted, nor will groundwater levels on the west side of the Menominee River. During operations, we will implement an extensive groundwater and surface water monitoring program to validate this assessment. In the unlikely event that monitoring shows that impacts could occur to domestic groundwater, we will have contingency plans ready to be implemented.

No. The term “acid rock drainage” (ARD) refers to the natural oxidation of sulfide minerals. Together with base minerals (e.g., zinc, nickel, copper) in the rock, sulfides react when exposed to air and water. This chemical reaction can occur naturally over time, like the hot springs in Yellowstone National Park or the cliffs along Pictured Rocks National Lakeshore. Human activities, such as mining, accelerate the process.

Past mining practices lacked an understanding of how it was formed and its consequences on the environment. Today, we have a heightened awareness and knowledge of how ARD is created, plus regulations, guidelines, and management tools to prevent its effects.

The Back Forty Mine will use multiple proven methods to mitigate the impact of ARD. We’ll mix high-grade lime with our waste rock to neutralize any acidity. Tailings, waste rock, and ore blending areas will be lined. Also, water that comes into contact with mining activities (pit dewatering, rain, snow, mill process water) will be sent to an on-site water treatment plant for processing. Last but not least, we’ll monitor water conditions throughout the life of the mine and after closure to ensure the environment, including the Menominee River, remains protected.

All water that comes into contact with mining activities, including rainwater and snowmelt, will be collected and sent to one of two contact water basins. From the basins, the water will be sent to an on-site water treatment plant. The quality of treated water will meet all water quality standards applicable to the Menominee River. In fact, the water treatment plant that will be used at the Back Forty Mine in Michigan uses advanced technologies that far surpass most typical municipal water treatment plants.

The Tailings and Waste Rock Management Facility (TWRMF) and Waste Rock Storage Facility are designed to prevent metals from getting into the groundwater. The facilities will feature a multi-layered pad with a leak detection system and sump. All water on site is collected is either reused in the mining process or sent to the water treatment plant for processing prior to discharging to the river.

Dust suppression and collection will be used in areas of concern when processing the ores. We will rely on haul road maintenance, speed limits, and watering to control dust from traffic areas.

The MDEQ is responsible for enforcing the mine’s permits. MDEQ representatives may enter the mine at any time for the purpose of inspecting and investigating conditions relating to the operation of the mine and associated facilities.

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