Alternative Evaluation Framework for Managing Dioxins/Furans in Dredged Material Proposed for Open-Water Disposal Tad Deshler Windward Environmental LLC

A tiered testing approach has been used successfully for many years, but this approach is largely chemical-independent Biological testing frequently involves laboratory bioaccumulation studies

Why might dioxins/furans merit a different approach? Given the toxicity of this chemical group, the environmental concern is often fish/shellfish consumers In such cases, laboratory bioaccumulation tests for dioxins/furans do not focus on the appropriate endpoint Bioaccumulation is lower for dioxins/furans as compared with that of other bioaccumulative compounds

Bioaccumulation of Dioxin/Furans Source: EPA BSAF database (v. 1.0) 50 th percentile (median) PCBs – 1.5 Dioxins/furans – 0.03

Dioxin/Furan Tissue Concentrations in Puget Sound

Alternate Framework At Tier 3 and above in the existing framework, project-specific decisions are made using sediment quality objectives for dioxins/furans, which were developed for the protection of benthic invertebrate communities For the protection of fish/shellfish consumers, suitability determinations would not be made on a project-by- project basis Instead, monitoring program would be developed for disposal sites to determine if dredged material is having an unacceptable impact on fish/shellfish resources

Alternate Framework (cont.) Pilot study should include baseline monitoring at disposal site and background areas Adaptive management approach based on future (bi-annual?) monitoring should be paid for by dredging proponents with money that might otherwise go to bioaccumulation testing If disposal site monitoring indicates increasing dioxin/furan concentrations in fish/shellfish, the sediment quality objective can be adjusted downward

Monitoring Strategy Include species consumed by people that are known to live in the vicinity of the disposal site Collect enough samples to document expected variability in concentrations Establish action thresholds Exceedance of thresholds would trigger evaluation of projects using the disposal site

Interpreting Monitoring Data Exceedance of tissue action thresholds would trigger evaluation of recent projects that used the disposal site Projects could be ranked with respect to dioxin/furan concentrations in dredged material Concentrations associated with higher-ranked projects could establish new sediment quality objective

Benefits of an Alternate Framework Provides more certainty for dredging proponents, particularly in urban environments where dioxins/furans are more likely to be found May reduce unnecessary upland disposal Expense of upland disposal (given overly protective evaluation procedures) may make some dredging projects infeasible Upland disposal can have greater adverse impact on environment and human health than does open water disposal when all impacts are considered

Questions? Tad Deshler