Denver council approves $20.6 million Sanderson Gulch flood-control project
The project will replace two undersized culverts, expand Sanderson Gulch and improve trails in Ruby Hill, with construction expected to span two low-flow seasons and finish by December 2028.
Denver City Council approved a roughly $20.6 million project Sept. 14 to improve flood protection along Sanderson Gulch, replace two road culverts, expand the channel and upgrade trails in the Ruby Hill neighborhood.
The approval authorizes a $4 million Federal Highway Administration grant and a $16,607,158 city cash match. The filed resolution authorizes project expenditures from April 1, 2026, through Dec. 31, 2029. The authorization does not mean construction or spending has begun.
What the project will build
The project covers about 2,500 feet of Sanderson Gulch between West Florida and West Arkansas avenues. Denver’s project description says the existing culverts at both avenues are too small to carry a 100-year flood. The Arkansas Avenue crossing also serves as a pedestrian underpass that does not meet city standards.
Planned work includes:
- Replacing the Florida Avenue and Arkansas Avenue culverts with larger box culverts.
- Lowering and widening portions of the gulch channel to carry more stormwater.
- Replacing a failing grouted-riprap drop structure.
- Widening and relocating sections of the multiuse trail, including a crusher-fines trail.
- Building or upgrading trail underpasses at both road crossings.
- Improving sidewalks, curb ramps, drainage, storm sewers and utilities.
The 2026 federal grant agreement projects that the increased channel capacity will remove seven properties from the floodplain. It also reduces planned channel improvements upstream of Florida Avenue from 500 feet to 400 feet because of space constraints, and reduces anticipated channel lowering at the crossings from as much as 5 feet to about 4 feet because of a sanitary-sewer conflict.
Construction schedule and impacts
A city project sheet published in 2024 anticipated construction beginning in early 2027 and ending in fall 2028. The later federal agreement sets a revised substantial-completion and open-to-traffic target of December 2028. It attributes the change to a 14-month right-of-way delay and says construction is expected to take 24 months rather than 12 because floodplain work is limited to low-flow seasons, generally October through April or May.