Beyond Riprap: Designs on Green Erosion Control

In the mid 2000s, a major road resurfacing, curbing, and stormwater improvement project in Loganville, Pennsylvania, caused problems downstream. A higher concentration of stormwater flow, traveling at higher velocities, resulted in severe erosion appearing at the outlets from two recently installed pipe networks. In addition to erosion issues, the formation of these channels also presented safety concerns and access problems for affected property owners. This article describes an erosion control and stormwater management project to reduce these problems. In order to meet the needs of the local government and nearby residents, a customized erosion control solution was developed. Realignment was performed for the most severely eroded areas to allow the bulk of construction to occur over virgin soil. For steep areas, a combination of grass-lined swales and dry-stacked rock vanes were installed to provide a channel with stepped elevations at the vanes. The vanes were designed with elevation drops that dissipated the force of the flowing water, as well as provided for flatter channel sections upstream and downstream of the vanes that could be stabilized with grass vegetation. A 10-foot portion of the swales directly downstream of the rock vanes was anchored with R-5 riprap to attenuate the impact of the water cascading over the vane. Storm pipe was installed in select areas to allow access to all areas for agricultural and maintenance vehicles, along with 550 feet of grass-lined channel. Temporary erosion control blanket and riprap aprons at pipe outlets also were used in the project. The result was not just a fully functioning erosion control and soil stabilization facility, but an eco-friendly, sustainable drainage system that was also safe, aesthetically pleasing and easily maintainable.