TagSAMP(642)

The Des Moines Airport Advisory Committee met on April 13, 2026, and is scheduled to meet again on May 11, 2026, to discuss issues related to Seattle-Tacoma International Airport's impact on the Des Moines, Washington community. Key agenda topics include updates on the Sustainable Airport Master Plan (SAMP) and its Draft Environmental Impact Statement, as well as a proposed workplan amendment covering noise and traffic mitigation measures, public education efforts, and a community survey. The committee also seeks a more comprehensive traffic analysis that accounts for impacts from the completed WSDOT Highway 509 project.

The Port of Seattle released a Draft Environmental Impact Statement (DEIS) under the State Environmental Policy Act (SEPA) for the Sustainable Airport Master Plan Near-Term Projects at Sea-Tac Airport, finding that surface transportation is the only category with significant impacts requiring mitigation. The review examined sixteen environmental categories including noise, air quality, and community impacts, with a 60-day public comment period running from May 22 to July 21, 2026, including in-person meetings in SeaTac, Burien, Des Moines, and Federal Way. A final SEPA determination is expected by the end of 2026.

This draft Environmental Impact Statement (EIS) evaluates proposed expansion projects at Seattle-Tacoma International Airport under Washington State's Environmental Policy Act (SEPA). It outlines a two-step screening process used to assess alternatives, including suggestions from public scoping such as building a new airport, using other transportation modes, and limiting growth — most of which were rejected for failing to meet the project's purpose of serving 56 million annual passengers at an optimal level of service. A No Action Alternative is also included, representing a future baseline without the proposed physical improvements.

This appendix outlines the traffic mitigation measures required for the Seattle-Tacoma International Airport Sustainable Airport Master Plan Near-Term Projects, as mandated by the FAA's Record of Decision and the Port of Seattle's State Environmental Policy Act Environmental Impact Statement. It details specific intersection improvements across multiple jurisdictions—including the City of SeaTac, City of Burien, City of Des Moines, and WSDOT—such as new traffic signals, roundabouts, and turn lane additions, along with proportionate-share cost contributions where full mitigation is not required. The measures are designed to address projected traffic impacts through 2037 and maintain acceptable levels of service at affected intersections near the airport.