TagSR509(117)

The City of Burien submitted formal comments in December 2024 arguing that the Port of Seattle's Sustainable Airport Master Plan (SAMP) for Sea-Tac International Airport contains serious flaws, including an unrealistically narrow study boundary that ignores noise and air pollution impacts on surrounding neighborhoods. The city contends that the plan fails to account for cumulative impacts such as the SR-509 highway extension, the 2008 opening of the airport's third runway, and emerging science on health risks from ultrafine particles and aircraft noise. Burien is calling for a full Environmental Impact Statement rather than the less rigorous Environmental Assessment currently underway.

This interlocal agreement between the Washington State Department of Transportation (WSDOT) and the City of SeaTac outlines a cooperative arrangement for road improvements on S. 204th Street between 32nd and 34th Avenues South, as part of the SR 509 Completion Project near Sea-Tac International Airport. WSDOT agreed to assign the construction work in that corridor to the City of SeaTac and reimburse the city up to $1,641,318 upon substantial completion. After construction, the City of SeaTac is responsible for maintaining all improvements, including sidewalks, lighting, and stormwater facilities.

The Des Moines Creek Basin Restoration Projects Interlocal Agreement (GCA-3921) is a cooperative agreement between the City of Des Moines, City of SeaTac, Port of Seattle, Washington State Department of Transportation, and King County to fund and manage several creek restoration projects. The projects aim to control stream flows, improve water quality and fish habitat, and address drainage and flooding problems in the Des Moines Creek Basin. The agreement also serves as part of the stormwater management strategy for the SR 509 highway extension, with costs and responsibilities shared among the participating agencies.

A June 2024 WSDOT presentation to the Des Moines Historical Society outlines the SR 509 Completion Project, part of the broader Puget Sound Gateway Program alongside the SR 167 Completion Project in Pierce County. The project aims to improve freight and passenger connections between the Port of Seattle, Sea-Tac Airport, and key regional distribution centers in King County. The presentation covers the project's history and two construction stages, with WSDOT emphasizing efficiencies gained by managing both highway projects under a single program.

The City of Burien and the Washington State Department of Transportation (WSDOT) have entered into a Memorandum of Understanding regarding the SR 509 Completion Project Stage 2, which extends the highway from S 188th Street to 24th Avenue South, with portions running through Burien's city limits. The project includes construction of a shared-use path, two roundabouts on S 160th Street, and short noise wall segments adjacent to highway on-ramps. WSDOT is responsible for costs associated with the proposed design and construction, while Burien bears costs for any changes it requests beyond standard design requirements.

The SR 509 Completion Project extends State Route 509 from 24th Avenue South to South 160th Street near Sea-Tac Airport, adding new interchanges, roundabouts, and connections to southbound I-5 and toward Seattle. Key features include a new interchange at South 188th Street with a shared-use path and Lake to Sound Trail access, as well as a South 160th Street interchange with noise walls to protect nearby residents. The project also includes wetland mitigation sites and infrastructure improvements along the Des Moines Memorial Drive corridor.

https://wsdot.wa.gov/construction-planning/search-projects/sr-509-completion-project

South Access Road Section 4(f)