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A MULTI-ORD LAB AND REGIONAL ASSESSMENT OF MONITORED NATURAL RECOVERY OF PCB-CONTAMINATED SEDIMENTS IN LAKE HARTWELL, CLEMSON, SC
Citation:
Mills*, M A., R C. Brenner*, J M. Lazorchak, J SchubauerBerigan, F H. McCormick, P T. McCauley*, T. Lyons,T.M., P dePercin*, D L. Lattier, H. K. Howard*, Zeller*, V. S. Magar, J. E. Abbott, AND Foote. A MULTI-ORD LAB AND REGIONAL ASSESSMENT OF MONITORED NATURAL RECOVERY OF PCB-CONTAMINATED SEDIMENTS IN LAKE HARTWELL, CLEMSON, SC. Presented at EPA Science Forum, Washington, DC, 5/2-7/2003.
Description:
Management of contaminated sediments poses many challenges due to varied contaminants and volumes of sediments to manage. Dredging, capping, and monitored natural recovery (MNR) are the primary approaches for managing the contaminated sediment risks. Understanding how well the approaches manage risk in different environments is critical for choosing appropriate remedies to predictably reduce risk to human and ecological receptors. MNR) of sediments is a risk management option that relies on natural environmental processes to permanently reduce risk, and includes careful assessment, modeling, and monitoring to ensure success.
To address the chemical, physical, and biological monitoring issues associated with MNR of contaminated sediments, a site where MNR was selected as the remedial action was essential. An appropriate site was identified in Lake Hartwell, near Clemson, SC. A collaborative project, involving several ORD Laboratories, Region 4, and contractor support (Battelle Memorial Institute), was established to address multiple issues involved at Lake Hartwell. Generally, the collaboration consisted of:
o NRMRL-Cincinnati: Physical, chemical, and biological characterization of sediment, water, and air; clam vs. SPMD studies; groundwater-surface water interactions; co-project management
o NERL - Cincinnati: Biological monitoring (fish, plankton, and macroinvertebrates); co-project management
o NERL - Athens: Modeling studies
o Region 4 - Atlanta: Project authorization and local coordination via EPA Remedial Project Manager
o Region 4 - Athens: Logistics and sampling support.
o NHEERL - Duluth: Scope review and input; data review.
To evaluate the physical, chemical, and biological processes and how these processes relate to the risk, a mechanistic understanding of these processes is needed. Empirical relationships are not sufficient to allow extrapolation to additional sites, contaminants, or remedial actions. To examine these processes, a mass balance approach was taken at Lake Hartwell. Site characterization and monitoring have been conducted at the site for three years to evaluate effective tools for characterizing the contaminants. As a synopsis:
o Year 2000 - Chemical (PCB) characterization and age dating of deep sediment cores in 5-cm increments at 10 stations along centerline of Lake Hartwell and most of its northern tributaries
o Year 2001 - Chemical (PCB) characterization and age dating of deep sediment cores in 5-cm increments at three stations across Lake Hartwell (bank to bank) plus chemical (PCB) characterization of overlying water column and atmosphere at air-water interface
o Year 2002 - Development and evaluation of biological and surrogate monitoring tools to assess recovery of entire Lake Hartwell ecosystem including indigenous fish, clams, plankton, and macroinvertebrates; evaluation of physical/chemical transport mechanisms for PCBs from the sediment to the water column; additional sediment, water, and air monitoring.
o Year 2003 and 2004 (Planned)-Extension of physical, chemical, and biological processes database to provide more refined model inputs (mechanistic and data); optimize monitoring and assessment tools for use at other contaminated sites.