Knob Hill Stream Restoration
Client: Village of Clemmons, NC
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Services provided in this project:
JEWELL Engineering completed a culvert outlet improvement and stream restoration project to reduce incidence of flooding. Houses around two street crossings immediately upstream of the project site experienced significant flooding problems and it was determined that the Knob Hill Drive culvert outlet constriction and lack of adequate downstream channel capacity were major factors contributing to the flooding. Prior to construction, the 66-inch RCP under Knob Hill Drive discharged to a vacant lot where the outlet and downstream channel constricted normal flow. After studying the hydraulics of the system, JEWELL determined that significant hydraulic performance improvement could be obtained by removing the outlet flow constriction and restoring a downstream channel with increased capacity. JEWELL also recommended implementation of a natural stream restoration in conjunction with channel improvements to improve aquatic habitat and yield a stable channel corridor capable of safely conveying stormwater flows.
JEWELL developed an outlet stabilization and stream restoration plan for the site. The plan included shortening the Knob Hill Drive culvert; installing a stilling basin to receive discharge from the culvert; removing downstream flow constrictions; and constructing a natural, meandering stream channel to tie into the existing channel at the downstream property line. The project was reviewed and approved by NC DENR DWQ and USACE, and 401 and 404 permits were obtained. An erosion and sediment control plan was prepared and approved by NC DENR DLR. The project was constructed by the Village of Clemmons maintenance personnel.