PW16 Ecological Risk Assessment (General)
Exhibit Hall
8:00 AM - Wednesday
(PW256) Ecological Risk Assessment of Contaminated Sediments at Ashland Lakefront Site, Lake Superior, Wisconsin.
Ingraham, C1, Janisch, T2, Broses, M1, Balcer, M3, TenEyck, M3, Call, D3, 4, Schmude, K3, Dunn, J5, 1 SEH Inc., Chippewa Falls, WI, USA2 Wisconsin DNR, Madison, WI, USA3 Lake Superior Research Institute - Univ of Wisconsin Superior, WI, USA4 University of Dubuque, IA, USA5 Wisconsin DNR, Spooner, WI, USA
ABSTRACT- The site, located along the shoreline of Chequamegon Bay, Lake Superior in Ashland, Wisconsin, includes a former manufactured gas plant, a 10-acre lakefront park, and 10 acres of offshore sediments beneath shallow surface water 0 to 10 ft deep. Past uses of the park site have included a wastewater treatment plant and a lumberyard. Contaminants include non-aqueous phase liquids, polycyclic aromatic hydrocarbons (PAHs), heterocyclic aromatic hydrocarbons, volatile organic compounds, and metal contaminants. The site has been the focus of environmental investigation since 1989. ERA studies conducted include development of a conceptual site model, identification of assessment and measurement endpoints, sediment and water chemistry analyses, fish tissue chemistry analyses, sediment benthic community analyses, and several laboratory toxicity studies. Sediment chemistry was evaluated in relation to many benchmarks including sediment quality advisory limits (SQALs), dry weight consensus based sediment quality guidelines (CBSQGs) and organic carbon normalized equilibrium partitioning sediment quality guidelines (ESGTUs). Benthic community analysis evaluated several indices including abundance, richness, and diversity for silty-sand and wood waste substrates at the site. Toxicity studies include solid phase and sediment elutriate tests conducted with Hyalella azteca, Chironomus tentans, Lumbriculus variegatus, Daphnia magna, and Pimephales promelas. In addition to standard testing, toxicity studies also evaluated elutriate dilution, solid phase sediment dilution, UV light exposure, and a modified 7-day procedure for P. promelas exposure to renewed water overlying solid phase sediments. A relationship appears to exist between PAH exposures and toxicity test results. Multiple lines of evidence were integrated to assess risks and develop Preliminary Remediation Goals (PRGs) for PAHs. Potential remediation costs range to several million dollars. Uncertainty analysis was conducted to identify areas of uncertainty associated with the conceptual model, results, and natural variation. Additional ERA studies are being conducted to further evaluate endpoints, reduce uncertainty, and refine PRGs.
Key words: sediment quality guidelines, ecological risk assessment of contaminated sediment, multiple lines of evidence, preliminary remediation goals