The Miller Creek Daylighting Project
June, 2020
Miller Creek Daylighting Project Restores Life to Vacant Land Near SeaTac Airport
The City of Burien, Washington, in financial partnership with the Port of Seattle Seattle-Tacoma International Airport (SeaTac airport), the City of Seatac, and Washington Department of Ecology awarded a contract to Otak to design a restoration plan for a 162-acre subarea of vacant, residential, and commercial land adjacent to the SeaTac airport. The project, known as Miller Creek Daylighting for the waterway that flows through property owned by the Port within the Cities of Burien and Seatac city limits, is scheduled to begin construction in 2021, following the Port of Seattle Commission’s approval of Otak’s plan. Otak is currently under contract to finalize the design, work with regulatory agencies, and provide construction management.
The property had several problems to address. It is in the flight path of the airport’s third runway, has degenerated over the years, and attracted activities that were considered a public safety concern. Miller Creek that crosses the property, flows through open stream, as well as through underground pipes and tunnels that have eroded and at one time caused a sinkhole. Stormwater runoff from an adjacent highly developed property is also destroying the natural habitat.
The first step was for Otak to evaluate the property for alternative uses that would be compatible with the airport and remain a tax revenue source for the city. The property use itself had to be considered along with stormwater management. Russ Gaston was brought in as the principal in charge to develop a top-down approach of how to work within the floodplain and stream buffers to correct stormwater management issues, and also create trails and recreation.
Otak’s role in the project was extensive, encompassing land use and conceptual master planning as well as capital facilities and infrastructure planning. Public outreach and participation were part of the design process, along with working through regulatory guidelines. Otak managed the development of the Supplemental EIS and provided technical analysis, and developed a master drainage plan, land use plan, and identified fish barriers for removal. The City also asked for improvements to roads, stormwater, and utilities, and then hired a lobbyist to work with the FAA to start a pilot program for redevelopment of the area.
In developing alternative plans, Otak was able to devise a way to daylight Miller Creek, taking a significant reach of the stream from flowing almost completely through a pipe network to bringing it up to ground level as a natural feature. This design brought an extended contract that also includes building a floodplain trailhead and trail that connect the Miller creek floodplain, an area that did not previously exist.
In addition to daylighting the stream, Otak also was able to include a fish passage in its design creating additional salmon spawning habitat along Miller Creek and working towards the goals of restoring the Puget Sound Watershed.
The final design also integrates with three regional stormwater infiltration facilities, a constructed floodplain wetland, and dispersed green stormwater treatment facilities, a new regional trail along the Miller Creek corridor, and public open space. The newly constructed green stormwater facilities will treat and infiltrate stormwater runoff from approximately 50 acres including runoff from seven acres of existing streets and 43 acres of future redevelopment of impervious areas. The plan allows for simulating the natural hydrology of the area through the addition of rain gardens, biofiltration, and the creation of wetlands that enhance habitat and a wildlife corridor.
Through the design process and as work proceeds, Otak will be working in partnership with multiple 3rd party agencies including the Port of Seattle, SeaTac airport, the City of Seatac, the FAA, WA Department of Ecology, and the City of Burien.