Manistique River, MI

A.40 Manistique River, MI

A.40.1 Contacts

U.S. Environmental Protection Agency, Region 5
77 W. Jackson Blvd.
Chicago, IL 60604-3590

Jena Sleboda Braun

USEPA Remedial Project Manager, Superfund Division
312-353-1263
[email protected]

Amy P. Mucha, PhD

USEPA RAP Liaison, Superfund Division
312-886-6785
[email protected]

A.40.2 Summary

Environment:	Tidal River and Harbor, Great Lakes area
Scale:	Full
Contaminants of Concern:	PCBs
Source Control Achieved Prior to Remedy Selection?	No; source controls were part of the final remedy.
Final Remedy:	Hydraulic dredging, capA covering over material (contaminated sediment) used to isolate the contaminants from the surrounding environment., MNR
Expected Recovery Time:	5 years
MNR viewed as a success?	Yes; remedial construction was completed in 2000; site delisting criteria were met in Sept. 2006.

A.40.3 Site Description

The Manistique River and Harbor is adjacent to Lake Michigan in Schoolcraft County, Michigan. The primary sources of contamination at this site include release of PCBs from point sources (discharges/releases from former paper mill and lumber mill operations, discharge from area industrial facilities) and nonpoint sources (runoff from area industrial operations, combined sewer overflows, discharge from wastewater treatment plant).

The Manistique River and Harbor in Michigan was heavily contaminated by PCBs from the late 1950s onwards. Responsible parties include Manistique Paper Inc., Edison Sault Electric, Inc., and Warshawsky Brothers Iron and Metal. In 1996, the USEPA Superfund Emergency Response Team conducted a $48M hydraulic dredgingDredging by use of a large suction pipe mounted on a hull and supported and moved about by a boom, a mechanical agitator, or cutter head which churns up earth in front of the pipe, and centrifugal pumps mounted on a dredge which suck up water and loose solids. program with substantial diver-assisted hand dredging, resulting in the removal of about 190,000 yd³ of waste. The 15-acre cleanup area included a 1.7 mile area of the Manistique River and Harbor where it empties into Lake Michigan. The response action represents one of the largest PCB sediment cleanups to date by USEPA in the Great Lakes Region. USEPA conducted a long-term monitoring program to evaluate residual PCBs in cleanup area sediments.

Historical uses of Manistique River waters in the Area of Concern include receiving wastes from sawmills, a paper mill, small industries, the municipal waste water treatment plant, plus navigation for shipping, ferrying, recreational boating, and commercial fishing. Large quantities of un-decomposed sawdust remain in harbor and river sediments from the white pine lumbering era over one hundred years ago, as well as the relatively sterile sandy sediment that eroded from river banks as a result of log drives on the river. Current uses of the river and harbor include receiving the wastewater discharges from Manistique Paper, Inc. and the City of Manistique Wastewater Treatment Plant. The Manistique Wastewater Treatment Plant recently completed improvements to its system toward elimination of combined sewer overflows. Recreational uses of the river and harbor continue to be boating, sightseeing, and fishing.

From 1994 thru 2000, the USEPA Superfund Emergency Response Branch removed 190,000 yd³ of PCB-impacted sediments from hot-spots adjacent to a former paper mill in the Manistique River and Harbor. The 15-acre remediationThe act or process of abating, cleaning up, containing, or removing a substance (usually hazardous or infectious) from an environment. area, located adjacent to Lake Michigan, was dredged over a 6-year period and capped with 40-mil (0.1-inch) HDPE material anchored by 38 two-ton concrete blocks placed around the perimeter of the cap. The cap was installed to prevent erosion of contaminated sediments within a hot-spot area. Final dredging, completed in 2000, was conducted by divers with hydraulic hoses to minimize resuspensionA renewed suspension of insoluble particles after they have been precipitated. of PCBs and to ensure a clean substrate when completed. Physical inspection of the cap, conducted in 2001, one year after installation, confirmed the cap was physically intact and most anchors still in place. In 2001, confirmation sampling verified that the 10-ppm average PCB concentration goal for the Harbor and River remediation area was met. In 2004, post-remedial sampling indicated 1 ppm PCBs remaining in river and harbor sediments, exceeding the project cleanup goal of 10 ppm.

CSM summary: Remediation of PCB-contaminated sediments in river and harbor areas was achieved through a “hybrid remedy” of hotspot dredging and cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment. with long-term remedial performance monitoring. Additional sediment hot spots were later identified and remediated by dredging.

A.40.4 Remedial Objectives

Concerns at this site included both ecological and human health risks associated with PCBs in sediments in the Manistique River and Harbor, adjacent to Lake Michigan.

