HA9 Ecological Risk Assessment: General Perspectives and Case Studies
8:00 AM - 12:00 PM, Thursday

() A Baseline Ecological Risk Assessment Completed for a Site on a Mississippi River Floodplain.

Harman, Charles1, Calhoun, Christy1, Gneiding, Laurie1, 1 AMEC Earth & Environmental, Somerset, New Jersey, USA

ABSTRACT- A Baseline Ecological Risk Assessment (BERA) was prepared for a Superfund site located in western Illinois on a floodplain adjacent to the Mississippi River. The objective of the BERA was to evaluate the potential for adverse ecological effects to biological receptors living within terrestrial ecosystems located on or adjacent to five distinct disposal areas as a result of exposures to Site-related constituents. The site is located in an area known as the American Bottoms. The five disposal sites are discontinuous and spread across an area approximately 2.6 miles in length and 0.6 miles wide. The disposal sites range in size from less than an acre to over 200 acres and contain a wide variety of organic and inorganic constituents, including PCBs, dioxins, mercury, chromium and lead. Ecologically, the disposal areas were covered with herbaceous and hardwood communities supporting a variety of wildlife. The BERA evaluated the potential for COPECs to impact Receptors of Interest (ROIs) which included the prairie vole, short-tailed shrew, osprey, mink and red fox. Risks to these organisms were calculated based on food chain models using concentrations of contaminants identified in surface soil, surface water, sediments, plant tissues, fish and invertebrate body burdens as input parameters. Additionally, surface soil screening values were utilized to evaluate potential impacts to plants. Food chain modeling indicated that ROIs utilizing the riverbank were not affected by COPECs present in fish and sediments, while modeling indicated that two of the disposal sites posed unacceptable risks to both the short-tailed shrew and the prairie vole. The results of the BERA were used to focus remedial actions at those disposal sites. This presentation will review the approaches, methods and results of the multiple lines of evidence developed in this ecological risk assessment

Key words: floodplain assessment, ecological risk assessment

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