A Preliminary Investigation of Contaminant Distribution and Movement at Grassy Island, Wyandotte Unit of Shiawassee National Wildlife Refuge, Michigan

The US Fish and Wildlife Service (USFWS), in collaboration with USGS Water Resources Division and Biological Resources Division, is funding an investigation of the distribution and composition of contaminated sediments on Grassy Island. From 1961 through 1983, Grassy Island, in the Detroit River (figure 1), was operated as a confined disposal facility (CDF) for the Detroit District of the Army Corps of Engineers (Corps). Dikes composed of river sediments and rubble were initially constructed and later augmented to increase the capacity of Grassy Island for dredged sediments. The disposal site was limited to 72 acres. Grassy Island was the first CDF on the Detroit River and did not incorporate later design features which reduce movement of contaminants from CDFs. Dredged river sediments, principally from the River Rouge, were deposited on the island. River Rouge sediments typically contain high concentrations of metals, organic compounds, and other contaminants. In 1961, Grassy Island and surrounding shallow waters became part of Wyandotte National Wildlife Refuge, principally because of the concentrations of migratory waterfowl which feed on the wild celery in the shallows on the west side of the island.

Figure 1. Map showing location of Grassy Island and proposed sample sites.

Previous investigations by the Corps, Michigan Department of Environmental Quality (MDEQ), US Environmental Protection Agency (EPA), and the Detroit River Remedial Action Plan (RAP) indicate that the River Rouge sediments and Detroit River sediments adjacent to Grassy island are contaminated by metals and organic compounds. Previous investigations by the USFWS indicate that Grassy Island sediments are contaminated and that migratory waterfowl show exposure to these same contaminants.

The goal of this interdisciplinary, multiagency investigation is to characterize the distribution and composition of contaminated sediments over Grassy Island. This will involve soil borings, monitoring wells, soil and water samples, and laboratory tests. A marine-geophysical study of the shoal grounds surrounding the Island was completed in October, 1996. These data are currently being analyzed and a report prepared. Water, soil, and sediment quality work is scheduled to begin by June, 1997, and will include the installation of piezometers using USGS standard methods as documented in OFR 89-396 and OFR 95-398.

 

Publications:

Sweat, M.J., 1997, Marine-Seismic Survey of Grassy island, Wyandotte Unit of Shiawassee National Wildlife Refuge: U.S. Geological Survey Administrative Report, in press.

 

Contacts:

Mike Sweat, U.S. Geological Survey, Water Resources Division, 6520 Mercantile Way, Suite 5, Lansing, MI 48911, (517) 887-8903, mjsweat@usgs.gov

Doug Spencer, U.S. Fish and Widlife Service, Shiawassee National Wildlife Refuge, 6975 Mower Road, Saginaw, MI, 48601, (517)777-5930, Doug_Spencer@mail.fws.gov

More Information:

U.S. Fish and Wildlife Service
Shiawassee National Wildlife Refuge

U.S. Geological Survey, Biological Resources Division
Great Lakes Science Center

U.S. Army Corps of Engineers, Detroit District