TagPort Of Seattle(2343)

This September 2025 Environmental Assessment evaluates three alternatives for near-term development projects at Seattle-Tacoma International Airport, comparing a No Action scenario against a Proposed Action and a Hybrid Terminal Option through analysis years 2032 and 2037. The study finds that while both action alternatives would increase aircraft operations to approximately 475,655 by 2032 and 509,892 by 2037, resulting in higher emissions and some biological resource impacts, none of the increases are considered significant. Mitigation measures, where warranted, include post-construction stormwater controls and nest protection protocols during construction activities.

This section of the Seattle-Tacoma International Airport (SEA) Environmental Assessment describes the airport's physical setting and surrounding communities as they existed in 2022, serving as the baseline for evaluating potential impacts from near-term expansion projects. SEA occupies approximately 2,800 acres in the City of SeaTac, bordered by state routes and residential neighborhoods in cities including Burien, Des Moines, and Tukwila. The assessment defines a General Study Area of 3,692 acres where direct or indirect impacts from proposed actions may reasonably be expected to occur.

This section of the Seattle-Tacoma International Airport Environmental Assessment lists the individuals and organizations responsible for preparing the EA for the Sustainable Airport Master Plan Near-Term Projects, finalized in September 2025. It includes contributors from the FAA, Port of Seattle, and multiple consulting firms covering areas such as noise analysis, air quality, surface transportation, wetlands, cultural resources, and public engagement. Key organizations involved include Landrum & Brown, Concord Engineering, Confluence Environmental Company, Parametrix, Stell Environmental, and others.

The Port of Seattle has issued a Determination of Non-Significance (DNS) under Washington's State Environmental Policy Act (SEPA) for its Flight Corridor Management Program at Seattle-Tacoma International Airport. The program, conducted approximately every five years, identifies and removes trees and other obstructions near the airport's runways that could interfere with flight paths, while also requiring ongoing ecological monitoring and tree replacement. A 15-day public comment period ran through September 11, 2025, after which the Port planned to formally adopt the determination, with any appeals required to be filed in King County Superior Court within 21 days of formal adoption.

The Port of Seattle's Flight Corridor Management Program is an ongoing effort to identify and remove trees near Seattle-Tacoma International Airport (SEA) that obstruct the flight paths of its three parallel runways, as required by FAA regulations. Approximately every five years, the Port surveys the area, removes obstructing trees, and replants replacements, with each cycle documented in publicly available Implementation Plans and Regulatory Memoranda. This 2025 programmatic environmental review under Washington's State Environmental Policy Act (SEPA) covers the long-term program rather than individual removal projects.