Ten miles of the Lower Willamette River in highly urbanized downtown Portland have been impacted with PCBs, metals, and PAHs by industrial, marine, commercial, defense, and municipal activities by 150 parties for more than 100 years.
The Record of Decision issued by EPA in 2017 described a combined remedy expected to remove three million cubic yards of sediment, cap 176 acres, take 12 years to implement, and cost $1.2 billion. Geosyntec was retained as the common consultant by the PRP group to co-lead and help them navigate the multi-million-dollar pre-remedial design and baseline sampling program. In addition, Geosyntec will develop and scope work plans, design a statistically robust random sediment sampling plan, collect quality data, and produce pre-remedial design (RD) reports for agency approval.
Scope of Services
Geosyntec's field staff collected 2,000+ data points, including surface grabs, sediment cores, surface water, sediment traps, fish tissue, background porewater, fish tracking, and bathymetry studies, all in a fast-track 12-month period. We used the results to establish baseline conditions, evaluate natural recovery time trends and background conditions, revise the conceptual site model (CSM), and refine and optimize the remedial footprint size, volumes, and costs for design. We also led a collaborative team to build a quantitative, transparent, and robust sustainability tool for Portland Harbor, evaluating over 27 environmental metrics. A neighborhood polling survey showed that construction times longer than about seven years were viewed much less favorably by local residents and businesses. Over 280 stakeholder groups were identified and a four-month inferred stakeholder mapping/value analyses grouped and ranked the metrics in terms of stakeholder values. Metrics were aggregated and the social sustainability analysis suggests that all remedial options have environmental, economic, and social impacts, which increase in proportion to the magnitude of the remedial alternative, regardless of the weighting approach used.
Geosyntec helped the PRP Group negotiate a well-defined work plan and finite scope of work for the Administrative Settlement Agreement and Order on Consent (ASAOC) that substantially limited potential scope creep and agency oversight costs. We ran sophisticated statistical power analyses to determine sample quantities and a randomized sampling grid that were used to evaluate current conditions and detect contaminant concentration changes over time with confidence. Our team successfully negotiated with USEPA that upriver sediment background samples should be located in soft sediment areas with finer grained material so that contaminant loads into the site are appropriately represented (and not biased low by sand and gravel substrate conditions). We also developed a transparent, robust sustainability tool that supported selection of a more sustainable alternative for the site, reducing cost and time to construction completion for all responsible parties; this tool may be applied to other large sediment sites as an effective means of communicating tradeoffs in terms of values and priorities. Finally, we developed a site-wide peer-reviewed remedial cost estimating tool specific for sediments that can be easily adapted for other sediment sites.
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- Location: Portland, Oregon
- Client: PRP Group
- Project Practice Areas: Contaminated Sites, Water & Wastewater
- Type of Facility: Urbanized waterway
- Services Provided: Pre-remedial design multi-media sampling, Background statistics and risk evaluations, Cleanup level evaluations, Sustainability assessment, Natural recovery and time trends analysis, Contaminated sediment assessment
- Type of Work: Pre-remedial design
- Governing Regulation: CERCLA