Using plants to filter out pollution
As part of the permitting process, the Tennessee Department of Environment and Conservation mandates the City of Kingsport offer educational and outreach activities regarding stormwater, the city’s various control measures and why those measures are important to the general public.
The following article discusses bioretention basins and how they use plants to filter out pollution.
A bioretention basin is a type of Stormwater Control Measure (SCM) that addresses both stormwater quantity and quality.
These basins are designed to hold water for 48 hours after a rain event, which helps prevent flooding. They also allow for stormwater infiltration and uptake by plants, thereby filtering out pollution.
Most bioretention basins have the same basic components to help them function properly, including:
- Inlets: pipes, channels or curb cuts that convey drainage into the basin from the surrounding area during a rain.
- Outlet Structure: Allows water to exit the basin in case the basin fills up.
- Pretreatment Areas: Typically consist of stones or grass to slow water entering the basin and thus catch trash, debris and sediment.
- The Main Basin: Consists of an engineered soil media to allow for infiltration, plants for stormwater uptake and an underdrain to convey excess water into the stormwater system.
- Cleanouts: Allow for maintenance of the underdrain.
Bioretention basins may be inspected by the local municipality to ensure they are functioning correctly. However, all maintenance is the responsibility of the property owner.
In order for the bioretention basin to work efficiently, vegetation needs to be kept healthy and watered in times of drought. All trash, debris and sediment should be removed from the basin at regular intervals. Any erosion should be repaired and mulched areas should be refreshed.
Excess sediment can clog the soil media and prevent the bioretention basin from functioning properly. The underdrain should be inspected for clogging and the basin should be observed during and after rain events to ensure it is functioning correctly.
If you have a concern about a specific bioretention basin in Kingsport, you may call Water Services at 423-229-9454 or email wsengineers@kingsporttn.gov. You can also report any possible issues with bioretention basins by using the ConnectKingsport app.
