OSWER/OSRTI

Washington, DC 20460

NATIONAL PRIORITIES LIST (NPL) 

***Final Site*** September 2010 

TEN-MILE DRAIN St. Clair Shores, Michigan

Macomb County

 Site Location:

The Ten-Mile Drain site consists of the concrete sewer pipes which compose the Ten-Mile Drain storm sewer system, and 

soils which surround the storm sewer pipes in an underground storm utility corridor, located near the intersection of Bon 

Brae Street and Harper Avenue, in St. Clair Shores, Michigan. The storm sewer pipes are heavily contaminated with 

polychlorinated biphenyls (PCBs). St. Clair Shores is located northeast of the City of Detroit and along the western shore 

of Lake St. Clair. PCBs have migrated and contaminated sediments throughout the Ten-Mile Drain, and are present in 

canals where the storm sewer currently and historically discharged, and in Lake St. Clair. 

 Site History:

The site was discovered in 2001 when the Macomb County Drainage Commission collected sediment samples as part of a 

proposed dredging project. The Michigan Department of Environmental Quality (MDEQ) was contacted because elevated 

levels of PCBs were found during sediment sampling. Additional investigations by MDEQ and EPA located highly 

contaminated soils near Bon Brae Street. The original source that contaminated soils and sediments in the utility corridor is 

unknown. 

 Site Contamination/Contaminants:

The heavily contaminated soils in the utility corridor are found in an area of approximately two city blocks. PCB 

contamination has migrated to the Ten-Mile Drain storm sewer, which covers an area of approximately 258 acres. PCBs 

have been found in four canals that are connected to Lake St. Clair where the sewer currently and historically discharged, 

and in Lake St. Clair. In total, these canals comprise approximately 1.4 miles.

 Potential Impacts on Surrounding Community/Environment: 

Potential impacts include health risks from potential exposure to PCBs in the surface water and sediments of the canals and 

lake, exposure to PCBs through consumption of fish caught in the canals and lake, and potential soil exposure to PCBs in 

the area of the historical discharge.

 Response Activities (to date):

At the request of the MDEQ, EPA performed a sediment removal action in two of the canals in 2002. However, sediments 

in these canals have been re-contaminated. In 2006, as an interim action, EPA also cleaned and installed a liner in a portion 

of the storm sewer where the heavily contaminated source soils are located. 

 Need for NPL Listing:

The State of Michigan referred the site to EPA to fully characterize the nature and extent of PCBs at the site. Other federal 

and state programs have been evaluated, but are not viable at this time. EPA received a letter of support for placing this site 

on the NPL from the state. 

[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change 

as additional information is gathered on the sources and extent of contamination.]

For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these 

substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet 

at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.