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PROJECT NARRATIVE
Cedar River Left Bank Levee Emergency Repair
City of Renton Public Works
Project Purpose
The City of Renton Public Works Department proposes emergency repairs to damaged
sections of the existing Cedar River Left Bank Levee (Section 205) adjacent to the Renton
Municipal Airport. The existing fiood protection system is located on both banks of the
lower Cedar River. The levee system consists of earthen levee embankments (levees) and
fioodwalls along both banks of the lower 1.25 miles of the Cedar River. The proposed
repairs are necessary to restore the integrity of the existing fiood protection system
following damage sustained during the atmospheric river event that occurred during the
week of December 6, 2025. High river fiows associated with this event caused erosion and
displacement of portions of the existing riprap slope protection along the riverward side of
the levee, resulting in localized damage that requires repair to maintain the levee's long-
term performance and public fiood protection function.
The proposed project is intended to restore the damaged portions of the existing levee to
substantially the same condition that existed prior to the storm damage. No expansion of
the levee system, increase in fiood protection capacity, or modiflcation to the overall
alignment of the existing fiood protection facility is proposed.
Project Description
The proposed project consists of repairing approximately 1,000 linear feet of the existing
Cedar River Left Bank Levee between approximately Stations 35+50 and 46+00. The repair
area is divided into two segments separated by the Boeing Bridge, where no construction
activities are proposed.
Repairs within Site 1 (approximately 600 linear feet) would include excavation and grading
of damaged slope areas, reconstruction of the riverward levee slope using Class III riprap,
placement of topsoil along the levee crest, and hydroseeding of disturbed areas. Existing
riprap that remains suitable for reuse would be incorporated into the repaired slope where
practical.
Repairs within Site 2 (approximately 400 linear feet) primarily consist of restoring localized
areas of displaced riprap, supplementing existing rock where necessary to reestablish a
stable, interlocking slope protection system, placing topsoil in disturbed areas, and
hydroseeding the repaired surfaces.
At both repair locations, the completed work would be transitioned into the existing levee
slopes upstream and downstream of the repair limits to restore a continuous and stable
levee embankment.
Construction Methods
Construction access would be provided from Airport Way and East Perimeter Road using
existing access routes. A temporary staging area would be established on the landward
side of the existing fioodwall adjacent to the Renton Municipal Airport. Construction
activities would be limited to the designated work and staging areas shown on the project
plans.
Repair activities would generally consist of:
• Clearing and removal of debris and unsuitable material from damaged areas;
• Excavation and grading to restore the levee slope;
• Reuse of existing riprap where feasible and placement of additional Class III riprap
as necessary;
• Placement of topsoil within disturbed upland areas;
• Hydroseeding disturbed surfaces with an approved seed mix; and
• Restoration of temporary construction access and staging areas to pre-construction
conditions.
Existing drainage outfalls and culverts located within the repair limits would be protected
throughout construction and maintained at their existing elevations.
Where in-water work is necessary, construction would occur during the approved in-water
work window.
Environmental Considerations
The proposed work is limited to repairing an existing public fiood protection facility within
its existing footprint. Disturbed areas would be restored upon completion of construction
through placement of topsoil and hydroseeding. Construction activities would employ
applicable best management practices to minimize temporary impacts to the Cedar River
and adjacent shoreline resources. No new fiood protection facilities are proposed, and the
completed project would restore the levee to substantially the same condition and
function that existed prior to the December 2025 storm damage.