An edge of field structure containing a carbon source, such as wood chips, installed to reduce the concentration of nitrate-nitrogen in subsurface agricultural drainage flow via enhanced denitrification.
How it helps
Bioreactors help improve water quality by reducing the nitrate-nitrogen content of subsurface agricultural drainage flow.
Planning ahead
Do water samples show there is a need to reduce nitrate-nitrogen concentration in subsurface drainage flow?
Do you have a good location at the edge of a field near an outlet pipe for a bioreactor?
Tech Notes
A bioreactor should be designed to:
treat peak flow from a 10-year, 24-hour drain flow event.
treat at least 15% of the peak flow from the drainage system.
treat at least 10% of the peak flow from the drainage system if systematic monitoring will be taking place through NRCS.
use locally proven criteria that will result in the treatment of at least 60% of the long-term average annual flow from the drainage system.
achieve at least a 30% annual reduction in the nitrate-nitrogen concentration of water flowing through the bioreactor.
Media Chamber:
Use a medium for a carbon source that is reasonably free from dirt, fines, and other contaminants. Distribute the media within the bioreactor for a uniform flow path.
Use geotextile or plastic lining for the bottom, sides, and top of the bioreactor to prevent migration of soil particles into the bioreactor.
Design the bioreactor for an expected life of at least 10 years.
Water Control Structures:
Design water control structures to provide the required capacity and hydraulic retention time.
Evenly distribute and collect water in the upstream and downstream ends of the media chamber.
Allows for completely draining the media chamber to facilitate management and maintenance.
Maintenance
NRCS will provide an operation and management plan to the landowner.
What it is