St. Louis County, Missouri
Client:
Ross Road Development, LLC
Terra Technologies designed bank stabilization measures that will ensure the integrity of eroded stream banks adjacent to a planned residential development in unincorporated St. Louis County. Our firm’s geomorphic study of the portion of Little Creve Coeur Creek adjacent to the development parcel and its watershed determined that the entire reach was adjusting its physical structure to match the new hydrologic conditions caused by upstream development and the associated increase in impervious surfaces. As with most urban and suburban stream systems, the increase in impervious surfaces results in flashier storm flows and less groundwater input into the stream base. While this stream reach was not experiencing any significant downcutting, it showed signs of considerable lateral instability.
The bank stabilization design featured a five-stack gabion wall to maintain the current stream configuration in an outer bend adjacent to a planned detention basin. Additionally, an angular rock blanket and shaping of a stream bend near several future residences will maintain the stream morphology in that immediate area. Finally, a coir log toe upstream and downstream of the project’s stormwater outlet pipe will ensure that the additional storm flows will not destabilize the stream bank in the vicinity of the pipe. All disturbed areas were seeded and planted with a diverse mix of native grasses, forbs and shrubs.
Terra Technologies performed significant permitting activities for this project, including the acquisition of federal, state, regional and local permits. These included the Clean Water Act Section 404 and 401 permits from the U.S. Army Corps of Engineers and Missouri Department of Natural Resources, project approval by the Metropolitan St. Louis Sewer District and Storm Water Pollution Prevention Plan approval by St. Louis County.
Construction was completed in the fall of 2008. |
