DECIDING WHEN TO INTERVENE

The Detroit River has experienced over a century of discharges from industry and municipalities. Demonstrable improvements have been made in water quality, loadings, and biota. Common with other International Joint Commission Areas of Concern, sediment of the Detroit River still exhibits organic and heavy metal contamination, toxicity, bioaccumulation potential, and impaired benthic macroinvertebrate communities. Over the past 10 years, considerable attention has been focused on the potential for sediment remediation due to other system improvements. The objective of this presentation is to provide sediment data assessment for the past decade, tools and procedures used to identify and prioritize sediment for potential remediation, and integrated considerations for remedial decision-making and the likelihood of sustainable success.

The Detroit River/Trenton Channel In-Place Pollutants (IPP) Study (Kreis 1988a; 1988b) conducted as part of the Upper Great Lakes Connecting Channels Study (UGLCCS 1988a; 1988b) indicated that sediment of the Trenton Channel was highly degraded using a number of assessment endpoints. Results were consistent with previous studies over the past 20 years which indicated severe sediment impairment in the mainland U.S. nearshore zone from the Rouge River, proceeding south to Lake Erie (MDNR and OMOE 1991). A simple, numerical ranking system was developed for sediment and applied using approximately 300 variables and 9000 measurements as determined during the Trenton Channel IPP Study which included organic and heavy metal analysis, sediment toxicity tests, resident benthos, and other sediment- related parameters (Kreis 1988b; 1989). This system was subsequently expanded by Wildhaber and Schmitt (1996). The measured values of individual variables were subjected to a scaling procedure which allows the relative magnitude of difference among measurements to be retained, results in a compatible scaling for all values, and allows individual variables or combinations of variables to be examined. Weighting procedures were also examined and applied to selected variables when desired. Scaled values were combined by site via averaging (arithmetic mean) individual or combined variables and assigned numerical ranks based on the averages. Numerous iterations which examined different procedures, weighting methods, and statistical evaluations indicated that results were extremely consistent for any method used and were intuitively reasonable based on the raw data. Results indicated that the nearshore area between Monguagon Creek and Elizabeth Park was the most severely degraded in the Trenton Channel. More recent data from the Detroit River (Farara and Burt 1993; Ostaszweski 1997), several prioritization procedure results (Long and Morgan 1990; USEPA 1992; Farara and Burt 1993; MDEQ 1996; Ostaszweski 1997), and comparison to sediment guidelines (USEPA 1977; Persaud et al. 1992) indicated consistent findings to the earlier ranking system.

The zonation of degraded sediment quality in the Detroit River is generally known and consistent for the past 20-25 years. All of the prioritization and ranking procedures applied yield the same or similar result. All of the procedures usually include the routinely recommended endpoints including organic and heavy metal concentrations, 3 or more toxicity/bioassay tests, resident benthos, and bioaccumulation assessment. Procedures provide quantitative and relative results which are additionally compared to guidelines/criteria and hazard is inferred. Although the general historical pattern of degraded conditions was observed, the overall area appears to be larger and includes much of the upper reach of the River, and mercury appears to be a re-emerging issue, based on sediment surveys and other datasets. It has been commonly recommended that sediment sampling should occur approximately once every 5 years to determine changing conditions and this appears to be appropriate.

Sediment remediation has occurred at Monguagon Creek and is proposed for Black Lagoon in the Trenton Channel, among other nearshore sites in the main trunk of the River. Removal of sediment from Monguagon Creek was conducted because degradation of this area has been known for approximately 3 decades, poor conditions had been demonstrated many times using different measures, and the area potentially posed human health hazards (UGLCCS 1988b; Carter and Hites 1992a, 1992b; MDEQ 1996; Conestoga-Rovers & Associates 1996). Removal of sediment occurred from the farthest upstream extent of contamination, downstream to the Detroit River. Because of this and other factors, it appears that this remediation will be long- term and sustainable. Considerations for sediment remediation in the main trunk of the Detroit River, for example the Black Lagoon, are similar to those of Monguagon Creek. The area has been routinely identified as a severely impaired area for approximately the past 15 years, vertical sediment has been examined using coring and acoustical methods, the area is moderately small and well defined, contaminant mass would be removed from the system for protection of downstream areas, and there would be distinct local improvements in environmental conditions (Kreis 1988a, 1988b; UGLCCS 1998a, 1988b; MDNR and OMOE 1991; Farara and Burt 1993; MDEQ 1996; Ostaszweski 1997). Because this area is in the main trunk of the River, upstream inputs and dynamic sediment action has potential to re-contaminate the area, although not to the extent of the present condition. Loadings of contaminants through controls and plant closures have decreased, remained stable, or in limited cases have increased, dependent upon the contaminant examined (UGLCCS 1988b; MDEQ 1996). Historical sediment samples and sediment cores exhibit mixed results as to whether improvements can be observed in sediment concentrations (MDEQ 1996; Ostaszweski 1997). Comparison of sediment-associated parameters of an area dredged for construction purposes after 1 year, to other sites in the Trenton Channel, indicated that contaminant concentrations, resident benthos, and toxicity were not significantly different (Besser et al. 1996). Available information suggests that re- contamination would likely occur from inputs and sediment transport, degraded conditions would continue to exist, and the remediation would not be sustainable. Even though major improvements in the Detroit River have occurred, these may not be to the degree necessary to restore beneficial uses. Decisions for sediment remediation would be greatly enhanced by mass balance transport models with predictive capabilities to simulate and forecast the concentrations of sediment which would be deposited at these sites. This tool would allow an assessment of the likelihood that a remediation would be beneficial and sustainable in the main trunk of the Detroit River.

