Coastal, River, & Wetland Restoration
- Shelby Bottoms Park Riverbank Protection Project
Nashville, Tennessee
the challenge The Shelby Bottoms Greenway and Nature Park is one of the true jewels of Nashville’s Park and Greenway system. This 810-acre park offers 5 miles of paved multi-use trails and another 5 miles of primitive hiking trails. The area is well known as a haven for migrating birds and other wildlife. Along the trails, visitors can enjoy boardwalks, scenic overlooks, interpretive stations and seven rustic bridges. In many locations, however, park trails and existing or planned structures, such as observation decks, were jeopardized by severe erosion of the banks of the Cumberland River. Dozens of trees had fallen into the river, experienced severe root scour, or were undermined and threatened by bank erosion. The Nashville District, U.S. Army Corps of Engineers tasked the Bioengineering Group to design measures to rehabilitate the riverbank and restore the park as a natural area for recreation and environmental protection. Furthermore, the riverbank was highly visible due to the numerous tour boats along the river and any protective measures need to maintain the natural look and feel of the viewshed.
the interdisciplinary approachThe project area involved the design of measures for the restoration and protection of a 3,000-foot reach of the Cumberland River. A site assessment was conducted followed by a hydraulic assessment that including modeling the effects of heavy barge traffic on the shoreline in order to establish the basic design criteria. Three different bioengineering treatments were then designed, employing techniques such as live poles through a rock toe and gabion mattress, live stakes, brush layers, and brush fascines. The designs made extensive use of willow and buttonbush, which are prevalent and easily harvestable in the area, thereby minimizing materials cost. Existing coarse woody debris was also incorporated into the design to reduce impacts related to removal. Construction plans, specifications, and cost estimates were prepared and engineering services were provided during construction to ensure the proper management of plant materials and installation of treatment measures.
the results Bioengineering Group staff developed a bioengineering design that was compatible with the existing hydrologic conditions, effectively stabilizes the eroding shoreline, utilized native plant materials, was extremely durable, and ultimately resulted in a cost effective and low maintenance solution. The vegetation scheme used only native species and addressed stabilization value while emphasizing aesthetics and preserving view corridors. This project produced a stable aesthetically pleasing shoreline that enhances the park experience while providing valuable habitat for the varied wildlife population that inhabits or uses the park.