TORCH LAKE AREA BROWNFIELDS
HOUGHTON COUNTY, MICHIGAN
The federal Agency for Toxic Substances and Disease Registry (ATSDR) and the Michigan Department of Community Health (MDCH) have a cooperative agreement for conducting assessments and consultations regarding potential health hazards at toxic chemical contamination sites within the State of Michigan. The Michigan Department of Environmental Quality (MDEQ), Superfund Section, has asked the MDCH to evaluate any health risks associated with several properties included in the Brownfield Pilot Projects in Detroit and other cities in Michigan.
The U.S. Environmental Protection Agency (U.S. EPA) defines Brownfields as "abandoned, idled, or under-used" industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived environmental contamination. Local governmental entities have asked the MDEQ to conduct environmental assessments of the Brownfield properties in their jurisdiction. The MDEQ has consulted with the MDCH concerning public health aspects of these assessments.
The MDCH health consultation for a Brownfield property includes consideration of the following fundamental questions:
- Are there any imminent or urgent threats to public health associated with the property?
- Does the proposed future use of the property pose any long-term public health hazard?
- What specific actions, if any, are necessary to make the property safe for future use?
- Is there enough information available to answer these questions, and if not, what additional information is needed?
The Torch Lake Area Brownfields properties are several parcels on and near Torch Lake, Houghton County, Michigan. From the 1860s until the 1920s, copper mills in the area deposited tailings, waste rock from copper mining operations, on these parcels. After 1920, as copper mining decreased, the mills treated the tailings with chemicals to extract the residual copper. Citing threats to humans and to biota in and near the lake, the U.S. Environmental Protection Agency (U.S. EPA) placed the lake, adjacent tailings piles, and several inactive copper mills and associated tailings piles in the area on the National Priorities List (NPL) on June 10, 1986. Because of reports of human access to several tailings piles near Torch Lake, the Michigan Department of Environmental Quality (MDEQ) investigated the piles in August 1997.
Based on the available information and data, the tailings piles pose no urgent public health hazard. Several of the piles contain concentrations of metals that would be of public health concern if the piles were developed for residential use, and two of those parcels are under consideration for such development. Those specific parcels should be further evaluated before any residential development goes forward.
The Michigan Department of Environmental Quality (MDEQ) has asked the Michigan Department of Community Health (MDCH) to evaluate the health risks associated with the Torch Lake Area Brownfields property as part of a Brownfields Pilot Project.
The Torch Lake Area Brownfields properties are several parcels on and near Torch Lake, Houghton County, Michigan (Figure 1). The areas investigated include parts of four communities along the west side of the lake, Lake Linden, Hubbell, Tamarack City, and Mason (locations A, B, C, and D in Figure 1), a City of Houghton sand stockpile (E), a closed copper smelter between Hancock and Ripley (F), closed copper mills at Calumet (G) and Boston (H), and tailings (waste from copper mining) deposits at the outlet from Torch Lake to Portage Lake (I), at the north entry to the Portage Lake Ship Canal (J), and near Gay, on the east shore of the Keweenaw Peninsula (K) (1).
Torch Lake is located in the Keweenaw Peninsula of northern Michigan, the site of large deposits of native metallic copper, which have been mined since the first humans reached the area. By the 1860s, large-scale mining operations were underway in the Keweenaw, and the first mill on Torch Lake began operation in 1868. The metal was isolated from the surrounding rock by crushing the ore to a gravel, then using water to separate the metal from the rock. The waste rock, called tailings or stamp sands, was often dumped beside or into the lake. After mining for copper in the Keweenaw peaked between 1900 and 1920, new technology was developed to recover the traces of copper remaining in the tailings. This involved treating the tailings with various chemicals, including cupric ammonium carbonate, lime, pyridine oil, coal-tar and wood creosotes, pine oil, and xanthates, to facilitate removing the remaining copper by flotation. After this reclamation process, the tailings were then returned to the lake and lakeshore. Mining activity in the area decreased after 1920, though copper recovery from the tailings continued until 1968, when the last mill on Torch Lake closed. At least 200 million tons of tailings were discharged into Torch Lake during the century of milling operations on the lake, filling at least 20 percent of the original volume of the lake and causing drastic changes to the shoreline. People living along the lake have used the new land provided by the tailings for a landfill, lagoons for two wastewater treatment plants, and a park with campground, bathing beach, and boat launching ramp (2, 3).
Because the U.S. Environmental Protection Agency (U.S. EPA) concluded the copper and flotation chemicals leaching out of the tailings could have an adverse impact on biota in the lake and humans living in the area, Torch Lake, tailing piles on its shores, and various other sites in the vicinity were placed on the U.S. EPA National Priorities List, also known as the Superfund list, on June 10, 1986. After a Remedial Investigation and other studies, the U.S. EPA decided to cover the tailing piles with vegetative covers (2).
On April 24, 1989, the Michigan Department of Public Health (MDPH),1 working under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR), prepared a Preliminary Health Assessment for the Torch Lake NPL site. The MDPH concluded that the site was of potential human health concern because of the possibility of human exposure to an as-yet unidentified etiologic agent. They noted that no human health effects have been documented as connected to the pollution in the lake. However, fish from the lake had shown a high incidence of tumors. The MDPH advised additional investigation of fish from the lake, private wells in the area, and rumors that drums had been dumped in the area (3). On May 25, 1995, the MDPH, under the same cooperative agreement with the ATSDR, issued a Site Review and Update for the Torch Lake NPL site. In this report, the MDPH concluded that the site posed a public health hazard from the copper, other metals, and polynuclear aromatic hydrocarbons found in the tailings. The cause for the tumors in the fish had not been identified, however, the incidence of tumors had decreased to normal levels. The recommended investigations of the site had been carried out, and more than 100 drums had been removed from the lake. The SRU recommended that a full Public Health Assessment of the site be carried out (2).
There have been reports of the tailing piles being used for recreation, for example, as off-road vehicle tracks, of residences being built on top of tailing piles, and tailings being excavated for winter use on roads to increase tire traction (1). Current and projected uses for the subareas of the Torch Lake Area Brownfields study are listed in Table 1 (4). In August 1997, the MDEQ investigated the Torch Lake Area Brownfields study areas to evaluate the potential for human health impact from these activities.