The Roles of Biology, Chemistry and Exposure in the Development of Resilient Remedies by Dr. Todd Bridges

Remediation of contaminated sediments is a widespread, complex, and expensive national problem. Uncertainties regarding contaminant exposure processes play a significant role in driving cleanup decisions, including the derivation of cleanup levels and the selection of remedial approaches. This research has focused on reducing these uncertainties by resolving the role of functional ecology (e.g., the animal behavior) in exposure. Laboratory research has combined the use of passive sampling, tissue analysis, and modeling to quantify the exposure processes that should enable more complete and accurate risk assessments and the design of more resilient remedies. Differences in exposure will be quantified among distinct animal groups (e.g., amphipods, polychaetes, bivalves, fish) in order to improve exposure models used in risk assessment, remedial design, and performance monitoring. In addition, this study is evaluating the relative performance of thin-layer sand caps and activated carbon amendments as a means of achieving resilience for in situ remedies challenged by ongoing sources of contamination. The results of this research will provide tools to evaluate, monitor, and guide active management of in situ remedies.

In Situ Treatment of Polychlorinated Biphenyl Impacted Sediments by Microbial Bioaugmentation by Dr. Kevin Sowers

The objective of this research is to develop and test the efficacy of a bioamended form of granulated activated carbon (GAC) to sequester PCBs from the food chain and concurrently dechlorinate and degrade PCBs in sediments at Department of Defense (DoD) sites. The innovative aspect of the technology is the application of anaerobic organohalide respiring and aerobic PCB degrading bacteria with selected activities to sediments with a GAC agglomerate (SediMiteTM) as a delivery system. The project goals are to (1) evaluate the efficacy of bioaugmentation for expediting degradation of highly chlorinated Aroclors in situ and (2) evaluate the efficacy of the delivery system for deploying biocatalysts into PCB-impacted sediments through a water column. In situ treatment by bioaugmentation has the potential to significantly reduce the environmental impact compared with dredging by minimizing the health risks associated with sediment disruption, reducing overall energy use and effectively negating the requirement for extensive waste management and habitat restoration. The results of an ESTCP-funded pilot study to demonstrate and validate this environmentally sustainable technology under simulated field conditions and at a PCB-impacted DoD field site will be the focus of this presentation.

Dr. Todd Bridges is the U.S. Army’s Senior Research Scientist for Environmental Science. Dr. Bridges’ primary areas of research activity at the U.S. Army Engineer Research and Development Center (ERDC) focus on: (1) the science and engineering of sustainable infrastructure development; (2) the development of risk and decision analysis methods applied to water resources infrastructure and environmental systems; and (3) contaminated sediment assessment and management. Dr. Bridges has served as the Principal Investigator on several research projects related to sediment toxicology, contaminant bioavailability, and sediment risk assessment and management. He currently serves as the Director of ERDC’s Center for Contaminated Sediments, as well as the Program Manager for the U.S. Army Corps of Engineers Dredging Operations Environmental Research Program. Dr. Bridges has published more than 60 journal articles and book chapters, as well as numerous technical reports. He received his B.A. (1985) and M.A. (1988) in Biology/Zoology from California State University, Fresno and his Ph.D. (1992) in Biological Oceanography from North Carolina State University.
 

Dr. Kevin Sowers is Associate Director at the Institute of Marine and Environmental Technology and Professor at University of Maryland Baltimore County. One of Dr. Sowers’ research areas for the past 20 years has focused on the process of microbial dechlorination of polychlorinated biphenyls (PCBs), and the development of sustainable in situ technologies for treating PCB contaminated sites. Dr. Sowers has been PI or co-PI on several DoD, NSF and NIEHS grants focused on identifying PCB dechlorinating bacteria, characterizing their physiology, and developing approaches for scale-up and deployment of both anaerobic dechlorinators and aerobic degraders at PCB impacted sediment sites. He is currently conducting field trials in collaboration with federal, municipal, and private stakeholders. His research has generated over 75 peer-reviewed journal articles, 20 book chapters, and several patents. His research on PCB degradation has been featured in radio interviews, newspaper articles, and a museum exhibit. Dr. Sowers received his doctoral degree in Anaerobic Microbiology from Virginia Tech in 1984 and conducted postgraduate research at the UCLA Department of Microbiology and Molecular Biology.