A.74 Torch Lake, MI

Torch Lake Superfund Site

A.74.1 Contacts

Regulatory Contact: Michigan DEQ & USEPA

Site Contacts: Scott Cornelius Michigan DEQ and Tom Alcamo USEPA Region 5

A.74.2 Summary

Environment:	Lake
Scale:	Full
Contaminants of Concern:	Very large list: Multiple heavy metals, PAH, PCB, phthalates, coal tars, nitrates, ammonia compounds, processing waste from explosives manufacturing
Source Control Achieved Prior to Remedy Selection?	Original remedy: Vegetative and soil cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment. of stamp sands. No control of industrial processing facilities, no attention to heavy metal and sludge discharges directly to the lake, no investigation of PCB sources, and insufficient characterization of waste disposed in Torch Lake. Extreme hot spots discovered in lake but not dealt with in administrative document.
Final Remedy:	Capping of the Stamp Sands, institutional controlsNon-engineered instruments, such as administrative and legal controls, that help minimize the potential for human exposure to contamination and/or protect the integrity of the remedy. to prevent capA covering over material (contaminated sediment) used to isolate the contaminants from the surrounding environment. damage, monitoring of the lake to assess MNR recovery
Expected Recovery Time:	Currently estimated to be 850 years or more due to increasing heavy metals at the sediment water interface
MNR viewed as a success?	Yes, but only moderately. The massive erosion and windblown sand has decreased dramatically. Inhalation of heavy metal dust and human exposure has been decreased. Torch Lake, however, shows increasing heavy metal contamination regardless of the decrease in erosional input of heavy metal rich sands. Other critical and significant human health and environmental inputs to the lake have not been acknowledged or investigated and no action has been taken to include the concerns in the ongoing evaluation of the remedy by USEPA. Evidence of massive residual contamination in the region that can serve as an ongoing source to the lake has been demonstrated conclusively and documented with formal reports.

A.74.3 Site Description

This site is located in the copper mining district of the Upper Peninsula of Michigan. It is located in the Keweenaw Peninsula of Michigan. Extensive processing of copper ore occurred all around the shores of Torch Lake. Chemical leachingLeaching is the extraction of certain materials from a carrier into a liquid; usually, but not always, a solvent. of copper, dredging of stamp sands for reprocessing, and intense heavy metal liberation into the ecosystem has occurred.

The ROD was not based on an adequate RI and many of the conceptual site model assumptions used for decision making at the time of the ROD are now proven to be inappropriate. The assumption was that natural recovery would allow the lake to improve, and the highly toxic metal concentrations as well as organic and other coal tar and other complex long chain hydrocarbons would be removed from contact with the ecosystem. It has been determined that the metals concentrations in the sediment at the surface are increasing, not diminishing. The geochemistry1) Science that deals with the chemical composition of and chemical changes in the solid matter of the earth or a celestial body (as the moon); 2) The related chemical and geological properties of a substance. and contaminant transport are apparently far different than what the site conceptual model anticipated. So much so that it now appears it will take hundreds of years (the study indicated at least a number above or below 850 years). There are extensive reports, studies, and data available on this site, and it is primarily a heavy metal contamination problem.

Several emergency removals have been initiated in and around this superfund site. Sediment removals in Torch Lake due to the discovery of heavy metal and PCB sludge in public swimming areas have also occurred. These areas along the beaches were previously assumed to be “clean.” Concentrations far above human direct contact criterion for heavy metals (lead in the range of 72,000 ppm for example) have been documented in areas that have been designated as swimming beaches. This same sludge contained significant concentrations of PCB, a contaminant known to be present in Torch Lake and also found in fish.

The aquatic problems and huge dead zones at the base of Torch Lake are clearly documented. The shore of the lake is available for swimming and wading. Multiple industrial processing sites surround the entire lake and the potential for sludge and industrial waste to be present is currently unknown due to limited assumptions and poor characterization in the late 1980’s and early 1990’s. More recent data, however, has found these earlier studies to be lacking.

The site problems stem from an inadequate characterization, a flawed site conceptual model, and poor sample collection for long term monitoring. The prior two mentioned above have also led to a poor data analyses and the inability to draw appropriate conclusions from data that has been collected. These are general statements to summarize the problems that can be highlighted from the data we currently have on the site. Heavy metals including mercury, PCBs

The sources are the extensive stamp sand deposits and the multitude of industrial stamp sand processing, chemical leaching, explosives manufacturing plants, and the smelting operations. These industrial facilities were not addressed in the ROD and the stamp sands were assumed by the USEPA to be homogeneous and essentially benign except for the ongoing high heavy metal concentrations going into the lake due to windblown and water driven erosion (thus the capping strategy). The areas sampled and the frequency and depth of the characterization sampling in and around the stamp sands were not sufficient for making the conclusion to cap these sands. They are now known to include heavy metal rich sludge, layers of industrial processing waste under the lake and adjacent to processing facilities. Ammonia plumes, nitrates, and heavy metal rich groundwater plumes are now known to exist that of course contribute to the metals concentrations in sediment under the lake.

