Hazard Ranking of Contaminated Sediments Based on Chemical Analysis, Laboratory Toxicity Tests, and Benthic Community Structure: Method of Prioritizing Sites for Remedial Action

M. L. Wildhaber and C. J. Schmitt
National Biological Survey
Midwest Science Center
4200 New Haven Road
Columbia, Missouri 65201

September 22, 1994

Prepared for:
Assessment and Remediation of Contaminated Sediments Program
Great Lakes National Program Office
U.S. Environmental Protection Agency
77 West Jackson
Chicago, Illinois 60604

U.S. Fish and Wildlife Service
National Biological Survey
Contract Number DW14933874-1

INTRODUCTION

Contaminated sediments have become a major focus of environmental concern and research, particularly in the Great Lakes (USEPA 1990). The concern is that even with elimination of current and future sources of contamination, those contaminants already present in sediments are a threat to aquatic life and human health. The Assessment and Remediation of Contaminated Sediments (ARCS) program was managed by the Great Lakes National Program Office of the United States Environmental Protection Agency (USEPA) specifically to address contaminated sediment issues in the Great Lakes and to examine new and innovative ways to both assess and treat contaminated sediments (USEPA 1990).

One goal of the ARCS program was to develop a method by which the relative risks associated with contaminated sediment from different sites can be evaluated. A general method of ranking contaminated sediments based upon direct sediment analyses and tests proposed by Kreis (1989) and was used to proportionally scale sediment variables so that they could be compared and combined. The ranking method developed for ARCS was modified and enhanced from the version proposed by Kreis (1989) by incorporating bioavailability, control-adjusted laboratory toxicity tests, and mean tolerance to pollution of the benthic community for the sediments of concern.

The numerical ranking system developed by Kreis (1989) was intended as a guide, to be used in evaluating regulatory and remediation alternatives for contaminated Great Lakes sediments. Kreis (1988) previously showed that the ranking process can be an effective tool for determining which sites, of a set of contaminated sites, have the highest concentrations of total contaminants and associated parameters. The results of the ranking process can then be used to prioritize sites for remediation; this prioritization is necessary due to the high cost of sediment remediation. As resources and technologies become available, the sediments needing remediation could each be "cleaned-up" in the order of their ranking. The remediation procedure or combination of procedures chosen is site-specific and would depend on ecological, chemical, economic, and engineering considerations.

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