Description and Benefits
Storm runoff that runs down open or farmed hillsides can be directed into an underground outlet (or pipe) and transferred down the slope without taking sediment and crops along with it. An underground outlet generally needs to be coupled with a sediment basin at its outlet to effectively handle the high flow volumes that underground outlets are designed to accommodate. An inadequate downstream conveyance can result in extreme erosion, sedimentation and/or flooding. When the concentrated water conveyed by the underground outlet is caught in a sediment basin, the outflow of water can be metered out gradually. This system is a permanent and highly effective solution.
When to use Underground Outlets
Underground outlets are cost-effective in settings with a permanent field configuration and should only be planned and implemented with guidance from a qualified professional. In general, such pipelines and their inlets are placed underneath permanent roads running through ‘low’ collection areas on slopes steep enough to generate high, concentrated runoff volumes. An underground outlet should be designed with a safe downstream outlet.