Sustainable Airport Master Plan Environmental Assessment: Chapter 3 – Affected Environment

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.

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Chapter 3 (Affected Environment) of the Seattle-Tacoma International Airport (Sea-Tac Airport) Environmental Assessment for the Sustainable Airport Master Plan (SAMP) Near-Term Projects, finalized September 2025. Describes existing conditions as of 2022 in and around Sea-Tac Airport, located in the City of SeaTac, King County, Washington, 12 miles south of Seattle and 20 miles north of Tacoma. Airport occupies approximately 2,800 acres bounded by SR 99, SR 509, S. 142nd Place, and S. 200th Street, with additional Port of Seattle land extending to S. 136th Street and S. 216th Street. Nearest cities include Burien, Des Moines, Normandy Park, SeaTac, Tukwila, Federal Way, Kent, and Seattle. General Study Area (GSA) encompasses 3,692 acres (5.8 square miles) bounded by S. 140th Street, 33rd Avenue S., S. 20th Street, and Des Moines Way. Predominant surrounding land use is residential with commercial and industrial areas. Prepared by Port of Seattle under NEPA/SEPA environmental review process.

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