SETAC Globe - Environmental Quality Through Science
13 April 2017
Volume 18 Issue 4
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Contaminated Sediment Site Professionals Meet in New Orleans

Patricia White and Andrew Bullard, Battelle

Environmental professionals recently met at Battelle’s Ninth International Conference on Remediation and Management of Contaminated Sediments, held from 9–12 January in New Orleans, Louisiana, to share experiences and expertise with managing contaminated sediments and remediating and restoring waterways and coastal areas. Battelle has hosted the biennial conference since 2001 to give the global sediment management community an opportunity to share their latest research, present case studies, discuss regulatory changes, and propose better ways to manage contaminated sediment sites and watersheds.

This year’s conference was attended by 1,200 scientists, engineers, regulators, site managers, contractors and service providers from more than 20 countries, including many SETAC members. Six short courses were offered on the first day of the conference. The technical program included nearly 600 platform and poster presentations and four panel discussions, presented in 51 technical sessions. Technical sessions were organized around five tracks: Characterization, Assessment and Monitoring; Environmental Processes and Modeling; Remediation and Restoration Alternatives; Remedy and Restoration Implementation; and Management Approaches and Policy. Conference activities also included a student paper competition and student-young professional events. A closing roundtable summarized the major themes and new developments that emerged from each technical track. Some of the high-interest topics at the 2017 conference are highlighted below.

Bioavailability and Bioaccumulation

A number of presentations discussed improved methods and approaches for assessing bioaccumulation of hydrophobic organic compounds (HOCs) in food webs using field measurements and modeling, and the use of food web model predictions in remedial decision-making. Advances in the use of passive samplers to assess contaminant bioavailability include new information on the relationship between passive sampler uptake and bioaccumulation, comparison of in situ and ex situ passive sampling approaches, case studies, end use of passive sampler data, and development of standard methods for use of passive samplers for assessing and managing contaminated sediments. Several presentations discussed the use of diffusive gradient in thin film (DGT) samplers to assess mercury bioavailability.

Emerging Contaminants

The conference program included three sessions on emerging contaminants, with a focus on polyfluorinated alkyl substances (PFAS), with presentations about analytical methods, environmental chemistry and behavior, human health and ecological risk, development of regulatory limits, and potential remedial technologies for treating PFAS contamination.

Sediment Remediation Approaches

Many case studies focused on the increased use of capping, in situ treatment, monitored natural recovery, and enhanced monitored natural recovery instead of dredging. Advances in capping include more precise and uniform placement of cap materials and increased use of multi-layer reactive caps. In situ treatment using carbon amendments to reduce HOC bioavailability is being used at an increasing number of sites, but long-term performance data are not yet available. The environmental dredging sessions reported improvements in dredging methods to minimize the generation of residuals. The “Advances in Sediment Remediation” panel discussed the evolution of sediment capping technology from thick isolation caps to thinner caps with tighter tolerances, with increased use of reactive amendments. A new in situ treatment technology using bioaugmentation, which combines activated carbon and microbial degradation components, shows promising reductions in sediment polychlorinated biphenyl (PCB) concentrations. The sorbent-polymer extraction and remediation from sediments (SPEARS) system is another emerging technology for in situ treatment of PCB-contaminated sediments. One case study described the use of in situ stabilization for treatment of non-aqueous phase liquid (NAPL)-contaminated sediments. The panel and audience discussed the problem of in situ remedies being physically disturbed over time, the need to develop in situ remedies that are readily and inexpensively rehabilitated, as well as more dynamic concepts of performance.

Recontamination

Recontamination continues to be a major concern at contaminated sediment sites. Presentations focused on methods for assessing recontamination potential, development of appropriate background estimates, and characterization and management of combined sewer overflow and storm water discharges.

Remedy Effectiveness

Monitoring and measuring the success of contaminated sediment site remedies continues to be a challenge. Remedial decision-making could be improved by expanding the range of metrics considered, including sustainability and restoration and revitalization outcomes. A variety of tools and approaches for evaluating sustainability were discussed, including life cycle assessment, societal cost analysis, ecosystem service values, green and sustainable remediation evaluation tools, net environmental benefit analysis, and development of stakeholder metrics.  

Large, Complex Sites

Numerous presentations and several panels tackled the issues associated with cleaning up large, complex sites and urban waterways. Sediment site management in the U.S. using the Superfund process continues to be a challenge. The “Superfund and Rivers: Costs, Benefits and Getting to Cleanup” panel explored other approaches, including Europe’s Water Directive Framework, Great Lakes Legacy Act concepts, incorporating habitat restoration as a component of remedies, and policies that emphasize source control and in situ treatment over dredging. The “Implementation of Adaptive Management – What’s the Obstacle?” panel showed how adaptive management can be used to address the uncertainties of complex site cleanup. An adaptive management framework could include an initial action (e.g., implementation of source control measures) followed by performance monitoring, and then iterative adjustments to the remedy over time to achieve acceptable risk reduction. The “Adaptive Management” panel used live polling to solicit audience input throughout the discussion.

Cross-Program Coordination

The “CERCLA and Clean Water Act Cross-Program Coordination Strategies” panel built on similar panels included in the 2013 and 2015 conference programs. The panel examined case studies of coordination successes and failures from geographically diverse locations, highlighted successful coordination processes between federally led CERCLA sediment cleanup and state-led Clean Water Act programs, explored planned coordination efforts, and discussed areas with an immediate need for developing coordination improvements.

Economic Revitalization

Discussion at the closing roundtable revealed the conceptual value of incorporating redevelopment potential into remedial decision-making at contaminated sediment sites. Might economic incentives for redevelopment of contaminated sediment sites, incorporating planners, local governments and remediation professionals, drive sustainable, effective and responsible solutions?

The conference proceedings were distributed to conference participants in March. The Tenth International Conference on Remediation and Management of Contaminated Sediments will be held in 2019.

Authors’ contact information: whitep@battelle.org and bullarda@battelle.org

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