The sediment cleanup action objectives for the site focused on achieving the PCB cleanup criteria of 10 mg/Kg for River and Harbor sediments. The project RAOs were defined in the original 1987 Remedial Action Plan, the 1996 RAP update, and the 2002 RAP update. Remedial performance monitoring conducted in 2001 and 2004, as well as the Human Health and Ecological Risk Assessments completed in 2005, provided a baseline assessment for the long-term monitoring program for River and Harbor sediments. Additional sampling conducted in 2006, 2007, and 2008 demonstrated that the project cleanup goals have been exceeded.

A.40.5 Remedial Approach

Final selected remedy: A “hybrid remedy” of hot-spot dredging and capping of PCB-impacted sediments in the Manistique River and Harbor was selected to meet the 10 ppm project cleanup level, with long-term monitoring to ensure the effectiveness of the remedy.

USEPA estimated that 95% of contaminated sediments in the project area would be removed, representing 13,000 to 14,000 pounds of PCBs. Removal and capping of PCB-impacted sediments would result in a reduction of PCB levels in the harbor and river, such that within two to three years after dredging/capping activities PCB concentrations in fish are expected to drop below current health advisory levels. The total project costs for hot-spot dredging, off-site disposal of PCB-impacted sediments, and capping was estimated to be $10 million. The remedy is expected to limit the future liability of the PRPs and the community and fully restore the river and harbor to unrestricted recreational and commercial uses.

The final “hybrid remedy” addresses PCB-impacted sediment in the river and harbor through removal, source controls, and institutional controlsNon-engineered instruments, such as administrative and legal controls, that help minimize the potential for human exposure to contamination and/or protect the integrity of the remedy.. The final remedy was based on a project action goal of 10 ppm PCBs for river and harbor sediments. Long-term remedial performance monitoring addressed residual PCBs in river and harbor sediments.

The hybrid remedy was based on average PCB concentrations at depth of 90 ppm in the harbor and river. The bedrock harbor floor virtually guaranteed substantial residual contamination would remain. Hot-spot removal with capping was determined to isolate 95% to 99% of the PCB mass in the harbor and river basin. The 16-acre cap would reduce the sacrificial concentrations in the overall 56-acre basin to 1 ppm. Risk reduction was determined to be 97% dredge/capping versus. 65% dredging alone. The combination of hot-spot dredging and capping was determined to be the most cost effective alternative, estimated at $5.5 million (including $1.7 million for 30 years of O&M) vs. $33-43 million for dredging alone. The high degree difficulty in siting a local CDF precluded a dredging-only alternative. Remedy evaluation was based on sound science and convincing risk reduction comparisons for hot-spot removal/capping with risk reduction of 97% vs. dredging with risk reduction of 65% to meet the 10 ppm PCB action level.

Remedial alternatives were evaluated with respect to the following criteria:

overall protectiveness
performance
long-term Effectiveness
short-term risk management
implementability
consideration of public concerns
restoration time-frame
probable cost

A.40.6 Monitoring

The final Remedial Construction Completion Report was submitted in late-2001. The long-term monitoring program continues to confirm that the remedial action objective has been met of 10 ppm PCBs in river and harbor sediments.

Since 2001, long-term PCB monitoring has been conducted (in 2001, 2004, 2006, 2007, and 2008) to evaluate the effectiveness of sediment remediation to ensure the remedy remains protective of human health and the environment in the Manistique River and Harbor.

Expected recovery time: 5-10 years

Projected monitoring costs: approximately $1.5M/year

RAOs/project objectives achieved? Remedial construction was completed in 2000. The 5-year reviews have confirmed that the RAOs were initially met and continue to be exceeded. The remedy is viewed as a success. Continued study of the project area since the 1996 bathometric survey concluded that removal of old dams up-river allowed the dredged areas to be covered with a substantial thickness (3-7 ft) of clean sediment through natural depositional processes.

A.40.7 Advantages and Limitations

Site Specific Challenges:

Regulatory—project schedule and winter weather delays, community acceptance, coordination with local industrial operations
Technical—deep excavation of sediments in tidal river, fractured bedrock bottom of river/harbor, winter weather delays over the 6-year project period, coordination of river boat traffic and local industry operations
Community—concern over habitat destruction and contaminant release in river

Acceptance: Final hybrid remedy was accepted by regulatory agency, public group, PRP group, and Great Lakes National Program Office (GLNPO) advisory group.

A.40.8 References

USEPA Manistique River Area of Concern, Lake Michigan. http://www.epa.gov/greatlakes/aoc/manistique/index.html.

USEPA, Region 5 Superfund, Manistique Harbor & River Site Ecological Risk Assessment.http://www.epa.gov/R5Super/ecology/casestudies/manistique.htm.

Manistique Site Update, U.S. EPA Continues Dredging Activities at the Manistique River and Harbor Site. http://www.epa.gov/region5/cleanup/manistique/pdfs/manistique_fs_199808.pdf.

SMWG Review and Analysis of Selected Sediment Dredging Projects (Revised). http://cluin.org/download/contaminantfocus/sediments/REVISED_SMWG_Review_and_Analysis_of_Selected_Sediment_Dredging_Projects.pdf.

Publication Date: August 2014

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