Terminal 117 Engineering Evaluation/Cost Analysis. (Lower Duwamish Waterway Superfund Site, Terminal 117 Early Action Area)

摘要

Terminal 117 (T-117) is one of seven sites within the Lower Duwamish Waterway (LDW) Superfund site that have been identified by the US Environmental Protection Agency (EPA) and the Washington State Department of Ecology as candidate sites for early cleanup because sediments at these sites are associated with greater ecological and/or human health risk. At T-117, the early action area (EAA) is located in the aquatic portion (i.e. sediment) of the site as defined in the LDW early action candidate site memorandum (Windward 2003b). In the time since the T-117 EAA was identified, the Port of Seattle (Port) and the City of Seattle (City) have conducted a series of environmental investigations there to further characterize environmental conditions in the nearshore area and shoreline bank, identify a removal boundary, and to identify potential sources of contamination. This report is an engineering evaluation/cost analysis (EE/CA) for such a removal action at T-117. It presents background information on the site, discusses available data and the proposed boundary of the removal action, documents the development and evaluation of alternatives for conducting the non-time-critical removal action (NTCRA) and discusses the rationale for the recommended removal action that will be implemented by the Port and the City, subject to EPA approval.