TagSEPA(233)

The Port of Seattle has released a Draft Environmental Impact Statement (EIS) under Washington State's environmental review law for 31 near-term construction projects at Seattle-Tacoma International Airport (SEA). The projects, which include a new 19-gate terminal and an elevated busway system, are designed to handle up to 56 million passengers by 2032. While a prior federal review found no significant environmental impacts requiring mitigation except for surface transportation, this state-level review evaluates two action alternatives alongside a no-action scenario.

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 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 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.

This report analyzes existing traffic conditions around Seattle-Tacoma International Airport as part of the Sustainable Airport Master Plan (SAMP) Near-Term Projects Environmental Review. It examines 108 intersections—including signalized, stop-controlled, and uncontrolled locations—along key travel routes connecting the airport to surrounding communities, focusing on weekday PM peak hour traffic volumes. The study also includes freeway analysis of SR 518 and I-5 ramps and segments at the request of WSDOT.

This draft Environmental Impact Statement (EIS) evaluates the potential environmental effects of near-term construction and expansion projects at Seattle-Tacoma International Airport, comparing a No Action Alternative against two action alternatives through a projected analysis year of 2032, with an out-year assessment extending to 2037. The study examines impacts across multiple environmental categories—including air quality, noise, greenhouse gas emissions, and surface transportation—using forecasted aircraft operations and passenger levels for each alternative. Mitigation and minimization measures are identified to address any significant adverse impacts identified through the analysis.

This section of the May 2026 Draft Environmental Impact Statement for Seattle-Tacoma International Airport examines how the airport's near-term construction projects may combine with other past, present, and planned developments to create cumulative environmental effects. The analysis covers 58 projects in the surrounding area—including housing, road improvements, and airport expansions—completed or expected between 2017 and 2032, within a study area defined by the airport grounds, the 65 DNL noise contour, and the surface transportation zone. Long-term airport expansion proposals beyond 2032 are excluded from the analysis because they lack sufficient detail and funding approval to allow meaningful review.

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.