TagEnvironmental Impact Statement(400)

The Port of Seattle has released a Draft Environmental Impact Statement for its Sustainable Airport Master Plan (SAMP), outlining 31 near-term construction projects at Seattle-Tacoma International Airport aimed at handling a projected 56 million passengers by 2032. Key proposals include a second terminal with 19 new aircraft gates, an elevated busway connecting terminals, expanded cargo facilities, airfield safety upgrades, and new sustainable aviation fuel infrastructure. The plan addresses longstanding capacity shortfalls in parking, check-in, security, and gate areas that were already undersized as of 2018.

This document is the References section of the Draft Environmental Impact Statement (EIS) for Seattle-Tacoma International Airport's Sustainable Airport Master Plan Near-Term Projects, published in May 2026 under Washington State's Environmental Policy Act (SEPA). It lists the sources cited across the EIS's chapters, covering topics such as aviation activity forecasts, terminal facility requirements, air quality standards, greenhouse gas emissions, geological surveys, and federal FAA design guidelines. The references draw from federal agencies (FAA, EPA), state bodies (WSDE, WDNR, WDFW), regional organizations (Puget Sound Regional Council), and consulting firms that informed the airport's environmental review and planning process.

This draft Environmental Impact Statement (EIS) evaluates proposed expansion projects at Seattle-Tacoma International Airport under Washington State's Environmental Policy Act (SEPA). It outlines a two-step screening process used to assess alternatives, including suggestions from public scoping such as building a new airport, using other transportation modes, and limiting growth — most of which were rejected for failing to meet the project's purpose of serving 56 million annual passengers at an optimal level of service. A No Action Alternative is also included, representing a future baseline without the proposed physical improvements.

This appendix outlines the traffic mitigation measures required for the Seattle-Tacoma International Airport Sustainable Airport Master Plan Near-Term Projects, as mandated by the FAA's Record of Decision and the Port of Seattle's State Environmental Policy Act Environmental Impact Statement. It details specific intersection improvements across multiple jurisdictions—including the City of SeaTac, City of Burien, City of Des Moines, and WSDOT—such as new traffic signals, roundabouts, and turn lane additions, along with proportionate-share cost contributions where full mitigation is not required. The measures are designed to address projected traffic impacts through 2037 and maintain acceptable levels of service at affected intersections near the airport.

This section of the Draft Environmental Impact Statement (EIS) for Seattle-Tacoma International Airport's Sustainable Airport Master Plan describes the existing environment surrounding the airport, which sits on approximately 2,800 acres in SeaTac, Washington, about 12 miles south of downtown Seattle. The study area covers roughly 3,692 acres bounded by nearby cities including Burien, Des Moines, and Tukwila, where surrounding land use is primarily residential, commercial, and parkland. Baseline environmental conditions are drawn from 2022 data to assess potential direct and indirect impacts of proposed near-term airport development alternatives.