Torch Lake was the site of copper milling and smelting facilities and operations for over 100 years. The lake was a repository of milling wastes and served as the waterway for transportation to support the mining industry. The first mill opened on Torch Lake in 1868. At the mills, copper was extracted by crushing or "stamping" the rock into smaller pieces, grinding the pieces, and driving them through gravimetric sorting in a liquid medium. The copper was sent to a smelter. The crushed rock particles, called "tailings," were discarded along with mill processing water, typically by pumping into the lakes. Mining output, milling activity, and tailing production peaked in the Keweenaw Peninsula in the early 1900s to 1920. All of the mills at Torch Lake were located on the west shore of the lake and many other mining mills and smelters were located throughout the peninsula. In about 1916, advances in technology allowed recovery of copper from tailings previously deposited in Torch Lake. Dredges were used to collect submerged tailings, which were then screened, re-crushed, and gravity separated. An ammonia leaching process involving cupric ammonium carbonate was used to recover copper and other metals from conglomerate tailings. During the 1920s, chemical reagents were used to further increase the efficiency of creosotes, wood creosote, pine oil, and xanthates. After reclamation activities were complete, chemically treated tailings were returned to the lakes. In the 1930s and 1940s, the Torch Lake mills operated mainly to recover tailings in Torch Lake. In the 1950s, copper mills were still active, but by the late 1960s, copper milling had diminished.

Over 5 million tons of native copper was produced from the Keweenaw Peninsula and more than half of this was processed along the shores of Torch Lake. Between 1868 and 1968, approximately 200 million tons of tailings were dumped into Torch Lake filling at least 20 percent of the lake's original volume. In June 1972, a discharge of 27,000 gallons of cupric ammonium carbonate leaching liquor occurred into the north end of Torch Lake from the storage vats at the Lake Linden Leaching Plant. The Michigan Water Resources Commission (MWRC) investigated the spill. The 1973 MWRC report discerned no deleterious effects associated with the spill, but did observe that discoloration of several acres of Lake Bottom indicated previous discharges. In the 1970s, environmental concern developed regarding the century-long deposition of tailings into Torch Lake. High concentrations of copper and other heavy metals in Torch Lake sediments, toxic discharges into the lakes, and fish abnormalities prompted many investigations into long-and short-term impacts attributed to mine waste disposal. The International Joint Commission Water Quality Board designated Torch Lake as a Great Lakes Area of Concern in 1983. Also in 1983, the Michigan Department of Public Health announced an advisory against the consumption of Torch Lake sauger and walleye. The Torch Lake site was proposed for inclusion on the National Priorities List (NPL) in October of 1984. The site was placed on the NPL in June 1986. The Torch Lake site is also on the Act 307 Michigan Sites of Environmental Contamination Priority List.

A Draft Remedial Action Plan ("RAP") for Torch Lake was developed by MDNR in October 1987 to address the contamination problems and to recommend the remedial action for Torch Lake. Revegetation of lakeshore tailings to minimize air-borne particulate matter was one of the recommended remedial actions in the RAP.

CSM summary: The remedy assumed cutting off the stamp sand erosion from wind and water into Torch Lake would reduce accumulation of heavy metals that caused the sediment toxicity. The reality is that this assumption was not correct and the characterization of the source areas was not sufficient to have drawn this conclusion.

We now know and acknowledge that this is the site of the world’s richest copper deposits and mining, and extensive mining and industrial processing of tailings including chemical leaching of the tailings occurred at this site. Tailings and industrial process wastes are scattered all over Houghton County. Torch Lake was the disposal point for the ore and segregation of the tailings was the first process. This removed the solid pieces of copper for processing. The stamped sands and ore containing less rich deposits were segregated some washed into the lake and some put in waste piles. The percentage of copper in these wastes was still greater than deposits around the world and in the U.S. so it was economical to process it again. Copper rich sands deposited in the lake were dredged out (over the history of the site several times) and chemically processed to leach out the copper. Any heavy metals associated with this extremely rich copper deposit were of course released to the lake and sludge rich in metals, fatty acids, ammonia compounds were deposited like deltas along the shore of the lake.

Large smelting and ore processing facilities involving much waste and again, heavy metals other than copper, were also scattered around the county. These facilities also used the lake as their disposal mechanism and a lot of process wastes were sent to Torch Lake for disposal.

Heavy metal smelting plumes downwind of the smelters have never been investigated to date even in populated areas. The mercury and metals of concern from these smelters that can wash continuously into the watershed are not yet acknowledged.

There are of course sources that are richer and more toxic than the smelter plumes. The human health exposure and neighborhood soils and erosion of these heavy metals could still be significant, however currently unknown.

