TagNEPA(463)

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 describes how planners evaluated different alternatives to the airport's near-term expansion projects, using a two-step screening process to determine whether each option met the project's stated goals and was practical to implement. Public suggestions submitted during the scoping process—such as building a new airport, using high-speed rail, limiting growth, or relying on other existing airports—were largely rejected because they could not meet current and future passenger demand at SEA. A No Action Alternative is also included, representing a future scenario in which none of the proposed new construction takes place.

The Port of Seattle is conducting an Environmental Assessment (EA) under federal law for 31 near-term improvement projects at Seattle-Tacoma International Airport (SEA), covering airfield upgrades, taxiway extensions, and passenger facility improvements. The projects, collectively known as the Sustainable Airport Master Plan Near-Term Projects, are intended to reduce congestion, improve safety, and enhance the passenger experience, with construction potentially beginning in late 2025 and completion targeted for 2032. The federal review will determine whether the projects could significantly impact the surrounding human environment, including potential noise and other effects on neighboring communities.

This document is the References section of the Environmental Assessment for Seattle-Tacoma International Airport's Sustainable Airport Master Plan Near-Term Projects, finalized in September 2025. It lists all sources cited across the assessment's chapters, including federal regulations, FAA advisory circulars, technical memoranda, city comprehensive plans, and environmental studies used to evaluate the airport's proposed development projects. The referenced materials cover topics such as air quality, facility requirements, stormwater management, land use, and aviation activity forecasting.

Appendix K of this environmental review examines socioeconomic conditions, environmental justice, and children's health and safety risks in the area surrounding the proposed project. It finds that 23.3% of the population in the study area is under 18—higher than both King County and statewide averages—and identifies two schools within the project boundary that could expose children to environmental health risks. The appendix also includes an economic impact analysis for the Northwest Seaport Alliance and a separate environmental justice memorandum prepared under Washington State's environmental review process.