Green Remediation/Sustainable Land Asset Management - Deer Lake Reservoir

Client: The Cleveland ??? Cliffs Iron Company

Location: Central Upper Peninsula, Michigan

Summary: The Deer Lake Area of Concern has been investigated for mercury contamination due to a historic gold and silver mine, an iron assay laboratory, discharges of untreated municipal wastewater, and continuation of mercury from the atmosphere. Cardno ENTRIX provided the investigation of this site and probable solutions for clean up. State of the art ?clean-hands, dirty-hands? sampling techniques were developed from USEPA?s method 1669 for snowpack, zooplankton, and seston sampling. Ultra-trace analytical techniques for mercury (1630 and 1631) as well as a proprietary mercury fractionation procedure were used to differentiate mercury inputs from all sources and to characterize the dynamics of mercury cycling.

Results revealed that atmospheric deposition is the most significant continuing source of methyl mercury to this system. Although the mercury content of sediments is relatively high, the sediments are not a significant methyl mercury source to the fish. Careful analysis of fish tissue monitoring data from 23 years revealed that the natural attenuation remedy selected in 1987 has been effective. Based on the Cardno ENTRIX investigations, the Michigan DEQ conceded that sediment dredging and capping remedies are not feasible for this lake. The client successfully commenced a voluntary remedy that manages the reservoir to minimize methyl mercury concentrations in fish.

The remedy has also been endorsed by the local Public Advisory Council (PAC) for this Area of Concern. A global settlement for the client?s total (including NRDA) liability at this site used non-core natural resource assets on CCIC lands to compensate for the contaminant-related liabilities, which reduced the client?s total settlement costs by $60 million and resulted in a sustainable solution. Cardno ENTRIX continues to support the client and the PAC through the Area of Concern delisting process. This project is an example of how Cardno ENTRIX can assist clients in leveraging both technical remediation with strategic land asset management to yield sustainable solutions that drive cost savings to the business as well as direct benefits for the environment.