References

Besser, J. M., Giesy, J. P., Kubitz, J. A., Verbrugge, D. A., Coon, T. G. and W. E. Braselton. 1996. "Assessment of Sediment Quality in Dredged and Undredged Areas of the Trenton Channel of the Detroit river, Michigan, USA, Using the Sediment Quality Triad." Journal of Great Lakes Research. 22(3):683-696.

Carter, D. S. and R. A. Hites. 1992a. "Unusual Alkylphenols and their Transport in the Trenton Channel of the Detroit River, Michigan." Journal of Great Lakes Research. (18):125-131.

Carter, D. S. and R. A. Hites. 1992b. "Fate and Transport of Detroit River Derived Pollutants Throughout Lake Erie." Environmental Science Technology. 26(7):1333-1341.

Conestoga-Rovers & Associates. 1996. Final Design Report: Monguagon Creek site, Riverview, Michigan. Romulus, MI.

Farara, D. G. and A. J. Burt. 1993. Environmental Assessment of Detroit River Sediment and Benthic Macroinvertebrate Communities - 1991, Volume I. Beak Consultants Ltd., Report to Ontario Ministry of Environment and Energy. London, Toronto, and Sarnia, Ontario.

Kreis, R. G., Jr. 1989. Numerical Ranking of Hazardous Sediment to Prioritize Sites for Remedial Action. U.S. Environmental Protection Agency, Office of Research and Development. ERL-Duluth, MN, and LLRS-Grosse Ile, MI. 28 pp.

Kreis, R. G., Jr. (Ed.). 1988a. Integrated Study of Exposure and Biological Effects of In-Place Sediment Pollutants in the Upper Connecting Channels. U.S. Environmental Protection Agency, Office of Research and Development. ERL-Duluth, MN, and LLRS-Grosse Ile, MI. 1200 pp.

Kreis, R. G., Jr. (Ed.). 1988b. Integrated Study of Exposure and Biological Effects of In-Place Sediment Pollutants in the Detroit River, Michigan: An upper Great Lakes Connecting Channel. U.S. Environmental Protection Agency, Office of Research and Development. ERL-Duluth, MN, and LLRS-Grosse Ile, MI. 153 pp.

Long, E. R. and L. G. Morgan. 1990. The Potential for Biological Effects of Sediment-sorbed Contaminants Tested in the National Status and Trends Program. NOAA Tech. Memo, NOS OMA 62. NOAA: Seattle, Wa. 174 pp.

Michigan Department of Environmental Quality (MDEQ). 1996. 1996 Detroit River Remedial Action Plan Report. MDEQ, Lansing, MI. 420 pp.

Michigan Department of Natural Resources (MDNR) and Ontario Ministry of the Environment (OMOE). 1991. Stage I Remedial Action Plan for Detroit River. MDNR, Lansing, MI, and OMOE, Sarnia, Ontario. 504 pp.

Ostaszewski, A. 1997. Results of the Trenton Channel Project Sediment Surveys 1993-1996. Michigan Department of Environmental Quality, SWQD, Lansing, MI. 105 pp.

Persaud, D., Jaagumagi, R. and A. Hayton. 1992. Guidelines for the Protection and Management of Aquatic Sediment Quality in Ontario. Water Resources Branch, Ontario Ministry of the Environment. Toronto, Ontario. 23 pp.

UGLCCS (Upper Great Lakes Connecting Channels Study). 1988a. Upper Great Lakes Connecting Channels Study: Volume I, Executive Summary. U.S. Fish and Wildlife Service, Ontario Ministry of the Environment, National Oceanic and Atmospheric Administration, U.S. Army Corps of Engineers, Detroit Water and Sewerage Department, Michigan Department of Natural Resources, U.S. Environmental Protection Agency, and Environment Canada. 50 pp.

UGLCCS (Upper Great Lakes Connecting Channels Study). 1988b. Upper Great Lakes Connecting Channels Study: Volume II, Executive Summary. U.S. Fish and Wildlife Service, Ontario Ministry of the Environment, National Oceanic and Atmospheric Administration, U.S. Army Corps of Engineers, Detroit Water and Sewerage Department, Michigan Department of Natural Resources, U.S. Environmental Protection Agency, and Environment Canada. 626 pp.

United States Environmental Protection Agency (USEPA). 1992. Sediment Classification Methods Compendium. USEPA Office of Water. Washington, D.C. EPA 823-R-92-006.

United States Environmental Protection Agency (USEPA). 1977. Guidelines for the Classification of Great Lakes Harbor Sediment. USEPA, Region V. Chicago, IL.

Wildhaber, M. L. and C. J. Schmitt. 1996. "Hazard Ranking of Contaminated Sediment Based on Chemical Analysis, Laboratory Toxicity Tests and Benthic Community Composition: Prioritizing Sites for Remedial Action." Journal of Great Lakes Research. 22(3): 639-652.