Due to upstream development resulting in more intensive storms, erosion on an un-named regulated drain in Richmond, Indiana had started to expedite, threatening an already failing vinyl sea wall, exposing a 36” sanitary line and a roadway collapse. The creek ran through Hidden Valley Subdivision and was a featured part of the subdivision with many residences backing up to the creek’s edge as a prominent feature. Design consultant, Butler, Fairmen & Seifert (BF&S), had a lot to consider while working within the complex tight easement. Part of their challenge was to find vegetative systems that would be not only more aesthetically appealing, but also minimize city’s safety concerns of riprap in this residential area.
To meet these challenges, three different types of vegetative sections were developed based on the location of the creek with the roadway, residences, sanitary sewer line and existing sea wall. Where there was enough horizontal space to install a vegetative slope, the standard design of a sacked gabion at the toe of slope and coir log to transition to vegetation reinforced with a permanent turf reinforcement mat was utilized. The velocity of the drain was 10 ft/s; therefore, in the bend areas, a soil confinement mechanism, GeoWeb, was installed to maintain the soil bed to prevent erosion at the toe of slope or further movement of sediment. Other areas of the project were much more complicated than these gentle slopes.
In the areas with limited space for grade changes, vegetative wall systems were investigated. The standard wall heights required were either 4’ or 10’ tall. After comparing several options, BF&S decided to pursue with a GeoWeb wall due to its superior drainage capabilities, natural appeal and limited future maintenance. Each wall was protected at the toe with a sacked gabion, 12” diameter 9 lb/ft3 density coir log and a permanent turf reinforcement mat.
The City of Richmond was extremely pleased with the ease of construction of these systems as well as finished appeal. Since construction, the systems have withstood several flood events without any complications.