Formatted Title:

Implementation of a Drum Removal Pilot Study in Torch Lake, Michigan

Background/Objectives:

The U.S. Environmental Protection Agency (USEPA) Great Lakes National Program Office (GLNPO) and Honeywell International Inc. (Honeywell) are performing a Focused Feasibility Study (FFS) to address contaminated sediment in the Torch Lake Area of Concern in Houghton County, Michigan, through a Great Lakes Legacy Act Project Agreement. Site investigations, including observations by divers and the use of side-scan sonar and remotely operated vehicles, have identified hundreds of drums on (and in) the sediment under approximately 5 to 80 feet of water within the Hubbell Processing Area (HPA). Results from these surveys indicate that the drums are in various levels of deterioration and that materials such as burlap or other fabric, solid waste, copper wiring, or electric motors could be in the drums. The presence and conditions of these drums represents a key issue that will influence the evaluation of remedial alternatives to support remedy selection as part of the FFS. This is in part because of their condition (and the associated feasibility of removing the drums) and the unknown risk potential posed by the drum contents. Therefore, the project team is conducting a drum removal pilot study (pilot study) to assess drum removal efficacy.

Approach/Activities:

The objectives of the pilot study, which is being conducted in August and September 2024, are as follows:

Determine the effectiveness of drum removal using mechanical methods in various water depths: Area 1 in less than 30 feet, Area 2 in 30 to 50 feet, and Area 3 in more than 50 feet.
Assess the effectiveness and implementability of various environmental controls during in-water operations.
Determine the drum contents following drum removal, as needed, and a suitable disposal location.
Determine the effectiveness of construction means and methods for debris and sediment handling and processing.

A barge-mounted crane with an environmental clamshell will be used to remove drums using two distinct approaches to assess effectiveness in varying conditions. In Area 1, the contractor will cover the entirety of the footprint with overlapping clamshell bucket bites (complete sweep). In Areas 2 and 3, the contractor will target a 10-foot-diameter area around single drum locations and a 15-foot-diameter area around drum clusters. A combination of resuspension controls will be used, including fixed and mobile turbidity curtains and bubble curtains, to evaluate the effectiveness in controlling the spread of resuspended solids released during the drum removal operations. Environmental conditions and numerous other operational parameters will be monitored throughout the work.

Results/Lessons Learned:

Following completion of the pilot study, the project team will evaluate the information collected to assess the effectiveness of removal, environmental controls and potential impacts, and lessons learned. The results will be used to inform the evaluation of FFS removal technologies and support the selection of a protective remedy for the HPA.

Arthur Peitsch

Affiliation

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Implementation of a Drum Removal Pilot Study in Torch Lake, Michigan