Posted on

Environmental Assessment for the Sustainable Airport Master Plan Near-Term Projects: Chapter 4 — Environmental Consequences

Document Library
SAMP
2025 NEPA ROD

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.

Open full document

Notes

Chapter 4 of the Final Environmental Assessment (EA) for Seattle-Tacoma International Airport (Sea-Tac Airport) Sustainable Airport Master Plan (SAMP) near-term projects, published September 2025 by Port Of Seattle. Presents environmental consequences for Alternative 1 (No Action), Alternative 2 (Proposed Action), and Alternative 3 (Hybrid Terminal Option) for analysis years 2032 and 2037. Covers forecasted aircraft operations (466,900–509,892) and passenger levels (57–64 million) by alternative. Table 4-2 summarizes impacts and mitigation for Air Quality (criteria pollutants, construction and operational emissions) and Biological Resources (Chinook salmon, Steelhead, Bull trout, Bocaccio rockfish, Yelloweye rockfish, Killer whale, 56.4 acres of migratory bird habitat, stormwater runoff, industrial wastewater). Farmlands and Wild and Scenic Rivers excluded as not present in GSA. Conducted under FAA Order 1050.1F; NEPA environmental assessment process.

Sidebar On/Off
V V