Groundwater is not acknowledged as a contaminant transport mechanism in the current ROD. It has however, been conclusively demonstrated to be a transport mechanism from these on-site industrial facilities to the lake. These sources need to be acknowledged, investigated, and very likely controlled to facilitate a shorter recovery time for this very large lake and watershed.

A.74.4 Remedial Objectives

The risks posed at the site are to human health through a variety of exposure routes including drinking water, direct contact, inhalation, and consumption of fish mostly due to heavy metal particulates in the air and heavy metals deposited in the sediment of the lake (PCB however are also found in the fish). The beneficial use of the resources has been extremely impaired due to heavy metal and other toxic organic contaminant sludge deposited in the lake.

RAO(s)/Project objectives: The objective was essentially to stop the ongoing loss of stamp sands from wind and water erosion to the lake as well as to reduce the inhalation of heavy metal particulates.

A.74.5 Remedial Approach

Final selected remedy: The soils and vegetated caps are currently minimally effective. The stamp sands are toxic to soil microbes and algae due to the high copper content so a fertile, well microbially populated soil profile will never develop. The soil cover was likely too thin and too lean in nutrient rich organic materials to sustain a culture that would support vegetative growth. These conditions continue to be documented and investigated. For this remedy to work long term, it is necessary to enhance the fertility of the topsoil in order to sustain an effective cover. Groundwater leaching through this material is not acknowledged in this remedy as an input to Torch Lake. These stamp sands are a mixture of industrial sludge rich in all of the waste toxic heavy metals as well as the original leaching fatty acids and ammonia and nitrate compounds that leached the copper from the stamp sands on the successive industrial processing. These types of contaminant transport dynamics were also not acknowledged in the decision documents. They have been documented and are known to be a problem.

These operable units are the first and third of three operable units for the site. The selected remedial action for these operable units addresses the tailings and slag piles/beach at the site. Operable Unit II, which is not a part of this ROD, addresses the groundwater, surface water, and sediments. The major components of the selected remedy include:

• Deed restrictions to control the use of tailing piles so that tailings will not be left in a condition which is contrary to the intent of this ROD
• Removal of debris such as wood, empty drums, and other garbage in the tailing piles for off-site disposal in order to effectively implement the soil cover with vegetation
• Soil cover with vegetation

Why the remedy was selected: Stabilization of the stamp sands with a vegetative cap should slow down the constant deposition of heavy metal contaminated sands into Torch Lake both from wind erosion and sedimentation due to run off and wave action erosion. Inhalation of the heavy metal dust was also determined to be of risk to the residents.

Primary lines of evidencePieces of evidence are organized to show relationships among multiple hypotheses or complex interactions among agent, events, or processes. A weight of evidence approach includes the assignment of a numeric weight to each line of evidence. used to investigate MNR: MNR is what is expected to happen in the lake as a result of cutting off the continued influx of heavy metals from the stamp sand deposits. The contaminant transport and geochemistry of the highly contaminated sediments were never investigated and the impact of groundwater and interaction of groundwater with these waste piles and chemical processing waste full of residual leaching chemicals entrained in sludge in the lake as well as on the shore were never acknowledged or considered by USEPA. Heavy metals are increasing in concentration at the base of the lake at alarming rates, and this was of course never anticipated by USEPA. Studies conducted on the sediment by Michigan Technological University have concluded that the MNA recovery time could be 850 years or more to reach concentrations where aquatic life could return to the bottom of the lake.

Expected recovery time: The time as mentioned in the MNR summary above is at least 850 years or more. This was not anticipated by the original ROD due to the poor characterization, not acknowledging the geochemical relationship of sediments or understanding how contaminated they were, nor defining the methods of contaminant transport that include extensive groundwater plumes that are still active from these extensive ongoing industrial sources as input of metals into the lake. No cost information is available.

A.74.6 Monitoring

The lake sediments will be monitored in selected areas to track the progress toward reduction in heavy metals. The monitoring thus far has conclusively demonstrated the most contaminated materials are in the upper column of the sediment profile and decreasing with depth. This contaminant profile is of course contrary to the disposal and stamp sand processing history of the site which would have left the most contaminated material at depth and the most recent processed materials with less metal content on the surface of the sediment profile. The stamp sands vegetative caps are also to be inspected annually and repairs to the cap made if necessary.

Monitoring elements: The elements include cap inspection, institutional controls for construction and disturbance of the cap as well as the ongoing lake sediment and biological monitoring that is needed to track the anticipated recovery of the lake.

RAOs/project objectives achieved? Not yet relevant. The construction of the caps is complete; however, it is too soon to determine their effectiveness. The input from stamp sands eroding and blowing into the lake has been reduced. The monitoring of the sediment confirmed that the sediments that predate the capping of the stamp sands show increasing concentrations that are not in any way related to the decrease in sedimentation due to the caps. There is a beneficial effect for the caps; however, it is difficult to assess how much at this point in time that this effort has reduced the rate of increase in heavy metal concentrations near the surface water interface in Torch Lake.

Publication Date: August 2014