As a tributary to the James River, Blackwater Creek winds its way through the heart of Lynchburg Virginia. Like many other urban waterways, Blackwater Creek is continually prone to flashing flows from heavy rain and urban runoff. In addition to the erosive flow, heavy rains bring in an influx of woody debris which further pressures the banks and has changed the location of the stream over time.
Like most urban waterways, Blackwater Creek is lined with buildings and infrastructure, making access and constructability costly and challenging. The City began to seek out a cost effective and permanent solution that would limit stabilize a stretch of bank and protect the existing sewer line from the damages of erosion.
The City of Lynchburg collaborated with Brandon Alderman and Emily Burgess of AECOM collaborated and Envirolok to develop a fully vegetative solution that would provide permanent bank stabilization and infrastructure protection. Access and site challenges would require minimum excavation and limit the use of large machinery. These sites are ideal conditions for a solution utilizing the Envirolok system. Due to the shallow bedrock in the stream, the engineering team recommended a geogrid reinforced wrap around the initial courses of the geobag system. Existing rip rap was reused at the toe of the Envirolok slope. In addition to providing protection from scouring, reuse of rip rap helped limit the construction footprint.
With overall bank heights of 15 feet or more, additional geogrid layering and earth anchors were used in conjunction with the Envirolok system to further strengthen and fortify the bank. The geobag wall was then constructed with a slope setback that replicates the natural bank slopes that surround the project site. Multiple flood events during construction slowed the process but showed the durability of the design and materials. Upon completing the installation in June, the Envirolok geobags where vegetated using a mixture of native grasses through hydroseed and live stakes placed between the bags. At the end of the first growing season, the slope is full vegetated and continues to grow strong.
"The vegetation is coming in great and the live stakes are thriving. I am so proud of our team and so glad to be able to complete a project that doesn't use riprap or other impervious hard armoring! Thanks again to City of Lynchburg and Eric Seidl at Envirolok for the support along the way! #greeninfrastructure#streamrestoration#greensolutions" - Branden Alderman
Envirolok, LLC | 608.226.2573 | www.envirolok.com
