Sanderson Gulch Ecological Design & Restoration

Quick Facts:

• Drainage Area: 9.7 square miles
• 100-year Flows: 3,200+ CFS
• Key Services: Open channel and wetland design; ecological assessment; planting plan; plant palette development; construction administration

Project Summary:

Great Ecology is leading the ecological design for restoration of a reach of Sanderson Gulch from the confluence with the South Platte River upstream past Lipan Street and Sanderson Gulch Park in southwest Denver. Sanderson Gulch has a 9.7 square mile drainage area with 100-year flows exceeding 3,200 cubic feet per second (CFS). The drainageway is being redesigned to remove nearly 100 homes and business from the FEMA regulated floodplain, improve ecological function of the channel, and contribute to water quality improvements for the watershed. Additionally, local public infrastructure will be better protected and public safety during storm events will be reduced. The site is constrained by multiple road crossings, a railroad bridge, and contaminated soils. Part of the design is to split the stormflows between the open channel and a series of large-capacity box culverts below the open channel. For base flow and storm events smaller than 10-year events (954 CFS), all water in the creek remains in the open channel. Any flows greater than the 10-year event are diverted into the box culverts below the surface channel to more effectively convey the large volumes of water and deliver it to the South Platte River. Great Ecology designed the open channel and wetland system to include overbank, vegetated bioswales to assist with water quality improvements in conjunction with a water quality vault. Great Ecology implemented a pilot study of the use of wood chips as a weed control mechanism by altering soil chemistry to favor native species. The pilot study includes a series of test plots to statistically demonstrate the effect and offer a new weed control tool to Denver Parks and Recreation that uses a forestry by-product to help establish native seeded areas. Great Ecology lead the ecological stream and wetland design, planting plan and plant palette development, as well as maintenance strategies and construction administration support.

Awards:

• 2020 CASFM Engineering Excellence Award