Copperfield Bioengineered Streambank Stabilization Project
O’Fallon, Missouri
September 24, 2010
Terra Technologies and Cole & Associates have designed one of the first large stream channel biotechnical engineering projects for the City of O’Fallon, Missouri. Terra Technologies designed stream bank stabilization measures along portions of an unnamed tributary to Belleau Creek to prevent further bank erosion and potential property damage.
Erosion has been occurring in a common ground property near residences built close to a suburban stream. Upstream development has increased the volume of storm flows in the streams and the stream geometry is changing to match the new hydrologic conditions.
Terra Technologies took a biotechnical engineering approach to bank stabilization and considered the geomorphic stream characteristics, hydraulics and hydrology, watershed conditions, geotechnical soils analysis and our previous experience on similar stream systems. The design consisted of a combination of toe armoring, grade control, bank stabilization and ecological restoration. Gabion baskets and coir logs will be used in some areas to stabilize the stream toe and banks in their present location, gabion basket rock weirs will provide grade control, and high tensile turf reinforcement matrixes, erosion control blankets and the roots of native vegetation will stabilize the stream bank slopes. A concrete energy dissipating structure that was designed by Cole and Associates will be installed at the upstream limit of the project area where storm water exits a pipe into the existing stream channel. This will slow the water’s velocity and decrease downstream scour.
In addition to designing the project, Terra Technologies guided the City of O’Fallon through the Clean Water Act Section 404 and 401 permitting process necessary to authorize the water quality impacts caused by the bank stabilization activities.
Construction of the project began in August 2010.
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