ITB No. 26-2992-8EAR - Tuckahoe Library Stream Res...

Henrico County Government -Department of Public Works

The Work consists of a restored reach length of 600 linear feet (LF). The channel will be restored utilizing priority level 2, which includes raising the stream bed slightly and creating a bankfull bench within the confined valley. The banks along the floodplain of the confined channel will be graded back allowing for slopes of 2 to 1 or less, creating greater stability. The restoration will utilize natural channel design (NCD) techniques, a B4c channel has been designed for the site with a steeper step pool sequence at the downstream extents of the stream. This approach allows for adequate cover over the sanitary sewer system, while tying into the elevation of the existing downstream culvert. Riffle, step, and pool cross sections were developed using a combination of Virginia regional curve data, reference reaches, and onsite bankfull data collection. In addition to the stream restoration, sanitary sewer rehabilitation and pipe replacement shall occur. The sewer system is currently exposed within the degraded stream channel, and shall be repaired and buried to restore and protect the system for future use. All denuded areas shall be re-seeded, fertilized, matted, and planted with native woody stems and herbaceous cover. Large growth trees shall be protected to the greatest extent practicable, allowing for increased seed dispersal and shade canopy for the newly planted seedlings. The Tuckahoe Library Stream Restoration is located on three Henrico County owned Parcels (753-747-1611, 753-746-6345, and 753-746-7124) and two privately owned Parcels (753-746-7862 and 752-746-2526). The site is located at Parham Road, and Spans to Cloisters Apartments, Southeast of Tuckahoe Library. The stream generally flows East to West. The site is bound primarily by offices, roads, and an apartment complex. The total drainage area to the site is approximately 65 acres, comprised of 44% impervious and 56% pervious surfaces. The entire stream channel is within a confined valley and is bound by existing culverts at the upstream and downstream extents of the channel. Various stream assessments were conducted at the site as laid out by Rosgen classification of natural rivers methodology, the channel is classified as a moderately incised type B4. Consistent land use changes in the boundary conditions have attributed to the lateral and vertical channel instability. Due to the unstable banks and pattern, significant sediment and erosional losses have been experienced.

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