The 2015 Surface Water Management Plan ranked and established a 15-year funding plan for eight stormwater capital projects. The Chennault Beach Road Drainage Improvements project is the highest-ranking capital project in Mukilteo’s SW Management Plan.
About the Project The existing drainage along the Chennault Beach Drive roadway is conveyed in an under-developed ditch-and-culvert system, as well as intermittent piping between 60th Avenue W and Marine View Drive. The piped portions of the system are located where the system outfalls to Upper Chennault Beach Creek at four locations: 60th Avenue W, McArthur Lane, 64th Place W, and west of Marine View Drive. During periods of high flows, roadway flooding occurs due to 1) diminished ditch capacity, 2) debris blocking driveway culverts and inlets, and 3) misplaced inlets. Periods of high flows tend to scour landscaping material (typically small rocks) located in the right-of-way (ROW), resulting in a debris source within existing ditches and culverts. Additionally, soil and vegetation on adjacent steep slopes slough into roadside ditches and create another source of debris that further reduces ditch capacity. Some of the existing inlets are located outside of the flow pathway enabling concentrated surface water to bypass the inlets and reach ditches with diminished capacity, further contributing to roadway flooding.
Project Description This project will improve the drainage system along Chennault Beach Drive, where the existing drainage system is under-developed, under-capacity, or bypassed. See Figure 1 (below). Flows currently routed to the existing Upper Chennault Creek outfall east of McArthur Lane will be routed through the new drainage system to the existing Upper Chennault Creek outfall east of 64th Place W. Existing inlets that are not currently collecting surface water will either be repositioned and connected to the new system or removed. Existing functional inlets may be connected to the new system. New inlets and laterals will be installed as needed.
The project consists of four (4) areas of proposed drainage improvements:
- Improvements to the westbound (north) shoulder of Chennault Beach Drive between 60th Avenue W and McArthur Lane, which consists of re-grading and paving the shoulder and installing an asphalt curb to channel water to the existing stormwater inlets.
- Installation of a 12-inch-diameter drainage system located in the alignment of the existing ditch-and-culvert system on the south side of Chennault Beach Drive, between west of 60th Place W and west of 62nd Place W.
- Installation of an 18-inch-diameter drainage system located in the alignment of the existing ditch-and-culvert system on the south side of Chennault Beach Drive, between west of 62nd Place W and 64th Place W. The new 18-inchdiameter drainage system discharges to the existing outfall to Upper Chennault Creek east of 64th Place W. A maintenance easement should be obtained along the extent of the existing outfall pipe.
- Installation of a 12-inch-diameter drainage system located in the alignment of the existing ditch-and-culvert system on the north side of Chennault Beach Drive, between 64th Place W and W Marine View Drive. This new drainage system will tie into the existing drainage system on Marine View Drive.
Goals and Benefits The Chennault Beach Road Drainage Improvements project is the highest-ranking capital project in Mukilteo’s SW Management Plan. It is the City’s goal to construct a new drainage system along Chennault Beach Drive, between 60th Avenue W and Marine View Drive, to improve the effectiveness of capturing and conveying surface water so as to mitigate roadway flooding, and improve conditions for the traveling public.
Public Outreach During the construction phase, the City will utilize various forms of communication to keep the residential community informed of the project, namely, through the City’s project website, informative door hangers and postcards, and through key points of contact to respond to requests for information regarding the construction operations. Public meetings are not anticipated during the PE phase of the project.
- No meetings scheduled at this time.
March, 2022 – Preliminary Engineering (PE) & Design Advertised
June, 2022 – Preliminary Engineering (PE) & Design begins
November, 2022 – PE & Design completed. Final Design & Environmental phase begins.
February, 2023 – Final Design & Environmental phase completed
March, 2023 – Advertised for Construction
May, 2023 – A project Pre-Construction conference will be scheduled with the start of construction anticipated for sometime in June, 2023.
The Chennault Beach Drive Drainage Improvements project will be funded with Local funds, with a design and construction budget of $4,790,000.