PW16 Ecological Risk Assessment (General)
Exhibit Hall
8:00 AM - Wednesday
(PW258) Ecological Risk Assessment of Contaminated Sediments in Newton Creek System, St Louis River AOC, Wisconsin.
Broses, M1, Janisch, T2, TenEyck, M3, Schmude, K3, Balcer, M3, Hosch, J4, Ingraham, C1, 1 SEH Inc., Chippewa Falls, WI, USA2 Wisconsin DNR, Madison, WI, USA3 Lake Superior Research Institute - Univ of Wisconsin Superior, WI, USA4 Wisconsin DNR, Superior, WI, USA
ABSTRACT- The Newton Creek System is located in Superior, Wisconsin and discharges to Superior Bay, part of the St Louis River Area of Concern. The headwaters of Newton Creek begin at an oil refinery treated wastewater impoundment and flow approximately 2 miles through industrial, commercial, residential and recreational properties to Hog Island Inlet, a 17-acre embayment. The system has been the focus of environmental investigation since 1990. Ecological Risk Assessment studies since 1993 include sediment and water chemistry analyses, fish and bird tissue chemistry analyses, multi-year sediment benthic community analyses, and several laboratory toxicity studies (1993, 1994, 2000, 2003). Sediment chemistry has been analyzed for oil and grease, diesel range organics, polycyclic aromatic hydrocarbons (PAHs) and alkyl substitutes, and metals (including AVS/SEM analysis). Sediment chemistry for PAHs and metals was evaluated in relation to dry weight consensus based sediment quality guidelines (CBSQGs), and organic carbon normalized equilibrium partitioning sediment quality guidelines (ESGTUs). Benthic community analysis included evaluation of several indices including abundance, richness, and diversity. Toxicity studies include solid phase and sediment elutriate tests conducted with Hyalella azteca, Chironomus tentans, Lumbriculus variegatus, Daphnia magna, Ceriodaphnia, and Pimephales promelas. Toxicity studies also evaluated photo-activated toxicity from UV light exposure. Multiple lines of evidence were integrated to assess risks and develop Preliminary Remediation Goals (PRGs) for PAHs. Uncertainty analysis was conducted to identify areas of uncertainty associated with the conceptual model, results, and natural variation. An interim remedial action was completed along Newton Creek in Summer 2003 and benthic community sampling results appear to indicate that colonization of the creek bed by moderately sensitive species is occurring. A remedial action for the inlet is planned for 2005.
Key words: sediment quality guidelines, ecological risk assessment of contaminated sediment, multiple lines of evidence, preliminary remediation goals