TagEnvironmental Impact Statement(400)

The cities of Burien, Des Moines, Normandy Park, and SeaTac are proposing a formal Interlocal Agreement to coordinate their response to the Port of Seattle's Sustainable Airport Master Plan (SAMP), which could bring significant growth and environmental impacts to surrounding communities over the next 20 years. Under the agreement, the four cities would jointly hire consultants and legal counsel to review environmental documents, submit formal comments during the SEPA and NEPA review processes, and potentially mount legal challenges to FAA or Port decisions. Burien's share of costs is estimated at approximately $100,000.

In September 2025, the Council on Environmental Quality (CEQ) issued updated non-binding guidance to federal agencies on how to conduct environmental reviews under the National Environmental Policy Act (NEPA), replacing earlier guidance from February 2025. The update streamlines the permitting process by incorporating a recent Supreme Court ruling limiting the scope of required environmental analysis, removing climate change and environmental justice considerations, and introducing an optional fee-based program that cuts review timelines in half. Agencies are encouraged to revise their own NEPA procedures using a provided template while continuing existing review processes without delay.

This traffic engineering report analyzes three signalized intersections along S 128th Street near SR 509 in the Sea-Tac area under projected 2032 No Action conditions during the PM peak hour. The study finds that the SR 509 ramp intersections are operating well over capacity, with an Intersection Capacity Utilization of 104.6% and an ICU Level of Service G, while the Des Moines Way S intersection operates more acceptably at 63.3% ICU. Overall intersection control delays range from approximately 19 to 27 seconds, with most approaches functioning at Level of Service B or C.

Appendix O of the Sustainable Airport Master Plan (SAMP) Environmental Assessment documents how the FAA engaged the public and agencies during the NEPA review process for Sea-Tac Airport, including public meetings, briefings, and outreach to communities, elected officials, and underrepresented groups. The summary notes that several Executive Orders and CEQ regulations referenced during the Draft EA have since been revoked, and that the FAA's final decision will rely on updated federal guidance including FAA Order 1050.1F and Executive Order 14154. Public comments received and submitted studies are also included as part of this appendix.

The City of Des Moines, Washington, formally requests that the Port of Seattle reject the Determination of Non-Significance (DNS) for the Sea-Tac Airport Flight Corridor Management Program, arguing that it fails to adequately assess impacts on the city's tree canopy and urban forest. City Manager Katherine Caffrey urges the Port to instead conduct a full Environmental Impact Statement (EIS) examining tree removal, urban heat, air quality, stormwater, and habitat effects. The letter emphasizes that Des Moines residents already face disproportionate noise and health burdens from airport traffic, making tree canopy preservation especially critical to their wellbeing.

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.