Formatted Title:

Great Lakes Legacy Act Sediment Remediation in the Detroit River Area of Concern

Background/Objectives:

The US Environmental Protection Agency (USEPA) Great Lakes National Program Office (GLNPO) and Bridgestone Americas Tire Operations, LLC (BATO) partnered to prepare a remediation design to remove approximately 30,000 cubic yards (CY) of contaminated sediment from the Detroit River Area of Concern (AOC) under the Great Lakes Legacy Act (GLLA) program. The project is one of a series of projects in the AOC being performed to remove beneficial use impairments from the AOC. The site includes approximately 800 feet of Monguagon Creek (MC) and approximately 1,000 linear feet and 2 acres of the Upper Trenton Channel (UTC), collectively referred to as the MCUTC Site.

Approach/Activities:

Contaminated sediment will be removed by mechanical dredging, placed in a barge, and transported to the United States Army Corps of Engineers (USACE) Pointe Mouillee confined disposal facility (CDF) for disposal. Steep slopes are present both in MC and the UTC, which required additional design elements to remove all sediment with chemical concentrations above the cleanup goals. In MC, vertical cuts along the water line, and steeper dredge slopes were evaluated and ultimately designed to maximize sediment removal in the very narrow creek. In the UTC, a temporary excavation support system was designed along the shoreline to facilitate dredging to the target dredge depth and maintain slope stability. The support system consists of a water side wall and a deadman wall located 50 feet (15 meters) into the upland site, and anchor rods and walers connect the two walls. After dredging is complete, the UTC slope will be restored to a stable condition by placing sand backfill and protecting the slope from erosive forces (current, wave action, and propeller wash) with a revetment consisting of gravel and rip rap placed over the backfill material. The temporary excavation support system will then be removed after revetment construction is complete.

Results/Lessons Learned:

The MCUTC project is another example of a successful partnership between USEPA and a non-federal sponsor (BATO) contributing to the remediation of contaminated sediment within the Detroit River AOC in a timely and cost-effective manner. The use of USACE’s Pointe Mouillee CDF for disposal of dredged sediment is important for executing the project, as it eliminates the need for dewatering and processing the dredged sediment at an upland dewatering facility, improves project efficiency, reduces disposal costs, and provides an overall more cost-effective remedy. In addition, the design of the temporary excavation support system and revetment were not anticipated during the feasibility study phase of the project. These elements were identified during design, during which time, USEPA, USACE, the state agency, and BATO worked collaboratively to adjust the schedule, budget, and design, to maximize the removal of contaminated sediment at the MCUTC Site.

Victor Warner

Affiliation

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Great Lakes Legacy Act Sediment Remediation in the Detroit River Area of Concern