TagWSDOT(123)

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.

This interlocal agreement establishes a cooperative framework between King County, the City of Des Moines, the City of SeaTac, WSDOT, and the Port of Seattle to implement the Des Moines Creek Basin Plan. The parties agreed to jointly fund and manage the preparation of a Final Design Report, Financing Plan, and environmental permits for capital projects addressing stormwater runoff, flooding, fish habitat, and water quality in the Des Moines Creek Basin. WSDOT's participation was motivated in part by the need to reduce the impacts of surface water runoff from State Routes 509 and 99 and Interstate 5 on the surrounding natural resource system.

The Washington State Department of Transportation (WSDOT) held the inaugural meeting of its Commercial Aviation Work Group on July 11, 2024, in Tumwater, WA, with both in-person and virtual attendance options. The all-day session covered organizational setup tasks including appointing voting members, developing a group charter, electing a chair, and selecting a consultant. While focused on statewide commercial aviation planning, the work group's activities may have relevance to noise policy discussions affecting airports such as Sea-Tac.

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.

RCW 47.06.140 defines transportation facilities and services of statewide significance in Washington State, including highways, the interstate system, ferry routes, freight railroads, and high-capacity transit systems, while explicitly excluding airport facilities and services from this designation. The law requires the Washington State Department of Transportation to set level of service standards for state highways and ferry routes, in consultation with local governments, while retaining final decision-making authority. Improvements to these statewide facilities are classified as essential state public facilities under RCW 36.70A.200.

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.