Stream Restoration at Alabama River Mitigation Bank

28
Mar
2014

The Alabama River Mitigation Bank’s (ARMB) in-channel stream restoration project is complete!  This project was instrumental in the restoration efforts being undertaken at ARMB.

an image of the Stream Restoration at Alabama River Mitigation Bank

The in-channel stream work involved Priority One (P1) and Priority Two (P2) Restoration, per U.S. Army Corps of Engineers requirements. The restored, low gradient channel replaces 2,895 linear feet (LF) of an entrenched “G5” stream type with 3,764 LF of an “E5” stream channel. The stream classification is based upon the Rosgen methodology. The newly constructed “E” channel consists of a riffle/pool system, which is beneficial for fish and other aquatic species.
Of the 3,764 LF of restored channel, 3,124 LF of the design involved P1 restoration. The P1 design consisted of re-establishing the channel on its original floodplain by constructing a new channel (i.e., new location). The remaining 640 LF involved P2 restoration. The P2 design consisted of establishing a new floodplain for the channel, at the proper bankfull elevation, in the existing location (i.e., bankfull benches). The restored channel is designed and constructed with proper pattern, profile, and dimension characteristics for a stable stream.
The newly constructed channel was stabilized using a variety of in-stream structures including toewood, rootwads, and digger logs. In addition, log cross vanes and J hooks were incorporated into the design to assist with surface flow through the new channel. Following construction of the new channel, which included the installation of the in-stream structures mentioned above, various stream bank stabilization techniques were used.
Temporary seeding of browntop millet (Panicum ramosum) was hand broadcasted onto the new banks to assist with early stabilization. Permanent grass seed such as; switchgrass (Panicum virgatum), little blue stem (Schizachyrium scoparium) and Indiangrass (Sorghastrum nutans), were also spread to aid in bank stabilization. Geotextile matting (bio-degradable) was then installed; followed by live staking, which included black willow (Salix nigra), buttonbush (Cephalanthus occidentalis) and silky dogwood (Cornus amomum). The live stakes will help anchor the matting in place (Photos 2).
The in-stream project concluded with the removal of a culvert, and installing a 5:1 low water crossing on the trail road which crosses the restored channel.

an image of the Stream Restoration at Alabama River Mitigation Bank

The photo below captures the first post construction “bankfull” event within the restored channel. Documentation of this event allows Westervelt the capability of pursuing the first credit release for the in-channel stream restoration polygons, following construction.

an image of the Stream Restoration at Alabama River Mitigation Bank

This restoration project is within the Alabama River Basin which is part of the Alluvial/Deltaic Plain physiographic region. The region’s ecology and geomorphology have historically been influenced by the Alabama River (approximately 2.2 miles southwest of the project). Tallatchee Creek, which is on the southern boundary of ARMB, is important to native species including six species of freshwater mussels. The ovate clubshell (Pleurobema perovatum), a federally listed mussel (i.e., Endangered), was identified within the Bank boundary, during the aquatic survey of Tallatchee Creek. This was the first recording in Monroe County, AL for Pleurobema perovatum. In addition, Westervelt Ecological, in cooperation with the U.S. Fish and Wildlife Service and the Alabama Department of Conservation and Natural Resources, released the Orangenacre mucket, a listed mussel (i.e., Threatened, 300 individuals), in Tallatchee Creek, within the Bank.