Disconnected Impervious Surface
Innovative Stormwater Projects
Disconnected Impervious Surface, or DIS, is a simple, cost-effective technique that directs runoff to a flat vegetated area like a lawn or rain garden where it can soak into the ground. This process, known as infiltration, recharges groundwater and filters out pollutants. Keeping runoff on-site and out of the storm sewer also reduces the burden on stormwater infrastructure, lessens downstream flooding, and protects water quality.
DIS in the Mountains is a pilot research project funded by the North Carolina Land and Water Fund to find innovative solutions to implementing DIS in steep slope areas. RiverLink is partnering with Blue Earth Planning, Engineering & Design, and Wildlands Engineering to develop and install innovative DIS designs that are suited to steep slope conditions.
In fall 2021, Asheville Drainage constructed DIS practices at six residential sites in the Central Asheville Watershed. Designs included “earth works” such as berms & swales and basins. The project team will monitor the stormwater features for two years to measure their effectiveness. Results from the research project will help make DIS a cost effective solution to runoff in mountainous areas.
• Total of 8 rain basins and 4 swales constructed on six sites; soil mechanically “fluffed” (12- to 18-inch depth)
• Total roof area disconnected = 5,490 sf
• Compacted earthen berms; All downspouts piped underground via 4-inch PVC pipes
• Goal of 1.5-inch storm volume
• Volunteers planted 900 plants and 14 native plant species
• Total construction budget = $22,000
In addition to the technical challenges, stormwater management also involves a number of social challenges and opportunities. In order to address social obstacles of implementing DIS on a wide scale, students from the Sustainability Studies Program at Lenoir-Rhyne University- Asheville will conduct social research using focus groups and surveys to assess residents’ awareness, understanding and perceived benefits and barriers of DIS. The social research findings will be used to develop educational materials on the negative impacts of stormwater runoff and emphasize DIS as a simple, cost-effective solution.