Lora Lake Apartments Site

Client: Port of Seattle
Remedial design and implementation of hot-spot excavation and on-site containment of contaminants in upland soil, groundwater, and freshwater sediments near Seattle-Tacoma International Airport.

Overview of Floyd|Snider Contributions

Designed/implemented a complex remedial investigation for soil, groundwater, and freshwater sediment
Negotiated the Site extent complicated by the ubiquitous nature of the Site contaminant of concern
Designed and implemented an agency-approved remedy
Permitted and received approval for filling of a man-made lake and rehabilitation to a wetland, improving the surface water system while addressing contamination

Project Summary

The Lora Lake Apartments Site is the location of a former barrel washing operation that cleaned and reconditioned barrels in the 1940s to 1950s before it was converted into an auto storage and wrecking yard.

The Site was converted to apartments in the 1980s, and it operated until closure associated with SeaTac Airport 3rd Runway expansion in 2007. Investigations identified the presence of dioxins/furans in Site soil and groundwater at concentrations ranging from those similar to ubiquitous urban background to more than 2,000 times the site residential cleanup level.

The Lora Lake Apartments Site is the location of a former barrel washing operation that cleaned and reconditioned barrels in the 1940s to 1950s before it was converted into an auto storage and wrecking yard. The Site was converted to apartments in the 1980s, and it operated until closure associated with SeaTac Airport 3rd Runway expansion in 2007. Investigations identified the presence of dioxins/furans in Site soil and groundwater at concentrations ranging from those similar to ubiquitous urban background to more than 2,000 times the site residential cleanup level.

Our Approach

Floyd|Snider assisted the Port of Seattle (Port) with design and implementation of a remedial investigation and cleanup action for upland soil, groundwater, and freshwater sediments.

Remedial construction was completed in 2019. Because the driver contaminant at the Site, dioxins/furans, is also a ubiquitous urban background contaminant, the project strategy required complex determination of the Site extent. This process used chemometric evaluations and statistical comparisons of Site data to available urban background data. With Ecology approval of the Site extent, Floyd|Snider was able to design and implement a remedy that allowed for hot-spot excavation of high concentrations and on-site containment via capping using future site redevelopment surfaces as the final soil cap. The selected sediment remedy for the freshwater Lora Lake consisted of open-water filling of the lake to contain contaminated sediments in place and rehabilitation of the artificial lake footprint to a scrub/shrub wetland. The cleanup remedy was permitted and approved by the USACE, Ecology, and the FAA.

Project Milestones:

2015. Final RI/FS Approved
2015. Site Consent Decree and Final CAP Approved
2017–2019. Remedial Construction Complete
2020. Agency Approval of the Cleanup Action

Floyd|Snider assisted the Port of Seattle (Port) with design and implementation of a remedial investigation and cleanup action for upland soil, groundwater, and freshwater sediments. Remedial construction was completed in 2019. Because the driver contaminant at the Site, dioxins/furans, is also a ubiquitous urban background contaminant, the project strategy required complex determination of the Site extent. This process used chemometric evaluations and statistical comparisons of Site data to available urban background data. With Ecology approval of the Site extent, Floyd|Snider was able to design and implement a remedy that allowed for hot-spot excavation of high concentrations and on-site containment via capping using future site redevelopment surfaces as the final soil cap. The selected sediment remedy for the freshwater Lora Lake consisted of open-water filling of the lake to contain contaminated sediments in place and rehabilitation of the artificial lake footprint to a scrub/shrub wetland. The cleanup remedy was permitted and approved by the USACE, Ecology, and the FAA.

Project Milestones:

2015. Final RI/FS Approved
2015. Site Consent Decree and Final CAP Approved
2017–2019. Remedial Construction Complete
2020. Agency Approval of the Cleanup Action

Project Team

Floyd|Snider
Environmental Science Associates
KPFF Consulting Engineers
Aspect Consulting
Gregg Glass
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