The Terminal 117 cleanup site (T-117), located on the west bank of the Lower Duwamish Waterway in South Park, is a joint cleanup project by the Port of Seattle and City of Seattle. This site was identified for early cleanup (before the larger river cleanup) because the upland property, river bank and sediments in the waterway have high concentrations of PCBs (polychlorinated biphenyls), dioxin/furans and other contaminants. The site also includes nearby streets and yards which are being investigated and cleaned up by the City of Seattle. T-117 is designated as an Early Action Area as part of the Lower Duwamish Waterway Superfund Site listed by the U.S. Environmental Protection Agency (EPA) under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).
PCB contamination is linked to the Duwamish Manufacturing Company operations and, later, Malarkey Asphalt Company. These firms produced asphalt roofing materials from 1937 to 1993. It was believed that oils used to power the asphalt manufacturing process contained PCBs.
In 1999, the Port of Seattle purchased parcels in the upland area from Malarkey, then consolidated upland parcels with previously owned bank line and mudflat land to create the existing T-117 facility. During the purchase, the port agreed to do a time-critical removal action (TCRA) on property under its ownership. This plan was formally agreed upon within an Administrative Order on Consent (AOC) with the Environmental Protection Agency (EPA). The AOC included contaminated stormwater removal, dewatering material removal, PCB contaminated soil removal, installation of a new surface cap for containment and institutional controls. During excavation, a 375-gallon underground storage tank (UST) was removed from the premises. Since this time, the port has continued monitoring and small scale remedial activities based on routine sampling.
Since T-117 is an EAA, the EPA stipulates a cleanup plan to be completed at the time of LDW remediation. To this end, an Engineering Evaluation and Cost Analysis (EE/CA) was created to assess the best method for remedial action. The EE/CA investigates risk associated with contamination on the site based on exposure pathways and contaminant type. Potential contamination risks are evaluated with regulatory cleanup levels to determine critical removal areas. This information is then weighed against the cost of correcting potential risks to find the preferred remedial action. This preferred option based on EE/CA data, is submitted to the EPA. A formal cleanup action plan was issued to the Port of Seattle and City of Seattle for T-117 on September 30, 2010.