This week, we’ve been at Battelle’s 2017 Remediation and Management of Contaminated Sediments Conference, which is always an excellent forum to gather with others from around the world to discuss advancements in this important field. The cost-effective management of potential human health and ecological risk associated with legacy sediment and surface water sites is a critical challenge facing many of our clients. We are continuously expanding our experience and best practices for the development of cost-effective, risk based solutions to address these challenges, and sharing that information with one another allows us to improve upon our work year after year.
At the 2017 conference in New Orleans, Louisiana, we sent three of our experts to present on recent successful projects related to sediment and surface water. For anyone who was unable to make it this year, here is a brief rundown of those presentations:
Dr. Kyle Apigian presented a poster session on the results of a study on a freshwater, polymictic lake that had an accumulation of heavy metals from treated process water at a nearby manufacturing facility; there was a concern that the metals in sediment may be affecting surface water quality. His study involved evaluating changes in spatial and temporal patterns of heavy metals in sediment and surface water over the past quarter century, and measuring the rates and patterns of sediment deposition within the lake. The results of the study, which supported the development of a closure program that does not require active sediment remediation, suggest that direct burial may not be the primary mechanism that would account for reductions in the heavy metal concentrations.
Anne Proctor presented a poster session on the optimization of an active hydraulic control system to prevent the discharge of dissolved copper and low pH groundwater to a wetland and intermittent stream. Our goal was to come up with a cost-effective long term alternative to the groundwater recovery and treatment system that had operated for 20 years. After considering ecological risk factors and evaluating remedial alternatives, the pump and treat system was replaced with a Permeable Reactive Barrier (PRB) trench, a sustainable, cost-effective remedy that provides a long term solution for the management of ecological risk while minimizing maintenance and monitoring requirements.
Janet Robinson gave two presentations this year—one platform and one poster. Janet’s platform presentation detailed the sampling and analytical approach used at an industrial site on a tidal river to develop site-specific ecological risk-based sediment cleanup standards. PAHs and metals had accumulated in shallow and deep sediment as a result of decades of manufacturing, and the project had stalled due to the difficulty in defining the nature and extent of sediment impact and establishing practicable site-specific cleanup goals. Initial toxicity and chemical constituent results for sediment and pore water varied widely, making derivation of site-specific cleanup standards quite challenging. We developed a detailed analytical and toxicity evaluation protocol and then applied a variety of statistical methods to successfully develop a site-specific sediment cleanup standard. The data and cleanup standards allowed the evaluation of cleanup options to proceed so the project could be completed and no longer represent a long term liability to the property owner.
Janet’s poster session focused on an ecological and human health risk assessment of a 96-mile section of the Columbia River next to the Hanford Superfund Site. The assessment evaluated the effects of radionuclides, metals, and other materials that had been discharged to the river during plutonium production at the site. Findings concluded that nearly all of the risk could be attributed to ingesting PCBs and pesticides in fish tissue that had actually most likely originated somewhere other than the Hanford Site. This information helped identify areas for further investigation of alternate sources as well as areas of potential risks related to the site.
It’s exciting to see our colleagues’ work in action and to be able to make important contributions to this field of research and practice. Our free whitepaper on defining background conditions is another great resource for those involved in sediment remediation projects. The science and available information on these topics are constantly evolving, please feel free to reach out for further insight on these presentations and our recent successes on similarly challenging projects.