The town of Wardensville, W.V., sits in the Appalachian Valley near the Virginia border. The town’s 120,000-gal-per-day wastewater treatment plant (WWTP) was damaged after Hurricane Juan delivered the worst flooding in state history. Four additional storms compounded the damage and threatened the safety of WWTP operations. Temporary repairs were attempted, but no permanent fix was found. Meanwhile, both the Federal Emergency Management Agency and state of West Virginia issued directives requiring a permanent solution.
Attempts at repairs consisted of increasing the height of the embankments. This project stalled, in part because more than 20,000 cu yds of special fill would be needed. Situated in an archeologically sensitive zone, Wardensville was limited to locally available replacement fill. This problem brought the use of gabions into consideration. Maccaferri Reno mattresses had been previously used and were specified for the project.
The durable steel-mesh structures lock rocks into place to create flexible but secure erosion-controlling planes that allow for vegetation establishment and utilized locally available stone. Water flows through the structures, so no additional structural elements were needed. They are easy to unroll, fill and lock into place. Installation requires a minimum number of connections and eliminates the need for special labor. The base sections are divided into compartments that restrict the movement of the stone.
For installation, 6 in. of topsoil was carved back from the dikes and the mattresses were situated. Using a combination of manual and machine methods, the stones were placed. The removed topsoil was reused and tall fescue seed was applied. The structure held and vegetation was established. The vegetation strategy along the protected slopes has grown in, securing the top soil and enhancing the structure of the dikes.