Investigation Report Summary

The Red Cliff Band of Lake Superior Chippewa is working with the U.S. Department of Defense and the U.S. Army Corps of Engineers under the Native American Lands Environmental Mitigation Program to locate and investigate approximately 1,400 barrels containing waste materials from the Twin Cities Army Ammunition Plant that were dumped into Lake Superior between 1959 and 1962. The lake is of unique importance to the Tribe,  and the Tribe is committed to protecting and preserving the lake’s cultural and natural resources for future generations. It is the Tribe’s priority to obtain sufficient information to assess and evaluate the environmental threat to the lake posed by the barrels and their contents.

Six dump sites have been identified to date )Lester River, Talmadge River, French River, Sucker River, Knife River, and Shoreview Road) that range in area from 0.4 to 4.5 square miles with water depths ranging from 37 feet to nearly 500 feet. As part of this investigation, geophysical survey work to locate the barrel dumps included collection of side scan sonar data during the summer of 2008 over a period of 12 days. Approximately 116 square miles of the lake bottom were scanned, which resulted in the identification of 909 sonar targets that were considered to be potential barrel locations. Additional surveys were performed with a remotely operated vehicle (ROV) and sector scan sonar at selected locations to confirm the presence of barrels on the lake bottom.

Barrel recovery work was performed over a two-week period from July 31 through August 13, 2012. A total of 25 barrels were recovered from the Talmadge River, Sucker River, and Lester River sites. Barrels from both the Talmadge River and Sucker River sites contained grenade parts in cardboard cases weighted with concrete. Barrels from the Lester River site contained partially incinerated munitions scrap, ash, slag, and production line refuse.

Samples were collected of barrel solid contents and water, as well as barrel-associated sediments. Samples were submitted to an analytical laboratory for analysis of explosive compounds, volatile and semi volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals, and conventional analytes. Samples of sediment and water form the environment surrounding the dump sites (referred to as dump perimeter samples in this report) were also collected and analyzed for the same analytical parameters as the barrel samples.

Analysis of barrel contents detected PAHs, PCBs, and metals at concentrations that exceed Sediment Quality Targets (SQTs) established by the Minnesota Pollution Control Agency. This pattern of detections was not replicated in sediment samples collected near the recovered barrels, suggesting that at the sites investigated the barrels are currently containing the contaminants; however, barrel quality observed included a range of conditions: minor rust, surficial corrosion, dents, holes, and severe structural deterioration resulting in failure during retrieval.

Analysis of sediment samples collected along the perimeter of the barrel dump areas detected concentrations of metals higher than observed in the barrel-associated sediment samples. Contaminant concentrations in the samples collected outside of the barrel dump areas were higher than contaminant concentrations observed in barrel sediment samples, raising the possibility that these results represent some systematic error in the sampling or analytical process. These environmental samples, therefore, do not appropriately represent natural background conditions.

Based on these preliminary investigation results, additional recovery and sampling of remaining barrels is recommended given that the cumulative dataset is limited relative to the number of barrels dumped. The presence of the barrels as solid waste in the lake continues to adversely affect the cultural resources and potentially the natural resources of the Red Cliff Band. Remaining barrel contents are still uncharacterized, and the potential exists for inadvertent recovery by the general public. While the barrels are presently containing their contents, they should not be expected to do so in the indefinite future.

Miigwech (Thank You)!