Battelle and EPA Examine Natural Recovery Processes at Two Superfund Sites

Past industrial activities have left their marks of chemical contamination on the environment. Recent Battelle studies at two Superfund sites provided new insight into remediation technologies for contaminated sediments. The investigations were conducted for the U.S. Environmental Protection Agency’s (EPA’s) National Risk Management Research Laboratory, and focused on the natural recovery of polynuclear aromatic hydrocarbon (PAH) contaminated sediments at the Wyckoff/Eagle Harbor Superfund site (Washington), and polychlorinated biphenyl (PCB) contaminated sediments at the Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund site (South Carolina). Wood-treatment operations using large quantities of creosote at the Wyckoff facility near Seattle, Washington, contributed to the PAH contamination of sediments in Eagle Harbor. Capacitor manufacturing activities between 1955 and 1978, upstream of Lake Hartwell, at the former Sangamo-Weston plant, resulted in the discharge of PCBs into Lake Hartwell.

In 2000 and 2001, Battelle demonstrated a quantitative approach to measure the recovery of PCB and PAH contaminated sediments at the two sites. Sediment cores were collected from 10 locations at the Wyckoff/Eagle Harbor site in 2000, and from 18 locations at the Lake Hartwell site in 2000 and 2001. These cores were divided into 5-cm segments and analyzed for PAH compounds for the Wyckoff site and for PCB congeners for the Lake Hartwell site. Results of this work provided insights on the ability of sediments to recover under natural conditions. Vertical contaminant profiles demonstrated the potential for surface sediment recovery. In addition, chemical forensics analyses distinguished between PAH sources like creosote contamination or urban runoff and provided evidence for creosote weathering, while detailed congener analyses provided evidence for PCB dechlorination with sediment depth and age.

The sediment profiling method combined with detailed analytical chemistry and chemical forensics provided a uniquely effective approach to understand the history of contaminated sediment deposition and contaminant sources at both sites. This profiling method also highlighted the ability of surface sediments to recover under natural conditions and the potential for contaminants to weather over time with sediment age and depth. For the Eagle Harbor site, the results were used to identify the occurrence of PAH weathering in off-cap surface sediments, and to distinguish between creosote and urban runoff sources in the harbor. The recognition of these distinct sources and their distribution patterns may influence future sediment management decisions with respect to long-term monitoring of surface sediments to assess cap performance.

The Lake Hartwell results provided strong evidence of surface PCB concentration reductions and PCB dechlorination with depth. Natural recovery processes continue to be investigated at this site by Battelle and EPA as the project team enters their fourth year of sediment monitoring and evaluation. Ongoing studies include fish catches, caged fish deployments, semipermeable membrane deployments, and volatilization studies to assess the fate of PCBs in the aquatic environment.

For more information or publications related to this work, please contact Victor Magar at (614) 424-4604, magarv@battelle.org.