TagSEPA(232)

This section of the May 2026 Draft Environmental Impact Statement for Seattle-Tacoma International Airport examines how the airport's near-term construction projects may combine with other past, present, and planned developments to create cumulative environmental effects. The analysis covers 58 projects in the surrounding area—including housing, road improvements, and airport expansions—completed or expected between 2017 and 2032, within a study area defined by the airport grounds, the 65 DNL noise contour, and the surface transportation zone. Long-term airport expansion proposals beyond 2032 are excluded from the analysis because they lack sufficient detail and funding approval to allow meaningful review.

This document is the References section of the Draft Environmental Impact Statement (EIS) for Seattle-Tacoma International Airport's Sustainable Airport Master Plan Near-Term Projects, published in May 2026 under Washington State's Environmental Policy Act (SEPA). It lists the sources cited across the EIS's chapters, covering topics such as aviation activity forecasts, terminal facility requirements, air quality standards, greenhouse gas emissions, geological surveys, and federal FAA design guidelines. The references draw from federal agencies (FAA, EPA), state bodies (WSDE, WDNR, WDFW), regional organizations (Puget Sound Regional Council), and consulting firms that informed the airport's environmental review and planning process.

This report analyzes existing traffic conditions around Seattle-Tacoma International Airport as part of the Sustainable Airport Master Plan (SAMP) Near-Term Projects Environmental Review. It examines 108 intersections—including signalized, stop-controlled, and uncontrolled locations—along key travel routes connecting the airport to surrounding communities, focusing on weekday PM peak hour traffic volumes. The study also includes freeway analysis of SR 518 and I-5 ramps and segments at the request of WSDOT.

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.

The StART (SEA Stakeholder Advisory Round Table) meeting scheduled for April 29, 2026 focuses on updates to the Sustainable Airport Master Plan (SAMP) Near-Term Projects and their environmental review process, including an explanation of how the state-level SEPA Environmental Impact Statement differs from the federal NEPA Environmental Assessment. The agenda includes a presentation by Port of Seattle staff, a community roundtable update, and an open public comment period. StART serves as a forum for cooperation between the Port of Seattle and communities neighboring Seattle-Tacoma International Airport.

The Port of Seattle is advancing a set of Near-Term Projects under its Sustainable Airport Master Plan (SAMP) for Seattle-Tacoma International Airport, covering infrastructure improvements such as new gates, taxiway extensions, runway blast pads, and cargo facilities. The plan is subject to both federal (NEPA) and state (SEPA) environmental review, with a Draft Environmental Impact Statement being prepared to assess potential impacts. Public and regulatory next steps include finalizing the EIS and communicating outcomes to stakeholders and surrounding communities.

Port Of Seattle Commission presentation (Item 8j supp) dated March 24, 2026 requesting $1,000,000 additional contract authorization for the Sustainable Airport Master Plan (SAMP) Near-Term Projects Environmental Review. Total authorizations including this request reach $9,750,000, following previous authorizations of $3,000,000 (11/10/2015), $3,400,000 (2/25/2021), and $2,350,000 (6/27/2023). Budget increase justified by enhanced outreach and engagement in