W4 PM Sediment Quality Assessment
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in Ballroom 4

(MAC-1117-830665) Development and Evaluation of Risk-Based Preliminary Remediation Goals for the Protection of Sediment-Dwelling Organisms.

MacDonald, D¹, Ingersoll, C², Smorong, D¹, Sparks, D³, Smith, J⁴, Meyer, J⁴, Gouguet, R⁵, Wang, N², Braun, G⁶, ¹ MacDonald Environmental Sciences Ltd., Nanaimo, BC, Canada² United States Geological Survey, Columbia, MO, USA³ United States Fish and Wildife Service, Bloomington, IN, USA⁴ Indiana Department of Environmental Management, Indianapolis, IN, USA⁵ United States Environmental Protection Agency (Region 6), Dallas, TX, USA⁶ National Oceanic and Atmospheric Administration, Seattle, WA, USA

ABSTRACT- A risk-based approach was used to derive preliminary remediation goals (PRGs) for the Calcasieu Estuary, LA and the Grand Calumet River, IN. The approach involved several steps, including: 1) Establishing remedial action objectives (RAOs) for each site; 2) Compiling site-specific, matching sediment chemistry and sediment toxicity data; 3) Developing concentration-response relationships for individual chemicals of potential concern (COPCs) and COPC mixtures; and, 4) Calculating PRGs that corresponded to pre-determined risk levels. More specifically, intermediate risk and high risk PRGs (i.e., PRG-IRs and PRG-HRs) were developed for both sites that corresponded to a 20% and 50% incidence of observing toxicity (i.e., % toxic samples) to the amphipod, Hyalella azteca, in 28-d toxicity tests, respectively. Similarly, PRG-IRs and PRG-HRs were developed for each COPC and COPC mixture that corresponded to a 10% and 20% magnitude of toxicity (i.e., reduced survival), respectively. The PRGs were based on dry weight- or organic carbon-normalized COPC concentrations. Subsequently, the reliability of the resultant PRGs was evaluated by determining the incidence of sediment toxicity above and below the PRGs within the data set that was compiled for the site. The results of this evaluation provided a basis for determining which PRGs were most consistent with the RAOs for the sites. Results of this study showed that PRGs developed using the same procedures with comparable data from different sites can differ markedly, emphasizing the importance of deriving site-specific PRGs. These PRGs are being used to evaluate various remedial alternatives at the site and establish cleanup goals.

Key words: sediment, PRGs, remediation, risk assessment