Lower Duwamish Waterway – Seattle, WA
Terminal 117 is the site of a former asphalt roofing materials manufacturing facility that operated from 1937 to 1993. PCB, petroleum, dioxin/furan, and PAH impacts in soil and sediment triggered EPA to designate the site an Early Action Area of the Lower Duwamish Waterway (LDW) Superfund site. CRETE successfully worked with the Port of Seattle and City of Seattle during several phases of the project, including: 1) design and oversight of a 2006 time-critical removal action in the Upland Area; 2) preparation of an Engineering Evaluation/Cost Analysis; 3) design of a non-time-critical removal action (NTCRA) in the Upland and Sediment Areas; and, 4) NTCRA bidding and construction support.
Key elements of the NTCRA included:
- Pre-design and pre-confirmation soil, sediment, and geotechnical sampling
- Removal of 46,000 cubic yards of soil and sediment in an Environmental Justice neighborhood
- Special approval by permitting agency to conduct in-water and riverbank work outside of the standard in-water work window established for protection of salmonids
- Deconstruction and diversion for re-use of existing site building materials
- Utilized adjacent commercial facilities for construction haul roads and storage to minimize impacts on the residential community
- Integrated the design with planned right-of-way cleanup activities by the City of Seattle
- Performed a Cultural Resource Assessment with reporting to the Tribes and the State Historical Preservation Office
- Prepared the technical bid documents for public bid, including the Port of Seattle’s first use of responsibility criteria
Upland construction was completed in the summer of 2014. The majority of the in-water work was completed in the winter of 2014 and the remainder was completed during the 2014/15 in-water work window.
Work Performed
- Regulatory negotiations – CERCLA/MTCA
- Permitting – TSCA risk-based disposal approval, EPA off-site rule, ESA Section 7 biological assessment, cultural resource assessment
- Sediment and upland cleanup design and bid documents
- Construction oversight
- Upland and sediment EE/CA
- Insurance cost recovery
- Groundwater-surface water fate and transport
- Dioxin forensics
Value Added
- Implemented project within an Environmental Justice residential area with intensive stakeholder involvement
- Designed the cleanup to integrate with adjacent cleanups, utility improvements, and future site development of a habitat mitigation site
- Obtained a non-potability determination for site groundwater
- Negotiated cleanup levels incorporating groundwater-surface water attenuation due to tidal influence
- Participated in a dioxin forensics work group that concluded that the site was likely not a significant contributor of dioxins to the neighborhood