Monitoring Identifies Anomaly in Sampling at Rio Tinto Eagle Mine

April  2013

Monitoring Identifies Anomaly in Sampling

at Rio Tinto Eagle Mine

Under the Rio Tinto Eagle Mine Community Environmental Monitoring Program (CEMP), the Superior Watershed Partnership (SWP) conducts independent monitoring of the Eagle Mine.

Overview

During the CEMP’s first quarter 2013 verification monitoring, laboratory analyses detected uranium in water from the Temporary Development Rock Storage Area (TDRSA) leak sump. The TDRSA is an environmentally secure storage facility for holding development rock. Development rock is rock that is not ore.

Uranium is a naturally occurring element, present at low levels in nearly all rock, soil and water. This detection is not a regulatory permit violation and it poses no health or environmental risk.

The level of uranium in the sump exceeds the drinking water standard set by the Safe Drinking Water Act. The TDRSA and the Water Treatment Plant (WTP) are not subject to this act. Instead, the facilities are regulated under Eagle’s mining permit and groundwater discharge permit.

The detected uranium is confined within the site’s water containment system and is sent to the WTP for processing. The WTP features ion exchange and reverse osmosis filtration as part of its treatment process. These two methods are recommended by the EPA for removal of uranium from drinking water.

The WTP produces two forms of solid waste during treatment. A trace amount of uranium was detected in the first solid waste. Uranium was not detected in the second solid waste, which indicates the WTP is removing the uranium. Both of these solid wastes are tested and disposed of properly at a municipal landfill.

In addition, uranium was non-detect in the water being discharged from the WTP. This is further indication that the WTP is treating the water properly.

SWP and Eagle will perform additional tests for uranium and work to locate the source.

Both organizations will report their findings to the community as they become available. For more information, please go to the Eagle Mine website and to the CEMP website. You may also review the Mining Journal’s article on the detection here.

On this topic and other matters, we encourage individuals to go to our website, visit our Information Center in downtown Marquette or call us at 906-339-7150.

Rio Tinto Eagle Mine
4547 County Road 601
Champion, MI 49814

www.riotintoeagle.com


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