CHERRY CREEK CORRIDOR IMPROVEMENTS PROJECT (QUEBEC TO IlIFF)
In 2014, Mile High Flood District (MHFD) and the City and County of Denver’s Department of Transportation and Infrastructure (CCD DOTI) set out to provide channel stabilization on a severely eroded reach of Cherry Creek downstream of the Cherry Creek Reservoir. By the time construction started five years later, a total of eight public agencies had invested in the project to help transform this reach of Cherry Creek from a public and environmental hazard into a 40-acre open space that not only improves channel stability and flood conveyance, but also provides huge benefits in recreation, ecological health, and water quality. Through the partnership formed among several public agencies, this project maximized the public benefit well beyond the original vision and scope.
Prior to the project, a two-mile stretch of Cherry Creek between South Holly Street and East Iliff Avenue had never received channel stabilization improvements. Increased runoff caused by urbanization in the surrounding watershed, coupled with an extremely erodible sandy channel, resulted in up to 20 feet of vertical downcutting and over 50 feet of lateral migration in several locations. The rate of erosion was exacerbated by the location of this reach being downstream of Cherry Creek Dam, bringing about lower sediment loads and annual dam gate flushes.
In response, a stabilization project was initiated for design of one grade control structure downstream of Quebec in 2013. During this design effort, it became clear that a localized improvement would result in a large structure that may not be consistent with the overall vision for the corridor.
The team took a step back to look at the entire reach between Holly and Iliff, resulting in a bigger picture visioning effort starting in 2014. A vision plan was developed that looked holistically at the corridor, including channel stabilization measures, environmental and water quality benefits, road and bridge improvements, open space enhancements, and opportunities to increase quality of life for the surrounding public. The vision plan provided a tool to collaborate and fundraise, expanding the slate of partners well beyond the original two.
In 2017, enough funds had been raised to initiate a first phase of final design and construction between Quebec and Iliff. A grant from CWCB helped to round out funding. This reach had experienced the worst of the erosion to date and was posing the biggest threat to properties and infrastructure.
Another major factor for selecting this reach was that Denver Water offered a land transfer to convert a portion of their private property, that spanned across the Cherry Creek corridor, into open space for Denver and Arapahoe County. This ultimately joined open spaces upstream and downstream of their property into one continuous open space that stretches over 5.3 miles. This land was converted into open space at no cost to the project.
The final design phase between Quebec and Iliff involved stream restoration and open space improvements along the one mile stretch of Cherry Creek. Project improvements were also coordinated with an adjacent Iliff road improvement project where our project was able to provide water quality treatment facilities for roadway drainage within Cherry Creek floodplain benches.
2 Concrete Box Culverts | 20 Grade Control Structures | 9 Storm Drain Outfalls | 1 Mile of Stream Restoration/Stream Design | 1.42 Miles of Trail