Background/Objectives: The Portland Harbor Superfund Site in Oregon is complex, with significant volumes of sediments above risk-based concentrations, water-dependent businesses requiring safe navigational access, tribal treaty rights, and substantial projected clean-up costs over $1 billion to be completed over several years.
USEPA Region 10 (EPA) released a proposed plan for the Site in June, 2016. Although the EPA plan addresses trade-offs in option selection, a sustainability analysis was not included in the comparative analysis of alternatives. The project team has developed a sustainability framework to evaluate the proposed remedial alternatives and to help identify cost-effective, sustainable and equitable remedies for the Site. The environmental results are presented here.
Approach/Activities: To assess sustainability in terms of the environmental quality pillar, over 30 environmental metrics which were indicators of the benefits of remedial options were evaluated based on data extracted from the 2015 EPA Draft Final and 2016 Final FS and were scored for each option using an environmental footprint tool (SiteWiseTM), GIS analysis, professional judgement and experience at other regional sites. Metric scores were then aggregated in a Net Environmental Benefit Analysis (NEBA) tool. Unlike NEBA approaches optimized for natural resource damage assessment and habitat mitigation, this approach "maps" metric benefits in terms of the CERCLA criteria: remedy permanence, long-term effectiveness, short-term risk management, implementability, and consideration of stakeholder and public concerns. This allows for the evaluation of remedial options directly in terms of program statutory drivers, an approach accepted into the ROD at another Region 10 site (Lower Duwamish River). The sorted environmental metrics were then aggregated to generate weighted-benefit scores for each remedial option considered.
Results/Lessons Learned: Five remedial options, A (the no action alternative) and the increasingly extensive options B, D, E, I (the EPA's preferred option) and F, were evaluated. Cost estimates and the associated total weighted benefits can be used to determine whether a remedial alternative's costs are disproportionate to the benefits provided by the alternative. The total weighted benefit scores show a significant net benefit for Option B, relative to A, but decreasing net benefit scores for the increasingly extensive options. Even though more dredging scores the highest in terms of permanence and effectiveness over the long term, options requiring more dredging have a range undesirable effects. More reliance on containment results in shorter construction times, lower emissions and resource use, and fewer short-term impacts such as dredging-induced resuspension and contaminant release. The incremental decrease in risk for more aggressive options is relatively small in Portland Harbor; the increased costs and impacts more than outweigh these benefits. Outputs of this work were integrated in the broader PHSP, which assessed environmental, economic and social impacts of remedial options in order to evaluate and communicate overall option sustainability and trade-offs.