Floodplain Protection with Colorado Springs’ First Enhanced Stream Stabilisation Project

Flowing through one of Colorado Springs’ premier golf courses, Pine Creek had degraded due to upstream development and major flooding. The City turned to HDR to restore the historic natural channel and stream system, preserve vegetation and provide bank stabilisation to protect surrounding development from catastrophic floods. 

For the first time in Colorado Springs, our team used natural elements including logs, root balls and cobble riffle structures to provide bank stabilisation, called “enhanced-stream stabilisation.” The effort is a test case for future drainageway design, including the next downstream channel segment. Further, this effort reduced the overall project cost by minimising the quantity of material hauled away and repurposing the material on-site.

The design goes beyond simply stabilising the channel against erosion. Standard stabilisation can be accomplished by lining the channel in concrete or other hardened structures. However, not only is this often expensive, but it also eliminates the ecological, aesthetic and recreational value of the drainageway — all of which are key design elements in this area. Our plan integrated riparian vegetation, grade-control features and flood storage provisions to emulate the function of natural features. We also performed hydraulic modelling for Pine Creek to determine design parameters for stream features and for Federal Emergency Management Agency floodplain permitting. 

Constructed at the same time as a city-funded pond upstream for water detention and discharge control, the revitalised creek creates additional aquatic habitat, improves water quality and reduces the sediment load by 99%, reducing the need to dredge downstream waterways. 

Overcoming project delays, public involvement concerns and construction during Colorado’s intense monsoon season, we used vertical and lateral grade protections as fail-safe measures against flooding while natural, repurposed elements enhanced the environment. Completed on-time and on-budget, the project removed the threat of structural damage with an environmentally friendly design. The natural stream corridor builds resilience for future events by restoring floodplain connectivity and predevelopment hydrology.